Marginal Micro-Seal and Tensile Bond Strength of a Biopolymer Hybrid Layer Coupled with Dental Prosthesis Using a Primerless-Wet System.

The aim of this study is to compare the marginal seal and tensile bond strength (TBS) of prostheses fixed to enamel-dentin using different adhesive systems. Resin-composite inlays directly fabricated from Class V cavities of extracted human molars/premolars and mini-dumbbell-shaped specimens of bonded enamel-dentin were prepared for microleakage and tensile tests, respectively. Four adhesive systems were used: primerless-wet (1-1 etching for 10-, 30-, or 60-s, and 4-META/MMA-TBB), primer-moist (All-Bond2 + Duolink or Single-Bond2 + RelyX ARC), self-etch (AQ-Bond + Metafil FLO), and dry (Super-Bond C&B) bonding. Dye penetration distance and TBS data were recorded. Failure modes and characteristics of the tooth-resin interface were examined on the fractured specimens. All specimens in 10-, 30-, and 60-s etching primerless-wet, Super-Bond, and AQ-Bond had a microleakage-free tooth-resin interface. Primer-moist groups showed microleakage at the cementum/dentin-resin margin/interface. Significantly higher TBSs (p < 0.05) were recorded in primer-less-wet and Super-Bond groups with the consistent hybridized biopolymer layer after the chemical challenge and mixed failure in tooth structure, luting-resin, and at the PMMA-rod interface. There was no correlation between microleakage and TBS data (p = −0.148). A 1−3 µm hybrid layer created in the 10−60 s primerless-wet technique, producing complete micro-seal and higher tensile strength than enamel and cured 4-META/MMA-TBB, may enhance clinical performances like Super-Bond C&B, the sustainable luting resin.

Dentin protection by a primer-less adhesive technique.

PURPOSE: To identify the remaining demineralized dentin (the permeable layer that allows leakage) when using primer-less wet bonding with a total etching period of 10 to 60 seconds compared with contemporary resin adhesives. METHODS: Extracted human molars were selected and Class V cavities were prepared on the axial surfaces at the CEJ, providing margins in enamel and dentin for leakage testing using a basic dye (n = 10). Seven groups of conditioned teeth [1-1 etched for 10, 30, and 60 seconds (primer-less wet), All-Bond 2 and Single-Bond 2 (wet), AQ-Bond (self-etched), Super-Bond C&B (dry)] were used as bonding systems for resin composite restoration. All specimens were stored in water at 37 degrees C for 24 hours before soaking in a 0.5% basic fuchsin solution for 24 hours. The distance of dye penetration was measured using stereomicroscopy. RESULTS: No leakage at the enamel- and dentin-resin interfaces was found for all etching periods of 1-1 primer-less, Super-Bond C&B, and AQ-Bond specimens. However, leakage was observed at dentin margins in two wet with primer systems, All-Bond 2 (1.31 +/- 1.39 mm) and Single-Bond 2 (0.37 +/- 0.28 mm), which required phosphoric etching to remove a weak smear layer on prepared dentin.

Influence of dentin substrates to simplify wet-bonding: a leakage-free and reliable tensile strength interface for long-lasting restorations.

The wet-bonding procedure can be simplified by eliminating the primer. An aqueous mixture of 1% citric acid and 1% ferric chloride (1-1) was hypothesized as providing an easier dehydratable thinner substrate to which 4-META/MMA-TBB resin can adhere reliably. The 1-1 was applied for 10 s and rinsed off with water for 10 s. Demineralized dentin under four conditions was prepared before bonding to PMMA rod using 4-META/MMA-TBB resin: air-dried 10 s (D-NP); air-dried 10 s, primed 60 s with 5% 4-META in acetone (D-P); blotted dry 10 s (W-NP); blotted dry 10 s, primed 60 s (W-P). The tensile strengths (MPa) using mini-dumbbell specimens were 4.0 ± 2.4 for D-NP, 10.6 ± 5.4 for D-P, 38.3 ± 4.4 for W-NP, and 42.9 ± 3.3 for W-P. There was no significant difference between W-NP and W-P with cohesive failure in the dentin and the cured resin. In the wet groups, the hybridized dentin was stable against both HCl and NaOCl challenges. TEM examination and a leakage tests confirmed a perfect seal with a leakage-free interface of W-NP. These results suggest that this primer-less wet-bonding is promising method to protect the underlying intact dentin and pulp, thus providing long-lasting dental treatment.