Morphologic quantification of the maxilla and the mandible with cone-beam computed tomography.

INTRODUCTION: The purpose of this pilot study was to use cone-beam computed tomography (CBCT) to determine the volumes of the maxilla and the mandible in subjects with skeletal Class I, Class II, and Class III malocclusions. Hypothesis 1 was that the volume (size) of a skeletal Class II maxilla is larger than those of Class I and Class III. Hypothesis 2 was that the volume of a skeletal Class III mandible is larger than those of Class I and Class II. METHODS: Thirty women patients were classified into 3 groups according to their skeletal pattern: skeletal Class I (0 degrees < or =ANB <6 degrees ), Class II (ANB > or =6 degrees ) and Class III (ANB <0 degrees ). The volumes of the maxilla and the mandible were measured with CBCT. CB MercuRay (Hitachi Medico, Tokyo, Japan) and CB works software (CyberMed, Seoul, Korea) were used to process the images. RESULTS: There was a trend that skeletal Class III subjects might have significantly greater mandibular volume compared with Class II subjects (P = 0.089). The ratios of maxilla-to-mandible volumes between the skeletal Class II and Class III groups were significantly different (P = 0.005). Differences were observed in the ratios of maxillary and mandibular volumes across the 3 groups. CONCLUSIONS: Hypotheses 1 and 2 were rejected; there was no trend for Class III subjects to have larger mandibles (P = 0.089) compared with Class II subjects. The ratio of the maxilla and mandible volumes in skeletal Class III subjects was significantly larger (P = 0.005) compared with Class II subjects.

Assessment of facial golden proportions among young Japanese women.

INTRODUCTION: Facial proportions are of interest in orthodontics. The null hypothesis is that there is no difference in golden proportions of the soft-tissue facial balance between Japanese and white women. METHODS: Facial proportions were assessed by examining photographs of 3 groups of Asian women: group 1, 30 young adult patients with a skeletal Class 1 occlusion; group 2, 30 models; and group 3, 14 popular actresses. Photographic prints or slides were digitized for image analysis. Group 1 subjects had standardized photos taken as part of their treatment. Photos of the subjects in groups 2 and 3 were collected from magazines and other sources and were of varying sizes; therefore, the output image size was not considered. The range of measurement errors was 0.17% to 1.16%. ANOVA was selected because the data set was normally distributed with homogeneous variances. RESULTS: The subjects in the 3 groups showed good total facial proportions. The proportions of the face-height components in group 1 were similar to the golden proportion, which indicated a longer, lower facial height and shorter nose. Group 2 differed from the golden proportion, with a short, lower facial height. Group 3 had golden proportions in all 7 measurements. The proportion of the face width deviated from the golden proportion, indicating a small mouth or wide-set eyes in groups 1 and 2. CONCLUSIONS: The null hypothesis was verified in the group 3 actresses in the facial height components. Some measurements in groups 1 and 2 showed different facial proportions that deviated from the golden proportion (ratio).

Autotransplantation of 28 premolar donor teeth in 24 orthodontic patients.

OBJECTIVE: To test the null hypothesis that premolar autotransplantation is not successful for orthodontic patients. MATERIALS AND METHODS: In the present study, 28 premolar transplants from 24 orthodontic patients were associated with orthodontic treatment. At a routine 3-month appointment, patients underwent a dental radiograph and a chair-side observation for periodontal problems. Three sets of dental radiographs were taken by one dental assistant using a custom holder at: preoperation (T0), 2 year postoperation (T1), and retention (T2) (4- to 14-year follow-up observation) stages. All transplants were conducted in a one-phase operation by one operator (Dr Inoue). Recipient sites were: ten for missing maxillary canines, nine for maxillary centrals and laterals, eight for lower second premolar, and five for other missing premolar sites. All recipients maintained the retained primary tooth with a socket. RESULTS: The success ratio of all 28 transplants was 100%, although four transplants shorter than a 4-year period of observation were omitted. Two transplant patients, one with a medical history of histiocytosis and the other with a history of osteomyelitis of the maxilla without a recipient socket, were also excluded from this study. Eleven of 22 premolar transplants had a root canal treatment (RCT), four of which had RCT within 2 years after the operation. CONCLUSIONS: The null hypothesis was rejected. The success ratio of premolar transplants was 100%.

Histomorphometric study on the effects of age on orthodontic tooth movement and alveolar bone turnover in rats.

The aim of this study was to investigate, in a rat model, the effects of age on the amount of tooth movement and concomitant changes in alveolar bone turnover activity adjacent to orthodontically treated tooth roots. Rats (n = 48) of four different age groups (10, 30, 50, and 80 wk of age) were used in the experiment. Maxillary first molars were tipped mesially with a nickel titanium alloy coil-spring for 2 wk by a continuous force of 10 cN. Forty-eight age-matched untreated rats were used as controls. The changes in alveolar bone turnover were assessed histomorphometrically. Two weeks after the start of tooth movement, the amount of tooth movement was found to decrease with age and was significantly different among the four age groups. The histomorphometric study demonstrated that, in all experimental groups, turnover of alveolar bone increased significantly compared with that of each age-matched untreated group. However, the rate of increase decreased in an age-related manner. These results suggest that the age-dependent decrease in alveolar bone turnover activity, in response to mechanical forces, may negatively affect the amount of tooth movement.

