Rina-Iwata Sakoda, Tomonori Iwasaki, Toshiya Tsujii, Soujiro Hisagai, Yoichiro Oku, Yusuke Ban, hideo Sato, Hitomi IshiI, Ryuuzo Kanomi and Youchi Yamasaki : Does rapid maxillary expansion improve nasal airway obstruction? A computer fluid dynamics study in patients with nasal mucosa hypertrophy and obstructive adenoids, American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.164, No.1, e1-e13, 2023.
(Summary)
Rapid maxillary expansion (RME) expands the maxillary dentition laterally and improves nasal airway obstruction. However, the incidence of nasal airway obstruction improvement after RME is approximately 60%. This study aimed to clarify the beneficial effects of RME on nasal airway obstruction in specific pathologic nasal airway diseases (nasal mucosa hypertrophy and obstructive adenoids) using computer fluid dynamics. Sixty subjects (21 boys; mean age 9.1 years) were divided into 3 groups according to their nasal airway condition (control, nasal mucosa hypertrophy, and obstructive adenoids), and those requiring RME had cone-beam computed tomography images taken before and after RME. These data were used to evaluate the nasal airway ventilation condition (pressure) using computer fluid dynamics and measure the cross-sectional area of the nasal airway. The cross-sectional area of the nasal airway significantly increased after RME in all 3 groups. The pressures in the control and nasal mucosa groups significantly reduced after RME but did not change significantly in the adenoid group. The incidence of improvement in nasal airway obstruction in the control, nasal mucosa, and adenoid groups was 90.0%, 31.6%, and 23.1%, respectively. The incidence of improvement in nasal airway obstruction after RME depends on the nasal airway condition (nasal mucosa hypertrophy and obstructive adenoids). In patients with nonpathologic nasal airway conditions, the obstruction may be sufficiently improved with RME. Furthermore, to some extent, RME may be effective in treating nasal mucosa hypertrophy. However, because of obstructive adenoids, RME was ineffective in patients with nasal airway obstruction.
Linze XIA, Fumiya Kano, Noboru Hashimoto, Cheng DING, Yang XU, Hideharu HIBI, Tomonori Iwasaki, Eiji Tanaka and Akihito Yamamoto : Conditioned Medium from Stem Cells of Human Exfoliated Deciduous Teeth Partially Alters the Expression of Inflammation-associated Molecules of Mouse Condylar Chondrocytes via Secreted Frizzled-related Protein 1, Journal of Oral Health and Biosciences, Vol.35, No.2, 52-60, 2023.
Fumiya Kano, Noboru Hashimoto, Yao Liu, Linze Xia, Takaaki Nishihara, Wakana Oki, Keita Kawarabayashi, Noriko Mizusawa, Keiko Aota, Takayoshi Sakai, Masayuki Azuma, Hideharu Hibi, Tomonori Iwasaki, Tsutomu Iwamoto, Nobuyasu Horimai and Akihito Yamamoto : Therapeutic benefits of factors derived from stem cells from human exfoliated deciduous teeth for radiation-induced mouse xerostomia, Scientific Reports, Vol.13, No.1, 2706-2719, 2023.
(Summary)
Radiation therapy for head and neck cancers is frequently associated with adverse effects on the surrounding normal tissue. Irreversible damage to radiation-sensitive acinar cells in the salivary gland (SG) causes severe radiation-induced xerostomia (RIX). Currently, there are no effective drugs for treating RIX. We investigated the efficacy of treatment with conditioned medium derived from stem cells from human exfoliated deciduous teeth (SHED-CM) in a mouse RIX model. Intravenous administration of SHED-CM, but not fibroblast-CM (Fibro-CM), prevented radiation-induced cutaneous ulcer formation (p < 0.0001) and maintained SG function (p < 0.0001). SHED-CM treatment enhanced the expression of multiple antioxidant genes in mouse RIX and human acinar cells and strongly suppressed radiation-induced oxidative stress. The therapeutic effects of SHED-CM were abolished by the superoxide dismutase inhibitor diethyldithiocarbamate (p < 0.0001). Notably, quantitative liquid chromatography-tandem mass spectrometry shotgun proteomics of SHED-CM and Fibro-CM identified eight proteins activating the endogenous antioxidant system, which were more abundant in SHED-CM than in Fibro-CM (p < 0.0001). Neutralizing antibodies against those activators reduced antioxidant activity of SHED-CM (anti-PDGF-D; p = 0.0001, anti-HGF; p = 0.003). Our results suggest that SHED-CM may provide substantial therapeutic benefits for RIX primarily through the activation of multiple antioxidant enzyme genes in the target tissue.
Anrizandy Narwidina, Aya Miyazaki, Kokoro Iwata, Rika Kurogoushi, Asuna Sugimoto, Yasusei Kudo, Keita Kawarabayashi, Yoshihito Yamakawa, Yuki Akazawa, Takamasa Kitamura, Hiroshi Nakagawa, Kimiko Ueda Yamaguchi, Tomokazu Hasegawa, Keigo Yoshizaki, Satoshi Fukumoto, Akihito Yamamoto, Naozumi Ishimaru, Tomonori Iwasaki and Tsutomu Iwamoto : Iroquois homeobox 3 regulates odontoblast proliferation and differentiation mediated by Wnt5a expression., Biochemical and Biophysical Research Communications, Vol.650, 47-54, 2023.
(Summary)
Iroquois homeobox (Irx) genes are TALE-class homeobox genes that are evolutionarily conserved across species and have multiple critical cellular functions in fundamental tissue development processes. Previous studies have shown that Irxs genes are expressed during tooth development. However, the precise roles of genes in teeth remain unclear. Here, we demonstrated for the first time that Irx3 is an essential molecule for the proliferation and differentiation of odontoblasts. Using cDNA synthesized from postnatal day 1 (P1) tooth germs, we examined the expression of all Irx genes (Irx1-Irx6) by RT-PCR and found that all genes except Irx4 were expressed in the tooth tissue. Irx1-Irx3 a were expressed in the dental epithelial cell line M3H1 cells, while Irx3 and Irx5 were expressed in the dental mesenchymal cell line mDP cells. Only Irx3 was expressed in both undifferentiated cell lines. Immunostaining also revealed the presence of IRX3 in the dental epithelial cells and mesenchymal condensation. Inhibition of endogenous Irx3 by siRNA blocks the proliferation and differentiation of mDP cells. Wnt3a, Wnt5a, and Bmp4 are factors involved in odontoblast differentiation and were highly expressed in mDP cells by quantitative PCR analysis. Interestingly, the expression of Wnt5a (but not Wnt3a or Bmp4) was suppressed by Irx3 siRNA. These results suggest that Irx3 plays an essential role in part through the regulation of Wnt5a expression during odontoblast proliferation and differentiation.
Tomonori Iwasaki, 猪子 芳美, 鈴木 浩司, 佐藤 光生 and Yoshitaka Suzuki : A glossary for dental sleep medicine, 睡眠口腔医学, Vol.9, No.2, 36-41, 2023.
8.
Kasey Li, Tomonori Iwasaki, Stacey Quo, Connor Li, Kara Young, Eileen Leary, Christian Guilleminault and Philippe Amat : Persistent pediatric obstructive sleep apnea treated with skeletally anchored transpalatal distraction, L' Orthodontie Française, Vol.93, No.2, 139-153, 2022.
(Summary)
Nasomaxillary expansion by skeletally anchored TPD improves OSA in children without transverse maxillary deficiency that were previously treated by RPE. A nearly parallel anterior-posterior opening of the mid-palatal suture achieves enlargement of the entire nasal passage with improvement of the airflow characteristics in the nasal and pharyngeal airway. The improved airflow characteristic is significantly correlated with the improved polysomnographic findings, thus demonstrating that nasomaxillary expansion in previously expanded patients is a viable treatment option.
Rika Kurogoushi, Tomokazu Hasegawa, Yuki Akazawa, Kokoro Iwata, Asuna Sugimoto, Kimiko Ueda Yamaguchi, Aya Miyazaki, Anrizandy Narwidina, Keita Kawarabayashi, Takamasa Kitamura, Hiroshi Nakagawa, Tomonori Iwasaki and Tsutomu Iwamoto : Fibroblast growth factor 2 suppresses the expression of C-C motif chemokine 11 through the c-Jun N-terminal kinase pathway in human dental pulp-derived mesenchymal stem cells, Experimental and Therapeutic Medicine, Vol.22, No.6, 1356, 2021.
(Summary)
The regulation of the mesenchymal stem cell (MSC) programming mechanism promises great success in regenerative medicine. Tissue regeneration has been associated not only with the differentiation of MSCs, but also with the microenvironment of the stem cell niche that involves various cytokines and immune cells in the tissue regeneration site. In the present study, fibroblast growth factor 2 (FGF2), the principal growth factor for tooth development, dental pulp homeostasis and dentin repair, was reported to affect the expression of cytokines in human dental pulp-derived MSCs. FGF2 significantly inhibited the expression of chemokine C-C motif ligand 11 (CCL11) in a time- and dose-dependent manner in the SDP11 human dental pulp-derived MSC line. This inhibition was diminished following treatment with the AZD4547 FGF receptor (FGFR) inhibitor, indicating that FGF2 negatively regulated the expression of CCL11 in SDP11 cells. Furthermore, FGF2 activated the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinases (JNK) in SDP11 cells. The mechanism of the FGFR-downstream signaling pathway was then studied using the SB203580, U0126 and SP600125 inhibitors for p38 MAPK, ERK1/2, and JNK, respectively. Interestingly, only treatment with SP600125 blocked the FGF2-mediated suppression of CCL11. The present results suggested that FGF2 regulated the expression of cytokines and suppressed the expression of CCL11 via the JNK signaling pathway in human dental pulp-derived MSCs. The present findings could provide important insights into the association of FGF2 and CCL11 in dental tissue regeneration therapy.
Tomonori Iwasaki, Spyridon N. Papageorgiou, Youichi Yamasaki, M. Ali Darendeliler and Alexandra K. Papadopoulou : Papadopoulou, Nasal ventilation and rapid maxillary expansion(RME): a randomized trial, European Journal of Orthodontics, Vol.43, No.3, 283-292, 2021.
