Objectives The study investigated the modification of composite-to-enamel bond strength by pre-treatment of enamel with a concentrated, acidic SnCl2-solution. Methods Six groups of flat human enamel specimens (n=44 per group) were treated as follows: OB-H: H3PO4 etching, Optibond FL application (primer+adhesive manufacturer's instructions) OB-S: SnCl2 pre-treatment, Optibond FL application (primer+adhesive) OB-HS: H3PO4 etching+SnCl2 pre-treatment, Optibond FL application (primer+adhesive) CF-N: Clearfil SE application (primer+bond manufacturer's instructions) CF-H: H3PO4 etching, Clearfil SE application (primer+bond) CF-S: SnCl2 pre-treatment, Clearfil SE application (primer+bond). Enamel specimens were then built up with resin composite (Clearfil Majesty Esthetic) and stored (100% humidity, 37°C, 1 week). μTBS-measurement and failure mode analysis of one-half of the specimens were performed immediately after storage, while the other half was analysed after a thermocycling procedure (8500 cycles 5°C and 55°C dwell time 30s). Additional specimens were prepared for SEM- and EDX-analysis. Results Highest values were measured for OB-H before and after thermocycling, lowest values for CF-N. Compared to OB-H treatment, OB-S treatment reduced μTBS before/after thermocycling by 23%/28% and OB-HS treatment by 8%/24% (except for OB-SH before (n.s.), all p≤0.001 compared to OB-H). In the Clearfil SE treated groups pre-treatment increased μTBS significantly compared to CF-N (before/after: CF-H: +46%/+70% CF-S: +51%/42% all p≤0.001). Conclusion Pre-treatment with H3PO4 or SnCl2 markedly increased the μTBS of Clearfil SE to enamel. However, thermocycling partly reduced the gain in μTBS obtained by SnCl2 pre-treatment. Clinical significance The application of an acidic and highly concentrated SnCl2 solution is a good option to increase the μTBS between enamel and a resin composite mediated by an adhesive system containing the multifunctional monomer MDP.
Source: Journal of Dentistry Full Text |
