Effect of Shortened Light-Curing Modes on Bulk-Fill Resin Composites.

CLINICAL RELEVANCE: Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units. SUMMARY: Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes.Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro-computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS.Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes.Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.

An Improved Direct Injection Technique With Flowable Composites. A Digital Workflow Case Report.

This article presents a clinical technique based on a case report for restoring the contours and shape of the upper teeth involved in the smile display of a young patient. After planning the treatment for the patient using digital tools (Digital pictures, Digital Smile Design, digital waxup, three-dimensional [3D] printed models, mockup), the upper teeth were restored using an improved injection technique. This improved technique involves the direct injection of flowable composite resin using clear polyvinyl siloxane molds made from 3D-printed models of the patient. The details and benefits of this new technique are described in the article.

Clinical criteria for the successful curing of composite materials

As composites have continued to be optimized, significant differences in physical, mechanical, and clinica performances between the available systems have lessened. Yet, despite all the improvements, one constant remains: direct composites need to be light-polymerized. Clinicians need to understand the principles of light-curing because unbound monomers are cytotoxic and improperly cured composites are less biocompatible. Presently, there are four technologies available to cure composites. Once the light source is chosen, the clinician should consider several factors to ensure that the composite is being cured satisfactorily. This article analyzes the various current technologies, their strengths and weaknesses, and the relevance of following certain protocols to ensure proper polymerization rates.