Application of Real-Time Surgical Navigation for Zygomatic Implant Insertion in Patients With Severely Atrophic Maxilla

Accuracy of freehand versus dynamic computer-assisted zygomatic implant placement: An in-vitro study

OBJECTIVE

To compare the accuracy of zygomatic implant placement using a dynamic computer-assisted implant surgery system (D-CAIS) versus the traditional freehand approach.

METHODS

An experimental in vitro study was conducted using 10 stereolithographic models randomized to two groups: D-CAIS (test group) and freehand placement (control group). A single zygomatic implant was placed on each side of the models. The accuracy of implant placement was assessed by superimposing the actual postoperative implant position, obtained via cone-beam computed tomography (CBCT), with the virtual preoperative surgical plan from the preoperative CBCT. Additionally, the operated side and surgery duration were recorded. Descriptive statistics and bivariate analyses were performed to evaluate the data.

RESULTS

The D-CAIS group demonstrated significantly greater accuracy across most outcome variables. Reductions in angular (MD = -5.33°; 95 %CI: -7.37 to -3.29; p < 0.001), coronal global (MD = -2.26 mm; 95 %CI: -2.97 to -1.55; p < 0.001), coronal horizontal 2D (MD = -1.96 mm; 95 %CI: -2.60 to -1.32; p < 0.001) and apical global deviations (MD = -3.37 mm; 95 %CI: -4.36 to -2.38; p < 0.001) were observed. Accuracy in the freehand group varied significantly between operated sides. However, the surgical procedures in the D-CAIS group were significantly longer (MD = 11.90 mins; 95 %CI: 9.37 to 14.44; p < 0.001).

CONCLUSIONS

D-CAIS navigation systems offer significantly greater accuracy in zygomatic implant placement compared to the traditional freehand technique. Additionally, D-CAIS systems may minimize discrepancies in accuracy between operated sides, though their use is associated with an increase in the duration of surgery.

CLINICAL SIGNIFICANCE

D-CAIS navigation systems improve the accuracy of zygomatic implant placement. However, an increase in the duration of surgery is to be expected.

Accuracy of freehand surgery, static and dynamic computer assisted surgery on zygomatic implant placement: A systematic review and meta-analyses

Real-time surgical navigation systems (dynamic computer-aided surgery, d-CAIS) and static guided surgery (static computer-aided surgery, s-CAIS) have been shown to enhance the accuracy of zygomatic implant (ZI) placement. The objective of this systematic review was to evaluate and compare the accuracy and risk of complications associated with d-CAIS and s-CAIS in ZI placement. A systematic review of published studies involving more than 4 patients was conducted to assess and compare the accuracy of d-CAIS and s-CAIS in zygomatic implant placement. Only one study included freehand ZI placement as a control. The primary outcomes measured were the accuracy of implant placement relative to preoperative planning, with a secondary focus on evaluating any potential complications. Out of 903 screened studies, 14 met the inclusion criteria. Freehand zygomatic implant placement was used as a control in only 1 study. The results revealed a mean apex deviation of 2.07 mm (95% CI: 2.01 to 2.13; I2 = 83.14%) for d-CAIS, 1.29 mm (95% CI: 1.15 to 1.43; I2 = 94.5%) for s-CAIS, and 4.98 mm (95% CI: 3.59 to 6.37; I2 = not assessable) for freehand placement. Reported complications included mucositis, reversible bilateral sinusitis, oroantral fistula, unspecified reversible postoperative complications, and fracture of the anterior wall of the zygoma. Both CAIS systems demonstrated high accuracy and safety in ZI placement, with a nearly 99% success rate at 6 months of follow-up. These findings suggest that both d-CAIS and s-CAIS are reliable methods for improving the precision and reducing the risks associated with ZI procedures.

