A cross-sectional study on three-dimensional compensatory characteristics of maxillary teeth in patients with different types of skeletal Class III malocclusion with mandibular asymmetry.

OBJECTIVE: The purpose of this study was to analyze three-dimensional dental compensation in patients with different types of skeletal Class III malocclusion with mandibular asymmetry, using cone-beam computed tomography (CBCT) and three-dimensional reconstruction measurement technology, thereby providing clinical guidance and reference for combined orthodontic and orthognathic treatment. METHODS: 81 patients with skeletal Class III malocclusion with mandibular asymmetry were selected in accordance with the inclusion criteria. According to a new classification method based on the direction and amount of menton deviation relative to ramus deviation, patients were divided into three groups called Type 1, Type 2, and Type 3. In Type 1, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was greater than that of ramus deviation. In Type 2, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was smaller than that of ramus deviation. In Type 3, the direction of menton deviation was inconsistent with that of ramus deviation. The maxillary occlusal plane (OP), anterior occlusal plane (AOP), and posterior occlusal plane (POP) were measured on reconstructed CBCT images. The vertical, transverse, and anteroposterior distances from maxillary teeth to reference planes and the 3D angles between the long axis of these teeth and reference planes were measured. These dental variables measured from the deviated and non-deviated sides were compared within each group, as well as among each other. RESULTS: Of the 81 patients with asymmetrical Class III malocclusion, 52 patients were categorized in Type 1, 12 patients in Type 2, and 17 patients in Type 3. There were significant differences between deviated and non-deviated sides in Type 1 and Type 3 (p < 0.05). In Type 1, the vertical distances of maxillary teeth on the deviated side were lower than those on the non-deviated side, and AOP, OP, and POP on the deviated side were larger than those on the non-deviated side (p < 0.05). In Type 3, the vertical distances of the maxillary teeth on the deviated side were lower (p < 0.05), and the AOP and OP on the deviated side were larger than those on the non-deviated side. In all three groups, the transverse distances of the maxillary teeth from the mid-sagittal plane on the deviated side were larger than those on the non-deviated side (p < 0.05), and the angles between the long axis of maxillary teeth and the mid-sagittal plane on the deviated side were larger, respectively (p < 0.05). CONCLUSIONS: The maxillary teeth on the deviated side were observed to have smaller eruption heights in Type 1 and Type 3. In Type 1, AOP, POP, and OP were greater on the deviated side, while in Type 3, only AOP and OP were greater on the deviated side. The maxillary teeth of patients in all three groups on the deviated side were buccal and buccally inclined. Larger sample observations are still needed to further verify these findings.

Three-dimensional changes of the upper airway in patients with Class II malocclusion treated with functional appliances: a systematic review and meta-analysis.

BACKGROUND/OBJECTIVE: To evaluate the three-dimensional (3D) changes of the upper airway in patients with Class II malocclusion treated with functional appliances (FAs). SEARCH METHODS AND ELIGIBILITY CRITERIA: A comprehensive search of seven electronic databases was conducted from the date of inception to 12 July 2020. Manual search was also performed in relevant Chinese and English periodicals. Prospective and retrospective studies evaluating the 3D airway changes after FAs applied on growing patients with skeletal Class II malocclusion were included. DATA COLLECTION AND ANALYSIS: Risk of bias assessment of each included study was performed referring to ROBINS-I. The effects of FAs on upper airway were evaluated by meta-analysis using STATA software. The outcome variables were the changes of oropharyngeal airway volumes (OAVs), nasopharyngeal airway volumes (NAVs), minimum cross-sectional area (MCA) and antero-posterior position of hyoid bone (HB). The overall quality of evidence for each outcome was rated based on Grading of Recommendations Assessment, Development and Evaluation recommendations. RESULTS: Nine studies were ultimately included in the systematic review and five were included and analyzed in meta-analysis. The results indicated that the pooled mean differences among these studies were 2162.80 [95 per cent confidence interval (CI): 1264.97, 3060.62), 382.20 (95 per cent CI: 140.95, 623.44), 59.91 (95 per cent CI: 41.45, 78.38), and 0.63 (95 per cent CI: -1.97, 3.23) for changes of OAVs, NAVs, MCA, and antero-posterior position of HB, respectively. CONCLUSION: Weak evidence suggests that FAs can increase OAVs, NAVs, and MCA in growing patients with Class II malocclusion. Weak evidence also suggests that antero-posterior position of HB cannot be affected by FAs. Further studies are necessary to assess the stability of its effect on the upper airway in the long term. REGISTRATION: The review protocol was not registered prior to the study.

The Effectiveness of Photobiomodulation on Accelerating Tooth Movement in Orthodontics: A Systematic Review and Meta-Analysis.

Objective: This meta-analysis evaluated the effectiveness of photobiomodulation therapy (PBMT) on accelerating orthodontic tooth movement (OTM) in clinical practice. Methods: Data from bilingual journals across seven different databases were compiled and analyzed. Randomized controlled trials (RCTs) and quasi-RCTs regarding the effect of PBMT on OTM in cases with four first premolar extractions in split-mouth design were selected. This study was conducted after approval from the IRB. The outcome variables were the cumulative tooth movement distances in 1, 2, and 3 months. Data extraction was performed by two authors independently and in duplicate. Risk of bias was assessed. Results: Eight RCTs and one quasi-RCT were ultimately included and analyzed in meta-analysis. This study revealed that the pooled mean difference (MD) among these trials was 0.30 [95% confidence interval (CI): -0.02 to 0.62], 0.69 (95% CI: 0.08 to 1.29), and 0.64 (95% CI: -0.01 to 1.29) for 1, 2, and 3 months, respectively. The results remained consistent after sensitivity analysis assessment. Conclusions: There is insufficient evidence to support that photobiomodulation accelerates tooth movement in orthodontic treatments. Our results suggest that the optimal parameters of PBMT on OTM in human might be about 20 mW, 5-8 J/cm2, 0.5 W/cm2, 0.2 J/point, and 2-10 J/tooth. More large-sample multicenter clinical trials carried out in similar settings are required to confirm and pinpoint treatment efficiency and optimal parameters. Registration: The review protocol was not registered prior to the study.