Influence of Hyrax screw position on dental movement and cortical bone: A study of finite elements

Effect of Anchorage Modifications on the Efficacy of Miniscrew-Assisted Rapid Palatal Expansion: A Systematic Review and Meta-Analysis

Mini-implant-assisted rapid palatal expansion (MARPE) offers a non-surgical alternative for expanding the basal bone, increasing skeletal effects while minimizing undesirable dental side effects. This systematic review and meta-analysis evaluate the effectiveness of MARPE in terms of transverse skeletal development, dentoalveolar changes, and periodontal effects, with consideration of appliance design. A review was conducted across multiple databases, including PubMed, MEDLINE, Embase, Scopus, and Springer, covering studies published between 2005 and 2024. Randomized controlled trials involving MARPE, with specific attention to design variations (e.g., miniscrew type, number, diameter, length, position, and activation protocol), were selected. Transverse skeletal expansion, assessed via changes in the nasal width, was reported in six of seven studies, with an average increase ranging from 0.31 mm to 2.90 mm for MARPE, compared to 0.11 mm to 2.46 mm for conventional Hyrax expanders. Maxillary width expansion ranged from 2.89 mm to 9.08 mm with MARPE and from 2.59 mm to 8.51 mm with Hyrax. Periodontal changes were reported in six studies, although details were generally unclear. The use of four self-drilling miniscrews with once-daily activation over an extended period produced greater nasal width expansion, greater average skeletal expansion of the maxilla, and less dental inclination and dentoalveolar expansion compared to Hyrax. No significant differences were observed between short and long miniscrews, although wider miniscrews resulted in improved outcomes. The MARPE technique, especially when using a design with four self-drilling miniscrews and daily activation until the targeted expansion is reached, offers notable benefits compared to the conventional Hyrax appliance. This method improves both nasal and maxillary skeletal expansion, lessens dental inclination, and reduces negative effects relative to traditional approaches.

Changes in Periodontal Tissues With Periodontally Accelerated Orthodontics: A Systematic Review and Meta-Analysis

Periodontally accelerated orthodontic (PAO) therapy has been found to increase hard tissue, helping to decrease orthodontic relapse rates and improve retention capacity. The aim of this study was to synthesize available evidence on clinical and tomographic changes in periodontal tissues when using PAO techniques. A systematic review with meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and registered in the International Prospective Register of Systematic Reviews (PROSPERO). The search was carried out in PubMed, Embase, Cochrane, Web of Science, Scopus, and Google Scholar. Randomized and non-randomized clinical trials comparing PAO versus conventional orthodontics were included. Quality assessment was performed using the Downs & Black scale, and the risk of bias was assessed using the revised Cochrane risk-of-bias tool. Mean differences and 95% confidence intervals (CIs) were calculated, and the mean difference was divided by a t-test. During the initial search, 465 studies were identified. Five articles studying 130 patients were included, which assessed both clinical and tomographic changes, along with treatment duration. PAO was administered to patients with skeletal class III in three studies, to class II patients in one study, and to individuals with dental crowding in another study. Two studies showed a moderate risk of bias, and the rest showed a low risk. The meta-analysis revealed a vestibular bone thickness increase of 0.32 mm (0.56-008; P = 0.008), a reduction of 3.12 mm (2.15-4.08; P= 0.001) in gingival retraction, and a treatment duration that was 7.07 months (8.79-5.36; P = 0.001) shorter in patients subjected to PAO compared to those undergoing conventional orthodontic treatment. Considering the limitations of the study and acknowledging that definitive conclusions cannot be drawn, the findings suggest that treatment time decreased in patients undergoing PAO, with an increase in vestibular bone thickness and less gingival retraction observed in those undergoing this intervention.

A Three-Dimensional Finite Element Analysis: Maxillary Dentition Distalization with the Aid of Microimplant in Lingual Orthodontics

Aim

To analyze the movement of anterior teeth by changing the height of the power-arm and changing the force application points during whole maxillary dentition distalization with the aid of micro-implants in lingual orthodontics to set a biomechanical reference for effective clinical use of lingual orthodontic appliance.

Methods

A three-dimensional finite element model of the maxillary teeth with lingual appliance and the associated support tissue was established. Maxillary dentition with the force of 200g was distalized using implant as anchorage, then the movement of anterior teeth was analyzed by changing the length of power-arm (1mm, 3mm, 6mm, 9mm) and by changing the force location from lingual side to buccal side.

Results

During whole maxillary dentition distalization with aid of the implants in lingual orthodontics: when the height of power arm was 1mm, the anterior teeth rotated clockwise, with the increasing of the height of power-arm, the anterior teeth rotated counterclockwise gradually. When the height of power-arm was 9mm, all anterior teeth rotated counterclockwise. Central incisor and lateral incisor rotated counterclockwise and canine rotated clockwise when the buccal side force was applied.

Conclusion

With the increase of the height of the power-arm, the movement pattern of the upper anterior teeth is different. The canine is more sensitive to the height of the power-arm than the central incisor and the lateral incisor. When the height of the power-arm reaches 9mm, the upper anterior teeth are displayed as crown tipping buccally movement. Compare with lingual side force, the buccal side force do better in preventing the loss of anterior tooth torque. If the upper anterior teeth are up-right or lingually tipped before treatment, it is preferable to use longer power-arm or buccal side traction force. If the anterior teeth are already tipped buccally, then short power-arm or lingual side force is advised.