20 Years of Clinical Evolution in Zygomatic Implant Rehabilitation: Long-Term Outcomes and Current States

Zygoma implants are an alternative for rehabilitating severe maxillary atrophy. Since 2004, when Prof. Branemark first reported the long-term findings on zygomatic implants using the original intra-sinus approach, various surgical techniques have been introduced. In 2006, an anatomy-guided approach was developed, applying different implant trajectories based on alveolar atrophy levels and sinus concavity. The purpose of this review is to clarify the existing techniques and long-term outcomes of ZI rehabilitation over the past 20 years. Additionally, it aims to enhance the quality of current practices and identify gaps in the understanding of ZI treatment for future studies.

Accuracy of augmented reality navigated surgery for placement of zygomatic implants: a human cadaver study

Purpose

Placement of zygomatic implants in the most optimal prosthetic position is considered challenging due to limited bone mass of the zygoma, limited visibility, length of the drilling path and proximity to critical anatomical structures. Augmented reality (AR) navigation can eliminate some of the disadvantages of surgical guides and conventional surgical navigation, while potentially improving accuracy. In this human cadaver study, we evaluated a developed AR navigation approach for placement of zygomatic implants after total maxillectomy.

Methods

The developed AR navigation interface connects a commercial navigation system with the Microsoft HoloLens. AR navigated surgery was performed to place 20 zygomatic implants using five human cadaver skulls after total maxillectomy. To determine accuracy, postoperative scans were virtually matched with preoperative three-dimensional virtual surgical planning, and distances in mm from entry-exit points and angular deviations were calculated as outcome measures. Results were compared with a previously conducted study in which zygomatic implants were positioned with 3D printed surgical guides.

Results

The mean entry point deviation was 2.43 ± 1.33 mm and a 3D angle deviation of 5.80 ± 4.12° (range 1.39-19.16°). The mean exit point deviation was 3.28 mm (±2.17). The abutment height deviation was on average 2.20 ± 1.35 mm. The accuracy of the abutment in the occlusal plane was 4.13 ± 2.53 mm. Surgical guides perform significantly better for the entry-point (P = 0.012) and 3D angle (P = 0.05); however, there is no significant difference in accuracy for the exit-point (P = 0.143) when using 3D printed drill guides or AR navigated surgery.

Conclusion

Despite the higher precision of surgical guides, AR navigation demonstrated acceptable accuracy, with potential for improvement and specialized applications. The study highlights the feasibility of AR navigation for zygomatic implant placement, offering an alternative to conventional methods.

Implant position accuracy using dynamic computer-assisted implant surgery (CAIS) combined with augmented reality: A randomized controlled clinical trial

Background/purpose

Computer-assisted implant surgery (CAIS) is increasingly performed to reduce deviations in implant position. Dynamic CAIS or navigation systems provide instant display of implant drilling instruments and patient positions directly on the computer monitor. Augmented reality (AR) technology allows operators to visualize real-time information projected onto the lenses of AR glasses. Although AR is being used in medical applications, there are few clinical studies on applying AR glasses to dental implants. The purpose of this randomized clinical study was to compare the accuracy of implant position using the dynamic CAIS with and without AR glasses.

Materials and methods

Twenty patients who needed a single dental implant were randomly divided into two groups: combined dynamic CAIS with AR glasses (AR glasses group, n = 10) and dynamic CAIS without AR glasses (non-AR glasses group, n = 10). Three-dimensional (3D) deviations of implant platform, apex and angular deviations were measured and analyzed using independent t-tests (P < 0.05).

Results

The 3D angular deviations in the AR glasses and non-AR glasses groups were 1.47 ± 1.01° and 2.42 ± 0.76°, respectively. Mean 3D entry point and apical deviations were 0.75 ± 0.45 mm and 0.87 ± 0.45 mm in the AR glasses group, whereas the non-AR glasses group were 1.11 ± 0.44 mm and 1.18 ± 0.50 mm, respectively. There was no statistically significant difference between the two groups.

