Research Paper: Investigation of Micro-leakage of Self-cured and Light-cured composite restorations using a universal bonding system

  Abstract Introduction: One-bottle light-cured adhesives systems have variable pH. In addition to ease of use, universal adhesives can be used in various restorations and different substrates. Due to the lack of studies, the purpose of this study was to compare the enamel and dentin micro-leakage of self-cure and light cure composite restorations using a universal bonding system. Materials and Methods:The CL V cavities prepared on 60 bovine incisors (dimensions of 5 mm mesio-distal, 2 mm occluso-gingival and 1.5 mm in depth). Occlusal and gingival margins were 1mm above and below the CEJ. All Bond Universal bonding agent was applied to the cavities according to the manufacturer's instructions by selective etch method. The teeth randomly divided into group 1 which were restored with Master-Dent self-cure composite and group 2 restored with light cure AELITE All-Purpose composite. After thermocycling, the micro-leakage rates evaluated in two occlusal and gingival margins by stereomicroscope. The Mann-Whitney U test used to compare the micro-leakage (P ≤ 0.05). Results: The rate of micro-leakage at both gingival (dentin) (p ≤ 0.035) and occlusal (enamel) (P ≤ 0.015) margins in the self- cure composites were significantly higher than the light cure composites. In each group, gingival micro-leakage was also recorded higher than the occlusal (however, this difference was not statistically significant in the self-cure composite group)  (P = 0.474). Conclusion:According to the results, the All Bond Universal adhesive agent is not compatible with self-cure composite and can result in increased micro-leakage.