Abstract
Bulk-fill (BF) dental resin composites are made to be polymerized in increments of up to 5 mm rather than the 2 mm increment recommended for conventional composites. This project aimed to determine microhardness (MH) profiles of BF resin composites at different depths and varying light cure (LC) distances from the light source in an attempt to mimic varying clinical situations. Forty-eight cylindrical specimens (4 mm diameter and 6 mm height) were prepared from 3 BF composites: Tetric N-Ceram Bulk-Fill (TBF), Filtek One Bulk-Fill (FBF), and Sonic-Fill 2 (SF2). Four different distances (0, 2, 4, and 6 mm) from the LC unit were investigated. Vickers MH was measured at the top and bottom of the samples and at every 1 mm, by creating 3 indentations at each depth. The bottom-top microhardness ratio (MHR) and percentage reduction in MHR were also measured. Data was analyzed using mixed-model repeated-measure ANOVA at 0.05 significance level. The main variables effects “material, LC distance, and depth” were significant (p < 0.001). Increasing LC distance and the depth of the tested BF significantly affected Vickers MH and MHR. None of the tested BF materials had sufficient MHR at the depths of 4–6 mm. SF2 showed the least MHR reduction.
Highlights
Dental resin composites are the direct filling material of choice for many clinicians due to their pleasing esthetics and good mechanical properties [1,2,3]
Tetric N-Ceram Bulk-Fill (TBF) was significantly different from Filtek One Bulk-Fill (FBF) and Sonic-Fill 2 (SF2) (p < 0.001)
At D4, D5, and D6 with LC6, SF2 showed the least reduction in microhardness ratio (MHR) among the tested materials, while TBF showed the highest values of reduction
Summary
Dental resin composites are the direct filling material of choice for many clinicians due to their pleasing esthetics and good mechanical properties [1,2,3]. In an effort to improve upon the existing materials, several bulk-fill dental resin composites were introduced by manufacturers These materials claim to be curable in 4- to 5-mm increments while adhering to the same exposure time recommended for conventional composites [7,8]. In theory, this is made possible by one of the following methods; reducing the filler content to create a flowable composite, by changing the photoinitiator, or by increasing the translucency of the material [1]. These changes allow the light to penetrate deeper into the restoration
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