Efficacy of Er,Cr:YSGG laser for debonding of ceramic brackets and prevention of enamel damage and intrapulpal temperature change

Abstract

Debonding of ceramic brackets can cause problems such as bracket fracture and enamel damage due to high bond strength and low fracture toughness. Laser irradiation, aiming to decrease the bond strength, may be able to enhance ceramic bracket debonding. Nonetheless, temperature rise following laser therapy can adversely affect the dental pulp. The aim of this study is to assess enamel damage and intrapulpal temperature change after debonding ceramic brackets with or without Er,Cr:YSGG irradiation. In this experimental study, 80 Fascination ceramic brackets were bonded to the buccal surface of extracted human premolars. The teeth were randomly divided into two groups of 40. In group 1 (control), polycrystalline brackets were debonded using the pliers recommended by the manufacturer. In group 2, brackets were irradiated by Er,Cr:YSGG (Waterlase iPlus, Biolase, USA, 12/2013), gold handpieces, and tip MZ8 and were operated at 50 Hz, 4.5 W, H-Mode (60 μs), 80% water, and 60% air. After laser irradiation, the brackets were debonded as in group 1. Before bracket bonding and after debonding, the buccal surface of the teeth was inspected under a stereomicroscope to assess the presence of enamel cracks. The number and length of enamel cracks before bonding and after debonding were compared using Scope Image version 9.0. A K-type thermocouple with 0.2-mm diameter was used to assess the intrapulpal temperature change following laser irradiation. Data were analyzed using SPSS version 22. No enamel fracture was noted in the control or laser group. Bracket debonding with the help of laser decreased the number and length of enamel cracks compared with the control group. Temperature rise in the laser group (2.63 ± 1.3 °C) was significantly lower than the critical threshold of 5.5 °C. The two groups showed significant differences regarding the adhesive remnant index (ARI) scores (P < 0.05). Er,Cr:YSGG laser irradiation can minimize enamel damage with no thermal damage to the pulp, and is an efficient and safe modality for enhanced debonding of ceramic brackets.