The Angle orthodontist最新文献

Objectives: To compare four first premolar extraction and nonextraction treatment effects on intra-arch width, profile, treatment duration, occlusal outcomes, smile aesthetics and stability.

Materials and methods: An electronic search of the literature to June 2, 2023 was conducted using health science databases, with additional search of gray literature, unpublished material, and hand searching, for studies reporting nonsurgical patients with fixed appliances regarding sixteen sub-outcomes. Data extraction used customized forms, quality assessed with ROBINS-I (Risk Of Bias In Non-randomized Studies-of Interventions) and Cochrane RoB 2 (risk-of-bias) tool. GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessed certainty of evidence.

Results: Thirty (29 retrospective studies, 1 randomized controlled trial) studies were included. Random-effect meta-analysis (95% CI) demonstrated maxillary (MD: -2.03 mm; [-2.97, -1.09]; P < .0001) and mandibular inter-first molar width decrease (MD: -2.00 mm; [-2.71, -1.30]; P < .00001) with four first premolar extraction; mandibular intercanine width increase (MD: 0.68 mm; [0.36, 0.99]; P < .0001) and shorter treatment duration (MD: 0.36 years; [0.10, 0.62]; P = .007) in the nonextraction group. Narrative synthesis included three and five studies for upper and lower lip-E plane, respectively. For American Board of Orthodontics Objective Grading System and maxillary/mandibular anterior alignment (Little's irregularity index), each included two studies with inconclusive evidence. There were no eligible studies for UK Peer Assessment Rating (PAR) score. Class I subgroup/sensitivity analyses favored the same results. Prediction interval indicated no significant difference for all outcomes.

Conclusions: Four first premolar extraction results in maxillary and mandibular inter-first molar width decrease and retraction of upper/lower lips. Nonextraction treatment results in mandibular intercanine width increase and shorter treatment duration. There was no significant difference between the two groups regarding maxillary intercanine width, US PAR score, and posttreatment smile esthetics. Further high-quality focused research is recommended.

Objectives: To assess the scientific evidence related to the role of the mandibular third molars on the late crowding of the lower anterior teeth in patients with or without previous orthodontic treatment. The secondary outcomes included changes in mandibular arch width and arch length.

Materials and methods: The databases PubMed, Scopus, ProQuest, and Google Scholar were searched from inception until April 2022. The included papers were studies evaluating the role of mandibular third molars on crowding of mandibular anterior teeth in patients of any age and gender, with mandibular third molars impacted or semi-impacted or erupted. Predetermined and prepiloted data collection forms were used to record the necessary information.

Results: Thirteen observational studies were included in the present systematic review. Most of them were assigned an overall risk of bias of moderate risk while the rest of them were at high risk. Four studies found an association between the presence of mandibular third molar and mandibular incisor crowding. Finally, seven studies were included in the quantitative analysis. Three different meta-analyses were conducted: for patients (a) with or (b) without previous orthodontic treatment and (c) in combination for patients with and without previous orthodontic treatment. According to the pooled results of all three meta-analyses, random effects model yielded a significant benefit for those without third molars compared to those with third molars regarding crowding, mean Little's irregularity index and mean arch length.

Conclusions: Lower third molars may contribute to mandibular crowding and lower arch constriction. Further prospective research of high quality is needed to clarify the impact of third molars on anterior mandibular crowding.

Objectives: To evaluate the effectiveness of distalizing maxillary first molars (U6) by temporary anchorage devices (TADs) according to their location (palatal, buccal, and zygomatic), their number, and appliance design.

Materials and methods: An electronic search of maxillary molar distalization with TADs was done through April 2023. After study selection, data extraction, and risk-of-bias assessment, meta-analyses were performed for the extent of distalization, distal tipping, and vertical movement of U6 using the generic inverse variance and random-effects model. The significance level was set at 0.05.

Results: Forty studies met the inclusion criteria: 4 randomized controlled trials (RCTs), 13 prospective studies, and 23 retrospective studies (total of 1182 patients). Distalization of the U6 was not significantly greater (P = .64) by palatal (3.74 mm) and zygomatic (3.68 mm) than by buccal (3.23 mm) TADs. Distal tipping was significantly higher (P < .001) in nonrigid (9.84°) than in rigid (1.97°) appliances. Vertical movement was mostly intrusive and higher but not significantly different (P = .28) in zygomatic anchorage (-1.16 mm).

Conclusions: Distalization of U6 with TADs can be an effective and stable treatment procedure, especially when performed with rigid palatal appliances. However, further RCTs or prospective cohort studies are strongly recommended to provide more clinical evidence.

Objective: To evaluate the mandibular alveolar bone thickness in untreated skeletal Class I subjects with different vertical skeletal patterns.

Materials and methods: A total of 50 preorthodontic treatment cone-beam computed tomography (CBCT) images of a skeletal Class I Chinese population with near-normal occlusion were selected. The buccal and lingual alveolar bone thicknesses of mandibular canines to second molars were measured at 2 mm below the cementoenamel junction (CEJ), mid-root, and root apex levels. Differences in the measurements were analyzed with Mann-Whitney U-test. The correlation between alveolar bone thickness and the sella-nasion-mandibular plane (SN-MP) angle was calculated using Pearson correlation coefficients and linear regression analysis.

Results: Buccal alveolar bone was thinner on all mandibular canines to first molars but thicker on second molars in comparison with lingual alveolar bone. Buccal alveolar bone was within 1 mm at the levels of 2 mm below CEJ and mid-root for the canines and first premolars. Significant differences were detected among subjects with different vertical patterns, with a negative correlation between the SN-MP angle and alveolar thickness, especially in the canine and premolar regions. The thinnest buccal and lingual alveolar bone were detected in the high-angle group canine region (0.50 mm at the levels of 2 mm below CEJ and mid-root for the buccal side, 0.90 mm at the level of 2 mm below the CEJ for the lingual side).

Conclusions: To avoid periodontal complications, buccal-lingual movement of the mandibular canines and first premolars should be limited, especially in high-angle patients.

Objectives: To investigate the post-treatment stability of anterior open bite (AOB) cases treated with upper and lower extrusion arches in adults.

Materials and methods: 23 patients with AOB were treated with extrusion arches and evaluated for dentoskeletal changes using lateral cephalometric radiographs before treatment (T0), after treatment (T1), and 12 months post-treatment (T2). Patients received bondable tongue spurs and vacuum-formed retainers as post-treatment retention/stability measures for 12 months. Post-treatment stability was further assessed qualitatively by the Photographic Openbite Severity Index.

Results: All the cases showed positive overlap between the anterior teeth at the end of orthodontic treatment, and 20 of 23 treated patients attended the recall visit after 12 months. A total of 85% of the cases maintained positive overlap at least 1 year post-treatment, 10% showed edge-to-edge bite, and only 5% showed no overbite.

Conclusions: Treatment of AOB in adults with extrusion arches proved to be stable 1 year post-treatment. Changes in the overbite after 1 year of follow-up were not significant.