Abstract
The aim was to evaluate the microtensile bond strength (mTBS) to dentin and interfacial stress in a class II cavity restored with bulk-fill or conventional composite resins and the margin interfaces. Vertical slot class II cavities in the mesial face, with the gingival end in dentin, were prepared in 72 third molars, being divided into groups (n=24): G1-Tetric N-Ceram; G2-Tetric N-Ceram Bulk-Fill; G3-SonicFill. Clearfil SE Bond adhesive system was used in all groups. Half of the teeth in each group (n=12) were submitted to thermo-mechanical cycling (TMC). Restored teeth (n=9) were cut perpendicular to obtain beams, which were submitted to a mTBS test in an EMIC machine. The cervical margins in dentin of the restored teeth (n=3) were assessed using SEM through epoxy resin replicas as well as the section of the restoration. Interfacial stresses after load application were calculated by 2D finite element analysis. The mTBS means-MPa followed by different letters represent statistical difference by ANOVA and Games-Howell's test (p<0.05): Without TMC: G1-15.68±6.10a; G2-10.08±5.21ab; G3-7.98±3.76b. With TMC: G1-9.70±5.52a; G2-5.79±1.42a; G3-4.37±1.87a. Interfacial stress (MPa) was 4.4 for SonicFill, 3.9 for Tetric N-Ceram, and 3.5 for Tetric N-Ceram Bulk-Fill. SEM images showed continuous margins for all composite resin restorations. It was possible to conclude that SonicFill obtained a slightly higher interfacial stress and lower bond strength to dentin in comparison with Tetric N-Ceram and Tetric N-Ceram Bulk-Fill. Continuous margin interfaces were obtained for Tetric N-Ceram, Tetric N-Ceram Bulk-Fill, and SonicFill. However, voids were observed in the SonicFill restorations.
Highlights
Composite resin as direct restorative material has been extensively used to restore posterior teeth due to its low cost and more complete preservation of the sound tooth substance, as well as its favorable clinical performance [1].The conventional composite resins require the incremental filling technique, with increments of less than 2 mm, aiming to decrease polymerization shrinkage stress and cuspal flexure as well as composite resin thickness [2]
After thermo-mechanical cycling, there were no significant differences in μTBS means among the composite resins (p>0.05)
Flat surfaces are used for testing bond strength in most studies, which does not resemble the clinical situations found in the oral cavity
Summary
Composite resin as direct restorative material has been extensively used to restore posterior teeth due to its low cost and more complete preservation of the sound tooth substance, as well as its favorable clinical performance [1].The conventional composite resins require the incremental filling technique, with increments of less than 2 mm, aiming to decrease polymerization shrinkage stress and cuspal flexure as well as composite resin thickness [2]. There is a tendency to use materials that require fewer steps and more simple procedures. Towards this end, bulk-fill composite resins are designed for a single application. Bulk-fill composite resins are designed for a single application These materials are claimed to enable the restoration build-up in thick layers of 4 or even 5 mm without a prolonged polymerization time [4]. This prevents void formation and contamination between the composite resin layers, providing more compact restorations. Bulk-fill composite resins are very attractive due to the possibility of quicker placement of restorations [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
