SA1 - Point-of-Care 3D Printing for Orthognathic Surgery: In-House vs. Out-Sourced Final Splints

Abstract: Outsourcing orthognathic virtual surgery planning (VSP) and splint fabrication has become the standard in the field of orthognathic surgery. However, Point-of-Care (PoC) planning and 3D printing may reduce working time and improve efficiency1. Concerns with third-party utilization include increased costs, miscommunication, slowed turnaround time, and inaccuracies in splint generation and delivery. PoC 3D design and printing applications in orthognathic surgery planning may provide a solution to these issues, but its validity has been minimally investigated. The purpose of this study is to show equivalence between the in-house (IH) and out-sourced (OS) manufactured final orthognathic splints. This study was an in-vitro retrospective study of (9) previously performed orthognathic surgeries completed at Virginia Commonwealth University. Exclusion criteria included cases with segmental Lefort surgery, genioplasty, or patient-specific implants. OS VSP and splints were provided by Materialise. IH VSP was completed utilizing Materialise Mimics CMF Enlight (Materialise NV., Leuven, Belgium), and models and orthognathic splints generated from the planning were printed on Formlabs 3B+ utilizing Model Resin V2 and surgical guide resin, respectively (Figure 1). The maxillary and mandibular dental models were set into occlusion using both the OS and IH splints and were mounted. After the splints were removed, the OS and IH models were then scanned in occlusion using 3Shape E4 Scanner. Standard tessellation language (STL) files were then imported into Materialise 3-matic (Materialise NV., Leuven, Belgium). OS and IH were overlapped to their OS and IH VSP file, respectively. Root mean square (RMS) surface analysis was then performed to compare equivalence. A two one-sided t-tests approach was used to determine the equivalence bounds at 0.05 level between the results of the two orthognathic splint workflows. The simulated surgical results of the OS splint workflow resulted in an average RMS deviation of 0.2642 mm with 95% CI [0.1923, 0.3362] (Table 1). The simulated surgical results of the IH splint workflow resulted in an average RMS deviation of 0.2315 mm with 95% CI [0.1428, 0.3201]. The average difference in the two methods was -0.0328, indicating the OS tended to have a larger RMS. The two were considered equivalent within +/- 0.2, with 90% equivalence bounds of -0.11, 0.047 (p-value=0.0022). OS and IH splints were equivalent when compared to their respective VSP files, and the IH splints RMS value fell within the reported clinically acceptable RMS value of 0.252. Our retrospective study is the first study proposing a workflow for comparing OS and IH splints for orthognathic surgery. More studies are needed to explore the utility of PoC 3D printing and planning for orthognathic surgery.(1) Steinhuber T, Brunold S, Gartner C, Offermanns V, Ulmer H, Ploder O. Is virtual surgical planning in Orthognathic surgery faster than conventional planning? A time and workflow analysis of an office-based workflow for single- and double-jaw surgery. J Oral Maxillofac Surg. 2018;76:397–407.(2) Zhang Z, Li P, Chu F, Shen G. Influence of the three-dimensional Printing Technique and Printing Layer Thickness on Model Accuracy. J Orofac Orthop. 80(4):194-204. 2019.

Figure 1
Table 1