Review of Matrix Metalloproteinases’ Effect on the Hybrid Dentin Bond Layer Stability and Chlorhexidine Clinical Use to Prevent Bond Failure

This review describes the relationship between dentin collagen hybrid bond layer degradation and the Matrix Metalloproteinases (MMPs) after their release by acid etch and rinse adhesives and self etching bonding adhesives that can reduce the bond stability over time. MMP-2, MMP-8 and MMP-9 are indicated as the active proteases that breakdown the collagen fibrils in the hybrid bond layer. Phosphoric acid in the acid etch and rinse bonding process and acid primers in the self etch process are implicated in the release of these proteases and their activation by several non-collagen proteins also released from dentin by the etching. MMPs are released in saliva by salivary glands, by cells in the gingival crevices to crevicular fluid and by pulpal odontoblasts cells to the dentinal fluids. These sources may affect the hybrid layer also. Evidence of the bond strength deterioration over time and the ability of Chlorhexidine to prevent bond deterioration by inhibiting MMP action are discussed. Dentin Bonding procedure utilizing Chlorhexidine for different application times and concentrations are being developed. The application of 2% Chlorhexidine to the phosphoric acid etch surface after rinsing off the acid is the only procedure that has been clinically tested for a longer period of time and shown to prevent bond strength degradation so far. The adoption of this procedure is recommended as means of improving bond stability at this time

Histomorphologic characterization and bond strength evaluation of caries-affected dentin/resin interfaces: Effects of long-term water exposure

Objectives. To evaluate the longevity of sound (SD) and caries-affected dentin (CAD) bonds made with etch-and-rinse and self-etching adhesives after a 6-month water-storage period, using bond strength and morphological evaluations. Methods. Extracted human molars with coronal carious lesions were selected. Flat surfaces of CAD surrounded by SD were bonded with etch-and-rinse (Adper Scotchbond 1) or with self-etching (Clearfil Protect Bond and AdheSE) adhesives. Trimmed resin-dentin bonded interfaces (1 mm(2)) were stored in distilled water for 24 h or 6 months and subjected to microtensile bond strength (mu TBS) evaluation. The quality of the dentin beneath fractured specimens was measured by Knoop microhardness (KHN). ANOVA and multiple comparisons tests were used (P < 0.05). Fractographic analysis and interfacial nanoleakage evaluation were performed by scanning electron microscopy (SEM). Resin-dentin bonded sections (10 mu m thick) were stained with Masson's trichrome and examined using light microscopy. Collagen exposure and adhesive penetration were examined qualitatively. Results. mu TBS to SD was significantly higher than that to CAD for all bonding agents. Bonds made with AdheSE were weaker than the other adhesives after 6-months storage regardless of the dentin substrate. CAD bonded specimens presented a significant mu TBS decrease over time. Lower KHN was recorded in CAD compared to SD. An increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration were observed in CAD interfaces. Significance. CAD bonded interfaces are more prone to hydrolytic degradation than SD bonds. Additionally, as compared to SD, there were remarkable differences in depth of demineralization, adhesive infiltration and interfacial bond strength with CAD. (C) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.24678679

In vitro influence of Carisolv on shear bond strength of dentin bonding agents

Objective: The aim of this study was to evaluate the influence of Carisolv on the shear bond strength (SBS) of hydrophilic adhesive systems in dentin. Method and materials: Two hundred bovine incisors were polished with 320- to 1,000-grit aluminum oxide paper and randomly divided into 10 groups (n = 20). The adhesive systems were used according to manufacturer's instructions, and a restorative resin composite (Definite) was inserted in a Teflon matrix and cured. The specimens were kept in humid storage for 7 days at 37 degreesC. The SBS tests were performed in an EMIC universal testing machine with a crosshead speed at 0.5 mm/min. The mean values (MPa +/- [SD]) were analyzed with analysis of variance and Dunnett and Tukey tests. Results: The results were expressed in decreasing values (MPa): G6 = 18.55 +/- 6.95; G3 = 17.55 +/- 5.73; G2 = 17.05 +/- 5.33; G8 = 16.95 +/- 7.13; G7 = 16.94 +/- 5.22; G4 = 16.31 +/- 3.38; G1 = 15.85 +/- 4.45; G9 = 14.21 +/- 5.87; G5 = 12.89 +/- 3.79; and G10 = 12.31 +/- 5.18. Conclusion: Carisolv did not interfere in the adhesion to dentin, but its cleanser technique did interfere.351080180

Influence of different tests used to measure the bond strength to dentin of two adhesive systems

Purpose: To investigate the behavior of two bonding systems: self-etching primer Clearfil Liner Bond 2V (CLB) and total-etch Single Bond (SB) when submitted to two bond strength tests: shear bond strength (SBS) and microtensile (MTBS). Methods: Flat dentin surfaces were obtained at the facial surface of extracted bovine incisors. mu TBS started with adhesive application and incremental resin composite insertion. Samples were then sliced into 1 mm slabs parallel to the long axis of the tooth. Half of the specimens from each group were trimmed in order to obtain 2 dumbbell-shaped (D) specimens with a cross-sectional area of 1 mm, and in the other half of the group, the slabs were cut into beams (3) with a cross section of I mm. 2 area. Specimens were individually fractured on a microtensile apparatus. For SBS, crown segments were embedded in polyester resin and a flat dentin surface was exposed for bonding. After adhesive and restorative procedures were accomplished, the specimens were kept in water for 24 hours prior to bond testing. The tests were performed in a universal testing machine. MPa values were analyzed by Tukey's test (P < 0.05), two-way ANOVA (mu TBS) and Student's t-test (SBS). Results: Mean values (SD) on mu TBS were: SB/B: 42.6 (15.1), SB/D: 35.4 (6.8), CLB/B: 14.3 (10.3) and CLB/D: 27.0 (7.9). SBS values (SD) were: SB: 17.3 (5.6) and CLB 15.9 (7.2). Beam specimens bonded with CLB presented the lowest results. SBS did not show statistical differences between groups. The results showed that the shear bond test seemed to lack the sensitivity that is required to detect subtle differences between bonding agents or procedures.191374