(Summary)
To assess three rapid maxillary expansion (RME) appliances in nasal ventilation. Three-arm parallel randomized clinical trial. Sixty-six growing subjects (10-16 years old) needing RME as part of their orthodontic treatment were randomly allocated (1:1:1 ratio) to three groups of 22 patients receiving Hyrax (H), Hybrid-Hyrax (HH), or Keles keyless expander (K). The primary outcome of nasal ventilation (pressure and velocity) and secondary outcomes (skeletal, dental, soft tissue, and nasal obstruction changes) were blindly assessed on the initial (T0) and final (T1, 6 months at appliance removal) cone-beam computed tomography (CBCT) data by applying computational fluid dynamics (CFD) method. Differences across groups were assessed with crude and adjusted for baseline values and confounders (gender, age, skeletal maturation, expansion amount, mucosal/adenoid hypertrophy, nasal septum deviation) regression models with alpha = 5%. Fifty-four patients were analysed (19H, 21HH, 14K). RME reduced both nasal pressure (H: -45.8%, HH: -75.5%, K: -63.2%) and velocity (H: -30%, HH: -58.5%, K: -35%) accompanied with nasal obstruction resolution (H: 26%, HH: 62%, K: 50%). Regressions accounting for baseline severity indicated HH expander performing better in terms of post-expansion maximum velocity (P = 0.03) and nasal obstruction resolution (P = 0.04), which was robust to confounders. Mucosal/adenoid hypertrophy and nasal septum deviation changes were variable, minimal, and similar across groups. The HH resulted in significantly greater increase in the nasal cross-sectional area (62.3%), anterior (14.6%), and posterior (10.5%) nasal widths. Nasal obstruction resolution was more probable among younger (P = 0.04), skeletally immature (P = 0.03), and male patients (P = 0.02) without pre-treatment mucosal hypertrophy (P = 0.04), while HH was associated with marginal greater probability for obstruction resolution. RME resulted in improvement of nasal skeletal parameters and simulated ventilation with the former being in favour of the HH and the latter not showing significant differences among the three appliances. Attrition in the K group due to blocked activation rods possibly leading to limited sample to identify any existing group differences. Replacement of blocked Keles expanders for finalizing treatment. The protocol was not published before the trial commencement. Australian and New Zealand Clinical Trial Registry; ACTRN12617001136392.
(Keyword)
Adolescent / Australia / Child / Cone-Beam Computed Tomography / Humans / Male / Maxilla / Nose / Palatal Expansion Technique / Respiration
Emina Msuda, Akiko Ishizaki, Kojiro Hirano, Tomonori Iwasaki and Takehiko Sambe : Computational fluid dynamics analysis in patients with nasal disease, The Showa University Journal of Medical Sciences, Vol.33, No.3, 88-95, 2021.
Tatsunori Takahashi, Noriaki Sakai, Tomonori Iwasaki, Timothy C. Doyle, William C. Mobley and Seiji Nishino : Detailed evaluation of the upper airway in the Dp(16)1Yey mouse model of Down syndrome., Scientific Reports, Vol.10, No.1, 21323, 2020.
(Summary)
A high prevalence of obstructive sleep apnea (OSA) has been reported in Down syndrome (DS) owing to the coexistence of multiple predisposing factors related to its genetic abnormality, posing a challenge for the management of OSA. We hypothesized that DS mice recapitulate craniofacial abnormalities and upper airway obstruction of human DS and can serve as an experimental platform for OSA research. This study, thus, aimed to quantitatively characterize the upper airway as well as craniofacial abnormalities in Dp(16)1Yey (Dp16) mice. Dp16 mice demonstrated craniofacial hypoplasia, especially in the ventral part of the skull and the mandible, and rostrally positioned hyoid. These changes were accompanied with a shorter length and smaller cross-sectional area of the upper airway, resulting in a significantly reduced upper airway volume in Dp16 mice. Our non-invasive approach, a combination of computational fluid dynamics and high-resolution micro-CT imaging, revealed a higher negative pressure inside the airway of Dp16 mice compared to wild-type littermates, showing the potential risk of upper airway collapse. Our study indicated that Dp16 mice can be a useful model to examine the pathophysiology of increased upper airway collapsibility of DS and to evaluate the efficacy of therapeutic interventions for breathing and sleep anomalies.
Tomonori Iwasaki, Takesi Sugiyama, Ayaka Yanagisawa-Minami, Yoichiro Oku, Anna Yokura and Youichi Yamasaki : Effect of adenoids and tonsil tissue on pediatric obstructive sleep apnea severity determined by computational fluid dynamics., Journal of Clinical Sleep Medicine, Vol.16, No.12, 2021-2028, 2020.
(Summary)
Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The most common cause of pediatric OSA is adenotonsillar hypertrophy. Adenotonsillectomy is the first-line treatment for pediatric OSA; however, OSA persists in a significant number of patients due, in part, to the method of evaluating enlarged adenoids and tonsil tissue. The reason for these effects on OSA severity is not clear. This study aimed to establish a method to diagnose the need for adenoidectomy or tonsillectomy. Twenty-seven Japanese children (mean age 6.6 years) participated in this study, undergoing polysomnography and computed tomography examination. Pharyngeal airway morphology (adenoids and tonsil tissue size, volume, and cross-sectional area [CSA]) and pressure on the upper airway were evaluated at each site using computational fluid dynamic analysis. Apnea-hypopnea index (AHI) showed a strong linear association with maximum negative pressure (P) (AHI = -0.055* events/h P -1.326, R² = .805). The relationship between minimum CSA (CSA) and P was represented by an inversely proportional fitted curve (P = -4797/CSA -5.1, R² = .507). The relationship between CSA and AHI was also represented by an inversely proportional fitted curve (AHI = 301.6 events/h/CSA, R² = .680). P greatly increased if CSA became ≤ 30 mm². The negative pressure of each site increased when CSA measured ≤ 50 mm². In children, when the CSA for each site is ≤ 50 mm², AHI is likely to be elevated, and the patient may require tonsillectomy or adenoidectomy.
Yoshito Shirazawa, Tomonori Iwasaki, Kazuhiro Ooi, Yutaka Kobayashi, Ayaka Yanagisawa-Minami, Yoichiro Oku, Anna Yokura, Yuusuke Ban, Hokuto Suga, Shuichi Kawashiri and Youichi Yamasaki : Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study., Orthodontics & Craniofacial Research, Vol.23, No.3, 313-322, 2020.
(Summary)
This study aimed to determine the anteroposterior depth (APD) of the pharyngeal airway (PA) where post-operative PA obstruction was predicted, using computer fluid dynamics (CFD), in order to prevent obstructive sleep apnoea after mandibular setback surgery. Nineteen skeletal Class III patients (8 men; mean age, 26.7 years) who required mandibular setback surgery had computed tomography images taken before and 6 months after surgery. The APD of each site of the four cross-sectional reference planes (retropalatal airway [RA], second cervical vertebral airway, oropharyngeal airway and third cervical vertebral airway) were measured. The Maximum negative pressure (Pmax) of the PA was measured at inspiration using CFD, based on a three-dimensional PA model. Intersite differences were determined using analysis of variance and the Friedman test with Bonferroni correction. The relationship between APD and Pmax was evaluated by Spearman correlation coefficients and non-linear regression analysis. The smallest PA site was the RA. Pmax was significantly correlated with the APD of the RA (r = .628, P < .001). The relationship between Pmax and the APD-RA was fitted to a curve, which showed an inversely proportional relationship of Pmax to the square of the APD-RA. Pmax substantially increased even with a slight reduction of the APD-RA. In particular, when the APD-RA was 7 mm or less, Pmax increased greatly, suggesting that PA obstruction was more likely to occur. The results of this study suggest that APD-RA is a useful predictor of good PA ventilation after surgery.
(Keyword)
Adult / Cephalometry / Cross-Sectional Studies / Humans / Hydrodynamics / male / Malocclusion, Angle Class III / Mandible / Orthognathic Surgical Procedures / Pharynx
Tomonori Iwasaki, Audrey Yoon, Christian Guilleminault, Youichi Yamasaki and Stanley Yung Liu : How does distraction osteogenesis maxillary expansion (DOME) reduce severity of obstructive sleep apnea?, Sleep & Breathing = Schlaf & Atmung, Vol.24, No.1, 287-296, 2020.
(Summary)
Distraction osteogenesis maxillary expansion (DOME) is a reliable method to expand the nasal floor and hard palatal vault in adults with obstructive sleep apnea (OSA). DOME results in a reduction in the apnea-hypopnea index (AHI) and subjective report of improved nasal breathing. Using rhinomanometry augmented computational fluid dynamic (CFD) modeling, we propose a mechanism of how DOME reduces upper airway pharyngeal collapse in adults with OSA. A retrospective cohort with 20 subjects and mean age of 29.6 ± 8 years who completed DOME at Stanford University from September 2014 to April 2016. Subjects were included if polysomnography, airway morphology, and rhinomanometry were available for use. From the CBCT data, 3D nasal and pharyngeal airway model were generated. Numeric CFD simulation of the airway models were analyzed under the following conditions: (1) the volume of air was flowing at a velocity of 300 cm/s, (2) the wall surface was not slippery, and (3) the simulations were repeated 1000 times to calculate mean values. Statistical analyses using SPSS v24 software included paired t tests, nonparametric Wilcoxon rank test, Friedman test with Bonferroni correction, and Spearman's correlation coefficients (p < 0.05). Mean AHI improved from 17.8 ± 17.6 to 7.8 ± 7.1 events per hour (p < 0.001). Mean lowest oxygen saturation improved from 88.2 ± 7.2 to 90.9 ± 4.2% (p < 0.05). Mean airflow velocity within the nasal airway decreased from 15.6 ± 7.3 to 7.4 ± 2.1 m/s (p < 0.001) after DOME. Mean negative pressure of the nasal airway, retropalatal airway, oropharyngeal airway, and hypopharyngeal airway is reduced from - 158.4 ± 115.3 to - 48.6 ± 28.7 Pa, from - 174.8 ± 119.9 to - 52.5 ± 31.3 Pa, from - 177.0 ± 118.4 to - 54.9 ± 31.8 Pa and from - 177.9 ± 117.9 to - 56.9 ± 32.1 Pa (p < 0.001), respectively. AHI positively correlated with nasal flow velocity (p < 0.05) and negatively correlated with pharyngeal airway pressure (p < 0.05). ODI was positively correlated with nasal velocity (p < 0.05) and negatively correlated with nasal airway pressure (p < 0.05), retropalatal airway pressure (p < 0.001), oropharyngeal airway pressure (p < 0.001), and hypopharyngeal airway pressure (p < 0.05). Anatomic expansion of the nasal floor with widening of the hard palatal vault from DOME is associated with reduction of nasal airflow velocity and downstream reduction of negative pressure in the pharyngeal airway. This dynamic interaction correlates with a reduction in the apnea-hypopnea index (AHI) and Oxygen Desaturation Index (ODI).
Ayaka Yanagisawa-Minami, Takeshi Sugiyama, Tomonori Iwasaki and Youichi Yamasaki : Primary site identification in children with obstructive sleep apnea by computational fluid dynamics analysis of the upper airway., Journal of Clinical Sleep Medicine, Vol.16, No.3, 431-439, 2020.
(Summary)
Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The identification of the primary site of OSA is essential to determine treatment strategy. This study aimed to establish computational fluid dynamics (CFD) analysis for determining the clinical severity of OSA and the primary site of OSA. Twenty children (mean age, 6 years) were divided into OSA and control groups according to their apnea-hypopnea index. Three-dimensional airways were constructed from computed tomography data. The pharyngeal airway morphology and the pressure and velocity of the upper airway were evaluated using CFD analysis. The maximum velocity and negative pressure of the upper airway in the OSA group were significantly correlated with the severity of OSA (r = .741, P < .001; r = -.653, P = .002). A velocity higher than 12 m/s indicated the primary site of OSA. In addition, we found that the primary site of OSA is not necessarily the same as the collapsible conduit site. CFD analysis allows both the evaluation of the disease severity of OSA and the identification of the primary site of OSA in children. The primary site of OSA is not necessarily the same as the collapsible conduit site; therefore, CFD analysis can be used to identify the appropriate intervention for treating OSA.
