Shear Bond Strength of Scotchbond XT with MTAD as a Dentine Conditioner

The purpose of this in vitro study was to investigate the effect of 1% NaOCl (15 min) and MTAD on dentine shear bond strength, when using the Scotchbond XT(3M ESPE) adhesive system. Thirty extracted, human, third molar teeth were embedded into metal rings with self-curing acrylic resin. The teeth were ground wet using 600-grit silicone-carbide paper to expose superficial dentine. The samples were randomly divided into 2 groups (n=15). In group 1 (SB) the dentine surfaces were treated according to the manufacturer’s instructions (etched with 37% phosphoric acid before application of the bonding resin). In group 2 (MTAD) the dentine surfaces were treated by rinsing it with 1% sodium hypochlorite for 15 minutes followed by the application of a freshly prepared solution of MTAD, left undisturbed for 5 minutes. Thereafter the solution was rinsed off with water, airdried, leaving the treated surface visibly moist. Following the application of the adhesive resin, composite resin were condensed into an Ultradent mould and then light-cured for 40 seconds. The bonded specimens were stored in 37 oC water for 24 hours. The shear test was performed in a Zwick testing machine. The mean values were analyzed using the Studentt test. The results were as follows: SB= 15.4 ± 3.4 MPa and MTAD=21.8 ± 3.6 MPa. There was a statistically significant difference in dentine bond strength between the two groups (p<0.05). Conditioning of the dentine with MTAD significantly increased the dentine bond strength of Scotchbond XT to dentine.