Influence of varied surface texture of dentin porcelain on optical properties of porcelain specimens

Abstract

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 × 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 (ΔE) 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 (α=.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 μm to 0.15 μm, 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 (ΔE) 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).