Abstract:
Orthodontics is a specialized branch of dentistry aiming to produce a healthy, functional bite, creating greater resistance to disease and improving personal appearance. Orthodontic brackets are small attachments used in orthodontics to fasten an arch wire. One of the types that used is ceramic brackets provide higher strength, more resistance to wear and deformation, better color stability and preferred for cosmetic reasons. After treatment ceramic brackets needs to be debonded from the enamel surface. Debonding may be unnecessarily time consuming and damaging to the enamel if performed with improper techniques or carelessly. There are several methods for debonding orthodontic brackets. All these techniques have their own advantages and limitations. Since the early 1990s, lasers have been used experimentally for debonding ceramic brackets as a new and established method. Using Lasers in debonding procedure reduces required debonding force and risk of enamel damage but thermal e ect during the laser radiation on dental tissues can cause undesirable results. The aim of this study is to develop a better technique for ceramic bracket debonding. A new ber laser (1070-nm Ytterbium ber Laser (IPG Laser, YLM-20- SC, GmbH) ) was tested, debonding procedure was quanti ed with a universal testing machine and intrapulpal temperature was monitored for limiting the injury or pain in present study . Experiments were performed in two sections according to the type of lasing mode: Adjusted Laser power was applied in Continuous Wave (CW) and in Pulse Mode. Debonding force, debonding time and work done by universal testing machine was signi cantly decreased by irradiation in both sections. Lasing caused a 50 % of reduction in required load for debonding and showed a 3- fold decrease in time. Intrapulpal temperature changes are below the accepted threshold value (5.5 oC) until the level of 3.5 watts of laser power in continuous wave mode. Also applying more than 3.5 watts of laser power showed a rapid increase in total applied laser energy. It can be reported that a sensible striding is observed after 88.6 joules of total energy applied on the ceramic brackets in both modes. Moreover, during debonding, the work done by universal testing machine is diminished up to 5 times by irradiation. Most of the groups in CW Mode and all groups are below the threshold value in pulse mode. Laser applications in debonding require further improvement because Laser could mean very rapid and painless debonding without the risk of either enamel tear outs or bracket fractures. If debonding can be achieved with lasing alone, mechanical operations during bracket removal become unnecessary, alleviating patient discomfort at bracket removal.