Hiroyuki Nakano, Katsuaki Mishima, Hokuto Suga, Tomonori Iwasaki, Kazuya Inoue, Takamitsu Mano, Chikara Yoshimura, Kei Suzuki, Naoko Imagawa, Takaaki Ueno, Yoshihide Mori and Yoshiya Ueyama : The Effect of Cranial Change on Oropharyngeal Airway and Breathing During Sleep, Journal of Hard Tissue Biology, Vol.29, No.1, 49-52, 2020.
(Summary)
<p>Mandibular micrognathia is one of the characteristics of obstructive sleep apnea syndrome. The purpose of this study was to assess the effects of bimaxillary surgery without maxillary advancement on the upper airway using computational fluid dynamics (CFD) results of comparing pre- and post-operative finite element model. Seven female patients with jaw deformity, who underwent two-jaw surgery (Le Fort1 osteotomy and bilateral sagittal split ramus osteotomy; BSSRO) were enrolled. Maxillary was moved for correcting occlusal plane and mandibular was moved to advancement. Pharyngeal airway space and breathing during sleep were evaluated, comparing the periods of 2 days before and 6 months after the operation. The cross-sectional area of the level of the hard palate (HP) and the level of the tip of the uvula (TU), and airway volume of total, HP-TU, and TP- the level of the base of the epiglottis (BE) were increased. AI and AHI in 2 days before and 6 months after were decreased. As the result of nasal ventilation condition, velocity of HP and TU in 2 days before and 6 months after were decreased. We think that it was revealed that movement of the maxilla without advancement did not affect to the morphology and function of airway.</p>
(Keyword)
Cranial change / Bimaxillary surgery / Oropharyngeal surgery / Breathing during sleep / computational fluid dynamics
Tomonori Iwasaki, Hokuto Suga, Ayaka Yanagisawa-Minami, Hideo Sato, Makiko Sato-Hashiguchi, Yoshito Shirazawa, Toshiya Tsujii, Yuushi Yamamoto, Ryuzo Kanomi and Youichi Yamasaki : Relationships among tongue volume, hyoid position, airway volume and maxillofacial form in paediatric patients with Class-I, Class-II and Class-III malocclusions., Orthodontics & Craniofacial Research, Vol.22, No.1, 9-15, 2019.
(Summary)
To clarify the associations among tongue volume, hyoid position, airway volume and maxillofacial form using cone beam computed tomography (CBCT) data for children with Class-I, Class-II and Class-III malocclusion. Sixty children (mean age, 9.2 years) divided into Class-I, Class-II and Class-III malocclusion groups according to the A-nasion-B angle. Cone beam computed tomography was used for three-dimensional reconstruction of the maxillofacial region and airway. The hyoid position and the tongue, airway and oral cavity volumes were evaluated. Upper airway ventilation status was calculated using computational fluid dynamics. The groups were compared using analysis of variance and Kruskal-Wallis tests; relationships among the parameters were assessed using Pearson's and Spearman's rank correlation tests. The tongue volume was larger in Class-III patients (50.63 cm ) than in Class-I patients (44.24 cm ; P < 0.05). The hyoid position was lower (49.44 cm), and anatomical balance (AB; tongue volume/oral cavity volume; 85.06%) was greater in Class-II patients than in Class-I patients (46.06 cm, 80.57%, respectively; P < 0.05 for both). The hyoid height showed a positive correlation with AB (r = 0.614; P < 0.001). Children with Class-III malocclusion have large tongue volumes and small AB; the reverse is true for children with Class-II malocclusion. The hyoid position is closely associated with AB in children with malocclusion.
(Keyword)
children / Cone-Beam Computed Tomography / face / female / Humans / Hyoid Bone / Imaging, Three-Dimensional / male / Malocclusion, Angle Class I / Malocclusion, Angle Class II / Malocclusion, Angle Class III / Maxilla / Nasopharynx / Retrospective Studies / Tongue
Tomonori Iwasaki, Hokuto Suga, Ayaka Minami-Yanagisawa, Makiko Hashiguchi-Sato, Hideo Sato, Yuushi Yamamoto, Yoshito Shirazawa, Toshiya Tsujii, Ryuzo Kanomi and Youichi Yamasaki : Upper airway in children with unilateral cleft lip and palate evaluated with computational fluid dynamics., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.156, No.2, 257-265, 2019.
(Summary)
Children with unilateral cleft lip and palate (UCLP) exhibit snoring and mouth breathing. They are also reported to show obstructive sleep apnea syndrome. However, their upper airway ventilation condition is not clearly understood. Therefore, this study was performed to evaluate upper airway ventilation condition in children with UCLP with the use of computational fluid dynamics. Twenty-one children (12 boys, 9 girls; mean age 9.1 years) with UCLP and 25 children (13 boys, 12 girls; mean age 9.2 years) without UCLP who required orthodontic treatment underwent cone-beam computed tomography (CBCT). Nasal resistance and upper airway ventilation condition were evaluated with the use of computational fluid dynamics from CBCT data. The groups were compared with the use of Mann-Whitney U tests and Student t tests. Nasal resistance of the UCLP group (0.97 Pa/cm/s) was significantly higher than that of the control group (0.26 Pa/cm/s; P < 0.001). Maximal pressure of the upper airway (335.02 Pa) was significantly higher in the UCLP group than in the control group (67.57 Pa; P < 0.001). Pharyngeal airway (from choanae to base of epiglottis) pressure in the UCLP group (140.46 Pa) was significantly higher than in the control group (15.92 Pa; P < 0.02). Upper airway obstruction in children with UCLP resulted from both nasal and pharyngeal airway effects.
(Keyword)
Adenoids / Anatomic Landmarks / children / Cleft Lip / Cleft Palate / Cone-Beam Computed Tomography / Epiglottis / female / Humans / Hydrodynamics / Hyoid Bone / Imaging, Three-Dimensional / Larynx / Malocclusion, Angle Class I / Nasopharynx / Nose / respiration / Sleep Apnea, Obstructive
Tomonori Iwasaki, Ayaka Yanagisawa-Minami, Hokuto Suga, Yoshito Shirazawa, Toshiya Tsujii, Yuushi Yamamoto, Yuusuke Ban, Makiko Sato-Hashiguchi, Hideo Sato, Ryuzo Kanomi and Youichi Yamasaki : Rapid maxillary expansion effects of nasal airway in children with cleft lip and palate using computational fluid dynamics., Orthodontics & Craniofacial Research, Vol.22, No.3, 201-207, 2019.
(Summary)
Rapid maxillary expansion (RME) improves nasal airway ventilation in non-cleft palate children. Children with unilateral cleft lip and palate (UCLP) may have nasal obstruction and experience an increased risk of obstructive sleep apnoea. The effect of RME in UCLP children is unclear. This retrospective study evaluated RME-induced changes in ventilation parameters in children with UCLP using computational fluid dynamics. Nineteen patients (10 boys, mean age 10.7 years) who required RME had cone-beam computed tomography images taken before and after RME. Twenty control participants (11 boys, mean age 11.1 years) received regular orthodontic treatment. Nasal airway ventilation parameters (air pressure, air velocity and airflow rate) were analysed via computational fluid dynamics, and nasal cross-sectional area (CSA) was measured. Maximum pressure, velocity and nasal resistance were significantly reduced by RME in the UCLP group. Air flow rate and CSA on the cleft side significantly were increased by RME in the UCLP group. In children with UCLP, increasing the quantity of airflow and CSA on the cleft side by RME substantially improved nasal ventilation.
(Keyword)
children / Cleft Lip / Humans / Hydrodynamics / male / Palatal Expansion Technique / Retrospective Studies
Hokuto Suga, Tomonori Iwasaki, Katsuaki Mishima, Hiroyuki Nakano, Yoshiya Ueyama and Youichi Yamasaki : Evaluation of the effect of oral appliance treatment on upper-airway ventilation conditions in obstructive sleep apnea using computational fluid dynamics., Cranio, 1-9, 2019.
(Summary)
To evaluate the effect of oral appliance (OA) treatment on upper-airway ventilation conditions in patients with obstructive sleep apnea (OSA) using computational fluid dynamics (CFD). Fifteen patients received OA treatment and underwent polysomnography (PSG) and computed tomography (CT). CT data were used to reconstruct three-dimensional models of nasal and pharyngeal airways. Airflow velocity and airway pressure measurements at inspiration were simulated using CFD. The apnea-hypopnea index (AHI) improved from 23.1 to 10.1 events/h after OA treatment. On CFD analysis, airflow velocity decreased at the retropalatal and epiglottis-tip levels, while airway pressure decreased at the retropalatal, uvular- and epiglottis-tip levels. The AHI of patients with OSA before OA treatment was correlated with airway pressure at the epiglottis-tip level. Treatment with OA improved the ventilation conditions of the pharyngeal airway and AHI. Results of CFD analysis of airway pressure and airflow velocity helped determine the severity and ventilatory impairment site of OSA, respectively.
Keika Mukaihara, Maiko Hasegawa-Moriyama, Tomonori Iwasaki, Youichi Yamasaki and Yuichi Kanmura : Evaluation of the pharyngeal airway using computational fluid dynamics in patients with acromegaly., Laryngoscope Investigative Otolaryngology, Vol.3, No.2, 133-138, 2018.
(Summary)
Perioperative airway management may be particularly challenging in patients with acromegaly undergoing trans-sphenoidal pituitary surgery (TSS). Management for airway obstruction is required prior to pituitary surgery to minimize perioperative hypoxia. The purpose of this retrospective study was to evaluate airway obstruction by simulation of computational fluid dynamics (CFD) using computed tomography (CT) images in patients who had undergone TSS. CT images of the nasopharyngeal airways of patients with acromegaly (n = 5) or nonfunctional pituitary adenoma (n = 6) undergoing TSS from April 2012 to January 2017 were used to construct these airways in three dimensions. Estimated airflow pressure and velocity in the retropalatal airway (RA), oropharyngeal airway (OA), and hypopharyngeal airway (HA) were simulated using CFD. Estimated pharyngeal airflow pressure in the HA, OA, and RA was significantly greater in patients with acromegaly than in those with nonfunctional pituitary adenomas whereas the estimated pharyngeal airflow velocity was significantly impaired only in the RA of patients with acromegaly. Minimum postoperative SpO both within 3 hours and from 3 to 12 hours after the end of anesthesia was significantly lower in the patients with acromegaly. Additionally, estimated volume of tongue and pharyngeal airflow pressure in the HA, OA, and RA correlated with minimum postoperative SpO. Pharyngeal airflow pressure estimated from CT images is high in patients with acromegaly, and these values correlate with postoperative minimum values for SpO. Preoperative evaluation of CT images by CFD can predict difficulty in airway management and perioperative hypoxia. 4.
