In vivo Degradation of Resin-Dentin Bonds in Humans Over 1 to 3 Years

Abstract

The longevity of resin restorations is currently an area of great interest in adhesive dentistry. However, no work has been conducted to investigate the durability of resin-dentin bond structures using human substrate in vivo. The purpose of this study was to investigate the degradation of the resin-dentin bond structures aged in an oral environment for 1, 2, or 3 years. Cavities were prepared in primary molars, and an adhesive resin system (Scotchbond Multi-Purpose) was applied to the cavity. After 1 to 3 years, following the eruption of the succedaneous permanent teeth, the resin-restored teeth were extracted. Immediately after extraction, those teeth were sectioned perpendicular to the adhesive interface and trimmed to produce an hourglass-shaped specimen. Then, a micro-tensile test was performed at a crosshead speed of 1.0 mm/min. The mean bond strengths were statistically compared with one-way ANOVA and Fisher's PLSD test (p < 0.05). Further, all fractured surfaces were observed by SEM, and the area fraction of failure mode was calculated by means of a digital analyzer on SEM photomicrographs. There were significant differences in tensile-bond strength among all 3 groups (p < 0.05), with mean values ranging from 28.3 +/- 11.3 MPa (control), to 15.2 +/- 4.4 MPa (1 to 2 years), to 9.1 +/- 5.1 MPa (2 to 3 years). Moreover, under fractographic analysis, the proportion of demineralized dentin at the fractured surface in specimens aged in an oral environment was greater than that in control specimens. Furthermore, degradation of resin composite and the depletion of collagen fibrils was observed among the specimens aged in an oral environment. Analysis of the results of this study indicated that the degradation of resin-dentin bond structures occurs after aging in the oral cavity.

Electric device improves bonds of simplified etch-and-rinse adhesives

“…Ideally, after acid-etching, the adhesive should completely infiltrate the delicate fibrillar network. Optimal resin infiltration is crucial to maximize bond strength [5,6] and bond durability [1], as unprotected collagen fibrils may be hydrolyzed over time [11,16,17].…”

Chlorhexidine does not increase immediate bond strength of etch-and-rinse adhesive to caries-affected dentin of primary and permanent teeth

“…Despite the adequate immediate bond strength, in vivo (12) and in vitro (13) studies have revealed that resindentin bonds deteriorate over time. It has been speculated that a decreasing concentration gradient of resin monomer diffusion within the acid-etched dentin, and a subsequent resin elution from hydrolytically unstable polymeric hydrogels within the hybrid layers (14) leave the exposed collagen fibrils susceptible to hydrolytic and enzymatic degradation, mediated by endogenous metalloproteinases (MMPs) (15).…”

Deproteinizing effects on resin–tooth bond structures

“…However, marginal discoloration or recurrent caries are frequently found in clinical resin restoration for long-term use. Several in vivo [1][2][3][4] and in vitro studies [5][6][7][8] have shown the degradation mechanism of the bonds. However, information on bond degradation is very limited.…”

“…However, information on bond degradation is very limited. Degradation analysis has mainly been conducted with the use of water storage testing [5][6][7][8] or human 2,3 and monkey models. 1,4 However, in these test methods the disadvantage is that a long test span (i.e., months or years) is needed to obtain results.…”

“…9 -11 Moreover, hydrolytic degradation of the bonds has been suggested as one cause of bond degradation over a long duration. 2,3,[5][6][7] In water, it has been suggested that the exposed unencapsulated collagen fibrils within the demineralized resin are digested over a long term even without the vital responses of the human oral environment (i.e. oral bacteria or food liquids).…”