الفهرس 
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Abstract
This study aimed to evaluate degree of conversion (DC), Vickers microhardness (VMH), depth of cure, and 2-year clinical performance of dual- and light-cure bulk-fill resin composites (BFRCs). Materials and Methods : One dual-cure (Fill-Up : Coltene Waledent AG, Altstatten, Switzerland) and two light-cure (QuiXfil : Dentsply, Konstanz, Germany ; and Tetric N-Ceram Bulk Fill : Ivoclar Vivadent, AG, Schaan, Liechtenstein) BFRCs were investigated. A universal adhesive (ONE COAT 7 UNIVERSAL : Coltene Waledent AG, Altstatten, Switzerland) was used with all restorations. For in vitro DC and VMH, eleven cylindrical specimens (5-mm diameter, 4-mm height) were prepared in split Teflon molds and light cured for 10 seconds for each tested BFRC (n = 11). DC was obtained by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and VMH was obtained using a micro-Vickers hardness tester. The specimens were measured for DC and VMH at top and bottom surfaces. Statistical analysis was performed using two-way analysis of variance (ANOVA), Tukey’s post-hoc, and Pearson correlation tests (p < 0.05). For clinical evaluation, thirty patients were included in the study (n = 30). Each patient received three Class ӀӀ BFRCs restorations. The three BFRCs were used for Class ӀӀ restorations following the manufacturers’ instructions. All restorations were clinically evaluated after 1 week (baseline), 6 months, 12 months, 18 months and finally after 24 months using the World Dental Federation (FDI) criteria. The following parameters were evaluated: surface luster, staining (surface, margin), color match and translucency, esthetic anatomical form, fracture of material and retention, marginal adaptation, occlusal wear, proximal contact, postoperative (hyper-) sensitivity and tooth vitality, recurrence of caries, and tooth integrity (enamel cracks, tooth fractures). Chi-Square test was used for comparison between BFRCs groups, and Marginal Homogeneity test was used for comparing between different follow-up times as compared to baseline value (p < 0.05). Results : For in vitro DC and VMH, Fill-Up and Tetric N-Ceram Bulk Fill revealed significantly higher DC and VMH values on the top surfaces than that on the bottom surfaces, whereas QuiXfil revealed no significant difference between top and bottom surfaces for DC and VMH. All tested BFRCs showed bottom/top ratios >80% for both DC and VMH. Each tested BFRC showed a significant positive correlation between DC and VMH. For clinical evaluation, all BFRCs restorations revealed no statistically significant differences between their clinical performance at base line and after 2-year recall period. Conclusions : All tested BFRCs have adequate depth of cure, but only QuiXfil (micro-hybrid light-cure BFRC) has a uniform depth of cure. Light curing of Fill-Up (dual-cure BFRC) can improve DC and VMH values of the light-cured surface. Although there is a positive correlation between DC and VMH of each tested BFRC, VMH cannot be used to directly compare DC of the different tested BFRCs. Both DC and VMH bottom/top ratios are effective for depth of cure evaluation. The three tested BFRCs showed acceptable clinical performance in Class ӀӀ restorations after 2-year clinical follow-up.