Mineral density, morphology and bond strength of natural versus artificial caries-affected dentin

Abstract

This study aimed to investigate an artificial caries-affected dentin (ACAD) model for in vitro bonding studies in comparison to natural caries-affected dentin (NCAD) of human teeth. ACAD was created over 7 days in a demineralizing solution. Mineral density (MD) at different depth levels (0-150 µm) was compared between NCAD and ACAD by transverse microradiography. Micro-tensile bond strengths (µTBS) of two two-step self-etch adhesives to sound dentin, NCAD and ACAD were evaluated. Caries-affected dentin type was not a significant factor when comparing MD at different lesion levels (p>0.05). Under SEM, the dentinal tubules appeared occluded with crystal logs 1-2 µm in thickness in the NCAD; whereas they remained open in the ACAD. The µTBS to caries-affected dentin was lower than sound dentin, but was not affected by the type of caries (p>0.05). In spite of their different morphologies, the ACAD model showed similar MD and µTBS compared to NCAD.

Bond Strength of Adhesive Luting Agents to Caries-affected Dentin

“…This method has been previously described and results in a substrate with similar mineral content to that observed in natural CAD. 2,8,17 Natural CAD presents as a hypomineralized tissue because of the cycles of demineralization and remineralization over a long period. 8 This process results in dissolution of mineral content, which precipitates into dentinal tubules, thus creating crystal logs.…”

“…[3][4][5] Significant alterations of mineral content have been described for CAD, where the intertubular dentin presents lower mineral content than normal dentin, and where acid-resistant minerals are observed obliterating the dentin tubules. [6][7][8] The obliteration of tubules can interfere with resin infiltration, thus preventing tags during bonding procedures. 9 Conversely, the lower mineral content of intertubular dentin in CAD permits deeper etching of this substrate.…”

“…13,14 The bonding mechanism of SARCS is attributed to a chemical reaction between phosphate methacrylates and hydroxyapatite as well as to the infiltration of these materials into the tooth tissues. 15,16 Reduced bond strength of adhesive systems to CAD has been demonstrated, 6,8,17 but little information is available about the bonding of SARCs to this clinically relevant substrate. One of the difficulties in evaluating adhesive systems' bonding to CAD involves obtaining a standardized substrate for the bondstrength studies.…”

Influence of FCP-COMPLEX on bond strength and the adhesive–artificial caries-affected dentin interface

“…However, the morphology of ACAD differed from that of the natural caries-affected dentin (NCAD) in that there was a lack of mineral casts in the dentinal tubules of ACAD. NCAD and ACAD tissues were superficially comparable in terms of intertubular nanohardness 5) . NCAD develops over a longer period of time than ACAD, in which the lesion was created over a short period of time under controlled conditions.…”

“…Joves et al created a model for assessing bonding to CAD, and compared its mineral profile, morphology, bonding properties, and nanohardness to those of natural caries 4,5) . The artificial caries-affected dentin (ACAD) had a similar mineral content and bond strength, yet lower variability, as compared to the natural cariesaffected substrate.…”