Conclusion

Implant position accuracy using dynamic CAIS with AR glasses was similar to dynamic CAIS without AR glasses during a single implant placement.

Comparative Evaluation of the Accuracy of Dynamic Navigation and Free Hand Methods During Zygomatic Implant Placement: A Randomized Controlled Trial

To assess and compare the precision and predictability of zygomatic implants in atrophic maxilla using conventional and dynamic navigation methods. This study was a randomized controlled clinical trial conducted in patients requiring zygomatic implant placements in the atrophic maxilla. Forty zygomatic implants were placed in systemically healthy individuals. Zygomatic implant placement was done using the freehand technique in the control group, and the test group involved implant placement using a dynamic navigation system, and the entry, apex, and angular deviations were evaluated. The mean deviations at the site of entry (2D) in the navigation system (2.531.42) as compared with the freehand (4.151.29) were statistically significant. The variation in the freehand group was greater than the navigation method at the apex (3D) (P < .05). The navigation method had a higher accuracy in angular deviation than the freehand method (4.02 ± 1.80 and 12.67 ± 2.11). Also, the accuracy was checked on the right and left sides in both the conventional and dynamic groups. The dynamic navigation technology had better predictability in terms of accuracy and precision, and it is the need of the hour for clinicians to master this technology and thereby aid in better prognostic level of implant placements.

Clinical efficacy of computer-assisted zygomatic implant surgery: A systematic scoping review

STATEMENT OF PROBLEM

Digital technology can improve the success of zygomatic implant (ZI) surgery. However, the reliability and efficacy of computer-assisted zygomatic implant surgery (CAZIS) need further analysis.

PURPOSE

The purpose of this scoping review was to provide an overview of the placement accuracy, implant survival, and complications of CAZIS.

MATERIAL AND METHODS

A systematic search of English and Mandarin Chinese publications up to May 2023 was conducted in PubMed, Web of Science, Embase, and Wanfang database. The nonpeer-reviewed literature was searched in the trial register (clinicaltrials.gov). Clinical studies and cadaver studies on CAZIS were included. After data extraction and collection, the findings were critically reviewed, analyzed, interpreted, and discussed.

RESULTS

Forty-one studies met the inclusion criteria. After excluding publications with duplicate data, retaining the most recent, 28 articles were included in this scoping review. Of these, 18 were on static computer-assisted zygomatic implant surgery (sCAZIS), 8 on dynamic computer-assisted zygomatic implant surgery (dCAZIS), and 2 on robot-assisted zygomatic implant surgery (rAZIS). Excluding the outliers, the mean deviations of ZIs in the sCAZIS group (with 8 articles reporting implant placement accuracy, 183 ZIs involved) were: 1.15 ±1.37 mm (coronal deviation), 2.29 ±1.95 mm (apical deviation), and 3.32 ±3.36 degrees (angular deviation). The mean deviations of dCAZIS (3 articles, 251 ZIs) were: 1.60 ±0.74 mm (coronal), 2.27 ±1.05 mm (apical), and 2.89 ±1.69 degrees (angular). The mean deviations of rAZIS (2 articles, 5 ZIs) were: 0.82 ±0.21 mm (coronal), 1.25 ±0.52 mm (apical), and 1.46 ±0.35 degrees (angular). Among the CAZIS reported in the literature, the implant survival rate was high (96.3% for sCAZIS, 98.2% for dCAZIS, and 100% for rAZIS, specified in 14 of 21 clinical studies). The incidence of complications was low, but, because of the few relevant studies (4/21 specified), valid conclusions regarding complications could not be drawn.

CONCLUSIONS

CAZIS has demonstrated clinical efficacy with high implant survival rates and placement accuracy. Of the 3 guided approaches, rAZIS showed the smallest 3-dimensional deviation.