Takayuki MIYAKAWA, Tomonori Iwasaki, Hokuto SUGA, Yuusuke BAN and Youichi YAMASAKI : Survey Regarding Effects of Mouth Breathing in Children on Sleep and Daytime Activities, The Japanese Journal of Pediatric Dentistry, Vol.56, No.1, 19-25, 2018.
(Summary)
<p>We conducted a survey to examine the effects of mouth breathing in children on sleep and daytime activities. There were 165 subjects aged 3 to 12 years (73 boys, 92 girls ;mean age 8.3±2.3 years) without a significant medical history who were examined at dental clinics in Kagoshima Prefecture,Japan, in July and August 2017. We found that 27.3% snored and 2.4% stopped breathing during sleep, while mouth breathing was observed in 16.4%. Children who exhibited mouth breathing also showed chest retraction, open mouth during sleep, snoring, difficulty with waking, history of common colds, a runny nose, dysphagia, daytime somnolence, attention deficit, and hyperactivity. We consider that our findings indicate that mouth breathing has major effects on sleep and daily activities of chil dren. Pediatric dentists seek to contribute to the healthy growth and development of children by care for their oral cavity. In addition to addressing morphological and functional problems, such as caries, hard -tissue disease, maxillofacial, dentition and occlusion disorders, and mastication and swallowing disorders, the present results show the importance of providing sufficient attention to potential respira tory disorders.</p><p></p>
Tomonori Iwasaki, Hideo Sato, Hokuto Suga, Yoshihiko Takemoto, Emi Inada, Issei Saitoh, Eriko Kakuno, Ryuzo Kanomi and Youichi Yamasaki : Relationships among nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial form in Class II and Class III children., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.151, No.5, 929-940, 2017.
(Summary)
The purpose of this study was to clarify the relationships between upper airway factors (nasal resistance, adenoids, tonsils, and tongue posture) and maxillofacial forms in Class II and III children. Sixty-four subjects (mean age, 9.3 years) with malocclusion were divided into Class II and Class III groups by ANB angles. Nasal resistance was calculated using computational fluid dynamics from cone-beam computed tomography data. Adenoids, tonsils, and tongue posture were evaluated in the cone-beam computed tomography images. The groups were compared using Mann-Whitney U tests and Student t tests. The Spearman rank correlations test assessed the relationships between the upper airway factors and maxillofacial form. Nasal resistance of the Class II group was significantly larger than that of the Class III group (P = 0.005). Nasal resistance of the Class II group was significantly correlated with inferior tongue posture (P <0.001) and negatively correlated with intermolar width (P = 0.028). Tonsil size of the Class III group was significantly correlated with anterior tongue posture (P <0.001) and mandibular incisor anterior position (P = 0.007). Anterior tongue posture of the Class III group was significantly correlated with mandibular protrusion. The relationships of upper airway factors differ between Class II and Class III children.
(Keyword)
Adenoids / Airway Resistance / children / Cone-Beam Computed Tomography / female / Humans / male / Malocclusion, Angle Class II / Malocclusion, Angle Class III / Nasal Cavity / Palatine Tonsil / Pathology, Oral / Retrospective Studies / Tongue
Tomonori Iwasaki, Hideo Sato, Hokuto Suga, Yoshihiko Takemoto, Emi Inada, Issei Saitoh, Eriko Kakuno, Ryozo Kanomi and Youichi Yamasaki : Influence of pharyngeal airway respiration pressure on Class II mandibular retrusion in children: A computational fluid dynamics study of inspiration and expiration., Orthodontics & Craniofacial Research, Vol.20, No.2, 95-101, 2017.
(Summary)
To examine the influence of negative pressure of the pharyngeal airway on mandibular retraction during inspiration in children with nasal obstruction using the computational fluid dynamics (CFD) method. Sixty-two children were divided into Classes I, II (mandibular retrusion) and III (mandibular protrusion) malocclusion groups. Cone-beam computed tomography data were used to reconstruct three-dimensional shapes of the nasal and pharyngeal airways. Airflow pressure was simulated using CFD to calculate nasal resistance and pharyngeal airway pressure during inspiration and expiration. Nasal resistance of the Class II group was significantly higher than that of the other two groups, and oropharyngeal airway inspiration pressure in the Class II (-247.64 Pa) group was larger than that in the Class I (-43.51 Pa) and Class III (-31.81 Pa) groups (P<.001). The oropharyngeal airway inspiration-expiration pressure difference in the Class II (-27.38 Pa) group was larger than that in the Class I (-5.17 Pa) and Class III (0.68 Pa) groups (P=.006). Large negative inspiratory pharyngeal airway pressure due to nasal obstruction in children with Class II malocclusion may be related to their retrognathia.
(Keyword)
Airway Resistance / children / Cone-Beam Computed Tomography / female / Humans / male / Malocclusion, Angle Class II / Nasal Obstruction / Pharynx / pressure
To evaluate the effect of a Herbst appliance on ventilation of the pharyngeal airway (PA) using computational fluid dynamics (CFD). Twenty-one Class II patients (10 boys; mean age, 11.7 years) who required Herbst therapy with edgewise treatment underwent cone-beam computed tomography (CBCT) before and after treatment. Nineteen Class I control patients (8 boys; mean age, 11.9 years) received edgewise treatment alone. The pressure and velocity of the PA were compared between the groups using CFD based on three-dimensional CBCT images of the PA. The change in oropharyngeal airway velocity in the Herbst group (1.95 m/s) was significantly larger than that in the control group (0.67 m/s). Similarly, the decrease in laryngopharyngeal airway velocity in the Herbst group (1.37 m/s) was significantly larger than that in the control group (0.57 m/s). The Herbst appliance improves ventilation of the oropharyngeal and laryngopharyngeal airways. These results may provide a useful assessment of obstructive sleep apnea treatment during growth.
(Keyword)
children / Computational Biology / Cone-Beam Computed Tomography / female / Humans / Hydrodynamics / male / Malocclusion, Angle Class II / Orthodontic Appliances, Functional / Pharynx / respiration / Treatment Outcome
Ken Morizono, Yoshihiko Takemoto, Emi Inada, Daisuke Murakami, Issei Saitoh, Hideo Sato, Tomonori Iwasaki and Youichi Yamasaki : Simultaneous Evaluation of Three-Dimensional Lip Kinetics and Tongue Pressure during Swallowing, International Journal of Dentistry and Oral Health, Vol.2, No.2, 2016.
(Summary)
Objectives: The purpose of this study was to evaluate the amount of lip movement and simultaneous tongue pressure changes on an artificial palatal plate during swallowing. Methods: Subjects were 9 healthy males (25.4 ± 2.1 years of age). Three-dimensional lip movement was measured by a wireless optoelectronic system, and tongue pressure was simultaneously recorded by a sensor sheet attached to the incisive papilla of an artificial palatal plate. Reflective markers were attached to the right and left corners of the mouth to measure the distance between them. All subjects were instructed to swallow 5 mL and 20 mL samples of water at will. The maximum change of distance between the corners of mouth, the maximum tongue pressure, and the time interval between the two maxima (lip-tongue interval) were calculated. Wilcoxon's test was used to detect significant differences in these measurements between the two volumes. Results: Maximum tongue pressure did not differ significantly between swallowed volumes. The maximum change of distance between the corners of mouth was larger and the lip-tongue interval was significantly shorter with the larger volume. Conclusions: We suggest that swallowing a larger volume is accomplished by larger lip movement rather than larger tongue movement. These results indicate that lip movement during swallowing can be evaluated objectively.
Stanley Yung-Chuan Liu, Leh-Kiong Huon, Tomonori Iwasaki, Audrey Yoon, Robert Riley, Nelson Powell, Carlos Torre and Robson Capasso : Efficacy of Maxillomandibular Advancement Examined with Drug-Induced Sleep Endoscopy and Computational Fluid Dynamics Airflow Modeling., Otolaryngology--Head and Neck Surgery, Vol.154, No.1, 189-195, 2016.
(Summary)
To use drug-induced sedation endoscopy (DISE) and computational fluid dynamics (CFD) modeling to study dynamic airway and airflow changes after maxillomandibular advancement (MMA), and how the changes correlate with surgical success based on polysomnography parameters. Retrospective cohort study. University medical center. DISE was rated with the VOTE (velum, oropharynx, tongue, epiglottis) classification, and CFD was used to model airflow velocity and negative pressure exerted on pharyngeal wall. Changes in VOTE score by site and CFD measurements were correlated with perioperative polysomnography outcomes of apnea-hypopnea index (AHI), apnea index (AI), oxygenation desaturation index (ODI), and lowest oxygen saturation. After MMA, 20 subjects (17 males, 3 females) with a mean age of 44 ± 12 years and body mass index of 27.4 ± 4.6 kg/m(2) showed mean decreases in AHI (53.6 ± 26.6 to 9.5 ± 7.4 events/h) and ODI (38.7 ± 30.3 to 8.1 ± 9.2 events/h; P < .001). Improvement in lateral pharyngeal wall collapse during DISE based on VOTE score correlated with the most decrease in AHI (60.0 ± 25.6 to 7.5 ± 3.4 events/h) and ODI (46.7 ± 29.8 to 5.3 ± 2 events/h; P = .002). CFD modeling showed significant positive Pearson correlations between reduction of retropalatal airflow velocity and AHI (r = 0.617, P = .04) and ODI (r = 0.773, P = .005). AHI and ODI improvement after MMA is best correlated with (1) decreased retropalatal airflow velocity modeled by CFD and (2) increased lateral pharyngeal wall stability based on VOTE scoring from DISE.
Emi Inada, Issei Saitoh, Yong Yu, Daisuke Tomiyama, Daisuke Murakami, Yoshihiko Takemoto, Ken Morizono, Tomonori Iwasaki, Yoko Iwase and Youichi Yamasaki : Quantitative evaluation of toothbrush and arm-joint motion during tooth brushing., Clinical Oral Investigations, Vol.19, No.6, 1451-1462, 2015.
(Summary)
It is very difficult for dental professionals to objectively assess tooth brushing skill of patients, because an obvious index to assess the brushing motion of patients has not been established. The purpose of this study was to quantitatively evaluate toothbrush and arm-joint motion during tooth brushing. Tooth brushing motion, performed by dental hygienists for 15 s, was captured using a motion-capture system that continuously calculates the three-dimensional coordinates of object's motion relative to the floor. The dental hygienists performed the tooth brushing on the buccal and palatal sides of their right and left upper molars. The frequencies and power spectra of toothbrush motion and joint angles of the shoulder, elbow, and wrist were calculated and analyzed statistically. The frequency of toothbrush motion was higher on the left side (both buccal and palatal areas) than on the right side. There were no significant differences among joint angle frequencies within each brushing area. The inter- and intra-individual variations of the power spectrum of the elbow flexion angle when brushing were smaller than for any of the other angles. This study quantitatively confirmed that dental hygienists have individual distinctive rhythms during tooth brushing. All arm joints moved synchronously during brushing, and tooth brushing motion was controlled by coordinated movement of the joints. The elbow generated an individual's frequency through a stabilizing movement. The shoulder and wrist control the hand motion, and the elbow generates the cyclic rhythm during tooth brushing.
