Curing depth of different shades of a photo-activated prosthetic compositematerial

This study determined the depth of cure of different shades of a prosthetic composite material with the aim of evaluating the influence of shade varia tion on post-curing material properties. Four light shades having small tab s (A1, B1, C1 and D2) and four dark shades having higher tabs (A4, B4, C4 a nd D4) of a prosthetic composite (Artglass) for body paste based on the Vit a Lumin Shade guide were selected. Specimens of each shade were exposed wit h the proprietary photo-curing unit (UniXS) for periods 20, 30, 60 and 90 s . The curing depth of the material for each shade was determined with a scr aping technique described by the International Organization for Standardiza tion (ISO 4049), and average values of groups of five specimens were compar ed using analysis of variance (ANOVA) and Scheffe's S intervals (P<0.05). T he L*a*b* colour parameters of five specimens after 90 s exposure were meas ured using a small-area dental colorimeter (ShadeEye) in order to determine the colorimetric differences. Three-factor ANOVA revealed that the depth o f cure was influenced by shade letter (A, B, C or D) and shade tab (1 and 2 , or 4) as well as by the exposure period (P = 0.05). Curing depth of the l ight shades was consistently greater than that of the dark shades. Among th e eight shades selected, B1 shade demonstrated the greatest curing depth, w hile A4 shade exhibited the lowest curing depth. For all shades, longer exp osure increased the depth of cure. All of the light shades exhibited higher L* values than any of the four dark. shades. Curing depth of the composite material was found to be related to the Vita shade variation and the expos ure period.