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In this study, we analyzed the clinical factors and mechanical parameters for predicting orthodontic mini-implant (OMI) failure in the mandible, which has different properties from the maxilla. A patient-specific finite element analysis was applied to 32 OMIs (6 failures and 26 successes) implanted between the mandibular second premolars and first molars used for anchorage. The peak stress and strain parameters were calculated for each sample. A logistic regression of the failure (vs. success) of OMIs on the mechanical parameters in the models was conducted. In addition, the influence of clinical factors on the mechanical parameters considered to be related to OMI failure was examined by a regression analysis. The mechanical parameter which best predicts OMI failure in the mandible was found to be a minimum principal strain of between 0.5 to 1.0 mm from the OMI surface (R

BACKGROUND Skeletal mandibular protrusion would influence to the muscle fatigue of the masticatory muscles. Establishing a diagnostic procedures combining physiological and biochemical information is necessary for quantitative evaluation of masticatory muscle fatigue. OBJECTIVE The transverse relaxation time (T2 time) of muscle functional magnetic resonance imaging (mfMRI), and 31 P-magnetic resonance spectroscopy (MRS) were used to investigate the reliability as parameters for measuring the masseter muscle in patients with skeletal mandibular prognathism. METHOD The subjects were 19 patients diagnosed as skeletal mandibular protrusions and 19 healthy subjects as a control group. Transverse relaxation time (T2 value) determined by mfMRI along with creatine phosphate (PCr) and inorganic phosphorus (Pi) determined by 31 P-MRS before, during, and after clenching were used for molecular imaging of muscle fatigue. RESULTS The average T2 value of the patient group was significantly higher than that of the healthy control group at rest. Furthermore, the average T2 value transiently increased in both groups during experimental clenching. The PCr and Pi showed a tendency toward a transient decrease and increases, respectively. The pH in the masseter muscle showed a transient decrease in both groups prior to and following experimental clenching. The pH in the masseter muscle of the patient group was significantly lower than that in the healthy control group at rest and recovery. CONCLUSION We showed mfMRI and 31 P-MRS are useful for evaluating masseter fatigue during clenching, and the masseter muscle in the prognathic patients showed more severe fatigue than the healthy controls.

The complications of orthognathic surgery may include but are not limited to postoperative unexpected bleeding, abnormal fractures, infections, and nerve damages. Peripheral facial palsy is rare. We report a case of 23-year-old woman with signs of malocclusion, including pectus excavatum, wrist sign, and thumb sign for Marfan syndrome (MFS) underwent peripheral facial palsy after orthognathic surgery with mandibular advancement. Because cardiovascular, thoracic, and ocular abnormalities were absent, she was suspected of having MFS but not definitively diagnosed. On the other hand, she was diagnosed with a maxillary protrusion with mandibular retrognathism. After presurgical orthodontic treatment, we performed Le Fort I osteotomy and 8 mm advancement by bilateral sagittal split ramus osteotomy. Because the periosteum is vulnerable, we checked the bleeding more are fully and frequently during the operation than usual. The day after the operation, peripheral facial palsy with inability to wrinkle the forehead, blink, and grimace were found. The patient was administered mecobalamin, linear polarized infrared irradiation, and stellate ganglion blocks. The patient was also administered valacyclovir for 6 days and steroid pulse therapy for 7 days. Six months after the operation, the facial palsy had disappeared completely. In 58 previous reports, the facial palsy was induced by the reasons, including the operative procedure, postoperative hematoma, edema, perioperative stress, and tissue vulnerability. In the present case, because of the suspected MFS, tissue vulnerability was considered to be one of the major cause of facial palsy, which should be paid attention more carefully in addition to general causes.

