Degree of Conversion of Luting Resins Around Ceramic Inlays in Natural Deep Cavities: A Micro-Raman Spectroscopy Analysis

Abstract

Clinical RelevanceContrary to previous evidence, the degrees of conversion of resin luting materials have been shown to reach statistically similar values in three different depths around ceramic inlays luted to natural cavities. Both dual-cure and light-cure materials have presented conversion homogeneity, although they have been shown to be material-dependent. SUMMARYThis study evaluated the degree of conversion (%DC) of luting agents around ceramic inlays placed in deep natural cavities. Thirty-six cylindrical Class I cavities (diameter = 4 mm, depth = 4 mm) were prepared in freshly extracted human teeth and randomly divided according to the luting materials used for luting CAD/CAM fabricated inlays (Empress CAD). The dual-cure resin cements Clearfil Esthetic Cement and Variolink II Low and the light-cure composites Grandio Flow and Grandio were luted using the total-etch technique. The self-adhesive dual-cure cements RelyX Unicem and Maxcem Elite were used as recommended by the manufacturer. All of the restorations were photo-activated using a quartz halogen unit (Elipar TriLight; 750 mW/cm²) for 40 seconds. After 24 hour dry-storage in the dark, all the teeth were vertically sectioned into two halves (n=12 per group) using a slow-speed diamond-saw in the bucco-vestibular direction under constant water lubrication to

Effect of light curing protocol on the degree of conversion of a light cured resin cement

“…The properties of lightcured cements are influenced by the thickness and composition of the ceramic used. This thickness affects the transmission of light [3] and its quality reaching the underlying cement layer [28,29] .…”

The influence of free-radical concentration on the shear bond strength of dental composites

“…3,4 The extent of the monomer-to-polymer conversion during the polymerisation process is expressed as the degree of conversion (DC) and can be studied by Raman spectroscopy, which measures the C=C double bond's stretching vibrations on the compo-site surface. 5,6 Consequently, the DC is directly related to the mechanical properties of the composites and their clinical performance. 7,8 Free radicals are reactive chemical species with an unpaired electron.…”

Degree of conversion of a flowable composite light-activated through ceramics of different shades and thicknesses

“…In general, the use of these light-activated cements should be limited to some clinical situations such as inlays, veneers and onlays, in which the thickness and shade of restoration do not affect the ability of light to reach and activate the cement 15 . Considering the light-activated resin cements for veneers and onlays cementation, the polymerization quality is related to several factors such as photo-activation light source, irradiance, irradiation time, material composition and light attenuation caused by ceramic 11,[13][14][16][17][18] . It was observed that the transmittance of light through ceramic decreases as function of the material interposed between the light source and the resin cement 19 .…”