Biocompatibility and influence on bond strength of dentin desensitizers

Methods: Thirty caries-free extracted second human molars were selected and sectioned at the occlusal third of the crown. Three desensitizers: Desen One (Ogna Laboratori Farmaceutici), Vivasens (Ivoclar Vivadent) and Gluma Desensitizer (Heraus Kulzer) were then applied to the sectioned surface and light polymerizated for 30s (Optilux 501, Demetron, Kerr). Composite built-ups were made using a three-step (OptiBond FL, Kerr) or a dual-step total-etch adhesive (Vivapen ExciTE, Ivoclar). Samples without desensitizers treatments represented the control group. Composite-dentin sticks, with a cross-sectional area of approximately 0.90mm2, were prepared and subsequently microtensile bond strength (μTBS) was measured by an universal testing machine. Desensitizers biocompatibility was evaluated by MTT assay on Balb3T3 cells. Mechanical and cell viability data were respectively analyzed by Multi-way ANOVA test and by Mann-Whitney's U test (p<0.05).

Results: μTBS of OptiBondFL control group was 26.07±7.02 MPa, while ExciTE control showed significant lower values (15.25± 3.53 MPa). Treatments with each desensitizers in combination with the adhesives tested had no significant influence on bond strength except for Vivasens with OptiBondFL (14.5±5.02 MPa). The biocompatibility tests resulted in a dose dependent decrease of cell viability after 24h exposure to Gluma and Desen One, whereas Vivasens did not show any significant toxic effect at concentration used (0.00-0.75mg/ml).

Conclusion: Our results indicated that desensitizers might influenced μTBS of adhesives depending on materials combination. The presence of chlorhexidine in Desen One agent did not affect the μTBS values compared to the other desensitizers. Moreover, materials substances inside the agents tested might caused different toxic responses in the cells.