Objective: To systematically review the effects of cortical bone thickness (CBT) and bone mass density (BMD) on miniscrew success rates. Methods: MEDLINE, the Cochrane Library and Scopus were searched up to June 2020. Of a total of 5734 articles, seven studies were finally selected for the review. Results: The overall mean success rate weighted by the number of miniscrews was 87.21% (89.87% in the maxilla and 79.24% in the mandible). There was a significantly higher success rate for miniscrews placed in the maxilla compared with those in the mandible (P < .05). CBT showed small positive effect on the success rate of the miniscrews although it failed to reach a statistical significance. The cortical BMD had a minimal effect on the success of the miniscrews. The cancellous BMD demonstrated a very strong effect on the success of the miniscrews in the maxilla, whereas it showed a moderately negative effect in the mandible. Limitations: Because of the small number and clinical heterogeneity of the included studies, the results should be interpreted with caution. Further randomized clinical studies with a large sample size are recommended.
Background: Mandibular setback surgery can change the position of the mandible which improves occlusion and facial profile. Surgical movement of the mandible affects the base of the tongue, hyoid bone, and associated tissues, resulting in changes in the pharyngeal airway space. The aim of this study was to analyze the 3-dimensional (3D) changes in the hyoid bone and tongue positions and oropharyngeal airway space after mandibular setback surgery. Methods: A total of 30 pairs of cone-beam computed tomography (CBCT) images taken before and 1 month after surgery were analyzed by measuring changes in the hyoid bone and tongue positions and oropharyngeal airway space. The CBCT images were reoriented using InVivo 5.3 software (Anatomage, San Jose, USA) and landmarks were assigned to establish coordinates in a three-dimensional plane. The mean age of the patients was 21.7 years and the mean amount of mandibular setback was 5.94 mm measured from the B-point. Results: The hyoid bone showed significant posterior and inferior displacement (P < 0.001, P < 0.001, respectively). Significant superior and posterior movements of the tongue were observed (P < 0.05, P < 0.05, respectively). Regarding the velopharyngeal and glossopharyngeal spaces, there were significant reductions in the volume and minimal crosssectional area (P < 0.001). The anteroposterior and transverse widths of the minimal cross-sectional area were decreased (P < 0.001, P < 0.001, respectively). In addition, the amount of mandibular setback positively correlated with the amount of posterior and inferior movement of the hyoid bone (P < 0.05, P < 0.05, respectively). Conclusion: There were significant changes in the hyoid bone, tongue, and airway space after mandibular setback surgery.
Objective The purpose of this study was to evaluate the esthetic preference for various Korean silhouette profiles. Methods The Korean average male and female profiles were modified by changing the lower facial height and anteroposterior lip position to produce nine types of profiles. In order to test intrarater reliability, the average profile was copied once more to be included for evaluation. A questionnaire containing 10 profiles for each sex, each of which had to be rated for preference on a numerical rating scale from 0 to 10, was administered to 30 adult orthodontic patients, 30 dental students, 30 orthodontists, and 30 dentists excluding orthodontists. The data were statistically analyzed using the intraclass correlation coefficient (ICC), independent t -test, and one-way ANOVA. Results The ICC of overall intrarater reliability was 0.629. For several profiles, significantly higher scores were given to male profiles than to female profiles ( p < 0.05). However, no significant differences were found in the scores for all profiles among the four rater groups. Among the short profiles, a significantly higher score was given to the retruded profile, and among the vertically average and long profiles, a significantly higher score was given to the horizontally average profile ( p < 0.001). Among all the profiles, significantly lower scores were given to the protruded profile ( p < 0.001). Conclusions This study revealed good overall intrarater reliability, with several types of male profiles being esthetically preferred over female profiles. Moreover, while retruded and horizontally average profiles were generally preferred, protruded profiles were not.
ObjectiveThe aim of this study was to analyze three-dimensional (3D) changes in maxillary dentition in Class II malocclusion treatment using arch wire with continuous tip-back bends or compensating curve, together with intermaxillary elastics by superimposing 3D virtual models.MethodsThe subjects were 20 patients (2 men and 18 women; mean age 20 years 7 months ± 3 years 9 months) with Class II malocclusion treated using 0.016 × 0.022-inch multiloop edgewise arch wire with continuous tip-back bends or titanium molybdenum alloy ideal arch wire with compensating curve, together with intermaxillary elastics. Linear and angular measurements were performed to investigate maxillary teeth displacement by superimposing pre- and post-treatment 3D virtual models using Rapidform 2006 and analyzing the results using paired t-tests.ResultsThere were posterior displacement of maxillary teeth (p < 0.01) with distal crown tipping of canine, second premolar and first molar (p < 0.05), expansion of maxillary arch (p < 0.05) with buccoversion of second premolar and first molar (p < 0.01), and distal-in rotation of first molar (p < 0.01). Reduced angular difference between anterior and posterior occlusal planes (p < 0.001), with extrusion of anterior teeth (p < 0.05) and intrusion of second premolar and first molar (p < 0.001) was observed.ConclusionsClass II treatment using an arch wire with continuous tip-back bends or a compensating curve, together with intermaxillary elastics, could retract and expand maxillary dentition, and reduce occlusal curvature. These results will help clinicians in understanding the mechanism of this Class II treatment.
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