Title: Evaluation of effectiveness of composite cure of three bulk fill composites in comparison with other conventional composites
Aim and Objectives: The aim of this study to evaluate the hardness ratio of many new bulk-fill composites by using the micro-hardness testing to measure the hardness ratio of a 4 mm composite specimens as an indicator for their effectiveness of composite curing (80%) in comparison with other conventional types.
Material and methods:
Three packable bulk-fill composites were used in this study: Tetric N Ceram (Ivoclar Vivadent), Filtek Bulk fill Posterior composite (3M ESPE) and X-tra Fill Bulk-fill packable composite (VOCO).And two conventional composites will be used also namely: Quadrant Universal L.C Composites (CAVEX) and Composan Bio-esthetic Nano-cream Composite (PROMEDICA).10 specimens were prepared from each type of composite material, each composite specimen was prepared by compressing sufficient amount of composite into a mould ( 6 mm in diameter and 4 mm in thickness ) ( total specimen n=50. Each composite specimen will be cured for 20 seconds from the top surface only with Woodpecker LED light curing unit by making the curing tip in intimate contact with the celluloid strips on the surface of the composite.After that, the composite specimen was incubated in distilled water at 37 C for 24 hours.Then the 50 composite specimens were submitted for microhardness testing for both top and bottom surfaces by making three indentations of both surfaces and considering the mean microhardness number for each surface.The hardness ratio of each specimen was calculated by using the formula
Results: The micro-hardness test showed a significant difference between the five groups being tested (ANOVA, p<0.05). The material with the greatest micro-hardness values at the top was X-travel followed by Filtek Bulk fill packable, Composan, Universal Quadrant L.C and Tetric N Ceram respectively.The material with greatest microhardness at bottom was Xtrafill followed by Filtek Bulk fill packable, Universal Quadrant L.C, Composan and Tetric N cream respectively. The material with the greatest depth of cure was Quadrant Universal L.C followed by X-trafill, Composan, Filtek Bulk fill packable and Tetric N cream respectively.
Xtrafill bulk-fill composite showed the highest hardness values at top, bottom surfaces and hardness ratio amongst the materials tested, while Tetric N Ceram didn’t achieve the standard depth of cure of 80% bottom to top ratio compared to other packable bulkfill composites used in this study. There was no difference in surface hardness of bottom of both Composan and Universal L.C Quadrant ,
Keywords: Micro-hardness , Surface hardness ,Bulk-fill composite and Conventional composite