Effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.

Lin Hu,Ming Fang,Yu-Hong Xiao,An-Qi Jia,Yu Gao,Ji-Hua Chen,Li Huang,Dengshun Miao

doi:10.1371/journal.pone.0116790

Abstract

ObjectiveThis study was designed to evaluate the effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.MethodsBonded dentin specimens were prepared using three different types of adhesive systems. Micro-tensile bond strength and degradation of collagen were tested before, and after 1 month or 4 months of aging in artificial saliva. The relationship between micro-tensile bond strength and collagen degradation was analyzed by calculating their Pearson’s correlation coefficient.ResultsAging induced time-dependent reduction in micro-tensile bond strengths for all the tested adhesive systems, although such reduction for the single-step self-etching adhesive G-Bond (GB) was not statistically significant. The bond strength of the two-step self-etching primer adhesive system Clearfil SE Bond (SEB) was similar to that of the two-step etch-and-rinse self-priming adhesive system Single Bond 2 (SB), and they were both significantly reduced after one or four months of aging. A negative correlation was found between the degree of collagen degradation and magnitude of micro-tensile bond strength (r = - 0.65, p = 0.003). The Pearson’s correlation coefficient was 0.426, indicating that 42.6% of the aging-induced reduction in bond strength can be explained by the degradation of collagen.ConclusionsIn the early phase of dentin bonding, there was a negative correlation between the degree of collagen degradation and the magnitude of micro-tensile bond strength. The reduction of bond strength was accompanied by the degradation of collagen. These results provide evidence for the causative relationship between the degradation of collagen and the deterioration of dentin-adhesive interface.

Highlights

The bonding between adhesives and dentin can be regarded as a process of materials exchange [1]
A negative correlation was found between the degree of collagen degradation and magnitude of micro-tensile bond strength (r = - 0.65, p = 0.003)
In the early phase of dentin bonding, there was a negative correlation between the degree of collagen degradation and the magnitude of micro-tensile bond strength

Summary

Introduction

The bonding between adhesives and dentin can be regarded as a process of materials exchange [1]. The minerals of dentin are replaced by resin monomers, which permeate into the porous collagen scaffold exposed by demineralization and subsequently polymerize to envelope the collagen fibrils and form inter-locking microstructures that provide bonding strength. Such a structure composed of resin-matrix reinforced collagen fibrils is termed as hybrid layer [2]. Dentin contains more water and organic components, especially type I collagen Such characteristic of dentin makes it difficult to be infiltrated by hydrophobic monomers, and renders the successful bonding of dentin challenging [3]. The major collagen fibrils of type I collagen with the diameter of 70 nm to 90 nm are connect with the minor branching fibrils of noncollagenous proteins which has diameters of 20 nm to 40 nm, forming a typical collagen banding of 67 nm [4]

Methods

Results

Conclusion