Purpose The purpose of this study was to assess the quantitative three-dimensional (3-D) effects of orthognathic surgery on skeletal and pharyngeal airway morphology. Methods The patients were 22 Japanese females with mandibular prognathism. Ten patients underwent bilateral sagittal split ramus osteotomy and 12 underwent bilateral intraoral vertical ramus osteotomy without reduction glossoplasty. Spiral/helical computed tomography (CT) was performed before treatment and after orthognathic surgery. A volume-rendering technique was used to create 3-D CT images. Results The antero-posterior width, lateral width, cross-sectional area of the soft palate plane, and upper volume of the oropharyngeal airway decreased significantly following mandibular setback surgery. Significant positive correlations were found between changes in ANB, FH-NB angle, mandibular plane angle, Y-axis, the amount of mandibular setback and change in total height of the pharyngeal airway, and between changes in Co width and changes in distance and vertical height between the hyoid bone and the 3rd cervical vertebra. There was no significant correlation between surgical changes and the volume of the PAS after surgery. Conclusions Combined orthognathic–orthodontic treatment improved skeletal 3 deformities. Orthognathic surgery reduced the volume and the antero-posterior width of the pharyngeal airway of patients with such deformities.

Purpose The purpose of this study was to quantify the three-dimensional movements of the lips during a posed smile and to verify the differences in the dynamic characteristics among normal occlusion and Class II malocclusion. Materials and methods The subjects included 30 healthy female volunteers with normal occlusion, 23 healthy female volunteers with dentoalveolar Class II malocclusion, and 20 adult female patients with skeletal Class II malocclusion. The three-dimensional measurements of the lips during a posed smile were generated using video-based tracking with three high-speed cameras. Eight landmarks on the lips were used to track lip movement. The Scheffe method of multiple comparisons was used to identify significant differences among the normal occlusion and both Class II groups. Results The lower lip point moved significantly faster and farther backward in the skeletal Class II group compared with the other groups. The upper quarter point in the skeletal Class II group in the posed smile was significantly more medial than in the other groups. The vertical movements of the cheilion point of the normal occlusion group were faster than those in the other groups. Conclusion Three-dimensional dynamic evaluation of posed smiles showed significant differences in the characteristics of lip movement between the normal occlusion and Class II subjects.

Objectives: The objective of this study is to test the hypothesis that there is a difference in the morphology of the lips of Class II div 1 and Class III malocclusion, before and after orthodontic treatment. Methods: The sample subjects included 20 adult female patients with Angle Class II div 1 malocclusion and 30 adult female patients with dento-skeletal Class III malocclusion. Frontal photographs were taken both before and after orthodontic and/or orthognathic treatment. Thirty-five landmarks were placed on each tracing made from the photograph. Thereafter, landmarks were digitized into an x and y coordinates system with the subnasal point as the origin. The Class II pretreatment and posttreatment groups of rest and smile conditions were compared with the Class III group respectively, using t-tests. Results: In the Class II pretreatment group, upper and lower lips positioned downward than that in the Class III group. When smiling, there was no statistically significant difference between the two groups before treatment, whereas after orthodontic treatment both Class II and Class III groups showed the significant difference at rest and on smiling conditions. On smiling condition Class III group showed more upwards and lateral movement of the mouth corners than Class II group. Conclusion: Orthodontic treatment induced larger amount in movement of lips at smiling in both Class II and III patients, which may reflect the emotional changes in the patients after treatment. DOI: http://dx.doi.org/10.3329/bjodfo.v1i1.15971 Ban J Orthod & Dentofac Orthop, October 2010; Vol-1, No.1, 5-12

Factors responsible for the success or failure of orthodontic mini-implants (OMIs) in clinical settings are unclear. Failure of OMIs was found to be associated with increased maximum principal strain (MaxPN) when assessed using the subject-specific finite element (FE) modeling technique. The purpose of the present study was to identify factors that increase MaxPN and thereby predispose the OMI to failure. Using the FE method, MaxPN was calculated around 28 OMIs placed in orthodontic patients, 6 of which failed during the first 5 months. Sixteen potential risk factors related to patients or to OMI position were measured on computerized tomographic images or calculated in FE models. The impact of these factors on MaxPN was verified using regression analysis. Three factors were found to have significant nonlinear relationships with MaxPN: cortical bone quality, vertical angulation of the OMI, and proximity of the OMI to the tooth in the direction of force. In conclusion, failure of an OMI is a multifactorial problem, and position and angulation of the implant are among the affecting factors. Slight apical inclination and positioning at least 1 mm off the root in the direction of force may significantly decrease failure probability.