(Keyword)
Adult / Arm / Dental Hygienists / female / Humans / Imaging, Three-Dimensional / male / Movement / Toothbrushing
Tomonori Iwasaki, Yoshihiko Takemoto, Emi Inada, Hideo Sato, Issei Saitoh, Eriko Kakuno, Ryuzo Kanomi and Youichi Yamasaki : Three-dimensional cone-beam computed tomography analysis of enlargement of the pharyngeal airway by the Herbst appliance., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.146, No.6, 776-785, 2014.
(Summary)
Pharyngeal airway size is increasingly recognized as an important factor in obstructive sleep apnea. However, few studies have examined the changes of pharyngeal airway form after dental procedures for treating obstructive sleep apnea during growth. The purpose of this study was to evaluate the effect of the Herbst appliance on the 3-dimensional form of the pharyngeal airway using cone-beam computed tomography. Twenty-four Class II subjects (ANB, ≥5°; 11 boys; mean age, 11.6 years) who required Herbst therapy with edgewise treatment had cone-beam computed tomography images taken before and after Herbst treatment. Twenty Class I control subjects (9 boys; mean age, 11.5 years) received edgewise treatment only. The volume, depth, and width of the pharyngeal airway were compared between the groups using measurements from 3-dimensional cone-beam computed tomography images of the entire pharyngeal airway. The increase of the oropharyngeal airway volume in the Herbst group (5000.2 mm(3)) was significantly greater than that of the control group (2451.6 mm(3)). Similarly, the increase of the laryngopharyngeal airway volume in the Herbst group (1941.8 mm(3)) was significantly greater than that of the control group (1060.1 mm(3)). The Herbst appliance enlarges the oropharyngeal and laryngopharyngeal airways. These results may provide a useful assessment of obstructive sleep apnea treatment during growth.
Daisuke Murakami, Emi Inada, Issei Saitoh, Yoshihiko Takemoto, Ken Morizono, Naoko Kubota, Tomonori Iwasaki, Takeshi Oku and Youichi Yamasaki : Morphological differences of facial soft tissue contours from child to adult of Japanese males: a three-dimensional cross-sectional study., Archives of Oral Biology, Vol.59, No.12, 1391-1399, 2014.
(Summary)
To evaluate morphological differences of the facial soft tissue surface between male Japanese adults and children. 20 adult Japanese males (average age 28 years) and 20 Japanese boys (average age 5.5 years) with normal occlusion were selected for this study. The images of the subjects' facial surface were obtained with a 3-D laser scanner. To evaluate the three-dimensional morphological differences of the facial soft tissue, we transformed the coordinates of 16 facial landmarks to a new reference plane and compared the adults' and children's facial form drawn to the same scale in the same coordinate system. The morphological difference ratio of the lower facial area was higher than in the upper facial area, and the nose and lower face changed more forward than downward. The morphological difference ratio of the mid face width was smaller than other areas. Our study suggests that the morphological facial soft tissue differences between Japanese adults and children are more forward and downward than laterally, manifesting in a facial form of adults that is deeper and narrow.
(Keyword)
Adult / Child, Preschool / Cross-Sectional Studies / face / Humans / Imaging, Three-Dimensional / Japan / Lasers / male / Maxillofacial Development
Tomonori Iwasaki, Yoshihiko Takemoto, Emi Inada, Hideo Sato, Hokuto Suga, Issei Saitoh, Eriko Kakuno, Ryuzo Kanomi and Youichi Yamasaki : The effect of rapid maxillary expansion on pharyngeal airway pressure during inspiration evaluated using computational fluid dynamics., International Journal of Pediatric Otorhinolaryngology, Vol.78, No.8, 1258-1264, 2014.
(Summary)
Recent evidence suggests that rapid maxillary expansion (RME) is an effective treatment of obstructive sleep apnea syndrome (OSAS) in children with maxillary constriction. Nonetheless, the effect of RME on pharyngeal airway pressure during inspiration is not clear. The purpose of this retrospective study was to evaluate changes induced by the RME in ventilation conditions using computational fluid dynamics. Twenty-five subjects (14 boys, 11 girls; mean age 9.7 years) who required RME had cone-beam computed tomography (CBCT) images taken before and after the RME. The CBCT data were used to reconstruct 3-dimensional shapes of nasal and pharyngeal airways. Measurement of airflow pressure was simulated using computational fluid dynamics for calculating nasal resistance during exhalation. This value was used to assess maximal negative pressure in the pharyngeal airway during inspiration. Nasal resistance after RME, 0.137 Pa/(cm(3)/s), was significantly lower than that before RME, 0.496 Pa/(cm(3)/s), and the maximal negative pressure in the pharyngeal airway during inspiration was smaller after RME (-48.66 Pa) than before (-124.96 Pa). Pharyngeal airway pressure during inspiration is decreased with the reduction of nasal resistance by the RME. This mechanism may contribute to the alleviation of OSAS in children.
Chiaki Yamada-Ito, Issei Saitoh, Kohtaro Yashiro, Emi Inada, Tomoaki Maruyama, Kenji Takada, Tomonori Iwasaki, Haruaki Hayasaki and Youichi Yamasaki : Smoothness of molar movement during gum chewing in children with primary dentition., Cranio, Vol.31, No.4, 260-269, 2013.
(Summary)
The purpose of this study was to test the null hypothesis that molar movement during gum chewing in children with primary dentition is as smooth as in adults. Twenty-two healthy children with primary dentition and 23 healthy adult females participated in this study. Mandibular movement during gum chewing was recorded using an optoelectronic analysis system with six degrees-of-freedom at 100 Hz, and 10 cycles were selected for analysis. Normalized jerk cost (NJC) at the incisors and working and balancing molars were calculated in each phase (i.e., opening, closing and occlusal level phases) for each chewing cycle. The NJC of the working side molar in children was larger than in adults in both the opening and occlusal phases. Inter-individual variances of the NJC in each phase in children and adults were smaller than corresponding intra-individual variances, except for the NJC during the occlusal phase of adults for the working and balancing side molars. The inter- and intra-individual variances of the NJC during the closing phase were the smallest in each phase for both children and adults. This indicates that the jaw movements of children with primary dentition are more variable, less smooth, and faster than that of adults.
(Keyword)
Chewing Gum / Child, Preschool / female / Humans / Linear Models / male / Mandible / Mastication / Molar / Movement / Tooth, Deciduous / Young Adult
Tomonori Iwasaki, Issei Saitoh, Yoshihiko Takemoto, Emi Inada, Eriko Kakuno, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Tongue posture improvement and pharyngeal airway enlargement as secondary effects of rapid maxillary expansion: a cone-beam computed tomography study., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.143, No.2, 235-245, 2013.
(Summary)
Rapid maxillary expansion (RME) is known to improve nasal airway ventilation. Recent evidence suggests that RME is an effective treatment for obstructive sleep apnea in children with maxillary constriction. However, the effect of RME on tongue posture and pharyngeal airway volume in children with nasal airway obstruction is not clear. In this study, we evaluated these effects using cone-beam computed tomography. Twenty-eight treatment subjects (mean age 9.96 ± 1.21 years) who required RME treatment had cone-beam computed tomography images taken before and after RME. Twenty control subjects (mean age 9.68 ± 1.02 years) received regular orthodontic treatment. Nasal airway ventilation was analyzed by using computational fluid dynamics, and intraoral airway (the low tongue space between tongue and palate) and pharyngeal airway volumes were measured. Intraoral airway volume decreased significantly in the RME group from 1212.9 ± 1370.9 mm(3) before RME to 279.7 ± 472.0 mm(3) after RME. Nasal airway ventilation was significantly correlated with intraoral airway volume. The increase of pharyngeal airway volume in the control group (1226.3 ± 1782.5 mm(3)) was only 41% that of the RME group (3015.4 ± 1297.6 mm(3)). In children with nasal obstruction, RME not only reduces nasal obstruction but also raises tongue posture and enlarges the pharyngeal airway.
Tomonori Iwasaki, Issei Saitoh, Yoshihiko Takemoto, Emi Inada, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Improvement of nasal airway ventilation after rapid maxillary expansion evaluated with computational fluid dynamics., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.141, No.3, 269-278, 2012.
(Summary)
Rapid maxillary expansion is known to improve nasal airway ventilation. However, it is difficult to precisely evaluate this improvement with conventional methods. The purpose of this longitudinal study was to use computational fluid dynamics to estimate the effect of rapid maxillary expansion. Twenty-three subjects (9 boys, 14 girls; mean ages, 9.74 ± 1.29 years before rapid maxillary expansion and 10.87 ± 1.18 years after rapid maxillary expansion) who required rapid maxillary expansion as part of their orthodontic treatment had cone-beam computed tomography images taken before and after rapid maxillary expansion. The computed tomography data were used to reconstruct the 3-dimensional shape of the nasal cavity. Two measures of nasal airflow function (pressure and velocity) were simulated by using computational fluid dynamics. The pressure after rapid maxillary expansion (80.55 Pa) was significantly lower than before rapid maxillary expansion (147.70 Pa), and the velocity after rapid maxillary expansion (9.63 m/sec) was slower than before rapid maxillary expansion (13.46 m/sec). Improvement of nasal airway ventilation by rapid maxillary expansion was detected by computational fluid dynamics.
Emi Inada, Issei Saitoh, Kuniko Nakakura-Ohshima, Tomoaki Maruyama, Tomonori Iwasaki, D Murakami, M Tanaka, Haruaki Hayasaki and Youichi Yamasaki : Association between mouth opening and upper body movement with intake of different-size food pieces during eating., Archives of Oral Biology, Vol.57, No.3, 307-313, 2012.
(Summary)
Head rotation is coordinated with mandibular movement during mouth opening, and the range of head rotation and mouth opening change with food size. However, past research did not include upper body movement, and no reports have related head and mandibular movement during realistic eating. The purpose of this study was to analyse head and mandibular movements with intake of different-sized food pieces during realistic eating. The test food consisted of apple cut into two different cube sizes (10mm and 20mm). Head and mandibular movements of 20 healthy young adults eating the apple pieces were simultaneously recorded in three dimensions by a wireless opto-electronic system. Reflective markers were attached to the upper lip and chin to measure the mouth opening range. Five markers were attached to eyeglasses frames to measure linear motion and rotation of the head. One marker was attached to the jugular notch of the sternum to measure linear motion of the upper body. Linear motion, and the inclination angle of the head and upper body, and mouth opening range were compared during intake of different-sized apple pieces. Mouth opening, head-neck rotation angle and the amount of upper body forward translation and inclination increased with larger apple pieces. However, isolated relative head motion was stabilized. We conclude that upper body forward motion and head-neck rotation assist mouth opening whilst stabilizing head orientation, and that the range of head-neck rotation angle, upper body translation and range of mouth opening change with food size during realistic eating.
