Title:
A clinically relevant accuracy study of computer-planned implant placement in the edentulous maxilla using mucosa-supported surgical templates.

Abstract:
The purpose of the study is to determine the clinically relevant accuracy of implant placement in the edentulous maxilla using computer planning and a mucosa-supported surgical template.
In each of in total 30 consecutive edentulous patients suffering from retention problems of their upper denture, two or four Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants in the maxilla were installed. Preoperatively, first, a cone-beam computer tomography (cone beam computer tomography) scan was acquired, followed by virtual implant planning. Hereafter, a surgical template was designed to allow flapless implant placement using the template as a guide. To inventory the accuracy of implant placement, a postoperative CBCT scan was obtained and matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally. The Implant Position Orthogonal Projection validation method was applied to measure the clinically relevant implant deviations (i.e., in both the bucco-lingual and mesio-distal plane). Also, the influence of type of surgery, use of fixation pins, and position on the dental arch were investigated with regard to implant deviations.
In total, 104 implants were installed. In bucco-lingual direction, a mean implant deviation of 0.67 mm was scored at the implant tip, of 0.51 mm at the shoulder, of -0.83 mm in depth, as also a mean deviation of angulation of 1.74°. In mesio-distal direction, a mean implant deviation of 0.75 mm was found at the implant tip, of 0.60 mm at the implant shoulder, of -0.75 mm in depth, and a deviation of angulation of 1.94°. Of all implants, 74% was placed not deep enough compared with the planning. Implant position on the dental arch, the use of fixation pins, and type of surgery showed no significant effect on implant deviations. However, a significant difference for implant deviations in both buccal and mesial direction was observed, explained by a nonoptimal positioning of the surgical template.
Computer-aided implant planning showed to be a clinically relevant tool for the placement of two or four implants in the maxilla of fully edentulous patients. Exact positioning of the surgical template in anterior/posterior direction is crucial in reducing implant deviations both in buccal and mesial direction.