Treatment Effects of Distal Movement of Lower Arch With Miniscrews in the Retromolar Area Compared With Miniscrews in the Posterior Area of the Maxillary

Soft and hard tissue changes after compensatory treatment in skeletal class III malocclusion

BACKGROUND

The camouflage treatment of skeletal class III malocclusion can include both premolar extraction and mandibular third molar extraction-based approaches. This study aimed to compare an all four second premolar extraction approach with a mandibular third molar extraction and temporary anchorage devices (TADs)-based approach for compensatory orthodontic treatment in mild to moderate skeletal class III malocclusion.

METHODS

31 subjects (mean age = 19.65 ± 3.91 years, male = 12, female = 19) with skeletal class III malocclusion were included in this retrospective, observational study. Lateral cephalograms taken before and after treatment were used to perform measurements for 7 dental indicators, 9 skeletal indicators, and 5 soft tissue indicators. Statistical analyses were performed to compare the cephalometric measurements between groups.

RESULTS

The patients' profiles were improved after treatment, and molars reached a neutral occlusal relationship. Dental cephalometric measurements showed that mandibular incisor to mandibular plane angle (IMPA) (-7.73 ± 4.72°), lower incisor-Nasion-B point angle (L1-NB angle) (-8.36 ± 4.57°),and the lower incisor-Nasion-B point distance (L1-NB distance) (-2.02 ± 1.42 mm) all significantly reduced (P < 0.05) in the premolar extraction group, while the changes were non-significant in the mandibular third molar extraction group, and the between-group differences were significant. The angle between the long axis of upper incisors and that of lower incisors (U1-L1) increased significantly (7.76 ± 8.55°) in the premolar extraction group but decreased significantly in the mandibular third molar extraction group (-4.64 ± 5.96°) (P < 0.05). Skeletal cephalometric measurements showed that Sella-Nasion-B point angle (SNB), decreased (premolar extraction group: -1.43 ± 0.87°, mandibular third molar extraction group: -0.71 ± 0.73°), A point-Nasion-B point angle (ANB) increased (premolar extraction group: 1.01 ± 0.86°, mandibular third molar extraction group: 1.22 ± 0.93°) and Wits increased (premolar extraction group: 1.39 ± 0.93 mm, mandibular third molar extraction group: 1.00 ± 0.60 mm) significantly in both groups, P < 0.05; with a significantly larger decrease in SNB in the premolar extraction group (P < 0.05). Soft tissue measurement items showed lower lip eversion (LL-E) decreased (premolar extraction group: 1.77 ± 1.61 mm, mandibular third molar extraction group: 0.76 ± 1.14 mm) and Lip Difference increased (premolar extraction group: 2.30 ± 0.58 mm, mandibular third molar extraction group: (2.01 ± 0.52 mm) significantly in both groups (P < 0.05), with between-group differences non-significant. Analysis of co-variance accounting for the pre-treatment values as the covariate, showed significant effects of the treatment group for the parameters IMPA, L1-NB (mm), L1-NB (°), U1-L1(°), SNA, SNB, and Wits value.

CONCLUSION

For mild and moderate skeletal class III malocclusion patients, both premolar extraction and mandibular third molar extraction with TAD-based approaches showed good clinical outcomes. The premolar extraction group showed greater SNB angle and compensatory lingual inclination of the lower incisors, along with significant reduction in OP-SN angle in the mandibular third molar extraction group, which contributed to the counterclockwise movement of the occlusal plane. Soft tissue changes mainly included improvements in lower lip protrusion with no significant differences noted between the two groups.

Evaluation of Treatment Effects of en Masse Mandibular Arch Distalization Using Skeletal Temporary Anchorage Devices: A Systematic Review

Mandibular arch distalization using temporary anchorage devices (TADs) is effective in correcting borderline Class lll cases without surgery. This review analysed the existing literature evaluating the dental, skeletal, and soft tissue changes after en masse mandibular arch distalization using TADs. We followed PRISMA guidelines and registered this review in PROSPERO database CRD42023450524. PubMed, Google Scholar, Cochrane, Web of Science, and SCOPUS databases were searched. Orthodontic patients requiring en masse mandibular distalization using TADs were compared with different modalities of distalization. Dental changes were evaluated along with skeletal and soft tissue changes and treatment duration. Randomized controlled trials (RCTs), cohort studies, longitudinal studies, and retrospective studies were eligible to be included. The risk of bias was assessed using ROBINS-I tool ("Risk Of Bias In Non-randomized Studies-of Interventions"). Of 1764 identified records, seven studies (one non-RCT, one prospective clinical trial, and five retrospective cohort studies) were included. One study had a low risk of bias, three had moderate bias, two had serious bias, and one had critical bias. All studies showed molar distalization and distal tipping with significant retraction of the lower lip. Miniplates showed greater distalization compared to miniscrews. Interradicular miniscrews exhibited the least distal tipping. Changes in SNB, ANB, occlusal plane angle, and mandibular plane angle were reported. Retromolar screws and ramal plates reported reduced treatment duration. TADs are effective in en masse distalization of mandibular dentition with intrusive or extrusive effects.

Comparison of posttreatment stability after total mandibular arch distalization with mini-implants and mandibular setback surgery

OBJECTIVES

To compare posttreatment stability in skeletal Class III patients between those treated by total mandibular arch distalization (TMAD) with buccal mini-implants and those by mandibular setback surgery (MSS).