(Keyword)
Adult / Biomechanical Phenomena / Eating / female / Head Movements / Humans / male / Mandible / Mouth / Movement / Neck / Range of Motion, Articular / Sex Factors / Thorax
Hiroko Hasegawa, Issei Saitoh, Kuniko Nakakura-Ohshima, Koki Shigeta, Toshihiro Yoshihara, Shigeaki Suenaga, Emi Inada, Tomonori Iwasaki, Yuko Matsumoto and Youichi Yamasaki : Condylar shape in relation to anterior disk displacement in juvenile females, Cranio, Vol.29, No.2, 100-110, 2011.
(Summary)
The purpose of the study was to test the hypothesis that condylar shape varies based upon the condition of anterior disk displacement in young adolescent patients with temporomandibular disorder (TMD). The study design consisted of 96 juvenile female patients (aged 9 to 20; 15.1 +/- 2.3 yrs.) with clinical signs and/or symptoms of TMD. Bilateral high-resolution magnetic resonance imaging scans were performed in frontal and horizontal views with the mandible in the closed position. Disk positions were evaluated to classify the patients into three diagnostic groups. The results of the study, using ANOVA and Bonferroni tests, demonstrated significant differences among the groups. The conclusion drawn from the study was that condylar shape and size vary based on anterior disk position in juvenile females with TMD. The study's results suggest that disk displacement results in a smaller condyle.
(Keyword)
Adolescent / Cephalometry / children / female / Humans / Image Enhancement / Image Processing, Computer-Assisted / Joint Dislocations / magnetic resonance imaging / Mandibular Condyle / Range of Motion, Articular / Temporomandibular Joint Disc / Temporomandibular Joint Disorders / Young Adult
Tomonori Iwasaki, Issei Saitoh, Yoshihiko Takemoto, Emi Inada, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Evaluation of upper airway obstruction in Class II children with fluid-mechanical simulation., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.139, No.2, e135-45, 2011.
(Summary)
The purpose of this study was to test the null hypothesis that dolichofacial and brachyfacial children with Class II malocclusion do not differ in upper airway obstruction. Furthermore, the ability of fluid-mechanical simulation to detect airway obstruction within the limitations of simulation was examined. Forty subjects from 7 to 11 years of age with Class II malocclusion participated and were divided into 2 groups, dolichofacial and brachyfacial, based on their Frankfort mandibular plane angles. Cone-beam computed tomography images supplied the shape of the entire airway. Two measures of respiratory function, air velocity and pressure, were simulated by using 3-dimensional images of the airway. The images and simulations were compared between the 2 facial types. The size of the upper airway did not differ statistically between facial types; however, the simulated maximal pressure and velocity of the dolichofacial type were significantly higher than those of the brachyfacial type. Airway obstruction differs with the Frankfort mandibular plane angle, even though the depth and cross-sectional area of the airway do not. The fluid-mechanical simulation system developed in this study detected differences in airway obstruction that were not apparent from morphologic studies.
Kuniyasu Kuroda, Issei Saitoh, Emi Inada, Yoshihiko Takemoto, Tomonori Iwasaki, Yoko Iwase, Chiaki Yamada, Miyuki Shinkai, Yuko Matsumoto, Hiroko Hasegawa, Youichi Yamasaki and Haruaki Hayasaki : Head motion may help mouth opening in children., Archives of Oral Biology, Vol.56, No.1, 102-107, 2011.
(Summary)
Concomitant head and mandibular movement during jaw function is well known in adults; however, its importance in children has not been studied. The brain attains 85-90% of its adult weight at 5 years of age, though the maximum rate of condylar growth is attained at approximately 14 years of age. These findings suggest that the coordination of the head and mandible may differ between children and adults. This study investigated head and mandibular movements of 19 children with complete primary dentition (average age: 5 years 5 months) and compared their functional integration of jaw and head movements to those of 16 female adults (average age: 20 years 3 months) with permanent dentition. Although the mandibular opening distance was significantly greater in the adults, the magnitude of concomitant head motion was greater in children. The results suggest that head extension in children helps increase the magnitude of mouth opening more than in adult women.
(Keyword)
Age Factors / brain / children / Child, Preschool / Dental Occlusion / Dentition, Permanent / Electronics / female / Head Movements / Humans / Imaging, Three-Dimensional / male / Mandible / Mandibular Condyle / Masticatory Muscles / Photography / Range of Motion, Articular / Rotation / temporomandibular joint / Tooth, Deciduous / Young Adult
Yoshihiko Takemoto, Issei Saitoh, Tomonori Iwasaki, Emi Inada, Chiaki Yamada, Yoko Iwase, Miyuki Shinkai, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Pharyngeal airway in children with prognathism and normal occlusion., The Angle Orthodontist, Vol.81, No.1, 75-80, 2011.
(Summary)
To test the hypothesis that there is no difference in the pharyngeal airway width and the position of the maxillofacial skeleton between prognathic and normal children. Twenty-five girls with prognathism (mean, 7.9 ± 0.9 years old) and 15 girls with normal occlusion (mean, 8.4 ± 1.5 years) participated in this study. On each girl's lateral cephalogram, the coordinates of all points were marked and systematically digitized using a mechanical three-dimensional digitizing system. An independent-groups t-test was used to detect significant upper and lower pharyngeal width differences between the two groups. Correlations between the horizontal positions of each point and upper and lower pharyngeal widths were examined. Prognathic girls had a significantly wider lower pharyngeal airway compared with those with normal occlusion (P = .01). Furthermore, the horizontal coordinate of Ar was significantly positively correlated with lower pharyngeal airway width in both groups of girls. The hypothesis is rejected. The mandible in prognathic girls tends to be positioned more anteriorly, resulting in a wider lower pharyngeal airway.
This cross-sectional study tested the reproducibility of a simple button-pulling system for measuring lip-closing strength in normal preschool children and compared their strength to that of normal adults. The sample consisted of 348 preschool children and 123 adults. Lip-closing strength was measured by inserting a button, fastened to a piece of string, into the vestibule between the incisors and lips with minimal mouth opening. The string was attached to a digital tension gauge and was pulled parallel to the floor. Maximum tension, with three repetitions, was recorded at the instant that the button was pulled out of the mouth. Multilevel statistical models were used to evaluate any differences in contractive muscle strength between age groups and between the genders. The strength in children increased significantly from three years to five years (p<0.01). Gender-related differences were found in adults but not in preschool children. Inter-individual variation at each age was larger than intra-individual variation. Measurement of lip-closing strength by button pulling is highly reproducible in children and has potential clinical and research applications.
(Keyword)
Adult / Age Factors / Child, Preschool / Cross-Sectional Studies / Facial Muscles / female / Humans / lip / male / Muscle Contraction / Muscle Strength / Muscle Tonus / Posture / Reproducibility of Results / Sex Factors / Stress, Mechanical / Supine Position / Young Adult
Youich YAMASAKI, Tomonori Iwasaki, Haruaki HAYASAKI, Issei SAITOH, Junko TOKUTOMI, Yasutaka YAWAKA, Mitsuko INOUE, Yoshinobu ASADA, Yasuo TAMURA, Ryuzo KANOMI, Kensi MAKI, Toshihiro YOSHIHARA, Takahiro FUNATSU, Yoko TESHIMA, Chika UESATO, Kazue YAMASHITA, Masamichi IDE, Tihiro KURIYAMA, Tsuguko KONDO, Mikio KATOH, Kyoko WATANABE, Yuuko FUJITA, Hiroko HASEGAWA, Emi INADA and Yoshinobu ASADA : Frequency of Congenitally Missing Permanent Teeth in Japanese Children, The Japanese Journal of Pediatric Dentistry, Vol.48, No.1, 29-39, 2010.
(Summary)
Congenitally missing permanent teeth (CMPT) is one of the most frequent anomalies in dentistry. CMPT affects not only the occlusal relationships within the maxilla and mandible, but also the total occlusion. In addition CMPT can lead to future skeletal and facial problems. The purpose of this study was to estimate the nation-wide frequency of (CMPT) in Japanese children. Prior to beginning this epidemiological study, the authors obtained permission for the investigation from the ethics committee of Kagoshima University Graduate School of Medical and Dental Sciences (June 25<sup>th</sup>, 2007).Seven pediatric clinics at dental colleges or universities and several private pediatric clinics participated in this study. The sample consisted of 15,544 pediatric dental patients (7,502 males and 7,502 females). Data were collected from longitudinal dental X-rays, orthopantomograms, and some dental models to determine CMPT (excluding 3<sup>rd </sup>molars) within 6 months. All patients were judged to be over 7 years of age if they had all their permanent teeth in the dental films. In cases where it was difficult to judge the kind of tooth or its location, the committee members from all 7 colleges/universities reached a consensus on the number of missing teeth and their locations on a case by case basis.A total of 1,568 subjects (10.09%) were diagnosed with CMPT. Of these, 685 were males (9.13%),and 883 were females (10.98%). Differences between the maxilla and the mandible were seen in 4.37% of males and 7.58% of females. Differences between the right and left sides were seen in 0.11% of males and 0.14% of females. The most common missing tooth was the lower second premolar ; missing in 2.96% of adolescents, 2.64% of males (1.32% both sides) and 3.31% of females (1.72% on the right side and 1.59% on the left side). In descending order the next most common missing teeth were the mandibular lateral incisors, the maxillary second premolars, and the upper lateral incisors.
(Keyword)
Japanese children / Permanent teeth / Congenital missing / Epidemiology / Nation-wide investigation
Naomi NISHIJIMA, Atsushi FUKAMI, Tomonori Iwasaki, Yoshihiko TAKEMOTO, Naoko KUBOTA, Emi INADA, Noriko IGATA, Takeshi OKU, Issei SAITOH, Haruaki HAYASAKI and Youichi YAMASAKI : Three-dimensional Analysis of Facial Surface Morphology in Japanese Infant : 2. Dimensional measurements, The Japanese Journal of Pediatric Dentistry, Vol.47, No.5, 726-731, 2009.
(Summary)
The process of facial growth is of interest in dentistry, physical anthropology, and even industry. Several Japanese national institutes, e.g., the Advanced Industrial Science and Technology and the Research Institute of Human Engineering for Quality Life have measured and reported aspects of human body size and shape, including the facial morphology of children and adults. However, the facial morphology of infants was not included in these reports.In this study, three-dimensional facial morphological measurements of infants were performed using a three-dimensional laser surface-scanner system (VIVID 910, KONICA MINOLTA SENCING, Inc. Osaka, Japan). One hundred and twenty normal developing children (20 boys and 20 girls each at 4, 5 and 6 years of age) had their faces scanned by VIVID. Four widths (inter-Exocanthion width,inter-Endocanthion width, inter-Alar crest width and inter-Cheilion width) and 6 heights (Nasal height, upper facial height, mouth height, total facial height, lower facial height and Vermilion height) were measured.Most measurements increased with age in both boys and girls. Although significant sex-related differences were detected among the three age groups, there were no consistent tendencies. The infants'growth rates for the measurements were not the same as those of adults from the literature. [I do not understand the next sentence. Perhaps you mean : "For example, widths in the upper part of the face at four years of age are already 80% that of adults. Most measurements differed significantly between 5 and 6 years of age, but only 2 measurements differed significantly between 4 and 5 years of age. These results suggest that facial growth is not constant between 4 and 6 years of age, with rates affected by both age and sex. Further investigation may be required to elucidate characteristics of facial growth during childhood.
