Comparison of Accuracy and Time for Four Implant Placement Techniques Supporting Fixed-Partial Denture
Various guiding methods are used to place implants. This ex vivo pilot study used a convenience sample to examine time and accuracy for placement of 2 dental implants supporting a 3-unit fixed prosthesis on a simulation model using freehand and 3 guided placement techniques. Four operators with no prior implant placement experiences were randomly assigned placement of 2 maxillary or mandibular implants for a fixed prosthesis. Techniques included dynamic navigation (DN), static guide (SG), template-based guide (TBG), and freehand placement (FH). Preoperative and operative times were recorded. Discrepancies between the planned and placed implant positions were assessed by superimposing preoperative and postoperative cone beam computerized tomography scans. Data were analyzed with repeated-measures regression with Tukey's adjusted pairwise comparisons (α = 0.05). Dynamic navigation was associated with the longest operative time (13.5 minutes vs 5–10.2, P = .0001) but overall fastest when incorporating preoperative time (32.1 minutes vs 143–181.5, P < .0001). All deviation measures were significantly associated with the placement method (P < .05) except apex vertical deviation (P = .3925). Implants placed by SG had significantly lower entry 2-dimensional deviation than the other methods, particularly on the mandible. The DN and SG methods had significantly lower Apex 3D and overall angle deviations, again particularly on the mandible. The mandible had significantly higher deviations than maxilla. Within limitations of this study, implant placement by novice operators is more accurate when using dynamic and static guidance compared to freehand and template-based techniques.
A diagnostic wax-up on PMMA jaw models is simulating restorations for the 3-unit FPD supported by 2 implants. The mandibular model is missing both right premolars and a first molar (a, b); maxillary model is missing left lateral incisor, canine, and first premolar (c, d).
Preparation of radiographic and template-based guides: a thermoplastic template was fabricated (a), an optimal implant position was marked (b) with implant insertion line planned using laboratory surveyor (c). Gutta-percha bars were secured inside the template (d), proposed crown space was filled with acrylic resin (e), and polished (f). The radiographic guide was transformed into the TBG by removing gutta-percha and expanding the access holes (g). Simulation setting using a manikin head mounted on a dental chair (h).
Static guides were 3D printed (a). The support structures were removed, guides polished, and metal sleeves inserted into the guide holes (b). For implant placement, a guided surgical kit and tube adapters were used (c, d).
A preoperative CBCT scan of the PMMA model tagged with four fiducial markers and a radiographic guide in place (a). Virtually planned implants (b). Drill-tag and jaw-tag are secured to enable continuous tracking during procedure (c). Computer displays in a color-coded graphic DN software real-time drill position and angulation in relation to the planned implant position (d). Equipment positioning should enable good visualization of the computer screen, placement of the stereoscopic camera above the operating field (e), and good access to the operating field (f). A postoperative CBCT scan of the model is taken after implant placement (g). Accuracy is assessed by superimposing preoperative and postoperative CBCT scans and by comparing the planned and placed implant positions by calculating apical, vertical, entry point and angle deviations (h).
Breakdown of procedure times by method.
Deviations calculated for assessing accuracy of placed implant position according to planned position.
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