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ABSTRACT: 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.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 02/2013; 143(2):235-45. · 1.33 Impact Factor
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ABSTRACT: 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.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 03/2012; 141(3):269-78. · 1.33 Impact Factor
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ABSTRACT: The purpose of this study was to clarify the characteristics of permanent and primary tooth-crown inclinations. Landmark points from cephalograms and dental casts of two groups; 23 women (mean 20.3 +/- 3.3 years) and 11 girls (mean 5.2 +/- 0.1 years) were digitized, and the coordinates were integrated and transformed to a standardized plane. The 3-dimensional crown inclinations were projected on the sagittal plane, and the angles between the tooth vectors and the FH plane were calculated. An independent-group t-test was used to test for group differences of each tooth inclination, and correlation coefficients were generated for the inclination angles among the permanent and primary teeth. Most maxillary tooth-crown inclinations showed significant age-related differences, while only the second premolar and primary second molar differed significantly in the mandible. The maxillary molars were parallel to the corresponding mandibular molars and correlated with each other, but the primary molars were not. Significant correlations were found between inclinations of most permanent teeth, but not the primary teeth. Maxillary tooth-crown inclinations change during growth, but tooth-crown inclinations of the mandibular teeth do not.
Cranio: the journal of craniomandibular practice 01/2012; 30(1):41-51. · 0.66 Impact Factor
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ABSTRACT: Occlusal contact area (OCA) is most important during the occlusal phase when food particles are being pulverized. OCA is most easily measured statically at the maximum intercuspal position (ICP). However, the assumption of coincidence between dynamic maximum closing position (MCP) and statically determined ICP has not been previously tested. The purpose of this study is to introduce a method of quantifying OCA of all teeth during dynamic mastication to determine whether the OCA at the dynamic MCP during chewing is similar to the statically determined maximum possible OCA.
Thirteen healthy females participated in this study. Morphologic tooth shape data were measured from dental models using an automatic 3D digitizer. Mandibular movement during gum chewing was recorded using an optoelectronic analysis system with 6 degrees of freedom, and ten cycles were selected for analysis. The dynamic OCA was estimated with a measurement system combining 3D tracking of mandibular movements with 3D digitization of tooth shape.
The estimated mean 3D difference between the incisor position at ICP and MCP was 0.129 mm. At the dynamic MCP, the maximum OCA was 98.5% (68.42 mm(2)) of the maximum possible contact area in the static ICP (69.46 mm(2)). Both between-subject and within-subject variation were least at the dynamic MCP.
The maximum OCA during chewing is nearly identical to statically determined maximum possible OCA.
Archives of oral biology 08/2011; 56(12):1616-23. · 1.65 Impact Factor
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ABSTRACT: 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.
Cranio: the journal of craniomandibular practice 04/2011; 29(2):100-10. · 0.66 Impact Factor
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ABSTRACT: 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.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 02/2011; 139(2):e135-45. · 1.33 Impact Factor
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ABSTRACT: 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.
The Angle Orthodontist 01/2011; 81(1):75-80. · 1.21 Impact Factor
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Atsushi Fukami,
Issei Saitoh, Emi Inada,
Takeshi Oku,
Yoko Iwase,
Yoshihiko Takemoto,
Chiaki Yamada,
Tomonori Iwasaki,
Hiroko Hasegawa,
Naoko Kubota,
Tomoya Murakami,
Kanami Harada,
Megumi Nishi,
Sachiko Kinjo,
Noriko Igata,
Haruaki Hayasaki,
Youichi Yamasaki
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ABSTRACT: 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.
