The Effect of a Desensitizing Agent on Dentin Permeability and Shear Bond Strength

Objective: The use of desensitizing agents has been promoted to decrease patient responses to cold stimuli. This study examined the effect of VivaSense (Ivoclar NA) on dentin permeability (DP) and shear bond strength (SBS). Methods: DP: Human mandibular molars were sectioned longitudinally in a mesial-distal plane. Each buccal and lingual half was hand ground on 400 SiC paper producing 1.5-2.0 mm thick slabs of dentin (n=12). 17% EDTA removed the smear layer, verified with magnification. The slabs were mounted and permeability measured using a common methodology (Derkson, Pashley & Derkson). The surfaces were treated with the desensitizer, the test rerun and percent reduction evaluated with a paired t-test. SBS: Flat occlusal dentin surfaces were prepared and finished with wet 600 grit SiC paper. Two groups were prepared (n=14). Group 1: Total-etch Excite (Ivoclar NA) using the sequence of 37% phosphoric acid (15 secs), rinse, air dry, adhesive applied, air dry, light-cure (10 secs), and 3.8 x 2.0 mm composite cylinder (Tetric Ceram A-2 in a compression jig) cured for 40 secs. Group 2: procedures were the same as for Group 1 plus a 10 second application of the desensitizer before the adhesive. All were thermocycled (x2500, 4^oC-48^oC), a circular knife-edge used to determine SBS at 1 week and results evaluated with a t-test. Results: DP: The mean percent reduction was 69.5 (19.7), p<0.001. SBS: For Group 1, the mean was 20.75 (7.42) MPa. For Group 2, 21.57 (7.38), p=0.771. Conclusion: The desensitizer produced a significant reduction in dentin permeability and produced no measured changes in the dentin shear bond strength. This study was partially supported by Ivoclar NA.