The Validity of Marker Registration for an Optimal Integration Method in Mandibular Navigation Surgery

Accuracy and patient-centered results of marker-based and marker-free registrations for dynamic computer-assisted implant surgery: A randomized controlled trial

OBJECTIVES

To compare implant placement accuracy and patient-centered results between the dynamic computer-assisted implant surgeries (d-CAISs) using marker-based and marker-free registration methods.

MATERIALS AND METHODS

A double-armed, single-blinded randomized controlled trial was conducted, in which 34 patients requiring single implant placement at the esthetic zone were randomly assigned to the marker-based (n = 17) or marker-free (n = 17) groups. The marker-based registration was performed using a splint containing radiopaque markers, while the marker-free registration used natural teeth. The primary outcome assessed implant positioning accuracy via angular and linear deviations between preoperative and postoperative implant positions in CBCT. Patients were also surveyed about the intraoperative experience and oral health impact profile (OHIP).

RESULTS

The global linear deviations at the implant platform (0.82 ± 0.28 and 0.85 ± 0.41 mm) and apex (1.28 ± 0.34 and 0.85 (IQR: 0.64-1.50) mm) for the marker-based and marker-free groups respectively showed no significant difference. However, the angular deviation of the marker-free group (2.77 ± 0.92° ) was significantly lower than the marker-based group (4.28 ± 1.58° ). There was no significant difference in the mean postoperative OHIP scores between the two groups (p = .758), with scores of 2.74 ± 1.21 for marker-based and 2.93 ± 2.18 for marker-free groups, indicating mild oral health-related impairment in both. Notably, patients in the marker-free group showed significantly higher satisfaction (p = .031) with the treatment procedures.

CONCLUSIONS

D-CAIS with a marker-free registration method for single implantation in the anterior maxilla has advantages in improving implant placement accuracy and patients' satisfaction, without generating a significant increase in clinical time and expenses.

Accuracy and Efficiency of Endodontic Microsurgery Assisted by Dynamic Navigation Based on Two Different Registration Methods: An In Vitro Study

INTRODUCTION

This study aimed to compare the accuracy and efficiency of dynamic navigation-assisted endodontic microsurgery (DN-EMS) using two different registration methods.

METHODS

Three-dimensional-printed jaw models, including 40 teeth, were divided into two groups (n = 20). Cone-beam computed tomography images of all teeth were scanned under the same exposing parameters. An endodontic dynamic navigation system (DHC-ENDO1) was used to plan the drilling paths. Dynamic navigation-assisted endodontic microsurgery (DN-EMS) was performed using either U-shaped tube (UT) or tooth cusp (TC) registration method. The accuracy was determined by platform deviation, end deviation, angular deviation, resection angle, and resection length deviation. The registration efficiency was defined as the time required to complete the registration procedure. Osteotomy volume of each resection was calculated by Mimics 21.0. Statistical analyses were performed using IBM SPSS Statistics 24.0. Comparisons between groups were performed using the independent sample t test or Mann-Whitney U test. P < .05 was adopted as significant difference.

RESULTS

The UT group was significantly more accurate in terms of mean platform deviation, end deviation, angular deviation, and resection angle (P < .05). Resection length deviation did not differ significantly between the registration groups. The UT group was significantly more efficient than the TC group (P < .05). No significant differences were found in the osteotomy volumes between the two groups.

CONCLUSIONS

In the model-based surgical simulation comparison, DN-EMS based on UT registration is more accurate and efficient than the TC method but requires an additional registration device. TC technique may be a reasonable alternative to UT registration in certain clinical tasks.

Accuracy of automatic and manual dynamic navigation registration techniques for dental implant surgery in posterior sites missing a single tooth: A retrospective clinical analysis

OBJECTIVES

To assess the relative accuracy of manual (U-shaped tube) and automatic (two-in-one) dynamic navigation registration techniques for implant surgery performed in posterior sites missing one tooth.

MATERIALS AND METHODS

This study included 58 partially edentulous patients with 58 implants, including 31 and 27 in the manual and automatic groups. Deviations between the planned and actual implant placement were assessed.

RESULTS

The angular deviation in the overall study cohort was 2.54 ± 1.21°, while the 3D deviations at the implant platform and apex were 0.90 ± 0.46 mm and 1.04 ± 0.47 mm, respectively. The respective angular deviations in the manual and automatic groups were 2.82 ± 1.17° and 2.21 ± 1.19° (p > .05), while platform deviations were 0.89 ± 0.48 mm and 0.91 ± 0.45 mm (p > .05), and apex deviations were 0.99 ± 0.48 mm and 1.11 ± 0.46 mm (p > .05). No significant differences in absolute buccolingual, mesiodistal, or apicocoronal deviations were detected between these groups at either level (p > .05) nor were did deviation distributions differ in the buccolingual, mesiodistal, or apicocoronal directions at the platform or apex levels (p > .05).