The aims of this study were to evaluate the morphological changes in the lips and to determine the degree of improvement in the smile after mandibular advancement surgery for hyperdivergent retrognathism. The subjects were divided into two groups: one group consisted of 10 adult female patients who underwent mandibular advancement surgery and a control group that consisted of 30 adult female volunteers with normal occlusion. The data were collected from cephalometric radiographs and frontal photographs taken at pre- and posttreatment at the start of the pre-surgical orthodontic treatment and the completion of post-surgical orthodontic treatment. Conventional cephalometric variables as well as the coordinates of the reference points were calculated. Thirty-five landmarks were placed on each tracing made from the frontal photograph. Thereafter, the landmarks were digitized into an x- and y-coordinate system with the subnasal point as the origin. The comparisons between pretreatment and posttreatment at rest and on smiling, and the comparisons between the treatment and control group were made using the Wilcoxon matched-pairs and signed-rank tests and the rank-sum tests. In the pretreatment stage, both the upper and lower lips were positioned inferior in comparison to the control group at rest. The lower lip was positioned downward in the smile in the pretreatment group in comparison to the control group. These characteristics of the hyperdivergent retrognathism in the smile still remained after orthognathic treatment. These findings of this report are considered to be important because they demonstrate that these changes can be quantitatively and reproducibly analyzed.

This case report presents a case that underwent orthognathic treatment with non-metallic appliances made of organic polymer. The patient was a 19-year-old female with mandibular protrusion and maxillary anterior crowding. The overbite was +3.0 mm, and the overjet −3.0 mm. She was allergic to nickel (Ni3+), cobalt (Co3+) and cobalt–chrome (Co–Cr3+). The pre-surgical orthodontic treatment included the extraction of the maxillary right-and-left second premolars and mandibular right third molar. An orthodontic appliance made of organic polymer was employed. Orthognathic surgery with bilateral sagittal split ramus osteotomy was carried out. After 32 months pre-surgical orthodontic treatment, the left and right sides were set back 9 and 7 mm, respectively. Rigid fixation of the splitted mandible was employed using two absorbency screws in each side, and the inter-maxillary fixation was performed with elastic threads for 8 days. Total treatment period was 42 months. For retention, a non-metal retainer was employed for the upper and lower dentition. The consistent non-metal treatment on orthognathic case of metal allergy was attained successfully. However, the maxillary molars and the mandibular anterior teeth appeared elongated. This was considered to be caused by the low rigidity of a plastic material.

This case report presents a case that underwent orthognathic treatment with intra-oral vertical ramus osteotomy (IVRO). The patient was a 19-year-old female with mandibular protrusion and severe maxillary anterior crowding. The overbite was +0.5 mm and the overjet −1.5 mm. She had orofacial pain and tenderness of the temporomandibular joints (TMJ) and surrounding muscles. The pre-surgical orthodontic treatment included the extraction of the maxillary right lateral incisor, maxillary right second premolar, maxillary left canine, mandibular left second molar and mandibular right second premolar. After 18 months of pre-surgical orthodontic treatment, the left and right sides of the mandible were set back 8 and 6 mm, respectively, via IVRO to improve mandibular protrusion. The total treatment period was 26 months. The patient showed the backward reaction of the mandible, which occurred after release of the maxillo-mandibular fixation. The usage of the Class II elastics during the post-surgical phase to maintain the overjet made the inclination of the maxillary incisors more lingual.

