Debonding of Ceramic Brackets bonded to Lithium Disilicate Glass-ceramics (E-Max) using Conventional Technique Versus Er:YAG and Er,Cr:YSGG Lasers

Aim of the study: To evaluate the effect of debonding technique of ceramic brackets on lithium disilicate glass-ceramics (E-Max) using conventional technique versus Er:YAG laser and Er,Cr:YSGG Laser.Materials and methods: A total of 45 LDC discs (IPS Emax CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein) were fabricated in a dental laboratory with a standard quality control and mounted on acrylic blocks. The specimens were randomly divided into three groups: group I: Non lased group (conventional debonding), group II: Er:YAG laser debonding technique, group III: Er,Cr:YSGG laser debonding technique. The three groups were tested for the shear bond strength (SBS) using Universal testing machine. Scanning Electron Microscopic (SEM) image was made to the LDC IPS Emax specimens before and after debonding of the ceramic orthodontic brackets to evaluate any surface cracks or fractures. Adhesive remnant index (ARI) score was tested using stereomicroscope.Results: Both group II and group III (lased groups) had significantly lower SBS than the non-lased group (control group). In group I, 33.3 % of the specimens demonstrated presence of cracks. Only 13.3% demonstrated presence of cracks in group II, while no cracks were found in group III. There were no significant differences in the distribution of ARI scores among the three groups (P=0.64). Conclusion: Er:YAG and Er,Cr:YSGG laser irradiation on ceramic brackets was efficient and significantly decreased the SBS. Significant presence of cracks on lithium disilicate surface was found in the non lased group. No significant differences were found in the ARI score in all groups.