Micro-shear bond strength of resin composite cement to coronal enamel/dentin, cervical enamel, cementoenamel junction and root cementum with different adhesive systems

The cervical area of teeth is the most unpredictable region for durable adhesive bonding. This study evaluated the adhesion potential of resin cement to coronal and cervical/root structures with a focus on enamel, dentin and cementum using etch-and-rinse and self-etch adhesive systems. Anterior teeth (N = 60) were randomly divided into six groups for adhesion tests: (a) unprepared enamel (UE), (b) ground enamel (GE), (c) mid-coronal dentin (D), (d) cervical enamel 2 mm above cementoenamel junction (CE), (e) cementoenamel junction (CEJ), and (f) root cementum (RC). Enamel and dentin surfaces were conditioned using either an etch-and-rinse (Syntac Classic-SY) or self-etch (Clearfil S3 Bond Plus-CS3) adhesive system. Resin cement (Variolink Esthetic) was adhered to the different substrates using polyethylene molds and photo-polymerized. Bonded specimens were stored in water for 24 h at 37 °C. Microshear tests (µSBT) were conducted in a Universal Testing Machine (1 mm/min) and failure types were analyzed after debonding. Data were analyzed using two-way ANOVA and t-test (alpha = 0.05). While substrate type (p < 0.001) and adhesive system (p < 0.001) significantly affected the bond results, interaction terms were not significant (p = 0.063). Within SY adhesive system, adhesion to all substrates were not significant ranging between (8.07 ± 2.39–6.80 ± 4.60) (p > 0.05), except for CEJ (5.19 ± 1.39) and RC (4.08 ± 1.13). With the CS3 adhesive system, all groups presented non-significant results (4.15 ± 1.35–6.04 + 2.38) (p > 0.05), except for D (3.57 ± 1.84) and RC (3.21 ± 1.13) (p < 0.05). µSBT values for D (7.19 ± 2.31) and RC (4.08 ± 1.13) were significantly higher for SY compared to that of CS3 (3.57 ± 1.84–3.21 ± 1.13, respectively) (p < 0.05).