CONCLUSIONS

Manual and automatic dynamic navigation registration techniques can achieve excellent accuracy when placing implants in posterior sites missing a single tooth. The two-in-one automatic registration technique can reduce the amount of time and intraoperative steps necessary to complete the registration process relative to the manual U-shaped tube registration technique. Further follow-up studies are necessary to expand on these results.

Target registration errors in navigation-assisted mandibular surgery according to the tracking methods and the type of markers: experiments using human dry mandibular bone

OBJECTIVES

This study was conducted to evaluate the accuracy of navigation process according to the type of tracking methods and registration markers. The target registration errors (TREs) were measured at seven anatomical landmarks of the mandible.

METHODS

Four different experiments were performed to obtain the TREs using two tracking methods, the optical tracker (Polaris) and the electromagnetic (EM) tracker (Aurora), and two types of registration markers, invasive and noninvasive markers. All comparisons of TREs were statistically analyzed using SPSS and Python-based statistical package.

RESULTS

The average TRE values obtained from the four experiments were as follows: (1) 0.85 mm (± 0.07) using invasive marker and Aurora, (2) 1.06 mm (± 0.12) using invasive marker and Polaris, (3) 1.43 mm (± 0.15) using noninvasive marker and Aurora, and (4) 1.57 mm (± 0.23) using noninvasive marker and Polaris. Comparisons between all the experimental results revealed statistically significant differences except for the type of tracking system. Although the comparison between the modality of the tracking system showed no significant differences, the EM-based approach consistently demonstrated better performances than the optical type in all comparisons.

CONCLUSIONS

This study demonstrates that irrespective of the tracking modality, using invasive marker is a better choice in terms of accuracy. When using noninvasive marker, it is important to consider the increased TREs. In this study, the noninvasive marker caused a maximum increment of TREs of 0.81 mm compared with the invasive marker. Furthermore, using an EM-based tracker with invasive marker may result in the best accuracy for navigation.

The accuracy and learning curves of active and passive dynamic navigation-guided dental implant surgery: An in vitro study

OBJECTIVES

Infrared dynamic navigation principles can be categorized into active and passive navigation systems based on whether the surgical instruments can emit or only reflect light, respectively. This in vitro study aimed to compare the accuracy of implant placement and the learning curves of both active and passive dynamic navigation systems using different registration methods.

METHODS

Implants (n=704) were placed in 64 sets of models and divided into active (Yizhime, DCARER, Suzhou, China) and passive (Iris-Clinic, EPED, Kaohsiung, China) dynamic navigation groups. Both marker point-based registration (M-PBR) and feature point-based registration (F-PBR) were employed by two groups mentioned above. Based on preoperative and postoperative cone-beam computed tomography imaging, the coronal, midpoint, apical, and angular deviations were analyzed from 2D and 3D views. The operation time was recorded for each group.

RESULTS

The active dynamic navigation group exhibited significantly greater accuracy than the passive dynamic navigation group for outcome variables (angular deviation, 4.13 ± 2.39° and 4.62 ± 3.32°; coronal global deviation, 1.48 ± 0.60 and 1.86 ± 1.12 mm; apical global deviation, 1.75 ± 0.81 and 2.20 ± 1.68 mm, respectively). Significant interaction effects were observed for both registration methods and four quadrants with different dynamic navigation systems. Learning curves for the two dynamic navigation groups approached each other after 12 procedures, and finally converged after 27 procedures.

CONCLUSIONS

The accuracy of active dynamic navigation system was superior to that of passive dynamic navigation system. Different combinations of dynamic navigation systems, registration methods, and implanted quadrants displayed various interactions.

CLINICAL SIGNIFICANCE

Our findings could provide guidance for surgeons in choosing an appropriate navigation system use in various implant surgeries. Furthermore, the time required by surgeons to master the technique was calculated for reference. Nevertheless, there are certain limitations to this in vitro study, and therefore further research is required.

Automated Machine Learning (AutoML)-based Surface Registration Methodology for Image-guided Surgical Navigation System

BACKGROUND

While the surface registration technique has the advantage of being relatively safe and the operation time is short, it generally has the disadvantage of low accuracy.

PURPOSE

This research proposes automated machine learning (AutoML)-based surface registration to improve the accuracy of image-guided surgical navigation systems.