This case report presents a case that underwent orthognathic treatment with anterior segmental osteotomies on both jaws. The patient was a 26-year-old female with maxillary protrusion, lip incompetence with an everted vermilion border. The overbite was +1.0 mm, overjet +1.0 mm. The pre-surgical orthodontic treatment included the extraction of the four first premolars and a multi-bracket treatment was started. After 12 months of pre-surgical orthodontic treatment, both the anterior maxillary and the anterior mandibular segments were retracted surgically by 5.5 mm. The total treatment period was 18 months. An anterior segmental osteotomy can induce the remarkable structural changes for bimaxillary lip protrusion patients.

Objective: To evaluate the morphological changes in the lips and to determine the degree of improvement in the smile after orthodontic treatment for Class II division 1 malocclusion.Materials and Methods: The sample subjects were divided into two groups: a group that consisted of 20 adult female patients with Angle Class II division 1 malocclusion and a control group that consisted of 28 adult female volunteers with normal occlusion. Frontal photographs were taken before and after orthodontic treatment, and 35 landmarks were placed on each tracing made from the photograph. Thereafter, landmarks were digitized into an x- and y-coordinate system with the subnasal point as the origin. The comparisons between pretreatment and posttreatment at rest and on smiling, and the comparisons between Class II division 1 and control group were made using Student's t-test.Results: Both the upper and lower lips in the smile of patients in the Class II division 1 pretreatment group were positioned downward, and the upward movement of the upper lip and mouth corners was smaller in comparison with the control group. These characteristics of the Class II smile improved after orthodontic treatment, but the differences with the control group remained unchanged immediately after treatment.Conclusion: The soft tissue morphology shows a relative improvement after orthodontic treatment.

This article presents an orthognathic treatment case after severe apical root resorption of maxillary anterior teeth using anterior segmental osteotomy. This case involved a 20-year-old female with the chief complaint of maxillary protruding and irregularly aligned mandibular anterior teeth. Her medical history showed no allergies or medical problems. The overbite was +3.0 mm, and the overjet +3.0 mm. After extraction of the four first premolars, a multi-bracket treatment was started. A severe root resorption of the maxillary anterior teeth was found 12 months after active treatment. The maxillary anterior segmental osteotomy was chosen as the compensatory treatment. The total treatment period was 2 years and 7 months. The post-retention panoramic radiograph showed no developmental root resorption.

This article presents orthognathic treatment in successful collaboration with autotransplantation of the maxillary third molar. The case report describes a 24-year-old man with severe mandibular protrusion and severe crowding in both dentitions. Overbite was 0 mm, overjet, −15 mm. Maxillary second molars and mandibular third molars were extracted, and presurgical multibracket treatment was begun. Maxillary third molars were impacted completely at 18 months in terms of presurgical tooth alignment. Autotransplantation of the teeth was achieved to substitute for extracted maxillary second molars. At 6 months after autotransplantation, the maxilla was advanced 4 mm on both sides through a Le Fort I procedure; left and right sides of the mandible were set back 15 and 18 mm, respectively, via sagittal split ramus osteotomy to improve mandibular protrusion. The total treatment period lasted 37 months. Autotransplantation treatment is an effective modality for tooth replacement when a donor tooth is available. Fully impacted maxillary third molars are potentially reliable candidates for autotransplantation.

Objective: To investigate the most reliable stress or strain parameters in subject-specific finite element (FE) models to predict success or failure of orthodontic mini-implants (OMIs). Materials and Methods: Subject-specific FE analysis was applied to 28 OMIs used for anchorage. Each model was developed using two computed tomography data sets, the first taken before OMI placement and the second taken immediately after placement. Of the 28 OMIs, 6 failed during the first 5 months, and 22 were successful. The bone compartment was divided into four zones in the FE models, and peak stress and strain parameters were calculated for each. Logistic regression of the failure (vs success) of OMIs on the stress and strain parameters in the models was conducted to verify the ability of these parameters to predict OMI failure. Results: Failure was significantly dependent on principal strain parameters rather than stress parameters. Peak maximum principal strain in the bone 0.5 to 1 mm from the OMI surface was the best predictor of failure (R2 = 0.8151). Conclusions: We propose the use of the maximum principal strain as a criterion for predicting OMI failure in FE models.

