Navigation starts with calibration of the drill, followed by the accuracy check. These steps have to be performed correctly to ensure best navigation accuracy.

Drill Calibration

Calibration is the process of mapping the drill tip to the DrillTag. This two step process starts with calibration of the drill-axis (which is performed only once), followed by calibration of the drill tip, performed for each drill being used.

Once the MicronTracker camera identifies the JawTag and DrillTag, Navident prompts the surgeon to calibrate the drill axis.

A common misperception, is that drill calibration has to be carried out when the NaviStent, with the DrillTag, is seated on the patient’s teeth. Calibration is actually performed against the JawTag itself, regardless of patient’s presence!

The accuracy of the calibration and of the registration of the CBCT image to the DrillTag are verified after calibration, by the accuracy check.

Drill Axis calibration:

This step can be performed conveniently by holding the JawTag (with stent outside of patient’s mouth) in one hand, and the handpiece in the other hand, in front of the MicronTracker camera.

  • Do not hide the X-points on the JawTag with the handpiece – otherwise the process wouldn’t initiate.

(correct position displayed above)

(Incorrect position displayed above)

  • Are the JawTag and DrillTag being illuminated evenly? if only part of the tag is strongly illuminated (by a head-light or the dental light) – the MicronTracker camera would not be able to track it.

(Incorrect illumination displayed above)

  • Make sure to place the handpiece chuck all the way down on the JawTag’s pin, before rotating it to initiate axis-calibration. Be careful not to apply any force that may bend the pin.
  • When calibration starts – stay still and do not continue rotating the handpiece. Wait for the axis calibration to complete (indicated on the screen and by sound). Only then take the handpiece off the pin.

(correct position demonstrated above)

(incorrect position demonstrated above)

Drill Tip calibration:

After the drill axis is calibrated, Navident prompts the surgeon to perform the drill tip calibration. This step can also be performed without having the NaviStent seated on patient’s teeth. However, it is more convenient to perform it when the Navistent with JawTag are already in place.

  • Install the first drill in the handpiece, making sure to lock it in place.
  • With one hand supporting the JawTag, and the other holding the handpiece, press the drill’s tip against the dimple. Navident measures the position of the middle of the dimple relative to the DrillTag and assumes this is where the tip is. To achieve high accuracy, it is, therefore, critical that:
    1. The drill tip is in the exact middle of the marked circle; and
    2. there is no lateral pressure on the tip which may move it away from the drilling axis.

(Correct position demonstrated above)

(incorrect position demonstrated above)

  • Wait for the calibration process to complete (also – indicated on the screen and by sound), then proceed to the accuracy check.

Accuracy Check

A mandatory step prior to starting the osteotomy, is verification of the accuracy of the mapping between the drill-tip and the jaw’s CT image, or “accuracy check”. It enables you to ensure that the on-screen drilling guidance will produce the desired result.

The accuracy check is performed by bringing the tip of the drill in contact with clearly visible surfaces that present a high contrast edge in the CT cross section. Any inaccuracy will show up on-screen as a gap between the overlaid tip outline and the high contrast edge. The magnitude of the deviation can be estimated by comparing it to the 1mm radius of the circle drawn around the overlaid tip.

(pictured: good accuracy)

(pictured: 1 mm gap)

(pictured: 2 mm gap)

Location, location, location

An accuracy check performed against a single surface enables assessing deviation only in the direction perpendicular to the surface. To assess the magnitude of the deviation in all 3 dimensions, the accuracy check needs to be performed by touching surfaces oriented in 3 different directions.

(3 dimensions demonstrated)

The guidance accuracy often gradually varies across the jaw. It is, therefore, more useful to perform the accuracy check on surfaces as close as possible to where guidance will be needed.

Considering the above, you’d usually want to pick a single natural tooth right next to the implantation site, and perform 3 checks on 3 different aspects of that tooth: (1) occlusal, (2) mesial or distal, and (3) buccal. For successful guidance, you should expect to see, in each of these checks, the tooth boundary edge appear with the 1mm circle in at least one cross sectional view.

Doin’ it

After the drill axis and the first drill tip are calibrated, verify the accuracy as follows:

  1. Hold the drill as perpendicular as possible to the tooth surface with its sharp tip touching it.
  2. Look at the viewports on the screen (NOT the panoramic): the pointed end of the drill’s blue image should be touching the tooth surface.

All 3 dimensions of space need to be checked and verified. Repeat this sequence for 3 times, each time on another aspect of the tooth (see pics):

  1. Touch the occlusal surface to verify accuracy in the Occluso-gingival aspect (or Z-axis).
  2. Touch the buccal or lingual/palatal surface for the bucco-lingual/palatal aspect (in X-Y plane).
  3. Touch the distal or mesial surface for the mesio-distal aspect (in X-Y plane).



  • Only the cross-sectional viewports (namely: Axial, Tangential, Cross-sectional) should be used for the accuracy check. The panoramic view’s, being a reconstructed image, is not accurate enough for this purpose.
  • It is recommended to repeat the accuracy check after each drill-tip calibration and whenever you wish to verify and confirm accuracy.
  • The actual tip of the drill should be touching the tooth – not the side of the drill (the drill’s on-screen image does not represent actual drill’s diameter)

(Correct position displayed above)

(Incorrect position displayed above)

  • Accuracy check should be performed against a tooth – not against the NaviStent. Checks against the stent are not indicative of the accuracy in relation to your patient’s jaw!
  • If the accuracy check shows a large deviation against a tooth, do perform an accuracy check against the NaviStent, near the location where you performed the accuracy check against a tooth. If the deviation against the NaviStent is much smaller than against the tooth, it indicates that the NaviStent is not seated on the jaw in the same way as during the scan.

(insufficient check displayed above)

If the drill-tip is touching the tooth (physically), but the pointed end of its blue image appears inside the tooth’s image or if there is a gap between them – this indicates an inaccurate navigation.

Stay tuned for more practical tips in our next bulletin. Navigate safely!