METHODS

The state-of-the-art surface registration concept is that first, using a neural network model, a new point-cloud that matches the facial information acquired by a passive probe of an optical tracking system (OTS) is extracted from the facial information obtained by computerized tomography (CT). Target registration error (TRE) representing the accuracy of surface registration is then calculated by applying the iterative closest point (ICP) algorithm to the newly extracted point-cloud and OTS information. In this process, the hyperparameters used in the neural network model and ICP algorithm are automatically optimized using Bayesian Optimization with Expected Improvement to yield improved registration accuracy.

RESULTS

Using the proposed surface registration methodology, the average TRE for the targets located in the sinus space and nasal cavity of the soft phantoms is (0.939 ± 0.375) mm, which shows 57.8 % improvement compared to the average TRE of (2.227 ± 0.193) mm calculated by the conventional surface registration method (p < 0.01). The performance of the proposed methodology is evaluated, and the average TREs computed by the proposed methodology and the conventional method are (0.767 ± 0.132) mm and (2.615 ± 0.378) mm, respectively. Additionally, for one healthy adult, the clinical applicability of the AutoML-based surface registration is also presented.

CONCLUSION

Our findings showed that the registration accuracy could be improved while maintaining the advantages of the surface registration technique. This article is protected by copyright. All rights reserved.

Computer-assisted navigation for removal of the foreign body in the lower jaw with a mandible reference frame: A case report

RATIONALE

In surgery of the lower jaw, the application of computer-assisted navigation is complicated and challenging due to the mobile nature of the mandible. In this study, we presented a computer-assisted navigation surgery for removal of the foreign body in the lower jaw with a mandible reference frame, basing on the strategy that the mandible is independent as an entity.

PATIENT CONCERNS

A 41-year-old male patient, identified as having a broken fissure bur that displaced into the mandibular lingual soft tissue, was referred to our department. The fissure bur broke accidentally and then displaced into the soft tissue when the patient underwent extraction of the left mandibular impacted third molar.

DIAGNOSIS

A metallic foreign body in the left lower jaw, confirmed by orthopantomography.

INTERVENTIONS

A computer-assisted navigation surgery with a customized mandible reference frame.

OUTCOMES

The broken bur was removed successfully. Satisfactory wound healing and mouth opening was achieved, without postoperative complications.

LESSONS

Surgeons should be alert to the presence of broken bur in the lower jaw and avoid its displacement into deep facial space, and computer-assisted navigation with a mandible reference frame is recommended for removal of the foreign body in the lower jaw.

Errors according to the number of registered markers used in navigation-assisted surgery of the mandible

Background

The aim of this study was to evaluate the accuracy of navigation according to the number of markers in terms of target registration errors (TREs) at each anatomical location during the registration process of the navigation system for the mandible.

Methods

The TREs were measured in five different experiments, varying only in the number of registration reference markers, which ranged from three to seven. To measure the TREs according to the number of registration reference markers, two experimental navigation devices were used: 1) Cbyon navigation surgery equipment 2) Polaris optical tracker. Both experiments were conducted to obtain the TREs at the anatomical locations of the mandible according to the number of registration markers during the navigation process. Statistical analysis was performed using the SPSS 23.0 software.

Results

At all anatomical locations, errors were 2 mm or less. Further, significant differences in the target errors measured by the Cbyon system were found according to the number of registration markers. Significant differences in the target errors measured by the Polaris optical tracker were found according to the registration markers at the posterior border only. In both groups, the target errors did not decrease as the number of registration markers increased.

Conclusions

This study demonstrates that an increase in the number of registration markers is not associated with a decrease in the TRE, and that a specific number of registration markers could reduce the TREs at each anatomical site. It is important to determine the minimum number of image registration markers at which the smallest TRE would be observed for different surgical sites.

Navigation accuracy after automatic- and hybrid-surface registration in sinus and skull base surgery

Objective

Computer-aided-surgery in ENT surgery is mainly used for sinus surgery but navigation accuracy still reaches its limits for skull base procedures. Knowledge of navigation accuracy in distinct anatomical regions is therefore mandatory. This study examined whether navigation accuracy can be improved in specific anatomical localizations by using hybrid registration technique.

Study design

Experimental phantom study.

Setting

Operating room.

Subjects and methods

The gold standard of screw registration was compared with automatic LED-mask-registration alone, and in combination with additional surface matching. 3D-printer-based skull models with individual fabricated silicone skin were used for the experiments. Overall navigation accuracy considering 26 target fiducials distributed over each skull was measured as well as the accuracy on selected anatomic localizations.

Results

Overall navigation accuracy was <1.0 mm in all cases, showing the significantly lowest values after screw registration (0.66 ± 0.08 mm), followed by hybrid registration (0.83± 0.08 mm), and sole mask registration (0.92 ± 0.13 mm).On selected anatomic localizations screw registration was significantly superior on the sphenoid sinus and on the internal auditory canal. However, mask registration showed significantly better accuracy results on the midface. Navigation accuracy on skull base localizations could be significantly improved by the combination of mask registration and additional surface matching.

