Dynamic Navigation for Dental Implant Placement

Summary

Dynamic computer-aided implant surgery (DCAIS) is a controlled implant surgical placement method performed without a surgical template using optical control. The real-time intraoperative control of movement and position of the surgical device simplifies the procedure and gives more freedom to the surgeon, providing similar precision as static navigation methods.

Abstract

In modern implantology, the application of surgical navigation systems is becoming increasingly important. In addition to static surgical navigation methods, a guide-independent dynamic navigation implant placement procedure is becoming more widespread. The procedure is based on computer-guided dental implant placement utilizing optical control. This work aims to demonstrate the technical steps of a new dynamic computer-aided implant surgery (DCAIS) system (design, calibration, surgery) and check the accuracy of the results. Based on cone-beam computed tomography (CBCT) scans, the exact positions of implants are determined with dedicated software. The first step of the operation is the calibration of the navigation system, which can be performed in two ways: 1) based on CBCT images taken with a marker or 2) based on CBCT images without markers. Implants are inserted with the aid of real-time navigation according to the preoperative plans. The accuracy of the interventions can be evaluated based on postoperative CBCT images. The preoperative images containing the planned positions of the implants and postoperative CBCT images were compared based on the angulation (degree), platform, and apical deviation (mm) of the implants. To evaluate the data, we calculated the standard deviation (SD), mean, and standard error of the mean (SEM) of deviations within planned and performed implant positions. Differences between the two calibration methods were compared based on this data. Based on the interventions performed so far, the use of DCAIS allows for high-precision implant placement. A calibration system that does not require labeled CBCT recording allows for surgical intervention with similar accuracy as a system that uses labeling. The accuracy of the intervention can be improved by training.

Introduction

To increase the accuracy of dental implant placement and reduce the complications, a range of navigation techniques based on imaging studies have been developed. Preoperative imaging and special 3D implant planning software can be used to plan the exact position of the dental implant^1,2.

The aim of implant surgery navigation is to accomplish a more anatomically precise placement of the dental implant to achieve the most ideal position, to reduce the risk of possible iatrogenic complications (nerve, vascular, bone, and sinus injuries). The navigated surgery decreases the invasiveness of the intervention (flapless surgery), which can lead to fewer complaints and faster recovery. The accurate implant placement is based on prior prosthetic planning (it is possible to perform the operation on the basis of a preoperative tooth installation) and the optimal implant positioning can help avoid bone grafting.

Nowadays, there are two types of computer-assisted implant (CAI) surgical placement navigation systems-static and dynamic navigation systems. Static navigation is a controlled implant placement method using a preplanned and prefabricated surgical template. Dynamic navigation is a preplanned computer-guided implant surgical placement method without a surgical template using optical control. The control procedure uses point cloud-based image registration to merge the virtual images with the real environment by applying 3D image overlay³.

DCAI systems make possible real-time, objectified instrument control within a GPS-like framework. Typically, they use optical tracking to detect and track the position of (optical) reference markers placed over the patient and the surgical instruments, and provide continuous visual feedback on the implant surgical placement process^1,2.

The movement and position of the surgical instrument during surgery can be monitored live on a three-dimensional image on a monitor. During the procedure, the camera system allows continuous monitoring and comparison of the position of the patient's jawbone and the position of the surgical instrument.

There are two types of dynamic navigation systems: one is the passive system, in which case the registration devices (reference bases) reflect light emitted from the light source back to the stereo cameras; the other is the active system, where the registration devices emit light which is followed by stereo cameras^4,5.

The next level of dynamic navigation systems uses servo motors to guide the surgeon's hand with tactile stimuli so that the device with robotic arms can determine the surgeon's movements or even replace them completely in the distant future^4,5,6,7.

Protocol

Informed consent was obtained from every patient before surgery. After the interventions anonymized retrospective data was used in this study.

1. Steps in the traditional workflow of dynamic navigation systems using labeled clip calibration method (only for use on jawbone with teeth):

