Accuracy of lingual straight-wire orthodontic treatment with passive self-ligating brackets and square slot: a retrospective study

Comparative Analysis of Displacements and Stress Produced by Square and Rectangular Bracket Slot With Incremental Torque: A Finite Element Analysis Study

INTRODUCTION

This study aimed to perform a comparative analysis of stresses and displacements with incremental torque on the maxillary incisors and surrounding cortical bone using conventional metal brackets with rectangular slots and passive self-ligating brackets with square slots using finite element analysis (FEA).

MATERIALS AND METHODS

An in vitro FEA study was conducted, in which a three-dimensional (3D) model of the maxilla was built using ANSYS software version 18 (ANSYS Inc., Canonsburg, PA). The conventional McLaughlin, Bennet, and Trevisi (MBT) bracket (3M Unitek, Monrovia, CA) of 0.022 × 0.028-inch slot with a 0.019 × 0.025-inch rectangular stainless steel (SS) archwire (model 1) was compared with the Pitts 21™ self-ligating bracket system (OC Orthodontics, McMinnville, OR) of 0.021 x 0.21-inch slot with a 0.020 × 0.020-inch square SS archwire (model 2) at incremental torques of 5°, 10°, 15°, and 20°. The von Mises stress was evaluated at the maxillary incisors and surrounding cortical bone. The torque moment, tipping angle, and displacement of the maxillary incisors were also measured and compared between the bracket systems.

RESULTS

The highest torque expression of 13.8 N-mm was observed in model 2, compared to a torque expression of 10.68 N-mm in model 1. The torque expression increased in both models from 0°to 20°. There was a play of 6.2°at 20°torque in model 2, whereas it was 9.32°​​​​​​​play in model 1. The torque expressions were better for the lateral incisors than for the central incisors. Increased incremental torque was associated with increased proclination of the incisors, and this movement was more pronounced for the central incisor and model 1. Furthermore, it was revealed that the stresses on the cortical bone and teeth were higher in model 2 than in model 1.

CONCLUSION

It was concluded that the Pitts 21™ passive self-ligating system produced better torque expression and less play with square SS archwire compared to conventional brackets with rectangular SS archwire.

Torque moments and stress analysis in two passive self-ligating brackets across different incisor inclinations: A 3-dimensional finite element study

Objective

To compare torque expression characteristics between rectangular slot (0.022″ x 0.028″) Damon Q passive self-ligating brackets (Ormco, Glendora, Calif) and square slot (0.021″ x 0.021″) Pitts 21 brackets (OC Orthodontics) using 0.019″ x 0.025″ Stainless Steel and 0.020″ x 0.020" Titanium Molybdenum alloy wires at various incisal inclinations using finite element analysis. The null hypothesis was that there were no differences in torque expression in both tested groups.

Methods

Reporting guidelines for in-silico studies using finite element analysis in medicine (RIFEM) were used. Damon Q and Pitts 21 brackets were scanned and 3D models generated. Brackets were placed on a 3-D model of a maxillary central incisor with its long axis inclined at 0⁰,5⁰,10⁰,15⁰ and 20⁰ to the occlusal plane. Final 0.019″ x 0.025″ SS and 0.020″ x 0.020" TMA archwires were inserted into slots of both tested brackets. Geometric models were converted into finite element models. Material properties were assigned for involved structures with automatic meshing performed by software. Torque movements were simulated with the FE program Ansys Space claim R 22.

Results

Torque moment values, torque expression and Von - Mises stress was higher in Pitts 21 than Damon Q at all inclination angles. There was a gradual increase in the magnitude of values with decrease in incisal inclination.

Conclusion

Square slot passive self-ligating brackets show superior torque expression characteristics as compared to rectangular wire-rectangular slot combinations. The FEM results should be validated with in-vivo studies in order to confirm the findings.

Effect of fence tray matching care on excess adhesive and bracket placement accuracy for orthodontic bonding: an in vitro study

OBJECTIVE

This study aimed to evaluate the effect of fence tray matching care (FTMC) in bracket bonding by measuring excess adhesive, as well as linear and angular deviations, and by comparing it with the half-wrapped tray (HWT).

MATERIALS AND METHODS

An intraoral scanner was used to acquire data on the maxillary dental arch of a patient with periodontitis.Furthermore, 20 maxillary dental arch models were 3D printed. Using 3Shape, PlastyCAD software, and 3D printing technology, 10 FTMC (method I) and HWT (method II) were obtained. By preoperative preparation, intraoperative coordination, and postoperative measurement, the brackets were transferred from the trays to the 3D-printed maxillary dental arch models. Additionally, the bracket's excess adhesive as well as linear and angular deviations were measured, and the differences between the two methods were analyzed.

RESULTS

Excess adhesive was observed in both methods, with FTMC showing less adhesive (P< 0.001), with a statistical difference. Furthermore, HWT's vertical, tip and torque, which was significantly greater than FTMC (P< 0.05), with no statistical difference among other respects. The study data of incisors, canines, and premolars, showed that the premolars had more adhesive residue and were more likely to have linear and angular deviations.

CONCLUSIONS

The FTMC had higher bracket bonding effect in comparison to HWT, and the adhesive residue, linear and angular deviations are smaller. The fence tray offers an intuitive view of the precise bonding of the bracket, and can remove excess adhesive to prevent white spot lesions via care, providing a different bonding method for clinical applications.

Evidence of Effectiveness of Lingual Orthodontics as an Alternative to Conventional Labial Orthodontics. A Systematic Review

In orthodontics, both the treatment goals and the impact of orthodontic equipment on patients' aesthetic appearance have contributed to a rise in patients' aesthetic demands over the years. Patients considering orthodontic treatment are significantly concerned about the potential compromise in facial appearance that conventional orthodontic therapy might cause. Clinical practice has integrated aesthetic materials and procedures to address these restrictions. This review will examine the present data and outcomes linked to lingual orthodontics. PubMed, Scopus, Web of Science, Cochrane Library, and Embase were the electronic databases searched. Research interests mainly included biomechanics, appliance design, bonding, laboratory settings, case reports, survey research, and treatment outcomes. The goal was to locate the most recent data regarding lingual orthodontics. A consistent and predictable pattern emerges from the available evidence on lingual orthodontics. Several areas have received a lot of attention over the past decade, including the ability to forecast outcomes and patients' preparedness to embrace these changes. The current state of knowledge on the biomechanical principles of lingual orthodontics is solid, as this review shows. Lingual orthodontic appliances can efficiently handle any orthodontic scenario that a labial appliance can handle. The reason is that the completely customized lingual appliance might bring about the desired result in terms of treatment.