Effect of Dentin Desensitizer on Contact Angle Values of Bonding Agents and on Bond Strength

Aim: To assess the effect of a desensitizing agent on the wettability of dentin surfaces and correlate to bond strength. Methods: Twenty-four caries free human dentin surfaces were used, and assigned to 3 groups. Group 1: surfaces with smear layer and bonding agent (Excite, Ivoclar Vivadent); Group 2: etched (Total Etch, Ivoclar Vivadent) surfaces and Excite; Group 3: etched surface, desensitizing agent (Systemp, Ivoclar Vivadent) and Excite. Calibrated amounts of Excite were delivered onto the surfaces under the Optima VCA Contact Angle Machine (AST Products Inc.). Sixteen readings were taken per group. For shear bonding, eight specimens were tested per group using the Notched Shear Bond Test Method (Ultradent) in an Instron (Instron) with a 5 KN load/cell and a 1 mm/min crosshead speed immediately after preparation. Inserts of microfilled composite (Heliomolar, Ivoclar Vivadent) were bonded to dentin surfaces. Results: Table 1. Values of contact angle (Treatment Group - Contact Angle in degrees + sd): No Etch + Excite: 51 + 10.9; Etch + Excite: 32.0 + 8.0; Etch + Systemp Desensitizer + Excite: 21.0 + 7.0. Table 2. Immediate Shear Bond Strenght in MPa. Treatment Group - MPa + sd): No Etch + Excite: 14.3 + 4.8; Etch + Excite: 21.5 + 1.5; Etch + Systemp Desensitizer + Excite: 22.0 + 1.4. Anova multiple comparison adjusted for Bonferroni’s method showed that in the contact angle values there was statistically significant difference between all groups (p>0.05). Etching gel greatly reduced the Contact Angle Values, which further decreased when Systemp Desensitizer was applied. The shear bond strengths were statistically different (p> 0.05) between Groups 2 and 3 vs Group 1. However, a higher value was measured in the group treated with Systemp desensitizer. Conclusion: the use of a desensitizer agent increases the wettability of dentin surfaces and increases the bond strength.