Vol. 4, Issue 2, Part A (2018)

Abstract: To evaluate the effects of pre-heated resin composite application on the shear bond strength (SBS) of orthodontic metal brackets. A total of 80 human premolar teeth randomly divided according to the composite type (microhybrid, nanohybrid, nanofilled and conventional) and temperature (25 °C-60 °C). Teeth were bonded with same light-cured adhesive and different composite types (n=15). Thermal cycling was then used for ageing procedure on all samples. After storage in distilled water for 24 h, the brackets were subjected to SBS test at a speed of 0.5 mm/min until bracket debonding. SBS values and the Adhesive Remnant Index (ARI) were evaluated. Data were analyzed using the one-way ANOVA and the Tukey post-hoc test (p<0.05). A statistically significant difference was found between test groups at 25 °C. Teeth bonded with preheated composites showed a statistically higher SBS than those bonded with lower temperature composites. Pre-heated nanofilled and conventional orthodontic composite showed the highest SBS among all the pre-heated groups. Pre-heating of nanofilled composites may be play an important role for improvement of the orthodontic bracket SBS.