Deformation of Stereolithographically Produced Surgical Guides: An Observational Case Series Report

Background: Template-based computer-guided implant placement holds the promise of more precise and less traumatic placement of dental implants. Errors in the fabrication process of the surgical guide may lead to unfavorable clinical outcomes. Purpose: This report discusses the potential of unintentional volumetric deformation of stereolithographically (SLA) produced surgical guides (NobelGuide, Nobel Biocare AB, Goteborg, Sweden) compared with the original scan denture. Materials and Methods: Three-dimensional radiographic data acquired by medical computerized tomography (CT) or cone beam CT (Newtom 3G, AFP Imaging Corporation, Elmsford, NY, USA) can be utilized in specialized software to develop treatment planning for dental implant placement. This information can then be transferred to the patient via a surgical guide. Stereolithography is a rapid prototyping process that can be used to create such a guide stent. Three cases are shown describing different levels of deformation of SLA-produced surgical guides. Results: Unintentional deformation of SLA-produced surgical guides is possible. Deformation of surgical guides can create dissimilarity between the virtually planned position and the actual position of the implants. Conclusion: Incorrect setting of the ISO values for the segmentation of the scan denture has been found to be a factor in the deformation of SLA-produced surgical guides, although more, at this time known but also less understood, issues appear to be involved. Only one manufacturer's product is discussed; further research is warranted to determine if the discrepancies are process or product based. It might be prudent to closely evaluate the volumetric congruence of SLA-produced surgical stents before their clinical use to prevent undesired clinical outcomes.