Depth of Cure and Microhardness of a New Composite vs. Bulk-fill Composites
Aim: To compare the depth of cure of new composite with bulk fill resin composites through using Vickers hardness profiles (VHN).
Materials and Methods: New composite and four bulk fill composite materials were examined: Tetric N Ceram®Bulk Fill, X-tra base, Compon, Filtek Posterior Bulk Fill, Sonic FillTM. Eight specimens of each material type were prepared in teflon molds which contained a slot of dimensions (8 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24 h, before measurement. The Vickers hardness was measured as a function of depth of material, at 1 mm intervals. Data were analyzed by one-way ANOVA using Turkey post hoc tests (p=0.05).
Results: The maximum VHN ranged from 46.7 to 68.1, whilst the 80% of max. VHN ranged from 37.4 to 54.5. The depth corresponding to 80% of maximum VHN ranged from 5.5 to 7 mm. This was taken as the depth-of cure.
Discussion: In this study, VHN, 80% VHN and depth profile properties of different Bulk Fill resin composites were measured and compared with the new composite by the determination of their VHN/depth profiles. There were statistically significant differences between different bulk fill composite materials in terms of max. VHN and depth of cure, corresponding to 80% of max. VHN. Depth of cure is related to the clinical success of restoration. When a more extensive polymerization and crosslinking occurs, greater VHN results are obtained. According to the manufacturer's claims bulk fill composites can be applied up to 4 mm, or even 5 mm in one time. In general, adequate polymerization along the recommended depth in bulk fill composites is critical to the long-term stability of restorations. According to the results of our research, the manufacturers' claim was approved for these materials.
Conclusion: New composite can be cured to an acceptable post-cure depth as Bulk fill resin composites, according to the manufacturers’ claims. X-tra base had the greatest depth of cure among the composites examined.