The precision of drill calibration for dynamic navigation.

OBJECTIVES: To quantify the reproducibility of the drill calibration process in dynamic navigation guided placement of dental implants and to identify the human factors that could affect the precision of this process in order to improve the overall implant placement accuracy. METHODS: A set of six drills and four implants were calibrated by three operators following the standard calibration process of NaviDent® (ClaroNav Inc.). The reproducibility of the position of each tip of a drill or implant was calculated in relation to the pre-planned implants' entry and apex positions. Intra- and inter-operator reliabilities were reported. The effects of the drill length and shape on the reproducibility of the calibration process were also investigated. The outcome measures for reproducibility were expressed in terms of variability range, average and maximum deviations from the mean distance. RESULTS: A satisfactory inter-rater reproducibility was noted. The precision of the calibration of the tip position in terms of variability range was between 0.3 and 3.7 mm. We noted a tendency towards a higher precision of the calibration process with longer drills. More calibration errors were observed when calibrating long zygomatic implants with non-locking adapters than with pointed drills. Flexible long-pointed drills had low calibration precision that was comparable to the non-flexible short-pointed drills. CONCLUSION: The clinicians should be aware of the calibration error associated with the dynamic navigation placement of dental and zygomatic implants. This should be taken in consideration especially for long implants, short drills, and long drills that have some degree of flexibility. CLINICAL SIGNIFICANCE: Dynamic navigation procedures are associated with an inherent drill calibration error. The manual stability during the calibration process is crucial in minimising this error. In addition, the clinician must never ignore the prescribed accuracy checking procedures after each calibration process.

The Accuracy of Intraoral Registration for Dynamic Surgical Navigation in the Edentulous Maxilla.

PURPOSE: Despite the high clinical accuracy of dynamic navigation, inherent sources of error exist. The purpose of this study was to improve the accuracy of dynamic-navigated surgical procedures in the edentulous maxilla by identifying the optimal configuration of intraoral points that results in the lowest possible registration error for direct clinical implementation. MATERIALS AND METHODS: Six different four-area configurations (left and right sides; n = 12) were tested by three operators against two negative controls (left and right sides) and one positive control (three-area and eight-area configurations, respectively) using a skull model. The two dynamic navigation systems (X-Guide and Navident) and the two registration methods (bone surface tracing and fiducial markers) produced four registration groups: XG tracing, ND tracing, XG fiducial, and ND fiducial. The accuracy of the registration was checked at the frontal process of the zygoma. Intra- and interoperator reliabilities were reported for each registration group. Multiple comparisons were conducted to find the best configuration with the minimum registration error. RESULTS: Ranking revealed one configuration in the tracing groups (Conf.3) and two configurations in the fiducial groups (Conf.3 and Conf.5) that had the best accuracy. When the inferior surfaces of the zygomatic buttress were excluded, fiducial registration produced better accuracy with both systems (P = .006 and < .0001). However, bilaterally tracing 1-cm areas at these surfaces resulted in similar registration accuracy to placing fiducial markers there (P = .430 and .237). Navident performed generally better (P = .049, .001, and .002), but the values had a wider margin of uncertainty. Changing the distribution of the four tracing areas or fiducial markers had a less pronounced effect with the X-Guide than with the Navident system. CONCLUSIONS: For surgery in the edentulous maxilla, four fiducial markers placed according to Conf.3 or Conf.5 resulted in the lowest registration error. Where implants are being placed bilaterally, an additional two sites may further reduce the error. For bilateral zygomatic implant placement, it is optimal to place two fiducial markers on the inferior surfaces of the maxillary tuberosities, two on their buccal surfaces, and another two on the anterior labial surface of the alveolar bone. Utilizing the inferior zygomatic buttress is recommended over the inferior maxillary tuberosities in other types of maxillary surgeries.