Relationship of Mandibular Ramus Dimensions to Lower Third Molar Impaction.

OBJECTIVES: The aim of this study was to investigate the mandibular ramus features that could contribute to the etiology of mandibular third molar impaction. MATERIALS AND METHODS: Two hundred and forty subjects were divided into two groups: impacted group: 115 subjects presented with an impacted mandibular third molar, and control group: 125 subjects with the normal mandibular third molar eruption. Digital panoramic radiographs were used, and four angular and twelve linear measurements were done. Comparisons between groups were done using Student's t-test. Pearson correlation and linear regression tests were used to assess the degree of relationship between retromolar space and mandibular measurements. RESULTS: Control group showed significant greater measurements in most of the variables, whereas the impacted group showed significant larger gonial angle and larger inclination of lower posterior teeth than the control group. Significant correlations were found between retromolar space and coronoid height, ramal heights, ramus notch depths, the inclination of lower posterior teeth, and retromolar space/3M width ratio in both groups. CONCLUSION: The present study found that the configuration of the mandibular ramus appears to be discrete in many aspects in the erupted other than impacted lower third molars subjects, which might be a possible cause for the impaction.

Orthodontic treatment combined with tooth transplantation for an adult patient with a missing mandibular first molar: long-term follow-up.

A Japanese woman, age 29 years 8 months, had a missing mandibular left first molar, bimaxillary dentoalveolar protrusion, and crowding. She had a skeletal Class II relationship and a long face with a steep mandible. She had previously undergone root canal treatment for the mandibular right second premolar, and the mandibular left third molar was impacted. The maxillary left first premolar was extracted for autotransplantation to the mandibular left first molar region. After confirmation of a favorable prognosis for the transplanted tooth, the maxillary right first premolar, the mandibular right second premolar, and the impacted mandibular left third molar were extracted for orthodontic treatment. The active orthodontic treatment period was 32 months. The patient returned for follow-up records 12 years 7 months after the active treatment, and her facial profile and occlusion were well maintained. At 13 years 9 months after transplantation, no abnormalities were observed with the transplanted tooth in the radiographic and clinical evaluations.

Craniofacial cephalometric analysis of Bangladeshi and Japanese adults with normal occlusion and balanced faces: A comparative study.

AIMS: To determine the cephalometric norm among Bangladeshi adults and to investigate the differences in craniofacial morphology compared with Japanese and Caucasian normative data. MATERIALS AND METHODS: Cephalometric radiographs were obtained from 46 Bangladeshi males (mean age 23.8 years) and 52 Bangladeshi females (mean age 24.6 years). Inclusion criteria were the following: Both parents from the same ethnic group, class-I occlusion with an arch length discrepancy less than 2 mm, overbite and overjet from 2 to 4 mm, balanced face, all teeth present except third molar, no previous orthodontic treatment, and no prosthetic replacement of teeth. Nine angular and five linear measurements were constructed for skeletal hard tissue analysis, four angular and six linear measurements for dental hard tissue analysis, and two angular and seven linear measurements for soft tissue analysis. Mean and standard deviations of measurements were determined for each gender. Polygonal chart and profilogram were made. Independent t-test was used to determine differences. RESULTS: The present Bangladeshi population has a smaller lower face height (P<0.01) and the antero-posterior position of the maxilla and mandible was found to be significantly (P<0.01) more protruded compared with the Japanese and the Caucasian norms. Significantly (P<0.01) more protruded upper incisor, less steep occlusal plane, and thinner soft tissue chin were the characteristics in Bangladeshi adults. CONCLUSIONS: Relative to the cranial base (SN), the maxillo-mandibular complex was more anteriorly placed compared with the Japanese and Caucasian adults. Further, the effective length of the maxilla and mandible was shorter compared with the Japanese and Caucasian adults. These findings should be considered carefully during orthodontic treatment planning of Bangladeshi adults.

Mesiodistal tooth width and tooth size discrepancies of Yemeni Arabians: A pilot study.

OBJECTIVES: The aims of this study were to determine the mean mesiodistal tooth size width and Bolton's anterior and overall ratios, find any possible sex differences, and study the frequency of tooth size discrepancies among Yemeni population and if there is a difference in tooth size between the right and left sides. MATERIALS AND METHODS: 176 subjects aged 13-25 years (94 females and 82 males) with different types of malocclusions (94 Angle Class I, 37 Class II division 1, 36 Class II division 2, and 9 Class III) were included in the present study. The mean mesiodistal tooth size width and Bolton's ratios were determined. RESULTS: The results showed that males had significantly larger teeth than females. The prevalence rates of clinically significant discrepancy greater than 2 SD were 29.53% and 14.20% in the anterior and overall tooth size ratios, respectively. Further, the results revealed that there were no significant differences in the tooth size width between right and left sides. CONCLUSION: The findings of the present study indicate that there was no significant difference between Bolton's ratio and that of Yemeni population.