MATERIALS AND METHODS

The samples included 40 Class III adults, 20 treated by TMAD using buccal interradicular mini-implants and 20 treated with MSS. Lateral cephalograms were taken at pretreatment, posttreatment, and at least 1-year follow-up, and 24 variables were compared using statistical analysis.

RESULTS

Mandibular first molars moved distally 1.9 mm with intrusion of 1.1 mm after treatment in the TMAD group. The mandibular incisors moved distally by 2.3 mm. The MSS group exhibited a significant skeletal change of the mandible, whereas the TMAD group did not. During retention, there were no skeletal or dental changes other than 0.6 mm labial movement of the mandibular incisors (P < .05) in the MSS group. There was 1.4° of mesial tipping (P < .01) and 0.4 mm of mesial movement of the mandibular molars and 1.9° of labial tipping (P < .001) and 0.8 mm of mesial movement of the mandibular incisors in the TMAD group. These dental changes were not significantly different between the two groups.

CONCLUSIONS

The TMAD group showed a slightly decreased overjet with labial tipping of the mandibular incisors and mesial tipping of the first molars during retention. Posttreatment stability of the mandibular dentition was not significantly different between the groups. It can be useful to plan camouflage treatment by TMAD with mini-implants in mild-to-moderate Class III patients.

Effectiveness of miniscrew-supported maxillary molar distalization according to temporary anchorage device features and appliance design: systematic review and meta-analysis

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.

Comparison of treatment effects after total mandibular arch distalization with miniscrews vs ramal plates in patients with Class III malocclusion

INTRODUCTION

This study aimed to compare treatment effects after total mandibular arch distalization with buccal interradicular miniscrews vs ramal plates in patients with Class III malocclusion.

METHODS

The sample consisted of 40 patients with Class III malocclusion; 20 were treated with distalization via buccal miniscrews (age, 25.8 ± 7.9 years), whereas 20 were treated with ramal plates (age, 26.4 ± 6.1 years). Twenty-three linear and angular measurements were analyzed on pretreatment and posttreatment lateral cephalograms. The changes in each group and differences in treatment effects between the 2 groups were evaluated.

RESULTS

The mean amount of distalization at the crown and root levels of the mandibular first molars and the amount of distal tipping was 1.8 mm, 0.6 mm, and 5.4° in the buccal miniscrew group vs 3.6 mm, 2.0 mm, and 6.8° in the ramal plate group, respectively. In addition, 2.2° of counterclockwise rotation of the occlusal plane was observed in the buccal miniscrew group after 1.3 mm of molar intrusion (P <0.001). The distal movement of the lower lip was 0.6 mm in the buccal miniscrew group vs 2.3 mm in the ramal plate group.

CONCLUSIONS

The buccal miniscrew group showed more molar intrusion and counterclockwise rotation of the occlusal plane than in the ramal plate group. The ramal plate produced more distalization of the mandibular dentition with clockwise rotation of the mandible. Therefore, these results can be useful when selecting the type of temporary skeletal anchorage devices to treat patients with Class III malocclusion, depending on their vertical pattern.

Miniplate-Aided Mandibular Dentition Distalization as a Camouflage Treatment of a Class III Malocclusion in an Adult

This case report describes orthodontic camouflage treatment for a 32-year-old African American male patient with Class III malocclusion. The treatment included nonextraction, nonsurgical orthodontic camouflage by en masse distalization of the mandibular teeth using skeletal anchorage devices. The total treatment time was 23 months. Normal overjet and overbite with Class I occlusion were obtained despite the compensated dentition to the skeletal malocclusion. His smile esthetics was significantly improved at the completion of his treatment.

Distalization of the mandibular dentition with a ramal plate for skeletal Class III malocclusion correction

The retromolar fossa is an anatomically suitable skeletal anchorage site. The aim of this report was to introduce a novel appliance for the correction of skeletal Class III malocclusions with mandibular dentition distalization. The placement site and the procedure of the ramal plate are described. The resulting force vectors are parallel to the functional occlusal plane leading to efficient molar distalization. This approach is demonstrated with 2 adult patients who refused a surgical treatment option. This ramal plate may be indicated for total arch distalization for nonextraction and nonsurgical cases.

Treatment effects of mandibular total arch distalization using a ramal plate

OBJECTIVE

The purpose of this study was to evaluate treatment effects after distalization of the mandibular dentition using ramal plates through lateral cephalograms.

METHODS

Pre- and post-treatment lateral cephalograms and dental casts of 22 adult patients (11 males and 11 females; mean age, 23.9 ± 5.52 years) who received ramal plates for mandibular molar distalization were analyzed. The treatment effects and amount of distalization of the mandibular molars were calculated and tested for statistical significance. The significance level was set at p < 0.001.

RESULTS

The mandibular first molar distalization at the crown and root were 2.10 mm (p < 0.001) and 0.81 mm (p = 0.011), respectively. In the evaluation of skeletal variables, there was a significant increase in the Wits appraisal (p < 0.001). In the evaluation of the soft tissue, there was no significant effect on upper lip position, but the lower lips showed a significant retraction of 2.2 mm (p < 0.001).

CONCLUSIONS

The mandibular molars showed a significant amount of distalization accompanied by limited extrusion and mesiobuccal rotation of the crowns. A ramal plate may be a viable device for mandibular total arch distalization in Class III patients who are reluctant to undergo orthognathic surgery.