Temperature increase during orthodontic bonding with different curing units using an infrared camera

Aim. To evaluate the effects of different curing units and light-tip tooth surface distances on the temperature increase generated during orthodontic bonding, using an infrared camera (IR) and artificial neural networks (ANN). Materials and methods. Fifty-two freshly extracted human premolar teeth were used. Metallic orthodontic brackets were bonded to the buccal surfaces of the teeth and thermal records were taken using an IR camera and ANN. Brackets were cured with a lightemitting diode (LED) and high intensity halogen (HQTH). Teeth were divided into four groups according to the curing units (LED and HQTH) and curing distances (from tooth surface and 10 mm away from tooth surface). The results were analyzed with analysis of variance (ANOVA) and the Tukey HSD test. Results. The ANOVA and Tukey HSD tests revealed that temperature changes were influenced by the type of light source and exposure times. All groups revealed significant differences between each other (p < 0.001). The highest surface temperature increase was gained from curing with a LED unit from the tooth surface (11.35 degrees C +/- 0.91 degrees C). The lowest surface temperature increase was gained from curing with a HQTH unit 10 mm away from the tooth surface (2.57 degrees C +/- 0.6 degrees C). Conclusion. The LED unit induced significantly higher temperature changes than did the HQTH. The temperature increase during orthodontic bonding was increased with long exposure time. A shorter light-tip tooth surface distance leads to greater increases in temperature.