Elemental distributions and microtensile bond strength of the adhesive interface to normal and caries‐affected dentin

Abstract

The aim of this study was to evaluate the microtensile bond strength (microTBS) and the elemental contents of the adhesive interface created to normal versus caries-affected dentin. Extracted human molars with coronal carious lesions were used in this study. A self-etching primer/adhesive system (Clearfil Protect Bond) was applied to flat dentin surfaces with normal and caries-affected dentin according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were cross-sectioned and subjected to a microTBS test and electron probe microanalysis for the elemental distributions [calcium (Ca), phosphorus (P), magnesium (Mg), and nitrogen (N)] of the resin-dentin interface after gold sputter-coating. The microTBS to caries-affected dentin was lower than that of normal dentin. The demineralized zone of the caries-affected dentin-resin interface was thicker than that of normal dentin (approximately 3 microm thick in normal dentin; 8 microm thick in caries-affected dentin), and Ca and P in both types of dentin gradually increased from the interface to the underlying dentin. The caries-affected dentin had lost most of its Mg content. The distributions of the minerals, Ca, P, and Mg, at the adhesive interface to caries-affected dentin were different from normal dentin. Moreover, a N peak, which was considered to be the collagen-rich zone resulting from incomplete resin infiltration of exposed collagen, was observed to be thicker within the demineralized zone of caries-affected dentin compared with normal dentin.

Bond Strengths of a 1-Step Self-etching System to Caries-affected and Normal Dentin

“…Interestingly, during the caries-forming process, the tubules become obliterated with whitlockites, thus reducing permeability of the caries-affected dentin. 15 In general, SEM analysis revealed a thicker hybrid layer formation for the Single Bond groups compared to the Adper Prompt L Pop groups. This is most likely due to the specific feature of each adhesive system, one being an "etch and rinse" system that uses an aggressive phosphoric acid etching and the other a self-etching adhesive that is less aggressive.…”

“…The hybrid layers of both Single Bond and Adper Prompt L Pop for the caries-affected dentin were thicker than those formed in normal dentin, an observation which was also previously reported. 9,15 This phenomenon may be due to the partially demineralized nature of intertubular dentin in caries-affected dentin, which permits deeper acid demineralization and deeper monomer infiltration compared to normal dentin.…”

Shear bond strength of different dentin substitute restorative materials to dentin of primary teeth

“…There are differences in modulus of elasticity and hardness between bonded CAD and bonded sound dentin in primary teeth 27) . The physical and chemical properties of sound dentin are unlike from those of CAD 28) . The latter is more porous and softer than sound dentin due to partial demineralization, with narrow and obliterated dentinal tubules due to deposition of intratubular dentin and with a hybrid layer thicker than that of sound dentin 18) .…”

Temperature Rise under Normal and Caries-Affected Primary Tooth Dentin Disks during Polymerization of Adhesives and Resin-containing Dental Materials

“…The affected layer is generally not removed during treatment [10][11][12] . Therefore, following caries removal and cavity preparation for an adhesive restoration, a large area of the cavity floor is composed of cariesaffected dentin 13) . The physical and chemical characteristics of caries-affected dentin are very different from those of normal dentin.…”

“…Moreover, most tubules of caries-affected dentin are occluded with mineral deposits 15,16) . Electron probe microanalysis also showed that elemental contents are different between normal and caries-affected dentin surfaces 13) . With due consideration of these differences, they may have significant implications for temperature rise between normal and caries-affected dentin.…”