Cranio: the journal of craniomandibular practice 10/2010; 28(4):232-7. · 0.66 Impact Factor
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ABSTRACT: Anterior crossbite (ACB) malocclusions are frequent; however, its characteristic functional features have not been fully described. The purpose of this study was to determine the characteristics of habitual mandibular open-close motion in children with ACB of their primary dentition. Two groups of children were selected for study; 17 with ACB (eight boys and nine girls; four years one month to seven years one month) and 19 with normal occlusion (eight boys and 11 girls; four years six months to six years seven months). The motion was recorded using an optoelectronic analysis system with six degrees-of-freedom. Mandibular incisor and condylar motion were analyzed by measuring their three-dimensional ranges and trajectories. Also estimated incisor and condylar pathways of the two groups were compared. Patients with ACB opened wider with more anterior-posterior condylar translation and more mandibular rotation. Although between-subject (inter-individual) variance of all variables in children with ACB was larger, they had less within-subject variance at the condyles. These results indicate that open-close mandibular motion in children with ACB is completely different from that of children with normal occlusion. The different motions might be related to morphological differences between the two groups.
Cranio: the journal of craniomandibular practice 01/2010; 28(1):10-8. · 0.66 Impact Factor
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Naoko Kubota,
Haruaki Hayasaki,
Issei Saitoh,
Yoko Iwase,
Tomoaki Maruyama, Emi Inada,
Hiroko Hasegawa,
Chiaki Yamada,
Yoshihiko Takemoto,
Yuko Matsumoto,
Youichi Yamasaki
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ABSTRACT: This study was undertaken to characterize jaw motion during mastication in children with primary dentition and to compare jaw motion with that in adults. The means and the variances of the traditional parameters for the chewing cycle, i.e., duration, excursive ranges and 3-D distances of travel at the lower incisor, molars and condyles were analyzed and compared in 23 children and 25 female adults. The duration of opening in children was significantly shorter than that of adults. Significant differences between children and adults were observed in lateral and vertical excursion of the incisor, lateral excursion at the molars, and vertical excursion at the condyles. Many of these measurements had larger between-subject and between-cycle variances in children than adults, suggesting that chewing motion in children has not yet matured. The results of this study indicate that chewing motion in children is different from that of adults.
Cranio: the journal of craniomandibular practice 01/2010; 28(1):19-29. · 0.66 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the relationship between cephalometric nasal and skeletal landmarks in preschool children. Lateral cephalograms of 80 Japanese preschool children (40 boys, mean age 5.4+/-0.3 years; 40 girls, mean age 5.2+/-0.1 years; total mean age 5.3+/-0.3 years) were traced, and 22 skeletal and 3 soft-tissue nasal points were digitized. The coordinates from each subject were transformed to a standardized plane using a custom-made program written in Microsoft Visual C++. In this standard plane, sella was the origin, Frankfort Horizontal (FH) plane was parallel to the X-axis, and all 25 points were rotated to match this reference plane. The three nasal landmarks used in this investigation were: (1) rhi', the intersection point of a line parallel to the FH plane at rhinion and the facial line; (2) pronasale (Prn), the most anterior point on the nose; and (3) subnasale (Sn), the most posterior-superior point where the columella met the upper lip. An independent-groups t-test was used to test for sex differences of coordinates of the nasal landmarks and their related skeletal landmarks. Significance was set at p<0.05. A stepwise regression analysis determined how combinations of skeletal landmarks explained the location of the nasal landmarks. Only one skeletal coordinate (N(X)) and no nasal coordinates showed a significant difference between boys and girls. The coordinates of rhi contributed significantly to the location of rhi' and Prn (except for the Y-coordinate of girls). Moreover A-point and ANS contributed to the location of Prn and Sn. For Sn, the X- and Y-coordinates of girls and the Y-coordinate of boys were related to lower incisor or dentoalveolar structure of the mandible. It appears that the nasal landmarks in preschool children can be predicted from selected skeletal landmarks, and there are no sex differences for the nasal landmarks in children.
Forensic science international 09/2009; 191(1-3):111.e1-4. · 2.10 Impact Factor
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ABSTRACT: The aim of the present study was to estimate the amount of overlap in children with the primary dentition.
The sample consisted of 20 Japanese boys between 3 and 5 years of age (mean age: 4 years 10 months). Landmarks on their maxillary and mandibular dental models were digitized using a three-dimensional mechanical digitizer in a single coordinate system. Multilevel statistical models created best-fit polynomial curves to determine overbite, overjet and buccal height of all primary teeth and describe the dental arch forms.
