Evaluation of structural loss caused by laser application on different bonding adhesives in relation to the quantity of absorbed water following thermal cyclus procedure

In today's dentistry, patients who undergo orthodontic treatment prefer ceramic brackets instead of metal brackets, due to their aesthetic appearance. One of the major disadvantages of the ceramic brackets is the difficulty during the debonding procedure. Dental lasers are applied to the bracket surface to make the ceramic onesremoved more easily. The debonding procedure assisted by laser is based on the photoablation effect of the laser on the bonding adhesive, which ensures adhesion of the bracket to the tooth. Photoablation occurs when the laser beam is absorbed by the target tissue and suddenly evaporates with an explosion related to the increasing pressure. Different types of adhesives can be used to bond ceramic brackets to the tooth surface. The structure and the content of the adhesives may differ from each other and this can lead to different responses related to the laser application. In our study, the material loss of different bonding adhesives following Er:YAG laser application was investigated via microcontrolled tomography BT device. Additionally, in order to evaluate the effects of water absorption, some samples were aged with the termal cyclus procedure to simulate the composite materials staying in the mouth conditions. The data obtained from the samples were evaluated statistically with Kruskal Wallis test. The complementary Mann Withney U test was applied. Five different brand of bonding adhesives were used in this thesis study. Material loss was found to vary according to the adhesive bonding brand. Additionally water absorption had been shown to to affect the material loss. Reliance and Opal brand adhesives shown statistically significant higher volume difference and higher crater volume (p = 0.007 and p = 0.043). Key words: Bonding Adhesive, Ceramic Bracket, Laser, Debonding, Micro Computer Tomografi, Thermal Cyclus