Tomonori Iwasaki, Haruaki Hayasaki, Yoshihiko Takemoto, Ryuzo Kanomi and Youichi Yamasaki : Oropharyngeal airway in children with Class III malocclusion evaluated by cone-beam computed tomography., American Journal of Orthodontics and Dentofacial Orthopedics (AJO-DO), Vol.136, No.3, 318.e1-9;discussion3189, 2009.
(Summary)
Upper airway size is increasingly recognized as an important factor in malocclusion. However, children with Class III malocclusion are somewhat neglected compared with those with a Class II skeletal pattern. Therefore, the purpose of this study was to establish the characteristic shape of the oropharyngeal airway (OA) in children with Class III malocclusion. The sample comprised 45 children (average age, 8.6 +/- 1.0 years) divided into 2 groups: 25 with Class I and 20 with Class III malocclusions. OA size of each group was evaluated by cone-beam computed tomography. Cluster analysis, based on OA shape, redivided the subjects into wide, square, and long types. The distributions of Class I and Class III subjects were compared among the types. The Class III group showed statistically larger OA area and width compared with the Class I group. Area was positively correlated with Class III severity. The square type included 84% of the Class I malocclusions but only 30% of the Class III malocclusions, indicating that the OA in Class III malocclusion tends to be flat. The Class III malocclusion is associated with a large and flat OA compared with the Class I malocclusion.
(Keyword)
Anatomy, Cross-Sectional / Cephalometry / children / Cone-Beam Computed Tomography / Epiglottis / female / Humans / Image Processing, Computer-Assisted / Imaging, Three-Dimensional / male / Malocclusion, Angle Class I / Malocclusion, Angle Class III / Mandible / Maxilla / Nasal Bone / Nasopharynx / Oropharynx / Palatine Tonsil
Norihito ISHITANI, Koki SHIGETA, Hiroko HASEGAWA, Tomonori Iwasaki, Takanobu MORINUSHI and Tadashi OGURA : A Survey of the Actual Condition in Adolescent Patients with TMJ Dysfunction Syndrome at the Pediatric Dentistry Clinic for 20 years, The Japanese Journal of Pediatric Dentistry, Vol.40, No.5, 797-802, 2002.
(Summary)
We investigated clinical data concerning adolescent patients who were referred to the Pediatric Dentistry CLinic in Kagoshima University Dental Hospital for consultation and treatment of TMJ Dysfunction Syndrome during a period of 20 years, from 1982 to 2001. We also examined the difference between the data obtained during the first 10 years and those obtained during the second 10years. The results are as follows.<BR>1. The number of patients during the second 10 years increased compared with that during the first 10years.<BR>2. The ratio of female patients showed a higher frequency than the ratio of male patients for the 20years. Furthermore, it showed a higher frequency during the second 10 years than during the first 10years.<BR>3. The ratio of pains was higher and the ratio of sounds was lower during the second 10 years than those during the first 10 years in the number of the patients categorized by the chief complaint, the number of initial symptoms felt by patients, and the number of clinical symptoms at the first medical examination.<BR>4. The frequency in the use of occlusal treatment decreased greatly and the frequencies in use of physical therapy and drug therapy increased greatly during the second 10 years compared with during the first 10 years.<BR>5. There was no significant difference in the effect obtained by treatment between during the first 10years and during the second 10 years.
(Keyword)
Adolescent / temporomandibular disorder / Actual condition
Tomonori Iwasaki and Tadashi OGURA : Developmental Changes of First Molar Position in Crowding Dentition, The Japanese Journal of Pediatric Dentistry, Vol.39, No.5, 1025-1035, 2001.
(Summary)
This study examined changes in angulation and anterior-posterior position of the first molar in crowding dentition. The subjects were divided into four groups depending on their dentition scores at Hellman's dental stage IV A: 1) normal males (n=5),2) males with crowding (n=5),3) normal females (n=5) and 4) females with crowding (n=5). Tooth position was determined by lateral cephalometric X rays taken longitudinally from III A to IV A, and the following results were obtained;<BR>(1) ANS-PNS and Me-Go for both males and females with crowding were smaller than that for normal males and females at all of the dental stages.<BR>(2) The forward displacement of the upper first molar from III A to NA for both males and females with crowding was significantly greater than that for normal males and females.<BR>(3)∠U 6-Pal. Pl. at III A for both males and females with crowding was smaller than that for normal males and females. The increase in ∠U 6-Pal. Pl, from III A to IV A for both males and females with crowding was larger than that for normal males and females.<BR>(4) The forward displacement of the lower first molar from III A to IV A for both males and females with crowding was not significantly different from that for normal males and females. One characteristic of developmental change of the first molar in crowding dentition is that the upper first molar erupts with distal tipping, and subsequently migrates mesially with mesial rotation.
(Keyword)
Crowding / First molar / Mesial movement / Lateral cephalometric X rays
Tomonori Iwasaki, Takanobu Morinushi, Seiichi Horikawa, Sinji Hinotsume and Tadashi Ogura : A Study of the Longitudinal Changes of the Dental Arch Form and Craniofacial Morphology on Subjects with Crowding Permanent dentition, The Japanese Journal of Pediatric Dentistry, Vol.34, No.4, 924-941, 1996.
(Summary)
The purpose of this study was to examine the constituents of crowding permanent dentition by longitudinal changes from stage II C of Hellman's dental age to stage IV A of the dental arch form and craniofacial morphology. The dental arch form was analyzed using dental casts, and the craniofacial morphology was analyzed using the roentgenocephalometric films. The subjects were divided into two groups by the level of arch length discrepancy of permanent dentition at stage IV A of Hellman's dental age. The two groups were classified into the normal dentition group (NDG) and the crowding dentition group (CDG). The NDG was comprised of 15 subjects, and the CDG of 11 subjects. The findings were as follow; 1) The mesio-distal lengths of maxillar or mandibular in the CDG tended to be short in comparison with the length in the NDG after stage III A.2) The axial inclination of the incisor in the CDG tended to be small in comparison with the axial inclination in the NDG after stage III A.3) There was a significant positive correlation between the arch length discrepancy and dental arch width at stage II C. The dental arch length and arch perimeter after stage III A related to the arch length discrepancy with a significant positive correlation. In contrast, there was a significant negative correlation between crown width and arch length discrepancy at stages III A and IV A.
(Keyword)
Crowding / Dental arch from / Craniofacial morphology / Longitudinal study
Tomonori Iwasaki : A Study on Longitudinal Variation in the Function of Masticatory Muscles of Children with Normal Occlusions and Crowding Dentitions, The Japanese Journal of Pediatric Dentistry, Vol.32, No.1, 135-161, 1994.
(Summary)
The purpose of this study was to clarify the functional difference of the masticatory muscles between 6 children with normal occlusions and 11 children with crowding dentitions, by investigating the interocclusal points and electromyographs from Hellman's dental stage IIA to IVA.<BR>1) As the stage progressed, it became clear in IIIC and IVA that the number of interocclusal points of the group with crowding dentitions became smaller than that of the normal occlusion group.<BR>2) From the results of the integrated value (the sum of the electric potential (S)S=TA+TP+M) of the electromyographs in the normal occlusion group, the ratio (M/S) of the electric potential in M to the total active potential became larger than that of TA/S, for the period from the IIIA to IIIB stage. In the group with crowding dentitions, however, M/S became larger than that of TA/S, for the period from the IIIB to IIIC stage.<BR>3) The length of all masticatory rhythms (druation, interval and cycle) in the group with crowding dentitions tended to decrease as the dental stage progressed. In the normal occlusion group, however, only the duraticn tended to decrease as the dental stagc progressed. All masticatory rhythms of children with crowding dentitions were longer than in the normal occlusion group for all the stages.<BR>4) The masticatory rhythms of the masseter muscle obtained by gum chewing tended to stabilize as the dental stage progressed in the both groups. The rhythms were more stable in the normal occlusion group than in the group with crowding dentitions for all the stages.<BR>5) The frequency of the occurrence of the silent period in the group with crowding dentitions was lower in comparison with that of the normal occlusion group in the IIIB, IIIC and IVA stage. The duration of the silent period in the group with crowding dentitions was longer than that of in the normal occlusion group.<BR>Based on the above-mentioned results, it is suggested that the developmental characteristics of the masticatory function in cases with crowding dentitions is retarded, compared with that in cases with the group with the normal occlusions.
Tomonori Iwasaki : Effects of Upper Airway Obstruction on Maxillofacial Dentition in Childhood and Contribution of Pediatric Dentistry to Treat Sleep Apnea, The Japanese Journal of Pediatric Dentistry, Vol.54, No.1, 1-8, 2016.
(Summary)
<p>A number of previous studies have reported the effects of breathing on maxillofacial morphology in childhood. However, accurate findings for evaluating the airway are difficult to acquire because it analysis of upper airway ventilation condition can be problematic. To improve this situation, we developed a three-dimensional upper airway model using cone beam CT data for highly precise analysis of the upper airway with computational fluid dynamics used to assesses the flow of air. As a result,we found that the pharyngeal airway morphology in Class III children showed that the long diameter type of pharyngeal airway and wide diameter type of pharyngeal airway with low tongue posture were shown. On the other hand, in Class II children, upper airway obstruction can be a cause of excessive vertical maxillofacial growth, and that this may be attributed to various parts of the upper airway, such as the nasal, nasopharyngeal, oropharyngeal, and hypopharyngeal airway. It was also revealed that when nasal obstruction is improved by rapid maxillary expansion, the volume of the pharyngeal airway increases and low tongue posture is improved. Thus, we succeeded in clarifying the mechanism by which rapid maxillary expansion improves upper airway obstruction. Pediatric obstructive sleep apnea syndrome occurs at a high frequency, with a prevalence of 2% in otherwise health children. With use of available medical treatment, the success rate is 70%. In the future, we hope to examine the efficacy of application of orthodontic procedures for treatment, such as rapid maxillary expansion or mandibular forward induction, for social contributions from the field of pediatric dentistry.</p>
(Keyword)
Class II / Class III / Upper airway computational fluid dynamics / Rapid maxillary expan sion / Obstructive sleep apnea
Tomonori Iwasaki and Youichi Yamasaki : Relation between maxillofacial form and respiratory disorders in children, Sleep and Biological Rhythms, Vol.12, No.1, 2-12, Jan. 2014.
Yuki Akazawa, Kimiko Ueda Yamaguchi, Hiroshi Nakagawa and Tomonori Iwasaki : A case of using a mouthpiece for bites in perioperative, Oral Care, Apr. 2022.
2.
Tomonori Iwasaki : Indicarion of the dental treatment for pediatric OSAS using computer fluid dynamics, The 21st Genaral Assembly, 41th annual Scientific Meeting and Dental Exhibition, Kaohsiung Taiwan, Oct. 2018.
