Effect of Er:YAG Laser Pulse Duration on Shear Bond Strength of Metal Brackets Bonded to a Porcelain Surface

Abstract

Objective: The aim of this study was to compare the effect of different Er:YAG laser pulse durations on the shear bond strength (SBS) of metal brackets bonded to porcelain with two different adhesive systems. Background data: Orthodontic brackets do not bond well to feldspathic porcelain surfaces, using resin cement. Various treatment methods have been suggested for the porcelain surface to improve bond strength. Thus far, no orthodontic study has evaluated the effect of different Er-YAG laser pulse durations on porcelain surfaces with or without sandblasting. Methods: In the present study, 150 porcelain crowns were assigned to 10 groups differing in adhesive system and surface treatment. In five groups, the adhesive system was RelyX (TM) U 200 and in the other five, Transbond XT was used. For each adhesive system, the porcelain surfaces were treated in one of five different ways: sandblasted, Er:YAG laser short pulse (SP), Er:YAG laser super short pulse (SSP), sandblasted + SP, or sandblasted + SSP. The sandblasted group with Transbond XT served as the control. SBS test was conducted for each group. Samples were examined by scanning electron microscopy. ANOVA and independent t test were used for statistical analysis. Results: The control group had increased roughness and the highest SBS. Er:YAG laser application to the sandblasted porcelain flattened the roughness, and the effects of SP and SSP were similar. Conclusions: Er:YAG laser application did not allow for elimination of the hydrofluoric acid step. RelyX U 200 is a viable alternative to Transbond XT on sandblasted porcelain.