The Accuracy of Zygomatic Implant Placement Assisted by Dynamic Computer-Aided Surgery: A Systematic Review and Meta-Analysis

PURPOSE

The present systematic review aimed to investigate the accuracy of zygomatic implant (ZI) placement using dynamic computer-aided surgery (d-CAIS), static computer-aided surgery (s-CAIS), and a free-hand approach in patients with severe atrophic edentulous maxilla and/or deficient maxilla.

METHODS

Electronic and manual literature searches until May 2023 were performed in the PubMed/Medline, Scopus, Cochrane Library, and Web of Science databases. Clinical trials and cadaver studies were selected. The primary outcome was planned/placed deviation. Secondary outcomes were to evaluate the survival of ZI and surgical complications. Random-effects meta-analyses were conducted and meta-regression was utilized to compare fiducial registration amounts for d-CAIS and the different designs of s-CAIS.

RESULTS

A total of 14 studies with 511 ZIs were included (Nobel Biocare: 274, Southern Implant: 42, SIN Implant: 16, non-mentioned: 179). The pooled mean ZI deviations from the d-CAIS group were 1.81 mm (95% CI: 1.34-2.29) at the entry point and 2.95 mm (95% CI: 1.66-4.24) at the apex point, and angular deviations were 3.49 degrees (95% CI: 2.04-4.93). The pooled mean ZI deviations from the s-CAIS group were 1.19 mm (95% CI: 0.83-1.54) at the entry point and 1.80 mm (95% CI: 1.10-2.50) at the apex point, and angular deviations were 2.15 degrees (95% CI: 1.43-2.88). The pooled mean ZI deviations from the free-hand group were 2.04 mm (95% CI: 1.69-2.39) at the entry point and 3.23 mm (95% CI: 2.34-4.12) at the apex point, and angular deviations were 4.92 degrees (95% CI: 3.86-5.98). There was strong evidence of differences in the average entry, apex, and angular deviation between the navigation, surgical guide, and free-hand groups (p < 0.01). A significant inverse correlation was observed between the number of fiducial screws and the planned/placed deviation regarding entry, apex, and angular measurements.

CONCLUSION

Using d-CAIS and modified s-CAIS for ZI surgery has shown clinically acceptable outcomes regarding average entry, apex, and angular deviations. The maximal deviation values were predominantly observed in the conventional s-CAIS. Surgeons should be mindful of potential deviations and complications regardless of the decision making in different guide approaches.

Retrospective analysis of the predictability of using three-dimensional models for preoperative planning of the length of zygomatic implants

PURPOSE

This present study aimed to retrospectively evaluate the predictability of using three-dimensional models (TDMs) to plan the preoperative lengths of zygomatic implants (ZIs).

METHODS

The records of all patients that received such implants between March 2007 and March 2019 were evaluated. The ZI lengths predicted on the TDMs were compared to the lengths of the implants the patients received.

RESULTS

In total, the records of 74 patients were evaluated, of which 37 records met the criteria of inclusion, and were included in the study. Twenty-seven (73%) of the patients were female and 10 (27%) were male, ranging from 34 to 80 years of age, with the average age being 55.7 years. Seventeen (43.2%) of these patients were classified as ASA I and 21 (56.8%) as ASA II. A total of 142 ZIs were planned and installed in the time frame mentioned. Without distinguishing the region of the maxilla, the implants used were, on average, 1.1 mm larger in length than those initially planned.

CONCLUSION

Overall, the data indicates moderate agreement between the planned and surgical lengths of the ZIs and indicates that using TDMs is a predictable and reliable preoperative planning technique of the length of posterior ZIs.

Survival and complications of zygomatic implants compared to conventional implants reported in longitudinal studies with a follow-up period of at least 5 years: A systematic review and meta-analysis

BACKGROUND

Zygomatic implants (ZI) have been frequently indicated to rehabilitate patients with extensive atrophies in alternatives to major bone reconstructions. It can be installed inside the maxillary sinus, called instrasinus zygomatic implant (IZI) or outside the maxillary sinus (EZI), depending on the surgery technique.

