From implant planning to surgical execution: an integrated approach for surgery in oral implantology

BACKGROUND: Using oral implantology software and transferring the preoperative planning into a stereolithographic model, prosthodontists can produce the related surgical guide. This procedure has some disadvantages: bone-supported stent invasiveness, lack of references due to scattering and non-negligible stereolithography cost. An alternative solution is presented that provides an ideal surgical stent (not invasive, precise, and cheap) as a result. This work focuses on the third phase of a fully 3D approach to oral implant planning, that starts by CT scanning a patient who wears a markers-equipped radiological stent, continues exploiting built-on-purpose preoperative planning software, and finishes producing the ideal surgical template. METHODS: A 5-axes bur-equipped robot has been designed able to reproduce the milling vectors planned by the software. Software-robot interfacing has been achieved properly matching the stent reference frame and the software and robot coordinate systems. Invasiveness has been avoided achieving the surgical stent from the mucosa-supported radiological mask wax-up. Scattering is ignored because of the surgical stent independency from the bone structure radiography. Production cost has been strongly reduced by avoiding the stereolithographic model. Finally, software-robot interfacing precision has been validated comparing digitally a multi-marker base and its planning transfer. RESULTS: Average position and orientation errors (respectively 0.283 mm ± 0.073 mm and 1.798° ± 0.496°) were significantly better than those achieved using methods based on stereolithography (respectively, 1.45 mm ± 1.42 mm and 7.25° ± 2.67°, with a general best maximum translation discrepancy of about 1.1 mm). CONCLUSIONS: This paper describes the last step of a fully 3D approach in which implant planning can be done in a 3D environment, and the correct position, orientation and depth of the planned implants are easily computed and transferred to the surgical phase.