Lateral cephalometric radiographs of 35 Japanese male patients suffering from Duchenne muscular dystrophy (DMD) were taken longitudinally from 10 to 20 years of age. Eighteen landmarks were placed and 15 angles and four linear distances calculated. Profile diagrams (profilograms) were produced to analyse changes in craniofacial morphological growth in the DMD subjects. The measurements were then compared with Japanese standards. In young patients with DMD, compared with the controls, the following were observed: a large gonial angle; clockwise rotation of the mandible; short sagittal length of the cranial base and protrusion of the upper incisors. In adult patients, the maxillary alveolus and the upper incisors were protruded, compared with the controls. Overbite in DMD subjects also showed a tendency to decrease. In the controls, mandibular growth direction tended to be straight down and forward, while in patients with DMD, the growth direction was down until approximately 16 years of age and, after that, a forward vector of growth was apparent. As a result, the tendency towards a clockwise rotation of the mandible in the adults was less than in the young patients. These findings showed that DMD significantly affects craniofacial morphology.

The purpose of this study was to evaluate the effects of four premolar extractions and orthodontic treatment on changes to the lips and vermilion height during a posed smile.Fifteen female patients who were diagnosed with bimaxillary protrusion and treated with four premolar extractions were selected. The control group consisted of 25 female volunteers with a normal occlusion. Frontal photographs of the patients during a posed smile were taken before and after orthodontic treatment. Thirty-five landmarks on the upper and lower lips were identified and used to generate measurements of lip area and vermilion height. Linear and angular cephalometric measurements were also obtained.The mean values for vermilion height and lip form before orthodontic treatment were significantly larger in the treatment group compared with those of the control group. Following treatment, values significantly decreased to the extent that there was no significant difference in the vermilion height and lip form between the post-treatment and control groups. Only three and four significant correlations were found between the changes in incisor position and changes in vermilion height and lip area for the upper and lower lips, respectively.The vermilion height and lip area in patients with bimaxillary protrusion approached comparative and normal values as a result of four premolar extractions and orthodontic retraction.

The purpose of this study was to evaluate the effects of orthodontic treatment, involving the extraction of four premolars, on vermilion height and lip area. Twenty-eight female patients (mean 21.9 ± 3.1 years) who were diagnosed with bimaxillary protrusion were selected for this study to be treated by extraction of four premolars. The control group consisted of 28 female volunteers (mean 25.0 ± 3.0 years) with Angle Class I normal occlusion. Frontal photographs of the patients were taken both before and after the orthodontic treatment in resting position. Thirty-five landmarks on the upper and lower lips were identified for the measurements of vermilion height and lip area. Lateral cephalograms were taken before and after active orthodontic treatment, and linear and angular measurements were performed. The mean pre-treatment values of vermilion height and lip area were significantly greater in the treatment group than those of the control group and decreased significantly after the orthodontic treatment towards the values in the control group. There were no significant differences in the vermilion height and lip area between the post-treatment and the control groups, except for lower lip area values. Significant correlations found between the changes in incisor position and the changes in vermilion height were few in number for the upper lip but greater in number for the lower lip. Thus, the results of this study show that bimaxillary protrusion cases can be treated by the extraction of four premolars to produce an aesthetic improvement in frontal facial features.

