Influence of Adhesive Systems on Microleakage Pattern of Composite Resin Restorations

AIMS: Microleakage is important for assessing the success of adhesive restorative materials. The aim of this study was to evaluate the microleakage of resin composite restorations bonded with three types of adhesive systems. MATERIALS AND METHODS: Twenty four sound human third molars were used. Class V cavities were prepared on the buccal surface by a diamond cylinder bur No. (1543M). Samples was assigned randomly to three groups (N = 8): Group Ι: Cavities were treated with total etch adhesive system (Adper Single Bond 2Adhesive, 3M ESPE, USA). Group II: Cavities are treated with one step self-etch adhesive system (OptiBond All In One, kerr, USA). Group III: Cavities were treated with two step self-etch adhesive system (CLEARFIL SE BOND, kurary, Japan). Cavities were restored in bulk technique withresin composite (Ceram X, DENTSPLY, USA). Restorations were polished and after storage in water for 24 hours at 37°C the samples were thermocycled between 5-50°C for 300 cycles in water baths then immersed in methylene blue solution for 24 hours. Dye leakage was assessed by examining longitudinal sections in a stereomicroscope at X10magnification. Data were analyzed with Kruskal-Wallis test and Mann-Whitney test at 5%significant level. RESULTS: A significant differences in microleakage were observed among restorations (p < 0.05).One step adhesive bonded restorations demonstrate significantly higher leakage value than two step. No significant differences were observed between total etch adhesive and self-etch adhesive (p>0.05).CONCLUSIONS: The microleakage of resin composite restoration was influenced by adhesive type. One step self-etch bonded restoration was more prone to leakage than total etch and two step bonded restoration. Keyword: Adhesive systems, microleakage, resincomposite. Abdulkadir EA, Nayif MM. Influence of Adhesive Systems on Micro-leakage Pattern of Composite Resin Restorations. Al–Rafidain Dent J. 2013; 13(3): 547-554. Received: 16/7/2012 Sent to Referees: 18/7/2012 Accepted for Publication: 23/10/2012 INTRODUCTION In 1968, Buonocore et al. introduced the so called „acid-etch technique‟ to micro mechanically interlock resin within enamel upon impregnation into the acid produced etch pits. Today, this technique is still the most effective for reliable and durable bonding to enamel. (1) The integrity Influence of Adhesive Systems on Microleakage Pattern of Composite Resin Restorations ISSN: 1812–1217 Al – Rafidain Dent J Vol. 13, No3, 2013 www.rafidaindentj.net 548 and durability of the marginal seal is an important factor in the longevity of adhesive dental restorative materials, particularly for resin composites. The absence of a seal at restoration margins permits the entry of oral bacteria and fluids, which can result in postoperative sensitivity, adverse pulpal responses and recurrent caries. (2) Technological advancements of dentin adhesives have evolved into two trends: total acid-etching techniques (5 th generation dentin bonding agents) and selfetching primer technique (6 th and 7 th generation). (2) Total etch adhesives are available as a three stepsystems (etchant, primer and adhesive) and two-step systems (combine the primer and adhesive materials into one component).Total etch adhesive system contains hydrophilic/ hydrophobic primers with the ability to penetrate into the demineralized enamel and dentin created after phosphoric acid etching and smear layer removal. A zone of interdiffusion is formed, and the resin dental substrate is defined as the hybrid layer. If the surface to which the adhesive will be applied consists of significantly more enamel than dentin total etch system is preferred. In comparison, self-etch adhesives generally demonstrate better adhesion to dentin than to enamel. (3) The basic mechanism for bonding with total etch system consists of demineralization of the enamel and dentin surfaces by the acid (etchant) then adhesive applied to penetrate the microscopic spaces created by the etchant. Curing of the adhesive will result in formation of resin tags that microscopically provide a mechanical bond and seal to dentin and enamel. (4) While self-etch system does not require a separate etching procedure. Thus there is no need to rinse and then dry the preparation prior to application of the adhesive. For these reasons, their popularity is increasing. (4) Self-etch adhesives, composed of aqueous mixture of acidic functional monomers that are generally phosphoric acid esters. Phosphoric acid esters, with a pH relatively higher than that of phosphoric acid etching gels. (5) Selfetch adhesivesproduce simultaneous conditioning and priming effects on dental substrates and do not remove the smear layer, but penetrate and modify it, creating a thin hybrid layer dependent on pH, composition, and concentration of polymerizable acids and/or acidic resin monomers. (6) Self-etch adhesives are available as two step systems and one step systems. In two step systems etch primer is applied without rinsing then a layer of adhesive resin is applied. (7) A possible advantage of applying the etchant and primer in a premixed solution is that the demineralization of dentin occurs concurrently with primer infiltration and the risk of leaving demineralized dentin that was insufficiently infiltrated by resin is thought to be much smaller. (8) One step self-etch systems is more simplified including a single application to the tooth. (7) This system is extremely hydrophilic as they contain high concentrations of both ionic and hydrophilic monomers. Due to their high hydrophilicity, one step self-etch adhesives behave as semipermeable membranes, allowing fluids to pass through and seriously jeopardizing bond durability. (9, 10) The hypothesis to be tested in this study is that no differences in the microleakage among the different adhesive systems .The objective of this study was to evaluate the microleakage in resin composite restoration following bonding with three different adhesive systems (Total etch, One and two step selfetch adhesives). MATERIALS AND METHODS Samples collection and mounting: Twenty four extracted sound human third molar were stored approximately for one week in distilled water until their use. Teeth were cleaned and polished. Roots of the teeth were covered with two layers of nail varnish and apices sealed with a sticky wax. Roots were embedded in cold cure acrylic resin (Ivoclarvivadent, Liechtenstein) inside polyvinyl plastic rings up to a cemento-enamel junction. Cavities preparation: Class V cavities (4 mm width and 2 mm in height and depth) were prepared in the middle third of the buccal surfaces of the teeth with abutt joint margins using a diamond cylindrical bur No. (1543M).In order to standardize cavity preparation the outline of the cavity was drawn on the tooth surface with the help of digital vernia to measure the dimensions Figure (1). Al – Rafidain Dent J Vol. 13, No3, 2013 Abdulkadir EA, Nayif MM