The Effect of Cement Shade on the Optical Properties of Additively Manufactured Permanent Crown Materials.

OBJECTIVES

To investigate the effect of cement shade and printing parameters on the optical properties of additively manufactured (AM) permanent crown materials.

METHODS

Two AM crown materials (Bego VarseoSmile Crown Plus and Formlabs Permanent Crown) and one conventional milled material were tested (n = 560). Dimensions for each specimen measured 10 × 10 mm and were categorized by thickness (1 and 2 mm). AM materials were additively manufactured (3D-printed) at three orientations: 0°, 45° and 90°. Specimens were cemented with four shades of dual-cure cement: light, neutral, warm, and translucent. Color change (ΔE) and translucency parameter (TP) measurements were calculated utilizing a spectrophotometer, VITA EasyShade V. Data was analyzed with a two- way ANOVA and Tukey's post hoc tests.

RESULTS

Neutral cement shade exhibited the lowest ΔE overall (2.30 ± 0.43). Translucent cement shade exhibited the least color difference between materials. Milled materials generally exhibited higher ΔE (5.57 ± 0.26-7.17 ± 0.33) than AM materials. Material thickness significantly affected the ΔE across all shades of cement (p < 0.05). 45° print orientation for 2 mm thick specimens exhibited the greatest clinically acceptable ΔE.

CONCLUSION

Cement shade may cause clinically unacceptable color changes based on material choice and 3D-printing parameters. Clinicians providing permanent AM crowns must consider the impact of cement shade and printing parameters on aesthetic outcomes.