Additive manufacturing (AM) offers precision and efficiency in occlusal splint fabrication; however, the combined influence of build orientation and post-curing duration on the mechanical performance of splint resins remains insufficiently explored. This in vitro experimental study evaluated the effects of three build orientations (0°, 45°, and 90°) and three post-curing protocols (uncured, standard, and extended) on the flexural strength (FS), flexural modulus (FM) and Vickers hardness number (VHN) of a Class IIa biocompatible occlusal splint resin (NextDent Ortho Rigid). A total of 180 specimens were fabricated using a vat polymerization-type 3D printing system. Statistical analyses were conducted using one-way analyses of variance and Tukey’s tests at a significance level of α = 0.05. Both build orientation and post-curing duration significantly affected FS and VHN (p < 0.001). The combination of 45° build orientations and extended post-curing produced the highest FS (169.76 MPa) and FM (7502.17 MPa), exceeding values typically reported for 3D-printed splints, while the 90° orientation with extended curing achieved the highest VHN (21.88). Hardness gains, however, plateaued beyond standard curing, indicating a trade-off between strength and surface hardness. These results demonstrate that print orientation and post-curing time are decisive parameters in optimizing the mechanical performance of 3D-printed occlusal splints. For high-load clinical applications such as bruxism, prioritizing flexural strength over surface hardness may improve appliance longevity, supporting 45° orientation with extended curing as an evidence-based manufacturing approach.

Objectives: The objective of this study was to conduct three-dimensional cone-beam computed tomography (CBCT) analysis of posterior mandibular anatomy in order to investigate its potential correlation with the occurrence of bad splits during sagittal split osteotomy (SSO). Methods: A retrospective review was conducted on 56 patients (112 hemimandibles) who underwent bilateral SSO between 2016 and 2022. Distances between the mandibular canal and the borders of the mandible, along with anatomical landmarks, were measured. Sites with and without bad splits were compared using chi-square and Mann–Whitney U tests (p = 0.05). Results: The overall incidence of bad split was 8.9% per site (10/112) and 14.3% per patient (8/56). Patient-related variables, including age, sex, skeletal deformity type (Class II vs. Class III), and the presence of impacted third molars, were not significantly associated with bad split (all p > 0.05). Among the morphometric parameters, the distance from the mandibular canal to the inferior cortical border at the mesial of the second molar (M2inferior) was significantly greater in the bad-split group (p = 0.04). Other measurements, including ramal thickness, anteroposterior length, and canal position relative to buccal and inferior cortices, were not significantly different. Reliability analysis demonstrated good to excellent agreement for all measurements. A greater inferior mandibular border thickness at the mesial of the second molar appears to increase the risk of a bad split during SSO. Conclusions: Routine preoperative CBCT evaluation and careful attention to inferior border osteotomy in this region may help reduce complications. Further prospective, standardised studies are needed to confirm these findings.