No significant side differences were detected. The primary canine showed the largest overbite (1.87 mm) and buccal height (9.07 mm). The primary second molar exhibited the largest overjet (2.76 mm). Buccal height was the least variable measurement.
Occlusal relationships of the primary dentition were evaluated in 3-dimensions, establishing overlap variables for clinical diagnosis and treatment planning.
The Journal of clinical pediatric dentistry 02/2009; 33(3):269-73. · 0.44 Impact Factor
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ABSTRACT: The purpose of this study was to determine whether the development of masseter muscle activity at mandibular rest position is characteristic for different angle classifications. The sample consisted of 64 boys and 108 girls, aged ten to 18. Electromyographic (EMG) activity from the right and left masseter muscles was recorded using an EMG scanner. First or second order polynomials were used to separately model the age-related changes in resting muscle activity of each gender and Angle's classification. The EMG activity of Class I boys and girls were expressed in positive second order polynomials. The EMG activities of Class II and Class III subjects were expressed in first order polynomials, and the EMG levels in Class III subjects were lower than in Class II subjects. These results indicated that development of resting activity levels might distinguish and characterize the anteroposterior mandibular position relative to craniofacial region.
Cranio: the journal of craniomandibular practice 02/2009; 27(1):39-45. · 0.66 Impact Factor
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ABSTRACT: The instantaneous center of rotation has been used to describe sagittal plane kinematics of mandibular opening and closing. Although, lateral excursions are also important because the closing pathways of masticatory movements frequently coincide with those of lateral excursions with occlusal contacts, there are no similar descriptions of mandibular lateral excursions. To compensate for this deficiency, lateral excursions of 20 women were recorded in this study. Reference points around each subject's mandible were tracked in three dimensions for each 0.1 mm interval of 3-D distance traveled by the incisor during the first 6.0 mm of lateral excursion. ICR was represented by the point that traveled the least 3-D curvilinear distance during each interval. To describe the entire series of intervals, a lateral excursion center was represented by the point with the smallest 3-D curvilinear distance throughout the excursive movement. In the results of this study, lateral excursions can be described as rotation around a single fixed lateral excursion center that is located close to the intercondylar axis, but 22 mm posterior to the initial position of the working side condyle.
Cranio: the journal of craniomandibular practice 11/2008; 26(4):253-62. · 0.66 Impact Factor
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ABSTRACT: In order to provide standard values for craniofacial growth of normal children, we evaluated the growth changes of skeletal and soft tissue cephalometric landmarks from lateral cephalograms of 180 Japanese children. They were divided into three groups: primary dentition, mixed dentition, and permanent dentition. Specific skeletal angles and distances showed significant gender differences with increasing age. The only significant soft tissue gender difference was nose height in the oldest group. Upper pharynx dimension and nose height differed significantly among the groups in both genders. Positions of both the upper and lower lip changed significantly between the intermediate and oldest groups of both genders. Nasolabial angle did not change significantly with growth. The results of this study should be useful for predicting craniofacial growth and development or determining the effect of orthodontic treatment.
Cranio: the journal of craniomandibular practice 08/2008; 26(3):170-81. · 0.66 Impact Factor
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ABSTRACT: Normalization of mandibular function in children is important for normal orofacial development because their function is not still matured. This case report examined jaw movement during chewing in a young patient with unilateral scissors-bite. He could hardly chew on the affected side, preferring to chew only on the unaffected side, and his minimum opening position was initially unstable, i.e., he had two positions before active treatment. Retention did not stabilize his minimal opening position and his dual-bite was not corrected. His minimal opening position was stabilized after equipping his upper canines with a resin cap. Although orthodontic treatment morphologically improved the patient's malocclusion, his function did not improve. Normal jaw movement on both sides was achieved after interfering with his old chewing pattern. Because normalization is needed for acquisition of normal function in children, long-term observations of their growth and functional changes are necessary after orthodontic treatment.
Cranio: the journal of craniomandibular practice 05/2008; 26(2):150-6. · 0.66 Impact Factor
