Abstract
Objective This in vitro study evaluated the influence of bioactive plant extracts as dentin biomodifying agents to improve the longevity of bonded restorations. For that, plant extracts were applied to the dentin surface prior to the adhesive system. Materials and Methods Bovine incisors were ground flat to obtain 2 mm thick slices in which conical preparations were made (N = 10). Tannin-containing plant extracts were applied to dentin before the application of the restorative system, as follows: control group (untreated, CTL), chlorhexidine 0.12% (CHX), mastruz (Dysphania ambrosioides, MTZ), cat's claw (Uncaria tomentosa, CTC), guarana (Paullinia cupana, GUA), galla chinensis (Rhus chinensis, GCH), and tannic acid (extracted from Acacia decurrens, TNA). The push-out bond strength test was conducted (0.5 mm/min). Dentin biomodification was assessed by the modulus of elasticity and mass change in bovine tooth sections (0.5 × 1.7 × 7.0 mm). The dentin staining after extract treatments of dentin slices was compared. The dentin surface wettability was also evaluated by means of the contact angles of the adhesive system with the dentin surface and compared with the untreated control group. Data were subjected to ANOVA/Tukey's test (α = 0.05). Results The bond strength of the restoratives to dentin was not significantly improved by the plant extracts, irrespective of the evaluation time (p > 0.05). Except for TNA, the elastic modulus of demineralized dentin significantly reduced after treatment with the plant extracts (p < 0.05). The dentin staining correlated with the tannin content of the extracts. The contact angle was significantly reduced when treated with CTC, GCH, and TNA. Conclusions The tannin-containing extracts had a questionable effect on the longevity of bonded restorations. The dentin modulus was negatively affected by the extract treatments. Although some of the extracts changed the contact angle, which seems to improve the adhesive monomer permeation, the tannin-rich plant extract application prior to adhesive application was proven to be clinically unfeasible due to dentin staining.
Highlights
At the tooth-restoration interface occurs an interaction of polymers, collagen, noncollagenous protein, and minerals with the dentin, forming a hybrid layer [1]. e main goal in the bonding of adhesive restorations to dentin is to obtain complete infiltration of the resin monomers into the previously demineralized dentin surface to avoid the degradation of this interfacial area [2]
Dentin biomodification is claimed to be a biomimetic method mediated by bioactive agents, which interact with various extracellular components of the dentin matrix, improving the biomechanics and stability of the dentin collagen matrix [6]
In the process of dentin biomodification, bioactive chemical mediators are regarded to improve the strength of collagen fibrils by forming crosslinks [6]. e collagen cross-linking favors the increase of the fibrillar resistance to enzymatic degradation [7] and provides improved tensile properties [8]
Summary
At the tooth-restoration interface occurs an interaction of polymers, collagen, noncollagenous protein, and minerals with the dentin, forming a hybrid layer [1]. e main goal in the bonding of adhesive restorations to dentin is to obtain complete infiltration of the resin monomers into the previously demineralized dentin surface to avoid the degradation of this interfacial area [2]. E main goal in the bonding of adhesive restorations to dentin is to obtain complete infiltration of the resin monomers into the previously demineralized dentin surface to avoid the degradation of this interfacial area [2] In this manner, the extent to which the adhesive resin envelops collagen fibrils helps e Scientific World Journal improve the durability of bonding to dentin [3]. Different approaches have been proposed to enhance and reinforce the dentin by superficially altering its biochemistry and biomechanical properties [6] Among these purposes, dentin biomodification is claimed to be a biomimetic method mediated by bioactive agents, which interact with various extracellular components of the dentin matrix, improving the biomechanics and stability of the dentin collagen matrix [6]. Tannins, which are polyphenols found in plants, are regarded to inhibit proteases and to present an affinity to dentin collagen, acting as a cross-linking inductor, preventing dentin matrix loss [6, 12]
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