Abstract
Aim: The present study investigated photocuring of bracket adhesive by transmission of light through glass fibers underneath the bracket. Materials and methods: Photocurable adhesive resin was cured under metal brackets, and the degree of monomer conversion (DC%) was measured. Continuous glass fibers were used under the bracket along with a DC% measuring sensor (n = 10 per group). In group 1 (control), the plain adhesive resin was light cured with the bracket. In group 2 (GFH), the bracket was bonded with the adhesive and unidirectional E-glass fibers were oriented along the direction of the curing light under the bracket. In group 3 (GFB), fibers were oriented perpendicularly to the direction of the curing light (GFV). Finally, in group 4 (GFB), a layer of bidirectional glass fiber fabric was added under the bracket and the curing light was directed at 90 degrees/0 degrees to the direction of fibers. DC% of the resin was determined by FT-IR in contact with the surface of the ATR-sensor. An analogue test set-up was used to measure light irradiance power under the bracket to demonstrate light scattering from the glass fibers. The results were analyzed by ANOVA and regression analysis. Results: The final DC% was significantly higher for groups GFH (55.4) and GFV (54.7), followed by GFB (45.8) and the control (38.0) (P <0.05). Groups GFV (95.0) and GFH (94.2) had significant irradiance values compared to GFB (83.8) and the control (74.4) (P <0.05). There was a correlation between light curing power and DC%. Conclusion: The presence of E-glass fibers under the metal brackets demonstrated improved curing of photopolymerizable adhesive.