A Study of the Accuracy of Static Guided Implant Surgery for Fully Edentulous Patients - Comparison of Pre-Planned Implant versus Actual Implant Positions
Abstract: Aim & Hypothesis Understanding of the maximum discrepancy of template guided surgical systems is extremely pertinent. Catastrophic failure of implants can occur as a result of these 3D deviations at time of implant placement. The aims of this study were to assess the positional 3-D deviations between the implant analogs in the casts generated from the Nobel Biocare CAD/CAM surgical ... read moretemplates, and the implant analogs in the post-surgical casts. The hypothesis is that there are differences between the 3-D positions of virtually planned implants and the actual implant positions for fully edentulous patients. Materials & Methods Study population The current study included the records of patients that were treated for the implant-prosthodontic treatment of fully edentulous arches. The stone casts were generated from 8 fully edentulous patients (12 edentulous arches) that underwent computer-planned and template-guided implant placement according to Nobel Guide concept (Nobel Biocare AB, Gothenburg, Sweden). In total, 59 implants (NobelReplace® Conical Connection) were inserted in 12 jaws (seven maxillae, five mandibles). Four patients were treated both in the maxilla and in the mandible. Group One (I): Full-arch open tray splinted implant impressions were completed using polyether based impression material (Impregum, 3M ESPE, St Paul, MN, USA). The post-surgical stone cast was fabricated with low expansion (0.06%) type IV die stone (New FujiRock® IMP GC Corp, Tokyo, Japan). Group Two (II): Surgical templates were used for fabricating master stone casts. Superimposition and Accuracy Measurements: The stone casts were scanned for digitalization with an extra-oral scanner (Activity 880 scanner; Smart Optics, Bochum, Germany). The scan bodies (NobelProcera® Position Locator Conical Connection) were first placed in the group I casts, and digitization completed, followed the group II casts. The stereolithography(STL) files were saved. The STL dataset overlap and matching were executed by 3D inspection and metrology software (Geomagic® Control™) for all casts of both groups. The 3D inspection software calculated positional deviation as the Root Mean Square Error (RMSE). A mixed-effects model was used in order to account for the lack of independence between observation from the same subject. Results Based on the RMSE values from both arches, one subject was considered an outlier for which the values were 691.52m and 670.92m for the maxilla and mandible respectively. The mean age of the subjects when excluding the outlier was 65.8 years (64.6 years with outlier) with a standard deviation (SD) of 7.7 (7.5 with outlier) and median of 66.5 (64 with outlier). The mean and median of the RMSE values obtained after the superimposition of the group I casts over the group II cast were 163.30m and 145.25m, respectively, excluding the arches from the outlying subject. The mean (SD) of the RMSE values for the maxillary arch, not including the outlier, was 165.51 (70.02) m. Corresponding numbers for the mandibular arch were 161.83 (79.23) m. The difference between arches was not statistically significant, whether excluding (P = 0.947) or including (P = 0.541) the outlier. Conclusion Within the limitations of this study, the following conclusions may be drawn: 1. There were measurable 3-D deviations between the implant analogs in the casts generated from the Nobel Biocare CAD/CAM surgical templates and the implant analogs in the post-surgical casts created with splinted full-arch open tray implant impressions. 2. No statistically significant differences were found in the positional 3-D deviations between the implant analogs in the maxillary and mandibular casts.
Thesis (M.S.)--Tufts University, 2017.
Submitted to the Dept. of Posthodontics.
Advisor: Panos Papaspyridakos.
Committee: Hans Peter Weber, Matthew Finkelman, and Yukio Kudara.
Keyword: Dentistry.read less