Introduction We evaluated the 3-dimensional craniofacial skeletal and pharyngeal airway morphology in growing patients with and without cleft lip and palate. Methods Our juvenile subjects consisted of 34 girls (ages, 9-12 years); 15 had cleft lip and palate, and 19 did not. The adolescent subjects consisted of 32 girls (ages, 13-17 years); 14 had cleft lip and palate, and 18 did not. Each subject was examined with cone-beam computed tomography. The dimensions of the craniofacial skeleton and pharyngeal airway were measured. The Scheffe method of multiple comparisons was used to identify relationships among skeletal and pharyngeal variables. Results The pharyngeal airway and mandibular size variables did not differ significantly between the juvenile and adolescent cleft lip and palate groups. Significant differences were observed between each cleft lip and palate group and its corresponding control group. FHN-A, FHN-B, FH-NA, FH-NB, and Co-Me were significantly smaller in the cleft lip and palate groups than in the corresponding control groups. Anteroposterior and lateral widths, heights, and volumes of the superior oropharyngeal airway were significantly smaller in the adolescent cleft lip and palate group than in the adolescent controls. Conclusions The mandible and the oropharyngeal airway were larger in the adolescent controls than in the juvenile controls without cleft lip and palate, but there were no significant differences between the adolescent and juvenile patients with cleft lip and palate.

OBJECTIVES: To test the hypothesis that there is no difference in the morphology of the lips and to determine the degree of improvement in the smile after orthognathic surgery for Class III malocclusion. MATERIALS AND METHODS: The sample subjects included 30 adult female patients with dento-skeletal Class III malocclusion and 28 adult female volunteers with normal occlusion. Frontal facial photographs were taken before and after treatment, and 35 landmarks were placed on each tracing made from the frontal facial photograph. Thereafter, the landmarks were digitized into an x and y coordinate system with the subnasal point as the origin. The pretreatment rest and smile conditions were compared with the posttreatment conditions, respectively, using paired t-tests. In addition, two sample t-tests were used to test for differences between groups. RESULTS: Both the upper and lower lips in the smiles of the Class III pretreatment group were positioned downward, and the upward movement of the upper lip and commissure points were smaller compared with the control group. When smiling, the horizontal direction of the mouth corners was statistically significantly different between the pretreatment and posttreatment conditions, whereas these were wider in the posttreatment than in the pretreatment conditions. These characteristics of the Class III smile improved after orthognathic treatment, but the differences with the control group remained unchanged immediately after treatment. CONCLUSION: The hypothesis is rejected. The soft tissue morphology of patients with dento-skeletal Class III malocclusion shows a significant improvement after orthognathic surgery.

To evaluate the morphological changes in the lips and to determine the degree of improvement in the smile after orthodontic treatment for Class II division 1 malocclusion.The sample subjects were divided into two groups: a group that consisted of 20 adult female patients with Angle Class II division 1 malocclusion and a control group that consisted of 28 adult female volunteers with normal occlusion. Frontal photographs were taken before and after orthodontic treatment, and 35 landmarks were placed on each tracing made from the photograph. Thereafter, landmarks were digitized into an x- and y-coordinate system with the subnasal point as the origin. The comparisons between pretreatment and posttreatment at rest and on smiling, and the comparisons between Class II division 1 and control group were made using Student's t-test.Both the upper and lower lips in the smile of patients in the Class II division 1 pretreatment group were positioned downward, and the upward movement of the upper lip and mouth corners was smaller in comparison with the control group. These characteristics of the Class II smile improved after orthodontic treatment, but the differences with the control group remained unchanged immediately after treatment.The soft tissue morphology shows a relative improvement after orthodontic treatment.

Objective: To test the hypothesis that there is no difference in the stability of the hard and soft tissue changes following a surgical mandibular setback using a sagittal split ramus osteotomy or an intraoral vertical ramus osteotomy. Materials and Methods: The samples consisted of 45 female patients with mandibular prognathism, who were divided into two groups. Twenty-three underwent a sagittal split ramus osteotomy (SSRO) with rigid fixation by titanium mini-screws and maxillomandibular fixation (MMF) for 14.0 ± 0.7 days. Twenty-two underwent intraoral vertical ramus osteotomy (IVRO) without rigid fixation, and MMF was released 21.5 ± 3.3 days after surgery. Data were collected from standardized cephalometric radiographs taken at the start of preoperative orthodontic treatment (T1), immediately after surgery (MMF, T2), and the completion of postoperative treatment (T3). Angular measurements were compared on each of T1, T2, and T3. Results: There were no significant differences in the pretreatment hard and soft tissue morphology between the SSRO and IVRO. However, when fixation was released, the mandible was posteriorly positioned in the IVRO group. In the soft tissue profile, the mental region was located backward in the IVRO group at postoperative stage (T3). Conclusions: The hypothesis is rejected. The soft tissue profile of the IVRO group especially showed a retromandibular position after postoperative treatment in comparison with the SSRO group. This tendency of the IVRO group would contribute to the database for treatment planning and prediction.