OBJECTIVE

To evaluate the survival and complication rates of ZI in longitudinal studies when compared with conventional implants (CI).

METHODS

An electronic search was performed in five databases and in Gray literature for articles published until April, 2022. The eligibility criteria comprised observational cohort studies (prospective or retrospective) and randomized clinical trials (RCTs) with at least 5 years of follow-up, reporting survival rate of ZI versus CI. A meta-analysis was conduct with 18 studies.

RESULTS

A total of 5434 implants (2972 ZI and 2462 CI) were analyzed in 1709 patients. The mean survival rate was 96.5% ± 5.02 and 95.8% ± 6.36 for ZI and CI, respectively (mean follow-up time of 78 months). There were observed no statistically significant between ZI and CI in prospective studies (risk ratio [RR] of 1.21; 95% confidence intervals [CIs]: 0.28 to 5.28; chi-squared [Chi² ] = 11.37; I²  = 56%; degrees of freedom [df] = 5; z-score = 0.25; P = 0.80), retrospective studies IZI (RR of 1.29; 95% CIs: 0.52 to 3.23; Chi²  = 4.07; I²  = 2%; df = 4; z-score = 0.55; P = 0.58) and retrospective studies EZI (RR of 0.72; 95% CIs: 0.31 to 1.66; Chi²  = 1.99; I²  = 0%; df = 3; z-score = 0.78; P = 0.44). The biological complications most related to ZI was sinusitis, followed by infection and oroantral communication.

CONCLUSION

ZI have a high long-term survival rate (96.5% with a mean of 91.5 months of follow-up), showing no significant difference when compared with CI. The most prevalent biological complication is sinusitis, being most commonly to the IZI technique. This systematic review (SR) was registered in INPLASY under number INPLASY202280025.

A novel technique to quantify bone-to-implant contact of zygomatic implants: a radiographic analysis based on three-dimensional image registration and segmentation

OBJECTIVES

The purpose of this study is to establish a novel, reproducible technique to obtain the BIC area (BICA) between zygomatic implants and zygomatic bone based on post-operative cone-beam computed tomography (CBCT) images. Three-dimensional (3D) image registration and segmentation were used to eliminate the effect of metal-induced artifacts of zygomatic implants.

METHODS

An ex-vivo study was included to verify the feasibility of the new method. Then, the radiographic bone-to-implant contact (rBIC) of 143 implants was measured in a total of 50 patients. To obtain the BICA of zygomatic implants and the zygomatic bone, several steps were necessary, including image preprocessing of CBCT scans, identification of the position of zygomatic implants, registration, and segmentation of pre- and post-operative CBCT images, and 3D reconstruction of models. The conventional two-dimensional (2D) linear rBIC (rBICc) measurement method with post-operative CBCT images was chosen as a comparison.

RESULTS

The mean values of rBIC and rBICc were 15.08 ± 5.92 mm and 14.77 ± 5.14 mm, respectively. A statistically significant correlation was observed between rBIC and rBICc values ([Formula: see text]=0.86, p < 0.0001).

CONCLUSIONS

This study proposed a standardized, repeatable, noninvasive technique to quantify the rBIC of post-operative zygomatic implants in 3D terms. This technique is comparable to conventional 2D linear measurements and seems to be more reliable than these conventional measurements; thus, this method could serve as a valuable tool in the performance of clinical research protocols.

