INTRODUCTION:Space opening with clear aligner therapy has been little researched. The aim of this retrospective observational study was to investigate the predictability of the Invisalign appliance (Align Technology, San José, Calif) in opening space for the permanent maxillary lateral incisor (PMLI). METHODS:Data from Align Technology's digital treatment planning software system, ClinCheck (Align Technology, San Jose, Calif), were evaluated to determine the initial, predicted, and achieved space opening for the PMLI in patients satisfying the selection criteria. Acquisition of the relevant measurement values was performed using the Geomagic (3D Systems, Rock Hill, SC) metrology system. A mixed-effects model was used to account for within-patient dependence among tooth spaces and the 2 one-sided tests for equivalence testing and Bland-Altman analysis were employed. RESULTS:Space opening for 41 PMLIs in 25 patients with a mean age of 21.2 ± 13.0 years was evaluated. Approximately 65.2%-69.8% of predicted space opening was achieved, with the mean differences between predicted and achieved values ranging from 0.9 ± 1.0 mm to 1.4 ± 1.2 mm (P <0.05). For patients <18 years of age, the mean difference between predicted and achieved canine angulation changes was 9.4 ± 9.1°, with 95% limits of agreement from -8.4° to +27.2° (P = 0.015). Mean differences between predicted and achieved canine angulation changes in patients ≥18 years of age (5.3 ± 6.4°) and central incisor angulation changes in patients <18 years of age (-0.1 ± 8.0°) and ≥18 years of age (-4.8 ± 7.6°) were not statistically significant. CONCLUSIONS:The findings can help clinicians better understand the planning of space opening for PMLIs before clear aligner therapy commences and provide baseline information for future research.
Introduction The objective of this study was to evaluate the relationship between mandibular first molar inclination, Andrews’ WALA-facial axis (FA) distance, and vertical skeletal pattern in adolescent and adult samples using cone-beam computed tomography and 3-dimensional intraoral scan data. Methods Cone-beam computed tomography and 3-dimensional model data from untreated adolescents (n = 20; mean age, 15.32 years) and adults (n = 50; mean age, 41.13 years) with near-normal occlusion were analyzed. Measurements included WALA-FA distance, buccolingual inclination of the mandibular first molars, and the Frankfort-mandibular plane angle. Statistical tests included t tests and correlation analyses. Results Adolescents had a significantly greater mean WALA-FA distance (2.85 mm) than adults (2.28 mm; P <0.0001). A significant positive correlation existed between molar inclination and WALA-FA distance in both groups. In adolescents only, a significant negative correlation was found between molar inclination and the Frankfort-mandibular plane angle. Molar inclination (approximately 15° lingual) did not differ significantly between the groups. Conclusions In subjects with normal occlusion, WALA-FA distances for the mandibular first molars are not constant; adults have smaller WALA-FA distances than adolescents, and mandibular first molars have a lingual inclination of approximately 15° in both adults and adolescents. Clinicians should consider the natural buccolingual inclination of the teeth and alveolar bone and apply individualized WALA-FA guidelines to support long-term stability and function.
INTRODUCTION:Patients with skeletal Class III malocclusion often have thin anterior alveolar bone and an increased periodontal risk. This study evaluated 3-dimensional (3D) alveolar bone volume changes in patients treated with or without periodontally accelerated osteogenic orthodontics (PAOO) using a deep learning-assisted cone-beam computed tomography (CBCT) approach. METHODS:A total of 42 adults undergoing orthodontic-orthognathic treatment were divided into a PAOO group (group S, n = 21) and a matched non-PAOO control group (group NS, n = 21). CBCT scans were obtained at baseline (T1) and posttreatment (T3), with a 6-month post-PAOO scan (T2) for group S. Labial, lingual, and total alveolar bone volumes were quantified using a deep learning-assisted automated segmentation tool. Linear mixed-effects models were used to analyze longitudinal changes and treatment effects, adjusting for baseline root length. RESULTS:In group S, labial alveolar bone volume increased from T1 (42.94 ± 23.15 mm3) to T3 (84.15 ± 36.82 mm3; P <0.001), contributing to an increase in total alveolar bone volume (139.92 ± 86.42 mm3 at T3 vs 114.20 ± 66.86 mm3 at T1; P <0.001). Group NS showed no change in labial bone volume (P = 0.846) but a reduction in total bone volume at T3 (93.76 ± 67.24 mm3; P <0.001), primarily driven by lingual loss. Group S had greater labial and total alveolar bone volumes than group NS at T3 (P <0.001). CONCLUSIONS:PAOO was associated with increased and maintained labial alveolar bone volume, which may help preserve total alveolar support during combined treatment. Deep learning-assisted CBCT segmentation can serve as an efficient volumetric evaluation tool.
