How the Build Angle Affects the Marginal and Internal Fit of 3D Printed Definitive FPDs : An in Vitro Study

STATEMENT OF PROBLEM: Printing parameters may influence the fit of additively manufactured dental restorations. However, the effect of small incremental build angles on the marginal and internal fit of stereolithography (SLA)-printed definitive 3-unit fixed partial dentures (FPDs) has not been sufficiently investigated. PURPOSE: The purpose of this in vitro study was to evaluate the effect of small incremental build angles (0°, 10°, 20°, and 30°) on the marginal and internal fit of SLA-printed definitive 3-unit FPDs. MATERIAL AND METHODS: A typodont maxillary first premolar and first molar were prepared to serve as abutments for a 3-unit FPD. After digital scanning, restorations were designed using dental CAD software and fabricated from a definitive resin using an SLA printer. Forty FPDs were produced at four different build angles (0°, 10°, 20°, and 30°) (n = 10). Marginal and internal fit were evaluated using microcomputed tomography. Gap measurements were obtained at five reference points for each abutment. Data were analyzed using one-way analysis of variance followed by Tukey honestly significant difference post hoc tests (α = 0.05). RESULTS: Build angle significantly affected the marginal and internal fit (p < 0.05). For both molar and premolar supports, the highest fit was achieved with 30°, followed by 20°. Differences between 20°-30° and 0°-10° were not statistically significant (p > 0.05). The marginal discrepancy was higher than the internal discrepancy. CONCLUSIONS: Within the limitations of this in vitro study, build angle influenced the marginal and internal fit of SLA-printed 3-unit FPDs. Among the orientations tested, the 30° build angle generally produced the smallest gap values.