Success Rates of Zygomatic Implants for the Rehabilitation of Severely Atrophic Maxilla: A Systematic Review

Zygomatic implants are a treatment solution for patients with severe maxillary atrophy. This treatment option allows delivering immediate fixed teeth within 24 h. Numerous peer-reviewed publications have reported different success rates, resulting in a disagreement on the topic. Therefore, the overall efficacy and predictability of this rehabilitation is still a matter of discussion. With this study, we aimed to identify the published literature on the use of zygomatic implants for the reconstruction of the severely atrophic maxilla and report the cumulative success rate (CSR) as a function of follow-up time. A systematic review of the literature on zygomatic implant for the treatment of severe maxillary atrophy was performed and 196 publications were included in the study. The cumulative success rate of zygomatic implants for the treatment of severe maxillary atrophy was 98.5% at less than 1 year, 97.5% between 1 and 3 years, 96.8% between 3 and 5 years and 96.1% after more than 5 years. The most commonly reported complications were soft tissue dehiscence, rhinosinusitis and prosthetic failures. The treatment of severe lack of bone in the upper maxilla with zygomatic implants is a safe procedure, reaching a cumulative success rate of 96.1% after more than 5 years.

Three-Dimensional Guided Zygomatic Implant Placement after Maxillectomy

Zygomatic implants are used in patients with maxillary defects to improve the retention and stability of obturator prostheses, thereby securing good oral function. Prosthetic-driven placement of zygomatic implants is even difficult for experienced surgeons, and with a free-hand approach, deviation from the preplanned implant positions is inevitable, thereby impeding immediate implant-retained obturation. A novel, digitalized workflow of surgical planning was used in 10 patients. Maxillectomy was performed with 3D-printed cutting, and drill guides were used for subsequent placement of zygomatic implants with immediate placement of implant-retained obturator prosthesis. The outcome parameters were the accuracy of implant positioning and the prosthetic fit of the obturator prosthesis in this one-stage procedure. Zygomatic implants (n = 28) were placed with good accuracy (mean deviation 1.73 ± 0.57 mm and 2.97 ± 1.38° 3D angle deviation), and in all cases, the obturator prosthesis fitted as pre-operatively planned. The 3D accuracy of the abutment positions was 1.58 ± 1.66 mm. The accuracy of the abutment position in the occlusal plane was 2.21 ± 1.33 mm, with a height accuracy of 1.32 ± 1.57 mm. This feasibility study shows that the application of these novel designed 3D-printed surgical guides results in predictable zygomatic implant placement and provides the possibility of immediate prosthetic rehabilitation in head and neck oncology patients after maxillectomy.

Marker-free registration for intraoperative navigation using the transverse palatal rugae

BACKGROUND

Registration is most important in navigation-assisted-surgery including the matching between the coordinates of the actual patient space and the medical image. Marker-based techniques mostly include marker application with subsequent radiography. In the edentulous patient, maker-free methods are generally less accurate and reproducible. This new method of a marker-free registration uses the transverse palatal rugae as registration structures.

METHODS

(1)Segmentation of bone and hard palatal mucosa from initial 3D imaging (DICOM), (2)Maxillary intraoral-scan (IOS) with transfer to the 3D imaging using an Iterative-Closest-Point-Algorithm (ICP), (3)Marking digital registration points with holes within IOS-stl, (4)Transformation of the spatially aligned IOS-stl to LabelMap and storage in DICOM (IOS-DICOM), (5)Alignment of DICOM and IOS-DICOM, (6)Controlled positioning of digital reg.points and clinical correlation.

RESULTS

Fiducial localization error (0.48mm) and target registration error (0.65mm) is comparable to those of tooth-supported registration methods.

CONCLUSION

This methodology is a promising approach to marker-free navigation-assisted-surgery in the edentulous patient. This approach of marker-free registration for navigation-assisted-surgery could improve the treatment in edentulous patients avoiding additional imaging and invasive marker insertion. This article is protected by copyright. All rights reserved.

A single-arm clinical trial investigating the feasibility of the zygomatic implant quad approach for Cawood and Howell Class 4 edentulous maxilla: An option for immediate loading

INTRODUCTION

The traditional way to treat maxillary edentulous Cawood and Howell Class 4 (CH4) patients who exhibit the knife-edge ridge form of edentulous jaws that are adequate in height and inadequate in width is extensive autologous bone grafting for conventional implant placement.

