Compressive strength of dental composites photo-activated with different light tips

Abstract

The aim of this study was to evaluate the compressive strength of microhybrid (Filtek TM Z250) and nanofilled (Filtek TM Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm 2 when using the fiber optic light tip and 596 mW cm 2 with the polymer. After storage in distilled water at 37 ± 2 C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min 1 . The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane's test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p < 0.001) between the microhybrid composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth.

Green LED as an Effective Light Source for Curing Acrylate-Based Dental Resins in Combination with Irgacure 784

“…Compressive strength has a particularly important role in the mastication process, since most of the masticatory forces are of compressive nature. The compressive strength values of our copolymer matrix are, at around 300 Mpa, in the order of those published by Galvão et al [36]. The high diametral tensile strength values may be attributed to the high degree of conversion of the methacrylate double bonds [37].…”

Comparison of two light guide tips used to photo-polymerize two dental composites. An in-vitro study

“…The efficacy of a CMLG tip (similar to the shape and dimensions of a MMLG tip) that allows the curing of a resin based composite to the status of sufficient compressive strength, similar to the compressive strength fracture of a human molar (305MPa 24 ) has not been investigated. This may be an alternative option, offering a suitable and inexpensive solution.…”

“…The conditions and specifications of an LCU and a light guide tip that allows adequate photo-polymerisation of resin based composite restorations is well known to the profession. [24][25][26][27][28][29][30] These conditions and specifications have to be operating optimally, together with the appropriate light curing techniques, in order for the resin based composite restorations to be successfully cured. 4,14,23,24,[29][30][31][32][33][34][35][36][37] The wavelength of the LCU used in this experiment initiated activation of the photo-initiator in both resin specimens.…”

“…Compressive strength tests have been used previously to compare different MMLG tips. 24 Resin based composites that are placed accurately under the appropriate conditions and cured adequately using appropriate techniques have a compressive strength that is able to resist the compressive forces of occlusion. 24 The compressive fracture strength of a human molar is approximately 305 MPa.…”

“…24 Resin based composites that are placed accurately under the appropriate conditions and cured adequately using appropriate techniques have a compressive strength that is able to resist the compressive forces of occlusion. 24 The compressive fracture strength of a human molar is approximately 305 MPa. 24 This value was used as the mechanical standard to compare the compressive fracture strengths (MPa values) of the Z100 TM The results indicate that the consistency of the specimens made and the repeatability of the study design was excellent (Coefficient of variation was <50% in both groups).…”