Dental and skeletal changes associated with the Damon system philosophical approach

Effect of time between archwire changes on intended dentoalveolar expansion in orthodontic patients treated with fixed appliances : A prospective controlled clinical trial

OBJECTIVE

To analyze the effects of the time span between archwire changes on the amount of transverse dental arch expansion. The design was a prospective, controlled clinical trial. Randomization was performed by computer-generated allocation tables.

METHODS

In all, 35 patients were evaluated in three groups treated with fixed appliances and the same four sequential leveling archwires, however, with different replacement periods: 28 days (4-week [4W] group), 56 days (8-week [8W] group), and 84 days (12-week [12W] group). Digital models were measured before the treatment (T0) and at the end of the evaluation period (T1) by a blinded operator with OrthoAnalyzer® software (3-Shape, Copenhagen, Denmark) and compared using MANOVA. A multiple linear regression was also used to evaluate the influences of age, initial dental crowding, incisor inclination, and facial pattern on the amount of expansion.

RESULTS

Mean expansion was 2.77 ± 0.84 mm (upper arch) and 3.12 ± 0.88 mm (lower arch) in the 12W group; 1.96 ± 0.82 mm and 2.27 ± 0.96 mm in the 8W group, and 1.11 ± 0.93 mm and 1.32 ± 0.91 mm in the 4W group, respectively for the upper and lower arches. The amount of expansion varied significantly between the groups in the area of the canines, first premolars, and second premolars for both arches. Expansion was less in older patients. Initial dental crowding, incisor inclination and facial pattern had no influence on dental expansion.

CONCLUSION

Longer time spans between archwire changes provided greater amounts of expansion, while age is inversely related, with younger patients expressing greater amounts of expansion. The results also suggest that the expansion provided by the fixed appliances is expressed mainly in the canine and premolar areas.

Cone-Beam Computed Tomography Evaluation of Maxillary Sinus Changes in Orthodontic Patients Treated With Extraction of Four First Premolars

The objective of this study was to assess alterations in maxillary sinus mucosa thickness and the distances between the apexes of specific teeth and the maxillary sinus base in adult patients undergoing orthodontic treatment with the extraction of four first premolars. Twenty-one adults, averaging 24.85 years of age, received orthodontic therapy involving the extraction of all four first premolars. Cone-beam computed tomography scans were conducted before and after treatment to evaluate changes. Notably, post-treatment scans revealed a significant increase (P= 0.044) in the distance between the apex of the second premolar and the maxillary sinus floor, with an average augmentation of 1.0141 millimeters. However, no notable alterations were detected in the distances between the apexes of other teeth and the maxillary sinus or in maxillary sinus mucosa thickness. These findings suggest that orthodontic treatment with the extraction of four first premolars may elevate the distance between the maxillary sinus floor and the second premolar apex, which provides a reference for risk assessment and surgical design of first premolar extraction during orthodontic treatment.

Evaluation of Stresses Generated with Two Different Self-Ligating Orthodontic Bracket Systems - A Finite Element Analysis

AIM

To determine stresses generated in the posterior teeth region by two different self-ligating systems, 3M Unitek SmartClip and Damon Q Self-ligating brackets, using the finite element method (FEM).

METHODOLOGY

Computed tomography (CT) scan of maxilla was taken using Mimics software, and the Dicom data were imported into Hypermesh 13.0 software to convert it into a geometric model and then into FEM. Physical models of both the brackets were constructed and positioned on the teeth. Post archwire modeling, contact is defined between the bracket slot and 0.014" NiTi arch wire. The final assembled model was exported to ANSYS 12.1 for analysis, and 60 grams of load was applied at the ends of the arch wire.

RESULTS

On using 0.014" CuNiTi in both the bracket systems, stresses generated on the root surface were found to be maximum on the first molar region, followed by the first premolar, second molar, canine, and second premolar regions. Comparison between the two bracket systems showed differences in the stresses generated, where higher stresses were generated at all regions in the Damon Q bracket system, except the inter-second premolar region.

CONCLUSION

Maximum stresses were observed with the 3M Unitek SmartClip bracket system at the second premolar cervical region when compared to the Damon Q system. In both the cortical bone and cancellous bone, maximum stresses were observed at the second premolar cervical in the Damon Q bracket system region.

An Umbrella Review of Systematic Reviews With or Without Meta-Analysis Assessing Treatment Outcomes and Efficiency of Self-Ligating Brackets

Introduction

Self-ligating bracket systems are popular and seem to demonstrate lesser friction, allowing tooth movement without exerting unwanted forces on surrounding structures. This umbrella review aimed to compare self-ligating and conventional bracket systems for treatment efficiency.

Methods

An electronic search in 8 databases was performed for literature published between January 1, 1990, and October 1, 2021, with manual hand-searching of references of retrieved articles. Quality assessment was performed using the risk of bias in a systematic tool by 2 independent reviewers. Data were extracted using a prepiloted form (Joanna Briggs Institute) for evidence synthesis. Corrected covered area was calculated to quantify study overlaps across systematic reviews with or without meta-analysis.

Results

605 articles were retrieved, of which 16 were selected. Most included studies had a low risk of bias, except for 6 that showed an unclear risk of bias. Data analysis revealed a reduction in lower incisor proclination, bacterial accumulation, and oral malodor using self-ligating appliances.

Conclusions

Self-ligating systems reduce mandibular incisor proclination, bacterial accumulation, external apical root resorption, chairside time, and oral malodor. No other differences could be demonstrated in comparison with conventional appliance systems.