Influence of preparation design and build orientation on the accuracy of ceramic-filled composite veneers printed using Tilted Stereolithography technology. An in vitro study.

OBJECTIVES

To evaluate the influence of preparation design, build orientation and interaction between these two factors on the accuracy of veneers 3D printed using tilted stereolithography technology (TSLA).

METHODS

Three maxillary central incisor typodont models were prepared to receive a full veneer preparation with three finish line designs: Cl I; labial reduction, Cl II; labial with butt joint incisal reduction and Cl III; labial and incisal overlap design then digitized to design the restorations which were 3D-printed using ceramic filled composite material (Dfab; DWS)(IrixMax monochrome A2; DWS)(N = 90). In each group, three subgroups were defined based on the build orientation (N = 10): 90°, 75° and 45° angles. Accuracy was evaluated using metrology software. Two-way Analysis of Variance (ANOVA) test was used to detect the differences between the groups (α=0.05).

RESULTS

Two-way ANOVA revealed a statistically significant interaction between different build angles and preparation design on RMSE trueness values (P = .003) and RMSE precision values (P = .001) Tukey post hoc test revealed that Cl II design had significantly lower RMSE values compared to both Cl I and Cl III designs (P<.001). 45° angle revealed significantly higher RMSE values compared to 75° and 90° build angles with P values .017 and .009 respectively.

CONCLUSIONS

Both preparation design and build orientation have an influence on the accuracy of TSLA printed laminate veneers. Butt-joint preparation design exhibited highest trueness compared to both window and incisal wrap designs. Among all finish line designs, 45° build angle exhibited the most significant deviation values and is not recommended for printing veneers using TSLA technology.

CLINICAL SIGNIFICANCE

The preparation design that best fits a given clinical situation should be selected. The print angle that yields the highest accuracy relative to the clinically selected and executed tooth preparation design should be chosen. With different veneer preparation designs, 45° build angle provides the highest deviation values with chairside TSLA printers and should be avoided when printing resin-based, monochromatic laminate veneers.