Vol 12, Issue 5, 2019 Online - 2455-3891 Print - 0974-2441 EVALUATION OF GRAPE SEED EXTRACT (VITIS VINIFERA) AS A CROSSLINKER ON THE STABILITY OF DENTINE COLLAGEN IN TOTAL-ETCH ADHESIVE SYSTEMS: AN IN VITRO STUDY D DENNIS, FENIKA MAITARI Department of Conservative Dentistry, Faculty of Dentistry, Center of Excellence, Green Chitosan and Advanced Material, Universitas Sumatera Utara, Indonesia. Email: dennis_dionisius@yahoo.co.uk Received: 10 February 2019, Revised and Accepted: 30 March 2019 ABSTRACT Objective: The bond strength between resin and dentine is determined by the integrity of collagen, dentine, and resin monomers. The susceptibility of the dentine bond results from the instability of the bonding structure that adheres to the bonding material. This can be achieved using collagen cross- linker, synthetically and naturally in dentine substrates which are effective in protecting collagen fibrils from degradation, as proanthrocyanidin. The aim of this study was to see the effect of grape seed extract as a crosslinker on the stability of dentine collagen and see the differences between groups. Methods: This study used 27 fresh premolars or third molars which were divided into three Groups, namely Group I giving grape seed extract 6.5%, Group II giving chlorhexidine 2%, and Group III only giving bonding ingredients. Samples were analyzed using scanning electron microscopy with ×1000 magnification. Results: Data were analyzed using kappa statistic, Kruskal–Wallis, and Mann–Whitney. The result of the study significant differences between treatment groups (p<0.05) and the 2% chlorhexidine group showed the highest value compared to the grape seed extract group and without treatment. Conclusion: Grape seed extract can be used as an alternative to chlorhexidine as a crosslinker to maintain bone strength of the composite restoration. Keywords: Bond strength, Proanthocyanidine, Grape seed extract, Crosslinker INTRODUCTION The use of composite resins for dental restorations in the past decade to restore carious teeth has greatly increased. The need for esthetics and low toxicity makes popular composite resins. The initial problem in using composite resins is low durability due to the use and loss of anatomical shape after use [1]. Composite resins contain bonds that are not stable, so they are easily degraded by acid or low pH. Acid causes polymer degradation and filler components which can affect the hardness and roughness of the composite resin surface [2]. Various studies have shown that there is a decrease in composite resin bonds in dentine which in this case can be attributed to the complexity of dentine structures such as increasing tubular numbers and diameter with intertubular dentine matrix which is much less than superficial dentine [3]. Successful adhesion to enamel with a strong adhesive value height cannot be achieved equivalent to dentine. Dentine has a higher water and organic content than enamel, which causes dentine to be moist, so that the adhesion system must be hydrophilic [4]. Dentine has a composition of 70% minerals (apatite crystals), 18% is in the form of organic components, namely collagen type 1 and non- collagen proteins, while 12% is water [4]. Dentin collagen is needed to form a cross bond that can provide strength and stabilization, so it is needed as a biomaterial [5]. Infiltration of resin monomers into dentinal tubular tissue and intertubule will form micromechanical retention areas called hybrid layers. Micromechanical retention between resin and dentin is the main mechanism of resin–dentine bond. The bond strength between resin and dentine is determined by the integrity of collagen, dentine, and resin monomers [6,7]. The resistance of the hybrid layer depends on the stability of each component, such as collagen fibrils and polymer chains. However, collagen fibrils which are not fully infiltrated by resin monomers when exposed to acid etching inhibit optimal protection against denaturation. Unprotected collagen is more susceptible to creep and cyclic fatigue ruptures after functioning for a long time. In the fibril collagen, resins are filled and surrounded by water, which participates in the matrix hydrolysis of resin by esterases and collagen by collagenolytic enzymes [8]. The susceptibility of the dentine bond results from the instability of the bonding structure that adheres to the bonding material. This is due to physical and chemical factors including hydrolysis and enzymatic degradation by matrix metalloproteinases (MMPs) which can increase the risk of degradation of collagen dentine in hybrid layers.[8,9] In the degradation of hybrid layers by MMPs, MMPs inhibitors act to protect collagen in the hybrid layer. Chlorhexidine 2% can inhibit MMP-2, -8, and -9 and, even at low concentrations, can maintain the integrity of the hybrid layer. The role of chlorhexidine is to delay dentine demineralization but does not stop the degradation of the bonds permanently. However, chlorhexidine also has deficiencies in the form of discoloration and bitter taste [10,11]. Mechanical properties of collagen and its resistance to enzymatic degradation can be improved by increasing the formation of intra- and inter-molecular and intermicrofibrillar cross-links. This can be achieved using synthetic and natural collagen cross-linker in the dentine substrate before bonding procedures [12]. The use of collagen cross-linking agent is proposed to improve the mechanical properties of the dentine matrix, reduce the level of biodegradation of collagen, increase the nature of dentine resin bonding, and extend the life of adhesive restoration [5]. One natural collagen cross-linker is proanthocyanidin. Proanthocyanidin, called condensed tannins, is a structure of flavan-3-ol [13]. Proanthocyanidin is found in fruits, vegetables, nuts, seeds, and flowers [14]. Grape seed compounds include flavonoids, polyphenols, anthocyanins, proanthocyanidins, procyanidins, and the stilbene © 2019 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2019.v12i5.32506 Research Article