Composition control of additively manufactured color-graded temporary veneer

The aim of this study was to design and assess composite resin composition for patient-specific esthetic color-graded temporary veneer.

Various compositions of composite structures (assorted by Ba₂SiO₄ filler, TiO₂ pigment, and photoinitiator) were prepared via additive manufacturing with 3 s UV exposure (405 nm, 10 W/cm²) per 50 µm thick layer followed by 20 min post-curing treatment after fabrication. The effect of each component on the generated color shades was observed and compared to the commonly used VITA shade guide. The coloration was explored by staining aging treatment under dry, wet, artificial saliva environments, coffee, and cola. The mechanical properties were also evaluated. Color measurement and comparison were done using a colorimeter (lightness (L*), green-red color (a*), and blue-yellow color (b*)), and the changes were calculated by CIEDE2000 (ΔE₀₀), translucency parameter (TP) and whiteness index (WI_D). The composition color analysis results were then applied to produce a color-graded temporary veneer for mimicking a natural look.

Mechanically, all composition result in adequate bending strength with maximum achievable strength of 111.64 MPa. At the same time, the composite color was affected by each constituent differently. The L* value, which indicates the color lightness of the composite, was considerably tuned by the TiO₂ pigment, whereas Ba₂SiO₄ filler only triggered minor changes. Photoinitiator concentration significantly affected the yellowness, indicated by the increased b* value. Similar tendency also observed toward the calculated TP and WI_D as well. Based on these evaluations, color-graded temporary veneer successfully generated, matching the VITA A3, A2, and B1 shades gradation. However, the stability of the composite color decreased at high amounts of Ba₂SiO₄ and photoinitiator.

The study presents a composition guide for fabricating temporary patient-specific color-graded veneer. It provides insights on the effect of the constituent material on dental esthetics.