Comparative Evaluation of Cavosurface Marginal Integrity by Assessing Microleakage Scores of Three Different Composites using a Universal Adhesive in Self Etch and Selective Etch Modes- A Stereomicroscopic Study

Abstract

Introduction: Composite resins are currently the most popular restorative materials due to their superior esthetics, strong mechanical properties and high resistance to dissolution. However, in spite of the improvements in resin composite formulations over the years, polymerisation shrinkage which necessitates incremental placement techniques still presents clinical challenges. Aim: To compare and evaluate cavosurface marginal integrity in Class I restorations by assessing microleakage scores using Tetric N-Flow Bulk fill, SureFil Bulk fill composites and Filtek Z350 XT and using selective etch and self etch modes of a universal adhesive. Materials and Methods: This in-vitro research study was carried out in the Department of Conservative Dentistry and Endodontics, Bapuji Dental College and Hospital, Davangere, Karnataka, India from April, 2018 to May, 2018. Sixty extracted non-carious, intact human mandibular molar teeth were selected for this study. Standardised Class I cavities of 4 mm depth were prepared by a single operator with a high-speed hand piece using carbide fissure # 245 (SS White Inc) bur under air-water coolant. Samples were randomly divided into two main groups in which Single Bond Universal was used: Group I: Selective Etch Mode (30), Group II: Self Etch Mode (30). These main groups were then divided into 3 subgroups each Subgroup TF: Tetric N- Flow Bulk fill (Ivoclar Vivadent), Subgroup SB: SureFil Bulk fill (Dentsply) and Subgroup FC: Filtek Z350 XT (3M ESPE). All the specimens were then sectioned longitudinally along the mesio-distal direction towards the center of the restoration. Each specimen was viewed under a stereomicroscope and grading was done according to dye penetration at the tooth-restoration interface. Kruskal-Wallis and Mann-Whitney U-test were used to analyse the results. Results: The results showed that there was statistically significant difference in the microleakage scores of Tetric N- Flow Bulk fill, Filtek Z350 XT and SureFil Bulk fill (p<0.001). Group I Subgroup TF yielded lower microleakage score 0.70±0.675 as compared to Group II Subgroup TF which had a higher score 1.60±1.578. This difference was not statistically significant. (p-value=0.266). Group I Subgroup SB yielded lower microleakage score 1.20±0.919 as compared to Group II Subgroup SB which had a higher score 2.10±0.568. This difference was statistically significant. (p-value=0.017). Group I Subgroup FC yielded lower microleakage score 2.50±1.354 as compared to Group II Subgroup FC which had a higher score 3.20±0.789. This difference was not statistically significant (p-value=0.260). Conclusion: Tetric N flow bulk fill flowable composite resin can be considered as a better choice when compared to SureFil bulk fill and Filtek Z350XT composite resins. Selective enamel etching with SureFil bulk fill should be considered as the better choice as compared to self-etch for providing adequate seal in mild universal adhesives in Class I cavities.