Analysis of deficient bonding with self-etching adhesive and self-curing resin

Objectives: To determine bond strengths to enamel and dentin of a self-etching primer adhesive and a self-curing core build-up resin composite when oxygen inhibition of the adhesive is prevented or when a self-curing resin mixture containing anion exchange resin (AI) filler is used as intermediate sealant. Methods: iBond adhesive (Heraeus, Germany) and the self-curing CorePaste (DenMat, USA) were investigated. Shear bond strengths (SBS) on human enamel and dentin prepared on wet SiC paper # 600 were determined. Eight specimens were produced for each the following adhesive curing modes: 1. Control application. 2. Cured adhesive wiped with Ethanol. 3. Adhesive light-activation (l.a.) under nitrogen. 4. Adhesive coated with glycerol during l.a. 5. Adhesive covered with glycerol immediately after l.a. for 1 minute. 6. As 5, however, 5 minutes glycerol. 7. Adhesive applied, no l.a., coating with s.c. resin (UDMA, TEGDMA, HEMA, 4-META, 4% w/w AI resin powder in OH-form). Cylindrical 3.5 mm wide CorePaste specimens were polymerized on the pretreated adhesive in a Teflon mold. Specimens were stored in 37°C water for 24 h. Shear de-bonding at 1 mm/min. Statistical analyses: One-way ANOVA and Duncan test at a<0.05. Results: Mean SBSs (MPa) to enamel/dentin by treatment groups 1 through 7 and homogeneous subsets by upper or lower case letters: 21,7 AB/3,2 c; 19,8 B/6,2 b; 18,4 BC/7,4 b; 7,1 D/0,9 c; 13,8 C/1,6 c; 17,0 BC/3,4 c; and 25,6 A/19,6 a. Conclusion: Oxygen inhibition had no impact on SBS to enamel unless the adhesive was either displaced by (4) or too shortly protected with (5) glycerol. On dentin SBSs of groups 2 and 3 were approximately twice the control figure. The assumed protective effect of glycerol was not significantly different from control. The AI resin filler deprotonizes the adhesive acid effectively and mediates high SBSs both on enamel and dentin.