INTRODUCTION:It is generally accepted that the optimal timing for functional orthodontic treatment in patients with Class II malocclusion and mandibular retrusion is during the circumpubertal growth period (cervical vertebral maturation stage [CS] 3-CS4). However, these patients often present with excessive overjet and a retrusive facial profile, which compromises esthetics and increases the risk of dental trauma. Early intervention during the mixed dentition period may reduce the risk of dental trauma and help safeguard children's psychological well-being. This study aimed to evaluate the therapeutic effects of rapid maxillary expansion (RME) and a modified Twin-block appliance-sagittal-guidance Twin-block (SGTB)-in mixed dentition patients and to compare the outcomes with an untreated Class II malocclusion control group. METHODS:After matching cervical vertebral maturation stages and observation/treatment durations, 3 groups-RME, SGTB, and untreated controls-were compared. Linear and angular cephalometric variables related to mandibular morphology were analyzed. All variables followed a normal distribution. In addition, one-way analysis of variance was performed, followed by Tukey's post-hoc tests. RESULTS:One-way analysis of variance of treatment-induced changes (T2 to T1) revealed statistically significant intergroup differences in vertical parameters, including FMA, posterior facial height (PFH), lower anterior facial height (LAFH), PFH/LAFH ratio, and mandibular ramus length, and sagittal parameters, including NSGn, total mandibular length (Co-Gn), and gonial angle. Tukey's post-hoc analysis revealed no statistically significant differences between the RME and control groups across all evaluated variables. In contrast, the SGTB group exhibited significant changes in vertical measurements (FMA, PFH, LAFH, and mandibular ramus length) and sagittal measurements (NSGn, Steiner analysis, Co-Gn, and Go-Gn) compared with controls. Annualized growth analysis demonstrated an additional Co-Gn increase of 4.53 mm/y in the SGTB group compared with the untreated controls. CONCLUSIONS:In mixed-dentition patients with Class II malocclusion and mandibular retrusion, RME alone does not significantly stimulate mandibular growth in the short term; its long-term effects require further investigation. SGTB significantly increased Co-Gn compared with the control group, primarily through enhanced vertical growth. However, given its limited vertical control, careful case selection is essential.
INTRODUCTION:The objective of this study was to evaluate the success rate, stability, and complications of Bollard-modified miniplate anchorage for bone-anchored maxillary protraction (BAMP) in a large cohort of growing patients treated by a single surgeon with long-term follow-up. METHODS:This retrospective cohort study included 299 growing patients with maxillary hypoplasia and Class III malocclusion who underwent Bollard-modified miniplate placement for BAMP between January 2007 and December 2019. A total of 1196 miniplates were placed. The mean follow-up duration was 4.2 years. Outcomes were assessed at both the miniplate level and the patient level. Patient-level logistic regression analysis was performed to evaluate the association of age at surgery and sex with adverse events. RESULTS:The overall success rate of Bollard-modified miniplate anchorage was 96.5%. During orthodontic loading, 50 miniplates (4.2%) developed mobility or inflammation; after conservative management, 18 regained stability, 24 were removed and successfully replaced, and 8 were removed and not replaced. Complications were more frequent in the maxilla than in the mandible (odds ratio [OR], 3.09; 95% confidence interval [CI], 1.70-5.61; P <0.001). Younger age at surgery was independently associated with a higher likelihood of complications (OR, 0.70; 95% CI, 0.51-0.96; P = 0.025), miniplate removal (OR, 0.68; 95% CI, 0.48-0.98; P = 0.036), and miniplate replacement (OR, 0.62; 95% CI, 0.42-0.92; P = 0.018). Sex was not significantly associated with any of these outcomes. CONCLUSIONS:Bollard-modified miniplate anchorage for BAMP showed high long-term success and low complication rates in growing patients. Complications were more frequent in the maxilla than in the mandible, and younger age was associated with a higher likelihood of adverse events. These findings support the use of Bollard-modified miniplates as a reliable skeletal anchorage system for BAMP in children and adolescents.
INTRODUCTION:This study aimed to assess the short-term 3-dimensional (3D) stereophotogrammetric soft-tissue, cephalometric, and airway effects of corticotomy-assisted rapid maxillary expansion (RME) and facemask (FM) therapy in late-adolescent patients with Class III malocclusion. METHODS:This prospective controlled clinical trial included 16 late-adolescent patients with Class III malocclusion (mean age, 14.90 ± 0.64 years) treated with corticotomy-assisted RME and Petit-type FM therapy and 16 untreated Class III controls (mean age, 14.03 ± 0.90 years). Lateral cephalograms and 3D stereophotogrammetric records were obtained at pretreatment and posttretment or at corresponding time points during the observation period. Paired t tests or Wilcoxon signed rank tests were used for within-group comparisons, and independent t tests or Mann-Whitney U tests were used for between-group comparisons (P <0.05). RESULTS:In the corticotomy group, SNA (2.36°), A-Na perp (2.67 mm), ANB (4.08°), SN-GoGn (3.41°), and overjet (5.97 mm) increased, whereas SNB (-1.71°), Pg-Na perp (-2.61 mm), and IMPA (-4.32°) decreased. A 3D soft-tissue analysis revealed increases in ANB angle (2.50°), maxillary length (1.16 mm), mandibular height (2.94 mm), and nasal ala and alar base width (1.57 and 1.97 mm), whereas mandibular corpus length (-2.58 mm), facial convexity (-4.84°), and bigonial width (-3.94 mm) decreased. After treatment, bilateral Al showed lateral displacement along the horizontal (x) axis, whereas bilateral alare curvature and subnasale showed anterior displacement along the sagittal (z) axis, with nonsignificant 2.5 mm between-group difference observed at Pg. An approximately 1-mm increase in nasopharyngeal airway length was observed, but no significant between-group differences were found. CONCLUSIONS:Despite reduced growth potential, corticotomy-assisted RME and FM therapy produced measurable short-term skeletal and 3D soft-tissue improvements in patients with true skeletal Class III malocclusion in late adolescence and may serve as an intermediate adjunctive option; however, long-term stability and randomized comparative data are required.