1. Attach a radiopaque fixation clip to the teeth of the jawbone where the treatment is to be performed (maxilla/mandible) using a thermoplastic material.
2. Make a CBCT examination of the patient with a labeled clip in the mouth (CBCT, FOV 8 cm x 11 cm, 12 mA, 95 kV).
3. Plan the position of the implant according to the prosthetic architecture with the appropriate software.
4. Calibrate the device (each step can be activated on display with the Play symbol).
   1. Register the handpiece.
      1. Calibrate handpiece chuck.
      2. Calibrate the rotating marker-disc inserted into the handpiece.
      3. Assemble the arm between the patient tracker and the labeled clip, and calibrate it.
5. Check calibration by holding the tip of the measured drill to the surface of the labeled clip (Figure 1).
   1. Fix the labeled clip holding the optical marker (tracker) on the teeth of the upper or lower jaw (on which jaw the implant placement occurs). Ensure to insert the clip in the same position registered on the preoperative CBCT.
   2. Calibrate the labeled clip by touching the metal spheres of the clip with the pivot of the probe.
6. Perform the navigated implant placement in local anesthesia, injecting 2 mL of articain (80 mg/2 mL articain/ampoule).
   1. Measure the drill length (touching the drill to the go plate) (Figure 2).
   2. Check the real-time visual accuracy before drilling (touching the drill to any tooth surface and checking that it is in the same position on the monitor and the mouth).
   3. Determine the entry point of drilling. Explore the operation site without the flap.
   4. Drill the bone with dynamic navigation control (Figure 3, Figure 4, and Figure 5) .
   5. Measure the implant length (touching the implant to the go plate).
   6. Place the implant with the handpiece wearing the tracker controlled by the dynamic navigation system.
   7. Close the wound with 5.0 monofilament, nonabsorbable polypropylene suture, or fix the prefabricated prosthetic work.
7. Acquire control radiologic imaging (CBCT, FOV 8 cm x 11 cm, 12 mA, 95 kV).

2. Steps in the dynamic navigation systems using the tracer calibration method (not labeled method):

1. Perform CBCT of the patient (without clip in the mouth).
2. Plan the position of the implant according to the prosthetic architecture with the appropriate software.
3. Calibrate the device as detailed in step 1.4.
4. Calibrate the system without a labeled clip (not labeled method).
   1. Transfer the plan of the implant surgical placement into the software of the used navigation system. Select the workspace on the 3D CT image of the navigation software.
   2. Fix the tracker on the teeth (with an unlabelled clip) or in case of an edentulous jaw with a special tracker-holding arm.
   3. Select the typical anatomical points (teeth or bone surface) on a 3D CT image of the navigation system (minimum three points).
   4. Identify the selected anatomical points in the mouth by touching them with a probe tool. (Figure 6).
   5. Perform refinement procedure on three to four areas by drawing on the surface of the anatomical structure with a probe.
5. Place the implant with navigation in local anesthesia, injecting 2 mL of articain (80 mg/2 mL articain/ampoule).
   1. Measure the drill length (touching the drill to the go plate).
   2. Check the real-time visual accuracy before drilling (touching the drill to any tooth surface and checking that it is in the same position on the monitor and in the mouth).
   3. Determine the drilling point. Explore the operation site without the flap.
   4. Drill the bone with dynamic navigation control.
   5. Measure the implant length (touching the implant to the go plate).
   6. Place the implant with the handpiece wearing the tracker controlled by the dynamic navigation control system.
   7. Close the wound with 5.0 monofilament, nonabsorbable polypropylene suture or fix the prefabricated prosthetic work.
6. Make control radiologic imaging (CBCT, FOV 8 cm x 11 cm, 12 mA, 95 kV).

Results

To use DCAIS correctly, the system must be calibrated. There are several calibration methods that can affect the accuracy of the implant placement. This study aimed to assess the potential impact of different calibration methods on the accuracy of DCAIS.

Based on the interventions performed so far, the use of DCAIS allows a high-precision implant placement. In our early studies, we compared 41 clip calibrated dynamic navigated implant placements with 17 tracer calibrated dynamic navigated impl...

Discussion

In the labeled clip-used dynamic navigation implant placement system, the traditional workflow is done by clip calibration. There are three radiopaque metal spheres on the surface of the clip, which are clearly visible on the CBCT scan. In the case of the tracer calibration method, these metal spheres containing clips are neither necessary for the CBCT scanning nor system calibration. In cases with existing teeth, both the labeled and unlabelled clips can be used (two different calibration methods). The clip is attached ...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
DTX Implant Studio Software	Nobel Biocare	106182	3D surgical planing software
MeshLab	ISTI - CNR research center	2020.12	3D mesh processing software
Nobel Replace CC implant	Nobel Biocare	37285	Implant
X-Guide	X-Nav - Nobel Biocare	SN00001310	dinamic navigation surgery system
X-Guide - XClip	X-Nav - Nobel Biocare	XNVP008381	3D navigation registration device
X-Guide planing software	X-Nav - Nobel Biocare	XNVP008296	3D surgical planing and operating software
X-Mark probe	X-Nav - Nobel Biocare	XNVP008886	3D navigation registration tool
PaX-i3D Smart	Vatech		CBCT
Prolene 5.0			5.0 monofilament, nonabsorbable polypropylene suture