Abstract
Objective: To evaluate the effect of a resin coating material on the microleakage of Class V composite resin restorations with and without post-operative bleaching. Material and Methods: Eighty class V cavities (3×3×1.5 mm) were prepared and filled with Z250 XT composite resin in the buccal and lingual surfaces of 40 sound human molars. Then the samples were randomly divided into 4 groups (n=20) and treated as follows: Group A: applying a resin coating (G-Coat Plus) on the restoration, then bleaching with 40% hydrogen peroxide; Group B: Post-Operative bleaching without prior use of resin coating; Group C: applying resin coating agent, and no further bleaching; and Group D: no resin coating, no bleaching. The specimens were thermocycled and immersed in 1% methylene blue for 24 hours, then cut into sections bucco-lingually. The samples were scored regarding the amount of dye penetration under a stereomicroscope (x20). Data were analyzed with Chi-squared and Fisher exact tests (p<0.05) . Results: The maximum gingival and occlusal microleakage was detected in group B, while the minimum was seen in group C. In all the groups, microleakage at gingival margins was higher than occlusal margins (p<0.001) . Conclusion: Application of a resin coating is an effective method in reducing microleakage of the restorations before and after bleaching.
Highlights
In current dentistry, composite resins are widely used due to improved mechanical properties, good aesthetic properties and strong bonding to the tooth structure
Office bleaching entails the application of 35–38% hydrogen peroxide on the tooth surface for 30–45 minutes; and the home bleaching is usually carried out with the use of 10–20% carbamide peroxide in prefabricated special trays, which are worn by the patients at nights [3]
Other studies that have showed that bleaching of teeth with 35% hydrogen peroxide and 10% carbamide peroxide does not have any effect on microleakage of class V tooth-coloured restorations [8,9,10]
Summary
Composite resins are widely used due to improved mechanical properties, good aesthetic properties and strong bonding to the tooth structure. Creation of microleakage at marginal areas will pave the way for secondary caries, enamel cracks, staining of restoration and post-operative sensitivity [1] In addition to these kinds of restorations, bleaching of discoloured teeth is becoming a common and popular treatment in dentistry as this approach is the most conservative and favorable procedure to improve the aesthetic appearance of teeth compared to other techniques [2]. Several studies have reported that the microleakage at the dentin margins of Class V resin composite restorations following exposure to home bleaching agents would increase [4,5,6] This increase in microleakage can potentially lead to a series of clinical problems, including bacterial accumulation, staining and pulp damage [7]. There is no consensus on the effect of bleaching agents on the tooth-coloured restorative materials, replacement of the restoration after tooth bleaching is often advised due to poor post-treatment colour match and the degraded properties of the restorative material [7], which itself might have detrimental effects on remaining tooth structure and pulp vitality
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