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MICROHARDNESS & DEGREE OF CONVERSION OF RECENTLY INTRODUCED BULK-FILL COMPOSITE RESIN USING DIFFERENT APPLICATION TECHNIQUES

INTRODUCTION: Recent advances in resin based technology, as regard to new monomers, translucency, initiator system and filler technology, overcome the disadvantages of conventional resin based materials and have led to the introduction of bulk-fill RBCs. OBJECTIVES: To evaluate the degree of conversion (DC%) and VHN of bulk fill composite using different application techniques in comparison with conventional composite material. MATERIAL AND METHODS: Bulk fill composite materials Sonicfill (SF), Tetric N Ceram Bulk fill (TB) and Smart Dentin Replacement (SDR) Flow were compared to conventional incremental layering Tetric NCeram composite in terms of microhardness and degree of conversion by Vickers Hardness Test and Fourier transform infrared spectroscopy (FTIR). Total of 40 composite discs were performed in Teflon mold with dimensions 6 mm in diameter 2mm or 4mm thickness and divided into four groups (10 each) according to the material used & its application technique. The Vickers hardness number (VHN) was measured as the mean value from top as well as from bottom of the specimen was obtained and statistically analyzed. For each specimen of each material FTIR spectroscopy with attenuated total reflectance method was performed to assess %DC. Data was collected and statistically analyzed. RESULTS: Statistically significant differences were shown between materials for all parameters tested using One-way ANOVA. The highest VHN were detected by SonicFill ( p < 0.001), while the lowest ( p ≤ 0.001) were detected by TetricNCeram. The greatest depth of cure ( 5.03 mm & 4.47 mm) were exhibited by SonicFill and Tetric NCeram Bulk Fill respectively which was significant different from SDR and TetricNCeram ( p ≤ 0.016). CONCLUSION: As claimed by the manufactuer, Bulk- fill composite resin materials can be polymerized to an acceptable depth of cure. SF and TB showed the highest values of VHN and DC% in comparison with SDR flow bulk & the conventional Tetric NCeram composite resin material.