In vitro μTBS of one‐bottle adhesive systems: Sound versus artificially‐created caries‐affected dentin

Abstract

This in vitro study aimed to evaluate a pH-cycling model for simulation of caries-affected dentin (CAD) surfaces, by comparing the bond strength of etch-and-rinse adhesive systems on sound and artificially-created CAD. Dentin substrates with different mineral contents and morphological patterns were created by submitting buccal bovine dentin to the following treatments: (1) immersion in artificial saliva during the experimental period (sound dentin, SD), or (2) induction to a CAD condition by means of a dynamic pH-cycling model (8 cycles, demineralization for 3 h followed by mineralization for 45 h). The bond strength of Excite or Prime and Bond NT adhesive systems was assessed using the microtensile bond strength (microTBS) test. Dentin microhardness was determined by cross-sectional Knoop evaluations. Resin-dentin morphology after the treatments was examined by scanning electron microscopy. SD produced significantly higher microTBS than CAD for both adhesives evaluated, without differences between materials. CAD exhibited lower microhardness than SD. Morphological analysis showed marked distinctions between SD and CAD bonded interfaces. Under the conditions of this study, differences in morphological pattern and dentin mineral content may help to explain resin-dentin bond strengths. The proposed pH-cycling model may be a suitable method to simulate CAD surfaces for bonding evaluations.

Bonding efficiency and durability: current possibilities

“…Although most the literature related to the performance of bonding agents refers to sound dentin as a standard substrate, 52 clinicians are frequently challenged by the presence of caries-affected and/or sclerotic dentin in their daily practice. In the same way, manufacturers base their new technologies on the adhesion to sound dentin which is far from representing a clinically relevant substrate.…”

Bond Strength of Adhesive Luting Agents to Caries-affected Dentin

“…Specimens were submitted to eight cycles of 48 hours; the demineralizing solution was renewed after the fourth cycle, and the mineralizing solution was renewed before the beginning of each new cycle. 17 The compositions of the solutions are listed in Table 1. After demineralization/ mineralization cycling, new Vickers hardness readings were performed on the dentin surfaces of the cycled specimens.…”

“…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.…”

Effect of Operator-specific Handling on Tooth-composite Interface and Microleakage Formation

“…Although there is no accepted experimental mode for the early experimental assessment of restorative systems, and clinical trials still remain the ultimate test, [3][4] experimental in vitro/in vivo bond testing may predict the results of clinical studies to a certain degree. 1,[4][5] Between bond strength measurements on enamel and dentin [6][7][8] and studies related to the biocompatibility of system components [9][10][11] and spectroscopic investigations, [12][13] numerous imaging methods can help to characterize restoration systems in great detail by investigating phenomena, such as marginal integrity, microleakage and the mechanisms of mechanical adhesion (interlocking/hybridization of enamel and dentin). 14 Such experimental screenings include investigating tooth substrates of different qualities (sound/carious dentin) 8,[15][16][17][18][19] and C-factors, [20][21][22] simulation of pulpal pressure and the oral environment, [23][24][25] the application of thermal and occlusal stresses, fatigue simulation [26][27] or, for better simulation of the clinical situation, studies on in vivo restored teeth that have been in use for a certain period of time.…”

“…1,[4][5] Between bond strength measurements on enamel and dentin [6][7][8] and studies related to the biocompatibility of system components [9][10][11] and spectroscopic investigations, [12][13] numerous imaging methods can help to characterize restoration systems in great detail by investigating phenomena, such as marginal integrity, microleakage and the mechanisms of mechanical adhesion (interlocking/hybridization of enamel and dentin). 14 Such experimental screenings include investigating tooth substrates of different qualities (sound/carious dentin) 8,[15][16][17][18][19] and C-factors, [20][21][22] simulation of pulpal pressure and the oral environment, [23][24][25] the application of thermal and occlusal stresses, fatigue simulation [26][27] or, for better simulation of the clinical situation, studies on in vivo restored teeth that have been in use for a certain period of time. 5,9,25,[28][29][30][31][32][33] In the past, one of the intentions of the authors of the current study was to combine the clinical assessment of enamel-dentin bonding systems with experimental in vivo and in vitro studies on the basis of the micromorphological evaluation of the tooth-composite interface and microleakage formation.…”