Fluorescence of feldspathic ceramics: in vitro pilot study

Abstract

Introduction: Ceramic veneers color is determined by the color and thickness of the ceramic, the cement and dental substrate color [1,2]. Changes in the thickness of feldspathic veneers, as well as the cement used, drastically influence the final color of the restoration [3]. Fluorescence is the optical property responsible for the perception of tooth vitality [4]. In a tooth, this optical property is mainly determined by dentin as it has more collagen (organic matter), which contains fluorescence-releasing amino acids, such as tryptophan, providing three times the fluorescence of enamel [5,6]. Aim of the study: Fluorescence emission evaluation of feldspathic ceramics using different cement colors as well as different ceramic thickness. Materials and methods: Feldspathic ceramic CEREC blocks (color A2) were cut with a manual microtome at a speed of 450 rpm with refrigeration to obtain 40 samples with a thickness of 0.5 and 0.8 mm. Filtek Supreme XTE Body composite resin discs with a thickness of 1mm [7] were produced using a resin frame. The discs were polymerized with a light-curing Elipar S10 Led. Surface treatment of the ceramic was carried out according to the manufacturer’s instructions. Ceramic samples were cemented to the composite resin discs with Relyx Veneer B0,5 / white or with Filtek Supreme XTE Body color A3 (previously heated in a resin oven). The cementation of the groups was done with a constant force of 50 Newtons for 60 seconds and polymerized for 40 seconds with Elipar S10 Led photopolymerizer. Fluorescence spectra were obtained on a SPEX Fluorolog2I2I spectrofluorometer at a wavelength of 380 nm and at room temperature. Results: An increase in thickness intensified the emission of fluorescence. The cementation material used in the study didn’t show statistically significant differences in fluorescence emission intensity when used in two different thicknesses (p = 0,378). Nonetheless, significant differences (p < 0.001) were found between the RelyX and Filtek group for each thickness. Discussion and conclusions: Fluorescence emission value is higher for the thicker group in the RelyX because this cementing material does not have components that add to the emission of fluorescence by the ceramic itself. The ceramic, having a greater thickness, presents a greater concentration of components that are able to emit fluorescence, which allows greater emission of fluorescence than the cementing material in use, such as in the study of Volpato et al. [8]. Like in the study by Pereira in 2015 the choice of different resin cements and ceramic thickness has to be taken into account when planning a case [9].