SEM and TEM analysis of water degradation of human dentinal collagen

Abstract

Recently several long-term studies have reported evidence of the hydrolytic degradation of collagen fibrils based on fractured surface observations after bond testing. Those studies suggested that one cause of the decline in the bond strength was the degradation of the collagen fibrils within the bonds. However, one concern has been raised that the dentinal collagen fibrils may be stable in water that does not contain oral bacteria or enzymes. Therefore, the present study aimed to clarify the micromorphological change in naked collagen fibrils after 500 days of water storage. To prepare exposed collagen fibrils, sectioned and polished human dentin surfaces were acid conditioned for 15 s with the use of two commercially available acid conditioners: All-Etch (10% phosphoric acid) and Uni-Etch (32% phosphoric acid) (Bisco, Inc.). Those specimens were stored in distilled water at 37 degrees C for 1 day (control) for 500 days. After the storage periods, the samples were examined with the use of SEM and TEM. Under SEM and TEM examination, micromorphological alterations (disarrangement of collagen web, widening the interfibrillar space, and the thinning diameter of collagen fibrils) were found in the specimens after 500 days in water.

The Effect of Polishing Techniques and Time on the Surface Characteristics and Sealing Ability of Resin Composite Restorations After One-year Storage

“…40,42 Morphological studies indicate that the resin and collagen matrix may suffer degradation from storage. [48][49] Even though enamel adhesion is considered more safe and stable than dentin, 50 the current study showed failure regarding marginal sealing for enamel margins and in nearly all experimental conditions, which means that water caused damage in enamel margins as well as in dentin.…”

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].…”

“…The existence of incompletely infiltrated collagen fibrils within the hybrid layers and additional entrapped water within the polymerized adhesives may expedite the degradation of resin-dentin bonds, resulting in clinical and visibly detectable microleakage [10][11][12].…”

The Role of Host‐derived Dentinal Matrix Metalloproteinases in Reducing Dentin Bonding of Resin Adhesives

“…A successful long-term dentin-resin bond depends on the formation of a homogenous and strong hybrid layer created by the perfect infiltration of resin monomers into dentin substrate (Nakabayashi et al, 1982). Morphological evidence of hydrolytic degradation of collagen in hybrid layers after an extended period has been presented in several studies (Sano et al, 1999;Hashimoto et al, 2000;Hashimoto et al, 2002;Hashimoto et al, 2003b;Hashimoto et al, 2003c). Degradation of collagen fibrils in the hybrid layer suggests the presence of exposed collagen fibrils.…”

“…For example: the application of simplified adhesives, insufficient resin infiltration (Hashimoto et al, 2000;Hashimoto et al, 2002;Hashimoto et al, 2003b;Hashimoto et al, 2003c;Tay and Pashley, 2003), sub-optimal polymerization (Eick et al, 1997;Cadenaro et al, 2005;Cadenaro et al, 2006), degradation of resin components (Hashimoto et al, 2000;De Munck et al, 2005;Tay and Pashley, 2003), high permeability of the bonded interface and activation of endogenous collagenolytic enzymes.…”