Digital fit and positional trueness analysis of a crown seated on additively manufactured casts fabricated using different manufacturing trinomials and build orientations

To evaluate the fit and positional trueness of a crown seated on additively manufactured casts fabricated using different manufacturing trinomials and build orientations. A reference maxillary model with a prepared left first molar was digitized to design a reference crown. Resin casts were additively manufactured from the model scan using digital light processing (DLP) or stereolithography (SLA) at 0-, 30-, 45-, and 90-degree build orientations (n = 7). A zirconia crown was fabricated from the reference design and digitized alone and while seated on each cast using an intraoral scanner. Crown fit was assessed using the triple-scan protocol (average gap), and positional trueness was determined by measuring surface deviations (occlusal, buccal, palatal, mesial, and distal) relative to the original design position. Data were statistically analyzed (α = 0.05). The reference crown had the highest average gap when seated on SLA-90, followed by DLP-90 ( P < 0.001). Combinations involving the DLP trinomial or 0- and 30-degree orientations generally led to lower positional deviations, whereas those with a 90-degree orientation tended to result in higher deviations ( P ≤ 0.033). Although manufacturing trinomial and build orientation affected fit and positional trueness, average gap values remained below the clinically acceptable threshold except for SLA-90. Higher positional trueness was mostly observed when the crown was seated on DLP casts or casts printed at 0- or 30-degree orientations.