PURPOSE

To evaluate the feasibility of the zygomatic implant (ZI) quad approach in edentulous CH4 patients who presented a knife-edge ridge form in the anterior maxilla for immediate loading.

MATERIAL AND METHODS

Eligible patients with maxillary CH4 edentulism treated with the ZI quad approach were enrolled. Bone reduction and implant placement were performed under the guidance of a navigation system according to preoperative planning. The outcome variable was the implant survival rate, and additional variables were the ratio of immediate loading, complications and the relationship of the zygomatic implant path to the sinus wall. Statistical analysis was performed with the SAS statistical package.

RESULTS

Fifteen patients (3 men, 12 women; age range, 19-71 years; average age 47.2 years) eligible for the study received the ZI quad approach from January 2017 through January 2020. All ZIs achieved osseointegration, with no implant loss after early healing and a mean follow-up of 17.2 ± 6.2 months. Thirteen of 15 patients (86.7%) received immediate loading. No critical anatomic structure injuries occurred during surgery. Most mesially placed implants (23/30, 76.6%) presented ZAGA 2 and 3, and most distally placed implants were distributed in ZAGA 0 (20/30, 66.7%).

DISCUSSION

In terms of realizing immediate loading in CH4 patients with a knife-edge ridge form in the anterior maxilla, quad approaches have advantages over other grafting methods. At the same time, it seems the survival rate of zygomatic implants is comparable with that of other indications. With the limitations of this study, the quad approach might be a feasible option to realize edentulous maxillary reconstruction and to make immediate loading possible.

Accuracy of digital planning in zygomatic implants

Background

Zygomatic implants have been described as a therapeutic alternative for patients with severe maxillary atrophy in order to avoid bone augmentation procedures. Taking that into account, in these treatments, the key factor is the position of the implant, the virtual surgical planning (VSP) is widespread among most clinicians before surgery on the patient. However, there are no studies which evaluate the clinical relevance of these VSP.

The aim of this study is to determine whether digital planning on zygomatic implants has any influence on the implant dimensions and position, even when performing conventional surgery afterwards.

Results

Fourteen zygomatic implants were placed in four patients. Pre-operative and post-operative helicoidal computed tomography were performed to each patient to allow the comparison between the digital planning and the final position of implants. Tridimensional deviation (TD), mesio-distal deviation (MDD), bucco-palatine deviation (BPD), and apico-coronal deviation (ACD) were evaluated as well as angular deviation (AD). Significative differences in apical TD were observed with a mean of 6.114 ± 4.28 mm (p < 0.05). Regarding implant position, only implants placed in the area of the first right molar reported significant differences (p < 0.05) for ACD. Also, implant length larger than 45 mm showed BPD significative differences (p < 0.05).

Conclusions

Zygomatic implant surgery is a complex surgical procedure, and although VSP is a useful tool which helps the clinician determine the number and the length of zygomatic implants as well as its proper position, surgical experience is still mandatory.

Immediate implant-retained prosthetic obturation after maxillectomy based on zygomatic implant placement by 3D-guided surgery: a cadaver study

Background

The aim of this study was to introduce a complete 3D workflow for immediate implant retained prosthetic rehabilitation following maxillectomy in cancer surgery. The workflow consists of a 3D virtual surgical planning for tumor resection, zygomatic implant placement, and for an implant-retained prosthetic-obturator to fit the planned outcome situation for immediate loading.

Materials and methods

In this study, 3D virtual surgical planning and resection of the maxilla, followed by guided placement of 10 zygomatic implants, using custom cutting and drill/placement-guides, was performed on 5 fresh frozen human cadavers. A preoperatively digitally designed and printed obturator prosthesis was placed and connected to the zygomatic implants. The accuracy of the implant positioning was obtained using 3D deviation analysis by merging the pre- and post-operative CT scan datasets.

