Decision-making patterns among expert and novice orthodontists and oral maxillofacial surgeons in the management of adults with Class III malocclusions and moderate degree of skeletal discrepancies.

OBJECTIVE: To explore the decision-making patterns among expert and novice orthodontists and oral maxillofacial surgeons in the management of adults with Class III malocclusions and moderate skeletal discrepancies. DESIGN: Self-administered questionnaire survey. SETTING: Faculty of Dentistry, National University of Singapore and the University Dental Cluster, National University Hospital, Singapore. PARTICIPANTS: A total of 55 clinicians, comprising 13 expert orthodontists, 20 novice orthodontists, 10 expert oral maxillofacial surgeons and 12 novice oral maxillofacial surgeons. METHODS: Clinicians assessed six adults with a Class III malocclusion and moderate skeletal discrepancy. They were asked to decide who could be managed exclusively by orthodontic camouflage, who would require combined orthodontic-orthognathic surgery as the only viable treatment, or who could be offered both treatment options. RESULTS: The study found variable decision-making patterns among the clinicians in each case. Only 18.2%-40.0% of clinicians agreed that the cases selected were of moderate skeletal discrepancies and could be offered both treatment options whereas the rest were either more inclined to recommend orthodontic camouflage or orthognathic surgery. Intra-clinician agreement (n = 20) was only fair (Kappa value = 0.31). There was only slight inter-clinician agreement (n = 55) on their clinical decisions (Kappa value = 0.10). Clinical experience and dental specialty did not significantly influence clinicians' decisions. Oral and maxillofacial surgeons were 1.98 times more likely to indicate orthognathic surgery as the only viable treatment compared to the orthodontists (95% confidence interval = 1.15-3.42). CONCLUSION: Variability in the patterns of decision-making for adults with a Class III malocclusion and moderate skeletal discrepancy was observed among the clinicians with low repeatability and agreement.

Mandibular asymmetry: Is there a difference in the bone and soft tissue thickness between both sides?

OBJECTIVE: The asymmetric mandible presents the clinician with unique anatomic challenges in orthognathic surgery correction. This study aims to investigate these characteristics of the asymmetric mandible: mandible bone thickness, soft tissue thickness, and the proximity of the bone cortex to the inferior alveolar nerve (IAN) canal. STUDY DESIGN: Three-dimensional virtual models were created of 35 participants of Asian descent with mandibular asymmetry. Mandibular bone thicknesses and soft tissue thicknesses were measured at certain landmarks. Statistical analysis of the thicknesses of both sides of the mandible was performed. Comparison of thicknesses between patients with minor and major asymmetry were also performed. RESULTS: The bone was significantly thinner at the longer side at all 4 mandible landmarks (P < .001). The bone lateral to the IAN was significantly thinner at the longer side, as well (P < .001). The soft tissue thickness did not differ significantly across sides, except at 1 landmark. These findings were even more exaggerated in the major asymmetry group. CONCLUSIONS: The longer side of the asymmetric mandible bone was thinner, and the bone lateral to the IAN was also thinner as a result. This asymmetric thinness was exaggerated in patients with severe asymmetry, which may predispose the longer side to IAN injury and unfavorable fractures. The differences in bone thickness in the asymmetric mandible may also result in residual postoperative asymmetry.

Influence of lip form on the perceived ideal incisal show at rest.

INTRODUCTION: A widely used guide of 2 mm incisal show at rest is used as an esthetic guide in treatment planning for many patients. However, this does not consider the lip form at rest. This study aimed to investigate the most esthetic incisal show at rest, at varying lip forms, perceived by dental professionals and laypeople. METHODS: Three volunteers of each gender and type of lip form (straight, moderate, and high) were recruited. For each volunteer, 6 images of their perioral region with a variable incisal display at rest were generated. A survey was conducted whereby respondents were asked to grade the attractiveness of each image using a numerical visual analog scale from 0-10. RESULTS: A survey sample of 107 respondents participated in the study (male-to-female ratio = 37 to 70; dental professionals-to-laypeople ratio = 50 to 57). Mann-Whitney U-test was used to analyze the differences in preferences between the various groups (P <0.05). Both dental professionals and laypeople responded that 2 mm incisal show at rest is only suitable for patients with straight lip form. However, for patients with moderate or high lip forms, an incisal show of 4-5 mm was preferred. There was also no significant difference between the perceived ideal incisal show of dental professionals and laypeople, except for the ideal incisal show of models with straight lip form. CONCLUSIONS: The guide of 2 mm incisal show at rest is appropriate only for patients with straight lip form. Patients with moderate or high lip form should have a greater incisal show. This finding was agreed on by both dental professionals and laypeople, regardless of their gender.

Maxillary third molar: patterns of impaction and their relation to oroantral perforation.

PURPOSE: The objectives of this study were to examine 1) the patterns of the impacted maxillary wisdom tooth and 2) the proximity of the impacted maxillary wisdom tooth to the maxillary sinus in relation to oroantral perforation during the removal of a maxillary wisdom tooth. MATERIALS AND METHODS: This retrospective study reviewed the clinical records and dental pantomograms of patients who underwent the removal of maxillary wisdom teeth under general anesthesia over a 6-month period. Using a modified version of the Archer classification of impacted maxillary wisdom teeth, types of impaction were classified according to depth, angulation of impaction, and proximity to the floor of the sinus. Clinical records showed the occurrence of oroantral perforation. RESULTS: In total, 845 maxillary wisdom teeth were removed; 66.8% were by routine extraction and 33.2% were removed surgically. The most common type of impaction was vertical followed by mesioangular. Most impacted teeth were at the level between the occlusal and cervical level of the adjacent second molar. Only 7 of the 278 excised wisdom teeth produced an oroantral perforation. Only 0.9% of all cases with a close sinus approximation showed an oroantral perforation. Statistical analysis with the Fisher exact test showed statistically significant associations of depth of impaction (P < .001), eruption status (P = .001), and long-axis position (P < .001) to the occurrence of an oroantral perforation. Sinus approximation showed no association with the occurrence of an oroantral perforation (P = 1.000). CONCLUSION: The depth of impaction of the maxillary wisdom tooth is a possible predictor of the possibility of oro-antral perforation if removal of the tooth is required. Due to the limitation of the radiograph, it is not a reliable to use radiographic close proximity of the sinus to predict the occurrence of oro-antral perforation when the maxillary wisdom tooth is removed.