Conclusion

Overall navigation accuracy gives no sufficient information regarding navigation accuracy in a distinct anatomic area. The non-invasive LED-mask-registration proved to be an alternative in clinical routine showing best accuracy results on the midface. For challenging skull base procedures a hybrid registration technique is recommendable which improves navigation accuracy significantly in this operating field. Invasive registration procedures are reserved for selected challenging skull base operations where the required high precision warrants the invasiveness.

Vision-based markerless registration using stereo vision and an augmented reality surgical navigation system: a pilot study

Background

This study evaluated the use of an augmented reality navigation system that provides a markerless registration system using stereo vision in oral and maxillofacial surgery.

Method

A feasibility study was performed on a subject, wherein a stereo camera was used for tracking and markerless registration. The computed tomography data obtained from the volunteer was used to create an integral videography image and a 3-dimensional rapid prototype model of the jaw. The overlay of the subject’s anatomic site and its 3D-IV image were displayed in real space using a 3D-AR display. Extraction of characteristic points and teeth matching were done using parallax images from two stereo cameras for patient-image registration.

Results

Accurate registration of the volunteer’s anatomy with IV stereoscopic images via image matching was done using the fully automated markerless system, which recognized the incisal edges of the teeth and captured information pertaining to their position with an average target registration error of < 1 mm. These 3D-CT images were then displayed in real space with high accuracy using AR. Even when the viewing position was changed, the 3D images could be observed as if they were floating in real space without using special glasses.

Conclusion

Teeth were successfully used for registration via 3D image (contour) matching. This system, without using references or fiducial markers, displayed 3D-CT images in real space with high accuracy. The system provided real-time markerless registration and 3D image matching via stereo vision, which, combined with AR, could have significant clinical applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12880-015-0089-5) contains supplementary material, which is available to authorized users.

A strategy for removal of foreign body in mandible with navigation system

Navigation surgery in the mandible has rarely been reported because of the complexities of navigating a mobile structure. In this article, we present a simple and novel strategy for removal of a foreign body in the mandible using a navigation system. A female diagnosed with a foreign body in the left mandible underwent navigation surgery using a BrainLAB system. We used a special open splint fabricated with acrylic resin to successfully perform the mandibular navigation. This strategy may be appropriate for many types of mandibular navigation surgery.

Verification of the usability of a navigation method in dental implant surgery: in vitro comparison with the stereolithographic surgical guide template method

OBJECTIVE

This study investigates the usefulness of a navigation method using a reference frame directly fixed to the mandible compared to the stereolithographic (STL) surgical guide template method in dental implant surgery.

MATERIALS AND METHODS

Twenty rapid prototyping (RP) mandibular models were divided into two groups. Simulation surgery was performed using SimPlant software for both groups. The actual dental implants were placed in the RP models using a real-time navigation system or the surgical guide template, which was fabricated based on STL data by a 3-dimensional printer. Positional implantation errors were measured by comparing the simulation surgery implant positions to the actual postoperative implant positions.

RESULTS

The vertical distance error of the top surface area in the first molar region was not significantly different between groups. Otherwise, the implantation method using real-time navigation showed greater errors except for the horizontal and vertical errors in the apical area of the canine region.

CONCLUSION

The STL surgical guide template was associated with fewer errors than the real-time navigation method in dental implant surgery.

A new nasopharyngeal dynamic reference frame improves accuracy in navigated skull base targets

OBJECTIVE

We questioned whether the position of the dynamic reference frame (DRF) influences the application accuracy in electromagnetically navigated cranial procedures. A carrier for an electromagnetic DRF was developed, which could be fixed at the posterior edge of the vomer near the center of the head. This nasopharyngeal DRF was compared with a standard DRF fixed to the surface of the forehead.

METHODS

Image coordinates and real-world coordinates were co-registered and the total target error (TTE) was measured in the frontal and the lateral skull base of formalin fixed human head. At each anatomical site, 10 targets served for TTE determinations and 5 different fiducial combinations were used for registration.

RESULTS

With the nasopharyngeal DRF, lower TTE values (2.8 ± 1.4 mm; mean ± SD) were observed when compared with the forehead DRF (3.7 ± 2.8 mm; P = .004). TTEs of both anatomical sites investigated were significantly lower when using the nasopharyngeal DRF (frontal skull base 3.4 vs 2.1 mm, P = .005 and lateral skull base 3.9 vs 3.5 mm, P = .013) than with the standard forehead mounted one.

CONCLUSION

Positioning the DRF in the center of the head significantly improved the application accuracy of targets in the skull base with electromagnetic navigation by 25%.