Soft and hard tissue changes after bimaxillary surgery in Japanese class III asymmetric patients.

OBJECTIVES: To assess the effects of bimaxillary surgery on Class III subjects with mandibular asymmetry, and to compare the effects of the type of surgery performed in the mandible on the facial profile especially in the presence of facial asymmetry. MATERIALS AND METHODS: Thirty-six patients in whom imbalance between the maxilla and the mandible were corrected by Le Fort I osteotomy combined with bilateral intraoral vertical ramus osteotomy (BIVRO group, n=9), bilateral sagittal split ramus osteotomy (BSSRO group, n=14), or a combination of intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) (IVRO + SSRO group, n=13). Cephalograms were taken before surgery (T1), and 1 year after surgery (T2). Hard and soft-tissue changes were compared. RESULTS: The postsurgical findings showed that greater mandibular backward displacement and greater upper lip forward movement were more pronounced among BIVRO group when compared with BSSRO group. Upper lip relation to E-line showed greater improvement in BIVRO group than BSSRO and IVRO + SSRO groups. The ratios of corresponding mandibular soft to hard tissue movements were higher than that of maxillary movements and were more pronounced in IVRO + SSRO and BSSRO groups when compared with BIVRO group. CONCLUSION: IVRO surgical technique appears to be more effective in positioning the mandible more posteriorly and improving upper and lower lips position and competence.

Long-term observation of autotransplanted teeth with complete root formation in orthodontic patients.

INTRODUCTION: The objective of this investigation was to examine the factors influencing the long-term prognosis of autotransplanted teeth with complete root formation. METHODS: Thirty-eight teeth, autotransplanted in 32 patients, were examined more than 6 years after transplantation. Periodontal health, condition of restoration, mobility, occlusal contact, level of gingival margin, and course of orthodontic movement were investigated clinically and with radiographs. RESULTS: More than 6 years after autotransplanation, 33 teeth survived in 27 patients. The survival rate was 86.8% (mean observation time, 9.2 years). Abnormal findings were observed in 9 teeth, so the success rate was 63.1%. An inadequate root filling tended to give rise to abnormal findings. CONCLUSIONS: The success of autotransplantation of a tooth with complete root formation is affected by the quality of root filling. When possible, clinicians should consider autotransplantation before root formation is complete.

A cross-sectional study on the relationship between craniofacial morphology and the coronoid process.

Although there have been some reports on the relationship between craniofacial morphology and the activity of the temporal muscle attached to the coronoid process, such relationship is still unclear. The aim of the present study was therefore to investigate the relationship between the coronoid process and overall craniofacial morphology using lateral cephalograms of 60 female subjects (mean age 9.6 years) without mandibular deviation. Statistical testing was undertaken using stepwise regression analysis. Anterior coronoid marginal depth correlated negatively (r = 0.71) with gonial angle, SNA, and overjet. The coronoid angle also correlated negatively (r = 0.86) with both the vertical and horizontal lengths from sella to the coronoid tip as well as with the horizontal length from sella to the posterior ramus margin. Furthermore, the coronoid length correlated positively (r = 0.61) with the coronoid angle and the anterior coronoid marginal depth. The coronoid width was also positively (r = 0.69) correlated with overbite. Coronoid process morphology is related not only to mandibular morphology and position but also to maxillary position and the dental relationship in the anterior region. It therefore seems clear that coronoid process morphology might be related to temporal muscle functioning and its associated craniofacial morphological measurements.

Relapse tendency in maxillary arch width in unilateral cleft lip and palate patients with different maxillary arch forms.

OBJECTIVE: The aim of this study was to investigate the relapse tendency in the maxillary dental arch widths in unilateral cleft lip and palate patients with different types of maxillary arch form. SUBJECTS: Thirty-two unilateral cleft lip and palate patients treated by one-stage surgical palatal closure were included. The subjects were divided into three groups according to the types of the maxillary arch forms: group A, symmetrical arch form; group B, collapse of minor segment; group C, collapse of both segments. METHODS: Using dental casts obtained at three different times, relapse in the intercanine, interpremolar, and intermolar widths in each group was assessed and differences between groups were investigated. RESULTS: Patients in group A showed stable results in all measurements. Patients in group B showed posttreatment relapse in the intercanine width only, whereas patients in group C demonstrated significant posttreatment relapses in the interpremolar and intermolar widths. Comparison between groups showed more significant relapse in the interpremolar and intermolar widths of group C than in those of group B. CONCLUSION: The types of the maxillary arch forms in unilateral cleft lip and palate patients might play a stronger role in the stability of the maxillary dental arch widths after orthodontic treatment in patients with collapse of both segments and a severe degree of maxillary narrowness.

