Optical characteristic of Fluoride-releasing Tooth-colored Restorative Material Containing S-PRG Filler

Objectives:

Color matching of direct tooth-colored restorations is intricately related to color tone, surface luster, translucency, and light diffusion; among them light diffusion, which influences color appearance, is an important factor for restorative materials. This study aimed to evaluate optical transmitted light distribution of a new fluoride-releasing universal tooth-colored restorative material (B) containing S-PRG filler having triple-layer structure, which employs the Pre-Reacted Glass-ionomer (PRG) technology.

Methods:

B in three shades (Inc,A3,A3O) was prepared with main components of Bis-GMA/TEGDMA resin and S-PRG filler. Test specimens were prepared by polishing cured discs (d=15mm, t=1mm) of B using sandpaper (600-grit, 1200-grit) to 0.8mm thickness, followed by mirror-surface finish, and measured for their two-dimensional transmitted light distribution (Fig.1) using a goniophotometer (Model GP-200, Murakami Color Research Laboratory) to compare light transmission properties of each shade. Also measured were: human enamel and dentin as a control; and commercial composite resins Filtek Supreme (F; A2E,A2B,A2D) and ESTELITE Sigma (E; Inc,A3,OA3) for comparison.

Results:

B exhibited different light transmission properties for each shade as follows; Inc: enamel-like regular transmission pattern (Fig.2:spear shape), A3O: dentin-like diffuse transmission pattern (Fig.3:oval shape), A3: a combination of the patterns of Inc and A3O, whereas F and E showed the same transmission pattern among shades: enamel-like regular transmission pattern (F) and dentin-like diffuse transmission pattern (E).

Conclusion:

It was considered that the structure, particle size, volume of filler and/or the difference in refractive index between filler and resin matrix contained in B contributed to the natural tooth-like light transmission properties of B. It is thus suggested that excellent color matching is achievable by layering different shades of B, depending on the regions to be restored.