Accuracy of digital interocclusal records at various protrusive mandibular positions: an in vitro study

The purpose of this in vitro study was to evaluate the trueness and precision of digitally recorded maxillomandibular relationships obtained with two intraoral scanners (Trios 5 and Medit i600) at maximum intercuspal position (MIP) and at various protrusive–vertical mandibular positions. A dentate typodont mounted on a semi-adjustable articulator was positioned at MIP and at six experimental mandibular conditions (2 V, 5 V, 2P + 2 V, 2P + 5 V, 4P + 2 V, and 4P + 5 V). For each mandibular condition and scanner, one polyvinyl siloxane interocclusal record was produced. This record was then scanned 20 times under standardized digital and ambient conditions. A high-accuracy laboratory scanner (Redon Freedom UHD) was used to obtain reference datasets. Four linear distances (D1–D4) between reference markers were measured following marker-based best-fit alignment in Geomagic Control X. Trueness was defined as deviation from the reference measurements, and precision as the variability among repeated scans. Data were analyzed using two-way analysis of variance (α = 0.05), and effect sizes were calculated using partial eta squared (η²p). Mandibular position and scanner type were significantly associated with differences in trueness and precision (P < 0.001). Certain vertically separated positions demonstrated lower trueness deviations compared with MIP, whereas protrusive positions showed scanner-dependent variations. A significant interaction was observed between scanner type and mandibular position (P < 0.001). Within the limitations of this in vitro study, mandibular position and scanner type were associated with variations in digital interocclusal recording performance. Mandibular position and intraoral scanner selection may influence the accuracy of digital interocclusal records. Inaccuracies in digital bite registration may lead to occlusal discrepancies and require additional intraoral adjustments. Consideration of these factors may assist clinicians when performing digital bite registrations under altered mandibular conditions.