Soft-tissue cephalometric norms in Yemeni men.

INTRODUCTION: The main purpose of this study was to develop soft-tissue cephalometric standards for Yemeni men and compare them with the cephalometric standards of normal North American white people. METHODS: Fifty Yemeni men (ages, 20-27 years; mean, 23.1 years) with normal occlusion were selected. With double selection by orthodontists and laypersons, a subsample of esthetically pleasing subjects was selected. Lateral cephalometric radiographs of all subjects were analyzed according to the Legan-Burstone and the Holdaway analyses. RESULTS: The Yemeni esthetically pleasing subjects (YPG) and the remaining subjects (YNG) showed significant differences with respect to mandibular prognathism, lower face-throat angle, nasolabial angle, mentolabial sulcus depth, and interlabial gap, when compared with the Legan-Burstone norms for white Americans; the YPG also had significantly less obtuse facial convexity angle than the YNG. Most values of both Yemeni groups were generally within the range of the values reported by Holdaway, except for 3 variables: skeletal profile convexity, basic upper-lip thickness, and H-angle, which were all significantly larger than those of Holdaway; the YPG showed less skeletal profile convexity than the YNG. CONCLUSIONS: These results show that the soft-tissue facial profiles of white Yemenis and Americans are different in certain respects; these racial differences must be considered during diagnosis and treatment planning. These results should serve as a useful reference for orthodontists and maxillofacial surgeons who treat Yemeni patients and also contribute to more satisfactory diagnosis and treatment planning for them.

Nonsurgical treatment of adult open bite using edgewise appliance combined with high-pull headgear and class III elastics.

This case report describes the effect of a combination of high-pull headgear and Class III elastics on the nonsurgical treatment of an adult open bite. The 19-year 1-month-old Japanese female presented with the anterior open bite of 4.0 mm and mild crowding. She had a skeletal Class II but a Class III molar relationship due to a severe proclination of the mandibular dental arch. Unilateral congenital missing premolars caused a discrepancy between the facial and dental midline. After extraction of two premolars and the impacted mandibular third molars, nonsurgical therapy was performed using the standard edgewise appliance combined with a high-pull headgear and Class III elastics. The successful treatment outcome and stability of the final occlusion indicates that a combination of high-pull headgear and Class III elastics is one of the effective devices in the nonsurgical treatment of open bite and, is especially helpful in uprighting the mandibular dental arch.

Relationship between bilateral condylar bone change and mandibular morphology: a study using morphometry.

This study was undertaken to evaluate the relationship between bilateral condylar bone change (BCBC) and mandibular morphology. Thirty Japanese women with BCBC as diagnosed from computed tomographic scans were compared to 2 control groups: 26 Class I and 25 Class II Japanese women. All cephalograms were traced and scanned, and 14 homologous landmarks were digitized. Coordinates were used for cephalometric analysis, Procrustes analysis, Euclidean distance matrix analysis (EDMA), and thin-plate spline (TPS) analysis. Comparison of the cephalometric data for the BCBC and Class I groups revealed significant shrinkage in the condylar process and ramus height, in addition to a shorter body length. The centroid size showed that BCBC mean geometric forms were smaller than those of Class I and Class II. The landmark morphology of the BCBC group differed from both Class I and Class II, as shown by the residuals (P < .001). EDMA showed expansion of infradentale-pogonion (9.9%) and along the anterior slope height of the condyle (28.6%), while the posterior slope height decreased (21.6%). The vertical ramus height (gonioncondylion) also decreased by 11.8% in comparison to Class I. Compared to Class II, BCBC ramus height was shorter by 8.9%, condylar width decreased 13.7%, and the posterior condylar slope was 22% shorter. TPS analysis showed increased antegonial notching, a vertically expanded symphysis, and a collapsed and more horizontal condyle in the BCBC group. The combination of the above methods was very helpful in assessing mandibular morphology and showed that BCBC might be related not only to changes in the condyle, but may dictate changes in the rest of the mandible as well.