Effect of Thickness on Light Transmission and Vickers Hardness of Five Bulk-fill Resin-based Composites Using Polywave and Single-peak Light-emitting Diode Curing Lights.

OBJECTIVES:: This study compared light transmission through different thicknesses of bulk-fill resin-based composites (RBCs) using a polywave and a single-peak light-emitting diode light-curing unit (LCU). The effect on the surface hardness was also evaluated. METHODS:: Five bulk-fill RBCs were tested. Specimens (n=5) of 1-, 2-, 4-, or 6-mm thickness were photopolymerized for 10 seconds from the top using a polywave (Bluephase Style) or single-peak (Elipar S10) LCU, while a spectrophotometer monitored in real time the transmitted irradiance and radiant exposure reaching the bottom of the specimen. After 24 hours of storage in distilled water at 37°C, the Vickers microhardness (VH) was measured at top and bottom. Results were analyzed using multiple-way analysis of variance, Tukey post hoc tests, and multivariate analysis (α=0.05). RESULTS:: The choice of LCU had no significant effect on the total amount of light transmitted through the five bulk-fill RBCs at each thickness. There was a significant decrease in the amount of light transmitted as the thickness increased for all RBCs tested with both LCUs ( p<0.001). Effect of LCU on VH was minimal (ηp2=0.010). The 1-, 2-, and 4-mm-thick specimens of SDR, X-tra Fill, and Filtek Bulk Restorative achieved a VHbottom/top ratio of approximately 80% when either LCU was used. CONCLUSIONS:: The total amount of light transmitted through the five bulk-fill RBCs was similar at the different thicknesses using either LCU. The polywave LCU used in this study did not enhance the polymerization of the tested bulk-fill RBCs when compared with the single-peak LCU.

Nanofilled Resin Composite Properties and Clinical Performance: A Review.

The aim of this review was to compile recent evidence related to nanofilled resin composite materials regarding the properties and clinical performance. Special attention was given to mechanical properties, such as strength, hardness, abrasive wear, water sorption, and solubility. The clinical performance of nanocomposite materials compared with hybrid resin composites was also addressed in terms of retention and success rates, marginal adaptation, color match, and surface roughness. A search of English peer-reviewed dental literature (2003-2017) from PubMed and MEDLINE databases was conducted using the terms "nanocomposites" or "nanofilled resin composite" and "clinical evaluation." The list was screened, and 82 papers that were relevant to the objectives of this work were included in the review. Mechanical properties of nanocomposites are generally comparable to those of hybrid composites but higher than microfilled composites. Nanocomposites presented lower abrasive wear than hybrids but higher sorption values. Their clinical performance was comparable to that of hybrid composites.

The Silorane-based Resin Composites: A Review.

This article aims to review the research done on the silorane-based resin composites (SBRC) regarding polymerization shrinkage and contraction stresses and their ability to improve the shortcomings of the methacrylate-based resin composites (MRBC). Special attention is given to their physical and mechanical properties, bond strength, marginal adaptation, and cusp deflection. The clinical significance of this material is critically appraised with a focus on the ability of SBRC to strengthen the tooth structure as a direct restorative material. A search of English peer-reviewed dental literature (2003-2015) from PubMed and MEDLINE databases was conducted with the terms "low shrinkage" and "silorane composites." The list was screened, and 70 articles that were relevant to the objectives of this work were included.

Assessment of the effect of casein phosphopeptide-amorphous calcium phosphate on postoperative sensitivity associated with in-office vital tooth whitening.

The aim of this study was to evaluate the efficacy of tooth mousse containing 10% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in reducing tooth sensitivity associated with in-office vital tooth whitening. In-office tooth whitening was performed for 51 participants using 35% hydrogen peroxide gel in a single visit. After the procedure, each participant was randomly assigned to one of three groups: gel without desensitizing agent (n=17), gel with 2% sodium fluoride (n=17), gel with 10% CPP-ACP (n=17). A small amount of the desensitizing gel assigned for each participant was applied directly on the labial surfaces of teeth and left undisturbed for three minutes. The participants were asked to apply the gel assigned to them for three minutes twice daily after brushing their teeth, and to continue this for 14 days. The participants were asked to return for follow-up visits after 24 hours and on days 3, 7, and 14, at which time teeth shade changes were assessed by one evaluator using a value-oriented Vita classic shade guide. The incidence, duration, and intensity of tooth sensitivity experienced was self-assessed on a daily basis for the 14-day study period using a visual analog scale (VAS). The effect of the three gels on tooth sensitivity was assessed using one-way analysis of variance and a χ (2) test (α=0.05). The general linear model was used to compare intensity-level differences in the three studied groups and for shade stability over the follow-up period. The results of this study showed that all three gels decreased the intensity of sensitivity associated with tooth whitening. The intensity of sensitivity was lower in the fluoride group than in the other two groups; however, it was not statistically significant (p=0.112 and p=0.532 on day 1 and day 2, respectively). The average shade change was 6.8. None of the tested materials affected the efficacy of tooth whitening, but the shade change among the fluoride group showed more color stability than that of the other two groups. This study suggested that using a gel after tooth whitening can reduce the intensity of tooth sensitivity associated with in-office whitening procedures without affecting the efficiency of tooth whitening. However, it failed to demonstrate that using a 10% CPP-ACP could provide additional therapeutic benefits.