ABSTRACT
OBJECTIVES: To analyze marginal integrity of resin composites dental restorations using optical coherence tomography (OCT). METHODS: Thirty extracted human premolars had occlusal cavities prepared and were randomly divided according to the restorative systems evaluated: Filtek P90™/P90 Adhesive System™, Filtek Z350™, and Filtek Z250™/Single Bond™ (3M/ESPE). The teeth were then stored in the dark for 24h in 0.9% saline solution. Restorations were finished and polished and stored again for 24h before thermocycling (500 cycles, 5-55°C). A commercially available OCT system was used (SR-OCT: OCP930SR/Thorlabs) with 930nm central wavelength. Cross-sectional images were obtained every 250µm and evaluated using Image J. A-scans were analyzed using the Origin 8.0 program, after a filter treatment using Matlab. RESULTS: The qualitative analysis of the internal margins did not observe gaps even after A-scan examination, although distinctive patterns were found for each restorative system. Penetration of Single Bond and Filtek P90 self-etch primer into dentin was also observed. A thick adhesive layer was found for Filtek P90 bonding agent. SIGNIFICANCE: Considering the characteristics of the OCT system, the setup used in this study was capable of evaluating the marginal integrity of resin composite restorations and detecting some interaction between dental bonding agents and dental substrates. OCT can be considered a promising method for the evaluation of the internal margins of restorations in vivo.
Subject(s)
Composite Resins/chemistry , Dental Marginal Adaptation , Dental Materials/chemistry , Dental Restoration, Permanent/methods , Tomography, Optical Coherence/methods , Bicuspid/pathology , Curing Lights, Dental , Darkness , Dental Cavity Preparation/methods , Dental Cements/chemistry , Dental Polishing , Dentin/ultrastructure , Dentin-Bonding Agents/chemistry , Humans , Image Processing, Computer-Assisted/methods , Materials Testing , Self-Curing of Dental Resins , Sodium Chloride/chemistry , Temperature , Time Factors , Tomography, Optical Coherence/instrumentationABSTRACT
Self-adhesive resin cements represents a new approach in indirect restorative dentistry, although little is known about its biological properties. The influence of the curing strategy on the biological response of a self-adhesive resin cement (Rely-X Unicem/3M ESPE) was evaluated through methyltetrazolium (MTT) and nitric oxide (NOx) assays. Cylindrical specimens (n = 48) were prepared and cured according to the following strategies: photoactivation with halogen light-curing unit (LCU) Demetron/Kerr, LED LCU Radii/SDI, and chemical activation. A control group with culture medium and a group with lipopolysaccharide, employed for cells stimulation, were used for comparisons (n = 8). After 24 h of direct contact between specimens and rat alveolar macrophages, the biological response was evaluated. Statistical evaluation of the data was performed with Kruskal-Wallis and Dunn's test (p = 0.05). The MTT test showed that the specimens cured by halogen light and chemical activation provided higher alterations on cell metabolism. For LED-cured specimens, cell viability was compatible to the results observed in the control group. For the NOx assay, all curing methods were cytotoxic to rat macrophages. Rely-X Unicem demonstrated different cytotoxic effects according to the curing strategy employed.
