Abstract
This in vitro study aimed to assess and compare premolars cuspal deflection that restored with different bulk fill resin materials types (SonicFillTM2, Beautifil Bulk Fill restorative, and FiltekTM Bulk Fill posterior restorative) to those incrementally restored group with conventional composite restorations (low shrinkage universal Tetric Evoceram). A total of 40 intact human maxillary first premolars were prepared into large MOD. Then teeth were randomly classified into four groups (n=10 for each group) according to restorative materials as following: Group A: Teeth were restored with Sonic FillTM2 composite, Group B: restored with Beautifil Bulk Fill restorative material, Group C: Teeth were restored with Filtek BulkTM Fill posterior restorative, and Group D: Teeth were restored with Universal Tetric Evo Ceram®. Digital microscope was used to measure intercuspal distance between two index reference points on the tips of the cusps before preparation, after preparation, and 15minutes after completion of restorations. The differences registered as cuspal deflection. All teeth were exposed to inward cuspal deflection after restoration and all groups that restored with bulk fill restoration reported lower cuspal deflection in compared to group D that restored with conventional composite in layering technique. Beautifil Bulk Fill restorative produced significantly greater cuspal deflection than other bulk fill groups. The study concluded that the use of new bulk fill restorative materials might reduce amount of cuspal deflection significantly. However, type of bulk fill restorative materials also influenced on amount of cuspal deflection so restoration with Sonic Fill™2 composite and Filtek Bulk™ Fill posterior reported lower cuspal deflection than Beautifil Bulk Fill restorative material.
Highlights
According to manufacturer’s, The SonicFillTM handpiece was turn through foot pedal to activate the sonic vibration, which changed the viscosity of the SonicFillTM2 composite material from high viscosity to low viscosity, the cavity was filled in one increment and cured with LED light cure unit for 20 seconds
This reduction may attribute to that the new bulk fill resin-based materials are induced lower shrinkage stress than those of a conventional composite through incorporation of stress-relievers to change the shrinkage dynamics, using novel chemistry, increase filler loading with decrease resin matrix, and reduce polymerization shrinkage stress[33,35,37]. This result is in disagreement with other studies, found that the bulk fill resinbased composites do not differ from conventional composites in the shrinkage stress, integrity of the margin, cuspal flexure and can be sufficiently cured at 4mm depth[29,38]
Group B show higher cuspal deflection than other bulk fill types used in this study, this may due to present polymerization modulators with high molecular weight in other bulk fill composites materials tested in this study, which reduce polymerization shrinkage by delaying gel point, and giving additional time to recompense of the shrinkage[41]
Summary
Non- carious human maxillary first premolar teeth were collected for this study. According to manufacturer’s, The SonicFillTM handpiece was turn through foot pedal to activate the sonic vibration, which changed the viscosity of the SonicFillTM2 composite material from high viscosity to low viscosity, the cavity was filled in one increment (bulk) and cured with LED light cure unit (power intensity of 800mw/cm2) for 20 seconds. Group B: Teeth were restored with Beautifil Bulk Fill restorative material according to manufacturer’s recommendations. It placed in one increment (bulk) and cured as in Group A. The cuspal deflection after cavity preparation (CD1) was measured by subtracting the intercuspal distance after cavity preparation from intercuspal distance for unaltered teeth. The cuspal deflection that occurred as a result of polymerization shrinkage stress (CD2) was measured by subtracting final distance from initial distance
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