3.
Tomonori Iwasaki, Hideo Sato, Hokuto Suga, Yoshihiko Takemoto, Emi Inada, Issei Saitoh, Eriko Kakuno, Ryuzo Kanomi and Youichi Yamasaki : Relationships between nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial dentition in Class II and Class III children, 10th Biennial Conference of the Pediatric Dentistry Association of Asia (PDAA), Tokyo, May 2016.
4.
Tomonori Iwasaki : Obstructive Sleep Apnea Syndrome, Stanford Sleep and Circadian Neurobiology Laboratory, Sleep seminar, Palo Alto, CA, USA, Nov. 2014.
5.
Tomonori Iwasaki : Can we prevent childhood obstructive sleep apnea syndrome? -Clinical application using computational fluid dynamics -, The 1st Annual Conference in Pediatric Dentistry between Gangneung-Wonju National University and Kagoshima University, Kagoshima, Jun. 2014.
6.
Tomonori Iwasaki : Can We Prevent OSA? - Tongue posture improvement and pharyngeal airway enlargement as secondary effects of rapid maxillary expansion, The 5th World Congress on Sleep Medicine, Valencia, Sep. 2013.
7.
Tomonori Iwasaki, Ryuzo Kanomi, Eriko Kakuno, Issei Saitoh, Haruaki Hayasaki and Youichi Yamasaki : Evaluations of upper airway ventilation conditions in children with different anteroposterior skeletal patterns using fluid-mechanical simulation, The 24th Congress of International Association of Paediatric Dentistry (IAPD), Seoul, Jun. 2013.
8.
Tomonori Iwasaki, Issei Saitoh, Mizue Harada, Keiichi Miyashita, Syouji Matsune, Yoshihiko Takemoto, Atsushi Fukami, Hideo Sato, Emi Inada, Hiroko Hasegawa, Eriko Kakuno, Ryuzo Kanomi, Haruaki Hayasaki, Yuuichi Kurono and Youichi Yamasaki : Detection of specific obstruction sites using fluid-structure interaction analysis in children with upper airway obstruction, 7th Asian Sleep Research Society Congress 2012, Taipei, Nov. 2012.
9.
Tomonori Iwasaki : Can We Prevent OSAS? Clinical Application to OSAS of Children Using Computational Fluid Dynamics, The 7th Asian Sleep Research Society Congress, Taipei, Nov. 2012.
10.
Tomonori Iwasaki, Issei Saitoh, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Improving tongue posture and pharynx airway as a side effect of rapid maxillary expansion in children: A cone-beam computed tomography study, 112th Annual Session 2012 - American Association of Orthodontists, Honolulu, May 2012.
11.
Tomonori Iwasaki, Issei Saitoh, Mizue Harada, Keiichi Miyashita, Shoji Matsune, Yoshihiko Takemoto, Emi Inada, Ryuzo Kanomi, Haruaki Hayasaki, Yuichi Kurono and Youichi Yamasaki : Detection of specific obstruction sites using fluid-structure interaction analysis in children with upper airway obstruction, World Sleep 2011, Kyoto, Oct. 2011.
12.
Tomonori Iwasaki, Ryuzo Kanomi, Haruaki Hayasaki and Youichi Yamasaki : Evaluation of upper airway obstruction in Class II children using fluid-mechanical simulation, 110th Annual Session 2010 - American Association of Orthodontists, Washington, D.C., Apr. 2010.
Kimiko Ueda Yamaguchi, Yuki Akazawa, Keita Kawarabayashi, Aya Miyazaki, Takamasa Kitamura, Tomokazu Hasegawa, Hiroshi Nakagawa and Tomonori Iwasaki : 当院小児摂食嚥下外来における初診時調査, The Japanese Journal of Pediatric Dentistry, Vol.61, 53-54, Feb. 2023.
MAEO Kei, Takamasa Kitamura, KOHIRA Wakana, 石井 瞳, 嘉ノ海 龍三 and Tomonori Iwasaki : 低位舌と上顎歯列形態ならびに鼻腔通気状態との関連 流体力学的研究, The Japanese Journal of Pediatric Dentistry, Vol.60, No.2, 103, Mar. 2022.
9.
Asuna Sugimoto, Takamasa Kitamura, MAEO Kei, Tomonori Iwasaki and Tsutomu Iwamoto : 心停止の既往がある先天性QT延長症候群の児に対し口腔内管理を行った1例, The Japanese Journal of Pediatric Dentistry, Vol.60, No.2, 205, Mar. 2022.
10.
奥 陽一郎, Tomonori Iwasaki, 佐藤 秀夫, 嘉ノ海 龍三 and 山崎 要一 : 骨格性II級小児の口蓋扁桃肥大が気道閉塞・舌姿勢・歯軸傾斜に及ぼす影響, The Japanese Journal of Pediatric Dentistry, Vol.60, No.2, 132, Mar. 2022.
11.
Takamasa Kitamura, KOHIRA Wakana, MAEO Kei, 岩本 勉 and Tomonori Iwasaki : 幼児期の骨破壊性病変が及ぼす顎口腔発育への影響, The Japanese Journal of Pediatric Dentistry, Vol.60, No.2, 202, Mar. 2022.
12.
Yuki Akazawa, Kimiko Ueda Yamaguchi, Hiroshi Nakagawa and Tomonori Iwasaki : 習癖による咬傷に対してマウスピースを使用した1例, The Japanese Journal of Pediatric Dentistry, Vol.60, 63-64, Feb. 2022.
13.
Rie Niji, Kimiko Ueda Yamaguchi, Yuki Akazawa, Takamasa Kitamura and Tomonori Iwasaki : Streptococcus mutans定着時期に低濃度フッ素化合物を応用した小児の5歳時の齲蝕罹患状況, The Japanese Journal of Pediatric Dentistry, Vol.60, No.2, 55-56, Feb. 2022.
Maiko Hasegawa-Moriyama, Tomonori Iwasaki, Keika Mukaihara, Mina Masuda and Yuichi Kanmura : Unsuccessful tracheal intubation in a patient with Kniest dysplasia undergoing repeated general anesthesia: a case report., JA Clinical Reports, Vol.4, No.1, 41, May 2018.
(Summary)
Kniest dysplasia is a type of chondrodysplasia characterized by severe craniofacial abnormalities including tracheomalacia, midface hypoplasia, and cleft palate. We previously described a 6-year-old girl with Kniest dysplasia, in whom glottic edema rapidly developed after tracheal intubation. At the age of 13 years, a reoperation was scheduled to correct talipes equinovarus but was subsequently canceled due to failure of tracheal intubation and subsequent glottic edema. Airway evaluation by endoscopy and computed tomography 1 month later revealed severe laryngeal narrowing. Therefore, the second anesthesia was maintained with spinal anesthesia combined with sciatic nerve block without tracheal intubation. Careful perioperative airway evaluation is required in patients with Kniest dysplasia, and alternative strategies for airway management other than tracheal intubation should be considered.
Emi INADA, Issei SAITOH, Daisuke MURAKAMI, Yoshihiko TAKEMOTO, Ken MORIZONO, Tomonori Iwasaki, 早崎 治明 and Youichi YAMASAKI : A Case of Comprehensive Long-term Management for a Patient with Severe Dental Caries in Early Childhood, The Japanese Journal of Pediatric Dentistry, Vol.51, No.4, 447-455, Apr. 2013.
重田 浩樹, Tomonori Iwasaki, 齊藤 一誠, 早崎 治明 and 山崎 要一 : 逆生埋伏した上顎右側中切歯の鼻側に埋伏過剰歯を有する症例の歯列咬合管理, The Japanese Journal of Pediatric Dentistry, Vol.47, No.1, 111-118, Mar. 2009.
Identification of the causative site of pediatric OSA using physical properties of peri-airway tissue calculated from CT values (Project/Area Number: 20K10230 )
Cause part identification of Down's syndrome child OSAS and examination of the effectiveness of the maxillary side expansion, MFT combination therapy (Project/Area Number: 18K09916 )
Construction of upper airway model using computational fluid dynamics in children with obstructive sleep apnea (Project/Area Number: 18K09860 )
Development of the fluid sound analytical method that efficacy to pediatric obstructive sleep apnea of the oral myofunctional therapy is detectable (Project/Area Number: 18K09859 )
The identification of the cause site of pediatric OSAS by the three-dimensional sleep breath model built using new technology (Project/Area Number: 17K11965 )
Relative elucidation of lips dysrhaphic state by the establishment of the new rating system of chewing, the deglutition function and the abnormal oral cavity function (Project/Area Number: 17K11964 )
What kind of influence does the lips dysrhaphic state in children have on kinetics of chewing and swallowing? (Project/Area Number: 16K20650 )
Rapid maxillary expansion of pediatric OSAS prevents a funnel chest - using fluid structure interaction analysis - (Project/Area Number: 16K15841 )
development of dental tereatment model applied with computated fluid dynamics for obstructed sleep apnea syndrome with downsyndrome (Project/Area Number: 16K11864 )
Improvement of lip closure strength cures its masticatory motion (Project/Area Number: 16K11802 )
Three-dimensional kinetic analysis of abnormal chewing and swallowing by the mouth breathing in children (Project/Area Number: 15K20604 )
The excessive inspiration negative pressure of upper airway ventilation obstructed children makes mandible retreat -Using fluid structure interaction analysis (Project/Area Number: 26670889 )
Relationship of pharyngeal airway respiration pressure on anteroposterior skeletal patterns of children: A CFD study of expiration and inspiration (Project/Area Number: 25670878 )
Motion Analysis of Food Intake during Weaning Period (Project/Area Number: 25463174 )
The comprehensive studies that an airway ventilation disorder and hyperplasia of palatine tonsil give to chewing and the deglutition function of children (Project/Area Number: 25293420 )
Does the breathing style have influence on "how to eat"? (Project/Area Number: 24792298 )
Construction of the airway obstruction evaluation system of the childhood sleep apnea syndrome using Fluid-structure analysis (Project/Area Number: 24659914 )
Development to new diagnostic procedure of pediatric OSAS and dental treatment by upper airway fluid simulation (Project/Area Number: 22792061 )
Identification of ventilation obstructionsite of OSAS of children by the fluid simulation and construction of the treatment predictive model (Project/Area Number: 22592292 )
Hypothesis: Feeding behavior is conjectured from occlusal condition. (Project/Area Number: 22592291 )
A ventilation function of the three-dimensional lumenairway form by the fluid simulation technique and allied evaluation of the jaw occlusion state (Project/Area Number: 22390392 )
Relationships among sleep disorders, sleep bruxism, psychological stress, respiratory and gastroesophageal symptoms and maxillofacial morphology in children (Project/Area Number: 19592361 )
Fluid mechanical study of the airway of the child and the maxillofacial form using CBCT (Project/Area Number: 19592360 )
An epidemiological survey about the prevalence of congenitally missing permanent teeth of Japanese children (Project/Area Number: 19390532 )