Facial soft tissue thickness in skeletal type I Japanese children.

Facial reconstruction techniques used in forensic anthropology require knowledge of the facial soft tissue thickness of each race if facial features are to be reconstructed correctly. If this is inaccurate, so also will be the reconstructed face. Knowledge of differences by age and sex are also required. Therefore, when unknown human skeletal remains are found, the forensic anthropologist investigates for race, sex, and age, and for other variables of relevance. Cephalometric X-ray images of living persons can help to provide this information. They give an approximately 10% enlargement from true size and can demonstrate the relationship between soft and hard tissue. In the present study, facial soft tissue thickness in Japanese children was measured at 12 anthropological points using X-ray cephalometry in order to establish a database for facial soft tissue thickness. This study of both boys and girls, aged from 6 to 18 years, follows a previous study of Japanese female children only, and focuses on facial soft tissue thickness in only one skeletal type. Sex differences in thickness of tissue were found from 12 years of age upwards. The study provides more detailed and accurate measurements than past reports of facial soft tissue thickness, and reveals the uniqueness of the Japanese child's facial profile.

Effect of age on alveolar bone turnover adjacent to maxillary molar roots in male rats: A histomorphometric study.

OBJECTIVE: The effect of age on alveolar bone turnover adjacent to maxillary molar roots of male rats was assessed histomorphometrically with special focus on bone formation and resorption. DESIGN: A total of 110 male Wistar rats ranging in age from 6 to 100 weeks were used for this study. Histomorphometric parameters were measured in fluorescence-labeled undecalcified ground and paraffin-embedded decalcified sections of the alveolar wall around the disto-lingual roots of the maxillary first molars. Bone formation was measured statically by determining the percentage of the bone surface that was double-labeled surface (dLS/BS), bone formation rate (BFR/BS), and mineral apposition rate (MAR). Bone resorption was quantified statically in terms of the number of osteoclasts (N.Oc/BS) and the percentage of the bone surface covered with osteoclasts (Oc.S/BS). RESULTS: For the total surface of the alveolar wall, the values obtained for all parameters of both bone formation and resorption decreased with advancing age. All these values rapidly decreased during the early part of the life span, from 6 to 30-40 weeks of age, of the rats. A site-specific difference between the distal and mesial sides of the alveolar wall was found for each age group. dLS/BS and BFR/BS were significantly greater (p < 0.0001) on the mesial side than on the distal one. On the other hand, the distal side showed significantly greater (p < 0.0001) value for N.Oc/BS and Oc.S/BS did the mesial one. However, there were no significant age-related changes in dLS/BS and BFR/BS on the distal side or in N.Oc/BS and Oc.S/BS on the mesial side throughout observation period. CONCLUSION: The results of the present study demonstrate that alveolar bone turnover of male rats decreased rapidly with advancing age but that in order to maintain the integrity of the tooth function mechanical stress may still have participated in bone formation and resorption of the alveolar wall even in rats 100-week old.

Chincup therapy for a young woman with anterior displacement and obtuse angle of the mandible in Class I malocclusion.

INTRODUCTION: Dolichofacial skeletal patterns are a challenge for the orthodontist. Even when treatment for a long-face patient begins before the adolescent growth spurt, excellent compliance is generally needed. The patient whose care is presented here started treatment at age 14. RESULTS: The extraction of 4 premolars, rapid palatal expansion, and excellent compliance wearing a combination occipital and vertical-pull chincup over a 2-year period led to good results at age 16, with minimal dental or skeletal relapse at age 18 years 5 months.

A morphological study of the relationship between arch dimensions and craniofacial structures in adolescents with Class II Division 1 malocclusions and various facial types.

INTRODUCTION: The objective of this study was to evaluate dental arch forms associated with various facial types in adolescents with Class II Division 1 malocclusions by using mathematical functions to describe the arch form at clinical bracket points. METHODS: Pretreatment lateral cephalograms and dental study casts of 73 white Brazilians were divided into 3 groups according to facial type: 17 brachyfacial, 24 mesofacial, and 32 dolichofacial. Fifteen landmarks on each dental cast were digitized. Computer-generated mathematical arch forms (fourth-degree polynomial equation and beta function) were used to evaluate arch form differences by superimposition. RESULTS: The constant term related to dental arch depth of the brachyfacial subjects was significantly greater than that of the mesofacial subjects in the maxillary arch (P = .004). Superimposition of maxillary arch analysis showed that the posterior segment width of the mathematically computed arch form tended to increase from dolichofacial type to brachyfacial type. The arch forms drawn by the 2 equations coincided at the incisal and molar regions. CONCLUSIONS: The beta function is appropriate for predicting the finishing arch form, and the polynomial equation is appropriate for the analysis (diagnosis) of various Class II malocclusions, including ovoid, tapered, and square arch forms and dental arch asymmetry.

