Comparing microleakage in Silorane based composite and nanofilled composite using different layering techniques in class I restorations: An in vitro study

Background: It won't be wrong to admit that composite resins are currently the back bone of aesthetic and conservative dentistry. However a major drawback of composite resins is that their setting reaction involves formation of polymer chains leading to polymerization shrinkage. Aim: To compare microleakage in silorane composite using oblique, vertical and horizontal layering techniques to microleakage of nanofilled composite using oblique, vertical and horizontal layering techniques. Materials and methods: 120 extracted maxillary premolar teeth were assigned to 2 groups based on the material used Group A nanocomposite and Group B-silorane and each group was divided further into 3 subgroups depending on incremental technique used for restoration into horizontal, oblique and vertical (sub groups A1, A2, A3, B1, B2 and B3). A Class 1 cavity measuring 3mm3mm2mm was prepared in all the teeth. In group A teeth Clearfil TMSE Bond (Kurary Medical inc. Okayama, Japan) was applied. Group A teeth were filled with FiltekTM Z350 XT (nanocomposite) (3M ESPE, St Paul, USA) using horizontal (A1), oblique (A2) and vertical (A3) incremental layering technique and each increment was cured for 30 seconds. In Group B teeth P90 system adhesive was applied and teeth were filled with FiltekTM P90 silorane (3M ESPE, St. Paul, USA) using horizontal (B1), oblique (B2) and vertical (B3) incremental layering technique. Specimens were thermocycled for 1000 cycles (5/55ºC, 30 seconds) and immersed in 2% methylene blue dye for 24 hours. Following immersion teeth were sectioned and observed under a stereomicroscope. Results were analysed using Kruskal-Wallis test followed by Mann Whitney U test. Results: Siloranes showed significantaly less microleakage than nanofilled composites. The difference between the horizontal group, oblique group and the vertical group was found to be statistically non-significant (P value >0.05) but mean microleakage was more in vertical group compared to oblique and horizontal group. Conclusion: Within the limitations of this study, we found that Siloranes exhibit significantly less microleakage as compared to nanofilled composites irrespective of the layering technique used.