Introduction The purpose of the study was to examine the changes in stability of pharyngeal airway space (PAS) and hyoid bone position after 2 types of mandibular osteotomies in comparison with a control group. Methods The subjects included 46 Japanese women with skeletal Class III malocclusion. Twenty-five patients with mandibular prognathism underwent single-jaw surgery with bilateral sagittal split ramus osteotomy (SSRO), and 21 patients underwent bilateral intraoral vertical ramus osteotomy (IVRO). The control subjects included 30 volunteer women with normal occlusion. The treated subjects were assessed at the beginning of treatment, immediately after surgery, and after postsurgical treatment. Results The Class III subjects had a significantly wider PAS than did the control subjects. Significant decreases in the lower PAS were observed after orthognathic surgery. The hyoid bone showed upward and forward movement with upward movement of the lower border of the PAS during the postsurgical stage in the SSRO group. In contrast, the anterior border of the PAS and the hyoid bone showed considerable backward movement in the IVRO group. Conclusions The posttreatment morphology of the PAS in both Class III groups approached that of the control group. The IVRO group showed a reduction in the airway dimensions, especially during the postsurgical period, which occurred during surgery in the SSRO group.

SUMMARY The purpose of the present study was to obtain quantitative values for human skull structures in a cross-sectional analysis of offspring and their parents. The offspring were classified into three groups according to age. For each of 11 maxillo-facial and nine dento-alveolar structural angular measurements, the mean and SD were calculated for each set of paternal, maternal, midparent and offspring. The standard deviation unit (SDU) values were calculated from the disparity between the measured value in a given individual, i.e. father, mother, midparent, offspring, and their corresponding group mean value. Three disparity values (D.v.), expressed by the difference between the SDU values in each pair (father-offspring, mother-offspr ing and midparent-offspring), were developed to evaluate the degree of familial resemblance for each of 20 morphometric measurements, and the differences among these values in three age groups were then investigated. The similarity ratio (S.r.), expressing the degree of correlation to the father and mother, was derived by processing the D.v. The relationship between the maxillo-facial S.r. and the dento-alveolar S.r. was analysed in each age group. There were significant differences between the D.v. in families and those in unrelated control groups. Consistency between the S.r. for maxillo-facial and that for dento-alveolar measurements was found in the older age groups. It is concluded that individual growth of skull morphology might be more predictable using the present method.

Introduction The purpose of the study was to examine the changes in stability of pharyngeal airway space (PAS) and hyoid bone position after 2 types of mandibular osteotomies in comparison with a control group. Methods The subjects included 46 Japanese women with skeletal Class III malocclusion. Twenty-five patients with mandibular prognathism underwent single-jaw surgery with bilateral sagittal split ramus osteotomy (SSRO), and 21 patients underwent bilateral intraoral vertical ramus osteotomy (IVRO). The control subjects included 30 volunteer women with normal occlusion. The treated subjects were assessed at the beginning of treatment, immediately after surgery, and after postsurgical treatment. Results The Class III subjects had a significantly wider PAS than did the control subjects. Significant decreases in the lower PAS were observed after orthognathic surgery. The hyoid bone showed upward and forward movement with upward movement of the lower border of the PAS during the postsurgical stage in the SSRO group. In contrast, the anterior border of the PAS and the hyoid bone showed considerable backward movement in the IVRO group. Conclusions The posttreatment morphology of the PAS in both Class III groups approached that of the control group. The IVRO group showed a reduction in the airway dimensions, especially during the postsurgical period, which occurred during surgery in the SSRO group.