INFLUENCE OF VARIED SURFACE TEXTURE OF DENTIN PORCELAIN ON OPTICAL PROPERTIES OF PORCELAIN SPECIMENS

Statement of problem. Differences in the texture of dentin porcelain surfaces may change the direction of incident light at the enamel-dentin porcelain interface and affect the optical properties of a ceramic crown. Purpose. The purpose of this study was to measure optical parameters of enamel-dentin porcelain complexes with different dentin porcelain surface textures, and to analyze the relationship between optical parameters and surface texture. Material and methods. Eighty dentin porcelain (ShoFu Vintage Halo, shade A2) disks (1.0 x 10.0 mm) were fabricated and assigned to 10 groups (n=8). The dentin porcelain specimens were given different surface textures with modified surface roughnesses (Ra) and different levels of waviness (Wa). Measurements of transmittance, reflectance, and CIE L*a*b* values were made with a spectrocolorimeter (PR-650) after standard finishing of the enamel-dentin porcelain complex. Translucency parameters (TP) and color difference (Delta E) were calculated with CIE L*a*b* values, respectively. The data were statistically analyzed by 1-way ANOVA and Fisher's LSD (least significant difference) post hoc tests (alpha=.05). Results. Transmittance, reflectance, and the translucency parameter were influenced significantly by surface roughness (P <.05) and waviness values (P <.01). With a decrease in the Ra value from 1.23 mu m to 0.15 mu m, mean reflectance values increased from 37.01% to 38.63%, while mean values of transmittance and the translucency parameter decreased from 1.04% to 0.87% and 19.44 to 18.03, respectively. With an increase of the Wa value from 0.0 mm to 0.2 mm, mean values of reflectance decreased from 37.06% to 30.30%, while transmittance and the translucency parameter increased from 1.10% to 2.05% and 19.15 to 20.01, respectively. Color difference values (SE) ranged from 0.30 to 1.45 (Ra group) and from 1.46 to 4.16 (Wa group), respectively. Conclusions. Surface texture of dentin porcelain significantly influenced the optical properties of enamel-dentin porcelain specimens, and surface waviness (Wa) had higher correlation coefficients with optical parameters than did roughness (Ra). (J Prosthet Dent 2011;105:242-248)