Aging Affects Two Modes of Nanoleakage Expression in Bonded Dentin

Abstract

Water sorption into resin-dentin interfaces precedes hydrolytic degradation. We hypothesized that these processes are morphologically manifested by the uptake of ammoniacal silver nitrate, which is thought to trace hydrophilic domains and water-filled channels within matrices. Water sorption is thought to be nonuniform and can be traced by the use of silver nitrate. Human teeth bonded with an experimental filled-adhesive were aged in artificial saliva (experimental) or non-aqueous mineral oil (control). Specimens retrieved for up to a 12-month period were immersed in 50 wt% ammoniacal silver nitrate and examined by transmission electron microscopy for identification of the changes in their silver uptake. Reticular silver deposits initially identified within the bulk of hybrid layers in the experimental group were gradually reduced over time, but were subsequently replaced by similar deposits that were located along the hybrid layer-adhesive interface. Silver uptake in water-binding domains of the adhesive layers increased with aging, resulting in water tree formation. These water-filled channels may act as potential sites for hydrolytic degradation of resin-dentin bonds.

Impact of Intracoronal Dentin Treatment Prior to Bleaching on Bond Strength of Restorative Materials

“…Composite resins adhere to dental substrate by mechanical imbrication within the tubules as well penetration of resin material inside the intertubular dentin collagen matrix (23). This mechanism explains the superior adhesion of microhybrid and flowable composite resins to intracoronal dentin, as demonstrated in the present study.…”

The Influence of Time and Cement Type on Push-Out Bond Strength of Fiber Posts to Root Dentin

“…The retention of posts in the root canal may also be influenced by the degradation of the adhesive system over a long period of time, 12 known as nanoleakage, 13,14 resulting in decreased bond strength. 12,15 The control of moisture, 16 inefficient polymerization of the adhesive system or resin cement, 17,18 and aggressive etching that leaves the collagen fibrils susceptible to the action of metalloproteinases 13,19 can all accentuate the degradation of hybrid layer and adhesive interface.…”

“…However, these adhesive systems are susceptible to an incompatibility with dual-cured and self-cured resin cements 9,20,21 and to the permeability of the adhesive interface, causing water blisters. 22,23 More recently, in an effort to reduce the technique sensitivity due to the difficult access to canal walls during handling and control of adhesive procedures, 14,24 self-adhesive resin cements were developed. These materials are not able to form a true hybrid layer, 25,26 and short-term studies show inferior bond strength values when compared with resin cements that require an adhesive system.…”

Clinical Performance and Wear Resistance of Two Compomers in Posterior Occlusal Restorations of Permanent Teeth: Six-Year Follow-up

“…1 More stained cavosurface margins were observed with aging, which might be a result of the degradation potential of the hydrophilic adhesive systems. 21 In this study, the restorations were placed after acid etching, and fifth-generation dentin adhesive systems were used for both compomers. Such a clinical approach can improve the marginal sealing and adap- tation of compomer restorations.…”