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°/0° 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.