Dental Model Analysis in Orthognathic Surgery: Accuracy of 3D Printed FDM and SLA Models in Comparison to Original STL File: An In Vitro Analysis

3D printing is an important part of orthognathic surgery by enabling accurate anatomical models for preoperative planning. While Stereolithography (SLA) is widely regarded as the gold standard due to its high precision, recent improvements in Fused Deposition Modeling (FDM) raise the question whether PLA-based dental models can provide comparable dimensional accuracy at a lower cost. This study compares FDM and SLA dental models to evaluate whether FDM represents a clinically viable alternative. STL files derived from maxillary and mandibular intraoral scans (IOS) of 20 patients, yielding 40 dental models, were fabricated using both printing techniques. All models were aligned to the reference STL files and analyzed for dimensional deviations. SLA models demonstrated significantly higher dimensional accuracy than PLA-based FDM models, with lower maximum deviations from the reference STL (1.42 mm vs. 1.84 mm). Both techniques achieved clinically acceptable accuracy for splint fitting, with mean deviations below 0.05 mm. Regarding internal validity, both printers showed high reproducibility, although FDM models exhibited a higher median deviation compared to SLA models (0.0267 mm vs. 0.00145 mm). While SLA remains preferable for high-precision indications, FDM offers a cost-effective alternative for routine clinical use without compromising clinical applicability.