Influence of Er:YAG laser on tensile bond strength of a self-etching system and a flowable resin in different dentin depths

Objective. The aim of this study was to evaluate the tensile resistance of a flowable resin in different dentin depths, after superficial treatment with Er:YAG laser. Methods. Eighteen molars were selected and roots were removed. Crowns were bisected in half, embedded in polyester resin and ground until dentin was exposed. The bonding site was delimited and samples were randomly assigned into two groups: superficial dentin (SD-1 mm from amelodentinal junction) and deep dentin (DD-2 mm from amelodentinal. junction). The samples were subdivided in three groups according to superficial treatment: non-rinsing conditioner (NRC) solely; Er:YAG laser (80 mJ/2 Hz) + NRC; Er:YAG laser solely. After conditioning, Prime and Bond NT/Dyract flow (Dentsply) was used for the manufacture of specimens. They were adapted to a metallic device, where resin cones were prepared. Samples were stored for 24 h and subjected to a bond strength test (50 kgf at 0.5 mm/min). Results. Means in MPa were: SD-NRC solely 12.29 (+/-4.40); laser + NRC 12.11(+/-3.23); laser solely 5.74(+/-3.01) and DD-NRC solely 9.60 (+/- 3.13); laser + NRC 10.44(+/-2.23); laser solely 3.50(+/-1.70). Data were submitted to statistical. analysis by ANOVA and Scheffe test (p < 0.05). Conclusions. SD produced better results and tensile bond strength, while on DD the treatment with NRC or Laser + NRC had higher tensile bond strength. The results suggest that when Er:YAG laser for dentin treatment is used, it is mandatory to associate it to a conditioning agent. (C) 2003 Etsevier Ltd. All rights reserved.