Facial soft tissue thickness in Japanese female children.

Facial reconstruction techniques used in forensic anthropology are based on soft tissue thickness measurements. Many studies of facial tissue thickness in adults have been published that take racial background into account. However, the only data on facial thickness in children are derived from studies of American, British, and Hispanic children. The authors therefore measured facial tissue thickness in Japanese children, with the aim of providing data for producing accurate facial likenesses and to evaluate matching of skull-photo superimposition images. Cephalometric X-ray images give an approximately 10% enlargement from true size and can demonstrate the relationship between soft and hard tissue. Facial soft tissue thickness was measured at 12 anthropological points using X-ray cephalometry.

Orthodontic treatment of an impacted dilacerated maxillary central incisor combined with surgical exposure and apicoectomy.

The impacted incisor was moved into its proper position with surgical exposure and orthodontic traction. Although apicoectomy was performed during the orthodontic treatment, the incisor showed good stability after the long retention period.

Craniofacial differences between Japanese and British Caucasian females with a skeletal Class III malocclusion.

The racial differences in the craniofacial structures of 28 Japanese and 24 British Caucasian females with Class III malocclusions associated with a severe skeletal pattern were examined using lateral cephalograms. The mean age of the Japanese and Caucasian patients was 19.6 +/- 3.5 and 20.2 +/- 3.8 years (+/- SD), respectively. The mean values of 14 linear and 13 angular cephalometric parameters were compared between the two groups. The results showed that the Japanese females had a significantly reduced anterior cranial base (P < 0.01), a more retrusive midfacial component (P < 0.05), and a significantly increased lower anterior facial height (P < 0.01) associated with a more obtuse gonial angle (P < 0.05) compared with the Caucasians. Analysis of the dento-alveolar component in Japanese patients indicated more proclined upper incisors (P < 0.01) compared with those of Caucasian subjects. The reduced anterior cranial base and midfacial component, and the high-angle facial pattern in the Japanese population, may be morphological features based on race, and these skeletal features seem to be less favourable for a skeletal Class III growth pattern compared with the Caucasian population.

Morphological differences in the craniofacial structure between Japanese and Caucasian girls with Class II Division 1 malocclusions.

The craniofacial features of 49 Japanese and 75 British Caucasian girls with Class II division 1 malocclusions were evaluated from lateral cephalometric radiographs, and the morphological differences between both races were examined. The subjects' ages ranged from 11 years 1 month to 12 years 11 months. The mean values of 13 linear and 13 angular cephalometric parameters were compared. The Japanese Class II division 1 sample had a significantly shorter anterior cranial base length (S-N; P < 0.001) and a more obtuse articular angle (S-Ar-Go; P < 0.001). Analysis of the dentoalveolar components in Japanese subjects showed more proclined lower incisors (L1/Go-Me; P < 0.05) and a steeper occlusal plane (Occ.P/S-N; P < 0.01) relative to those of Caucasians. The short anterior cranial base length and excessive vertical development in the Japanese population might be common racial morphological features, but the main reason for the Class II division 1 skeletal disharmony in both races was different; it was caused by the anteriorly positioned maxilla in Caucasians and the backward rotated mandible in the Japanese.

Craniofacial features of patients with Class III abnormalities: growth-related changes and effects of short-term and long-term chincup therapy.

The craniofacial features of patients with Class III abnormalities, including growth-related changes and effects of short-term and long-term chincup therapy, were studied. Twenty female subjects were treated with chincups and an orthopedic force of 500 g for 31 months (short-term treatment group). Another 36 female patients were treated with chincups and a force of 250 to 300 g for 86 months (long-term treatment group). All subjects treated with chincups had lateral cephalograms taken before treatment (T0), after treatment (T1), and at retention (T2). Cross-sectional lateral films of 562 skeletal Class III girls were selected from the records of 1265 Class III patients at a public hospital and private clinics as controls. The controls were selected to approximately match the ANB angle, Wits appraisal, and chronological age of the treated groups. Short-term treatment resulted in a slight improvement in ANB angle and Wits appraisal, while long-term treatment resulted in a significant improvement in ANB angle and Wits appraisal. Such treatment also resulted in a significant inhibition of the growth of the ramus (2.2 mm) and body length (3.6 mm) of the mandible, a backward rotation of the mandible, and a reduction (8.2 degrees ) of the gonial angle. However, there was no alteration of any parameter of the maxilla and the cranial base, except the length of S-N and N-S-Ar in the long-term treatment group. Subjects who completed the long-term treatment protocol retained the changes by wearing the appliance during sleep, with a force of 200 g applied to the center of the chin.