Aims: The purpose of this in vitro study is to compare and evaluate the effect of Diode Laser and LED activated bleaching on colour and micro leakage of nano hybrid composites in Class V cavities.

Methods and Material: Standardized Class V cavities were prepared on fifty freshly extracted human first maxillary premolar teeth, and restored with nano hybrid composite (Tetric N-Ceram). The samples were randomly divided into three groups and bleaching agent used is 40% Opalescence Boost (Ultradent) in all the three groups. Group 1 was activated with Diode laser (Picasso), Group 2 was activated with a blue hybrid LED (Bluephase) and Group 3 did not receive any light activation. Group 4- control group (unbleached restoration n=5). Restoration colour was measured before bleaching and after bleaching using VITA Compact Easy shade spectrophotometer and CIELAB values of ΔE, Δa*, Δb* and ΔL* were obtained. The same samples with the control group were subsequently immersed in dye solution of 2% Methylene blue and subsequently dye extraction technique was used to evaluate the micro leakage using spectrophotometer.

Statistical analysis used: The results were subjected to ANOVA, Tukey and HSD tests (p<0.05).

Results: There was clinically perceptible change in colour (ΔE>3.3) in all the three groups. One-way ANOVA indicated no statistical difference in colour difference (p<0.05) among the groups bleached with Diode laser, LED and chemical bleaching techniques. One-way ANOVA indicated statistical difference in micro leakage (p<0.05) among the groups bleached with Diode laser, LED and chemical bleaching techniques and the unbleached control group. Nevertheless LED activated bleaching showed greater colour changes and least micro leakage as compared to other groups.

Conclusions: Activation of various light sources (Diode/LED) resulted in shorter duration and effective in-office bleaching. However, it may exert a negative influence on colour stability and micro leakage of Nano hybrid composites and can result in restoration failures.