Multiple possibilities in detection of materials defects in ceramic fixed partial prostheses. Numerical simulation and photoelasticity methods employed for evaluation and prognostic

Introduction. For the evaluation of marginal adaptation in class V composite restorations, several methods have been developed (bacterial penetration, fluid transport, clarification, penetration of radioisotopes, electrochemical methods and gas chromatography). Dye penetration tests (microleakage tests) however, are to be the most widely used due to their ease of application and low costs. Their main disadvantage is that the samples are sectioned. In previous works the advantages of using en face optical coherence tomography investigation in this research direction were demonstrated. The purpose of this study is to increase the scattering of the adhesive layers in order to facilitate the interpretations. Material and Methods. En Face Optical Coherence Tomography was employed to investigate 147 class V cavities samples. Standardized class V cavities, prepared in human extracted teeth, were filled with Premise (Kerr) composite. The specimens were thermo cycled. The interfaces were examined by Optical Coherence Tomography method (OCT) combined with the confocal microscopy. The optical configuration uses two single mode directional couplers with a superluminiscent diode as the source at 1300 nm. The scanning procedure is similar to that used in any confocal microscope, where the fast scanning is en-face (line rate) and the depth scanning is much slower (at the frame rate) Results. Marginal adaptation at the interfaces and gaps inside the composite resin materials were identified by means of optical coherence tomography. Exploration of the recent advances in OCT in terms of different excitation wavelengths and wider bandwidths can lead to state-of-the-art imaging systems in odontology. Conclusion. OCT has numerous advantages which justify its use in the oral cavity in comparison with conventional dental imaging. OCT can achieve the best depth resolution of all known methods (in principle one micron if the source exhibits a sufficiently wide spectrum) and is safe. It is important to use an improved adhesive in order to be spotted on the imaging investigation.