Precision of Computer-Guided Implant Placement in the Edentulous Mandible - an In Vitro Study

Objectives: Restorative-driven implant-placement requires a continuous diagnostic treatment-planning before the surgery. The implant design and position can be planned digitally using a CT-scan with a radio-opaque stent as well as special software. The aim is to make a surgical template for guided and therefore predictable implant-placement. This in-vitro-study compares the precision of different implant-planning software programs in combination with the corresponding surgical templates regarding to the implant position in the edentulous mandible. Methods: 30 radio-opaque resin-based mandibles with elastic mucosa (n=30) were used to test three different implant-planning software programs (SimPlant, Materialise Dental; coDiagnostiX, Straumann; SKYplanX, Bredent). The mandibles were standardized prepared for six reference pins (titanium) and scanned (CT, Multisclice Somatom Sensation, Siemens) with the system-specific radio-opaque stent. Each system was used to plan 4 implants (Standard plus, RN, Ø4,1mm, 10mm, Straumann) in the position of tooth #21, 23, 26, 28, manufacture the surgical stents and place the implants guided. A post-operative CT-scan was made and the measurements of both CT-scans were statistically analyzed (t-test, p0.05) Results: Measurements were made from the neck and the apex of each implant to each reference pin. The placed implants had the highest deviation at the neck and the apex for SimPlant (0.61mm, 0.71mm) and the lowest for SKYplanX (0.47mm, 0.38mm). There was no significant difference between pre- and post-operative measurements (SimPlant p=0.14; coDiagnostiX p=0.2; SKYplanX p=0.31) as well as between the three systems. Conclusion: The results of this in-vitro-study show low deviation for the three software programs between planned and actual implant position. Thus, the precision of guided implant placement in the edentulous mandible depends on the stability of the surgical stent. Keywords: implants, edentulous mandible, computer guided surgery, 3D navigation