Nd:YAG Laser Influence On Micro-tensile Bond Strength And Ultrastructure Of Different Bonding Systems To Non-carious Sclerotic Dentin

OBJECTIVEThe purpose of this study was to investigate Nd:YAG laser influence on micro-tensile bond strength of different bonding systems for non-carious sclerotic dentin, and examined the change of the ultrastructure.METHODSFifteen human occlusal wearing molars which were classified into above three degree were selected and cut into nearly equal halves,divided into A(A1,A2),B(B1,B2) and C(C1,C2) three groups at random.Then teeth in A2 and C1 were processed with Nd:YAG laser(1W,10Hz),and combined with ScotchbondTM, A1 and B1 were processed with Nd:YAG laser(1W,10Hz), and combined with Adper Prompt L-Pop,and B2 and C2 were processed with ScotchbondTM alone, filling with composite resin(Z350) and saving in physiological saline (37℃)for twenty-four hours.And then made fatigue test piece, evaluated the micro-tensile bond strength, examined every specimen under stero-microscope.The micro-tensile bond strength was performed using one-way analysis of variance and SPSS13.0 software package. Twelve occlusal wearing molars for the observation of ultrastructure were divided into four groups at random, processed respectively as followed:Nd:YAG laser associated with ScotchbondTM, Nd:YAG laser associated with Adper Prompt L-Pop, ScotchbondTM,and not processd. Observed the change in ultrastructure with scanning electron microscope. RESULTSThe micro-tensile bond strength of the three groups were Nd:YAG laser combined with ScotchbondTM (A2,Ci) (26.11±1.62) MPa, Nd:YAG laser combined with Adper Prompt L-Pop (A1, B1) (23.46±3.93) MPa and ScotchbondTM (B2,C2) (22.27±2.16) MPa. The bond strength of Nd:YAG laser combined with ScotchbondTM (A2,C1) group compared with the other two groups was statistically significance.The breakage mostly happened in adhesive dentine surface.CONCLUSIONThe micro-tensile bond strength of non-carious sclerotic dentin which were processed with ScotchbondTM can be improved by Nd:YAG laser,and processed with Nd:YAG laser associated with ScotchbondTM can own better bonding strength.