Page 57 - Craniomaxillofacial Implant Surgery - Jeroen P.J. Dings

Reliability and accuracy of surgical templates for craniofacial implant placement
DISCUSSION
In this study single-type personalized surgical templates were 3D-printed after the computer-based transfer of the 3D-planned implant position from both CBCT and MDCT imaging modalities. The Brånemark system was the first implant system to be used extraorally30.
In contrast with studies focusing on transfer accuracy of computer-aided oral 3 implantology the actual CMF implant positions in our study showed a considerable
deviation as compared to their virtual planned position31. However, it is difficult to
make direct comparisons between studies due to differences in study design (in vitro
versus in vivo versus ex vivo), type of support, single versus multiple surgical templates, number of implants and inconsistency in reported observations13,21.
Few studies evaluated the influence of surgical templates on deviations of CMF implants. As such, Van der Meer et al19 showed a high concordance between planned and actual implants in the nasal floor. However, accuracy of actual implant positions were only described for two nasal implants in one patient19. In their study, distance deviations for the implant shoulder were 0.496 and 1.924 mm, for the apex 0.702 and 0.9441 mm and deviation in angulation was 0.98 and 4.66 degrees. In contrast with our study design, surgical templates were fitted on the dentition in all three patients. Unfortunately, all cadaver heads in this study were fully edentulous since maxillary teeth cusps serve indeed as ideal fixed reference points.
Another study of Van der Meer et al20 reported on the magnitude of error in transferring the planned position of auricular implants with the aid of a skin-supported surgical template. In comparison to this study, they described less pronounced differences between actual and virtual positions encompassing 1.56 mm (SD 0.56) for the implant shoulder, 1.40 mm (SD 0.53) for the apex and 0.97 degrees (SD 2.33) for the angulation. Other studies include several technical papers and notes with regard to the fabrication and use of surgical templates for CMF implant placement but without validation of accuracy11,32-34.
Deviations found in this study are presumably more clinically relevant in the orbital and nasal region with regard to maintaining a zone of at least 2 mm of peri-implant bone to ensure a predictable restorative outcome procedure28,35-39. However, possible influence
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