Debonding forces and failure modes of customized three-dimensional printed nano-ceramic hybrid resin fixed lingual retainers.

BACKGROUND

Retention preserves the optimal esthetic and functional positions of teeth following the termination of active orthodontic treatment. Conventional stainless-steel multistrand fixed retainers have limitations and drawbacks, mainly related to retainer failure.

OBJECTIVES

Nano-ceramic hybrid resin (SprintRay OnX) was employed to fabricate new, customized three-dimensional (3D)-printed lingual retainers, and their debonding forces and failure modes were evaluated.

MATERIALS AND METHODS

Pairs of premolars were embedded in acrylic blocks. Fifty acrylic blocks were divided into five groups, including three different cross-sections of customized 3D-printed wires- round (1 mm), oval (1 × 1.5 mm), and semi-elliptical (1 × 1.5 mm)- and comparative stainless steel multistrand retainers (G and H and Respond). Retainers were bonded to the teeth using Transbond™ LR Light Cure Adhesive. The models were stored in distilled water for 24 hours, simulating the wet intraoral conditions. Debonding forces and failure modes were then evaluated. A vertical debonding force was applied to the interdental area of the bonded retainer. Post-retainer debonding failure mode was examined under a stereomicroscope (×10 magnification).

RESULTS

Semi-elliptical 3D-printed retainers yielded the highest debonding forces, followed by oval 3D-printed retainers, twisted G and H retainers, round 3D-printed retainers, and Respond retainers. The debonding forces of oval and semi-elliptical 3D-printed retainers did not differ significantly. The 3D-printed retainer groups presented predominantly cohesive failure due to the strong adhesion between the 3D-printed resin and adhesive.

CONCLUSION

Oval and semi-elliptical 3D-printed retainers exhibited favorable debonding forces.