Results

The preoperatively designed and manufactured obturator prostheses matched accurately the per-operative implant positions. All five obturators could be placed and fixated for immediate loading. The mean prosthetic point deviation on the cadavers was 1.03 ± 0.85 mm; the mean entry point deviation was 1.20 ± 0.62 mm; and the 3D angle deviation was 2.97 ± 1.44°.

Conclusions

It is possible to 3D plan and accurately execute the ablative surgery, placement of zygomatic implants, and immediate placement of an implant-retained obturator prosthesis with 3D virtual surgical planning.The next step is to apply the workflow in the operating room in patients planned for maxillectomy.

Dynamic-Assisted Navigational System in Zygomatic Implant Surgery: A Qualitative and Quantitative Systematic Review of Current Clinical and Cadaver Studies

PURPOSE

The goal of this systematic review is to assess the accuracy and complications (including failure) of dynamic navigation in placing zygomatic implants.

METHODS

PubMed, Cochrane Library (CENTRAL), trial register (clinicaltrial.gov), and Google Scholar were searched systematically up to May 2020. In addition, the reference lists of included systematic reviews were hand searched. The New Castle Ottawa and Joanna Briggs Institute Critical Appraisal Checklist for Case Reports were used for quality assessment.

RESULTS

Ninety-four studies were assessed, and finally, 12 articles were included. According to Joanna Briggs Institute tool, the mean score of case reports (±standard deviation) was 6.4 (range, 5/9 to 8/9) and the mean score of observational studies (±standard deviation) was 5.66 (range, 5/9 to 7/9) as measured by New Castle Ottawa tool. Included materials pointed out that higher accuracy and drastic cut down on the risk of perioperative/postoperative complications were reported by using the dynamic navigation system compared with freehand implant placement.

CONCLUSIONS

Application of dynamic navigation systems is a reliable technology for zygomatic implant placement, especially in difficult cases with a history of maxillary deficiency. Evidence of reliability and accuracy of dynamic navigation technique in multicenter large randomized and prospective controlled studies is still lacking.

Combined bone- and mucosa-supported 3D-printed guide for sinus slot preparation and prosthetically driven zygomatic implant placement

The use of zygomatic implants to rehabilitate the severely atrophic maxilla has been well documented since first being introduced by Brånemark. Placement of zygomatic implants is technically complex, with catastrophic complications and numerous prosthetic challenges resulting from imprecise placement. The purpose of this report was to demonstrate a technique that allows transfer of the preoperatively planned sinus slot position to the surgical field by using cone beam computed tomography (CBCT) and an implant planning software program to fabricate a combined bone- and mucosa-supported 3D-printed surgical guide. This facilitates optimal zygomatic implant positioning and promotes favorable biomechanics with a predictable prosthetic outcome.

Full arch rehabilitation in patients with atrophic upper jaws with zygomatic implants: a systematic review

Background

The main objective of this systematic review was to present the outcomes of the treatment with zygomatic implants (ZIs) in the rehabilitations of atrophic upper jaw.

Findings

An electronic database search in PubMed, along with a manual search, taking into account language and study period, was performed by two observers; any type of clinical trial and series that included the use of ZIs was used. In the search strategy, the following search terms were used: zygom* AND dental (Implant OR implants) AND edentulous NOT (biomechanic* OR finite element) NOT cadaver. The search was limited to English language, full text, and humans. Literature reviews and clinical case reports were not considered. Forty-two articles published between March 2003 and April 2019 were included in this analysis. The cases of 1247 patients were recovered; these patients received 2919 ZIs. Fifty-two ZIs were removed during the follow-up time. The survival rate of these implants was 98.22%, with a minimum follow-up of 1 month and a maximum of 228 months. Different surgical techniques were used to place ZIs; however, the intrasinusal technique was the most used (23 studies). Post-surgical sinusitis was the most common complication reported in the studies (39 cases).

Conclusions

Based on this review, ZIs were commonly used for rehabilitation of patients with atrophic upper jaw. The survival rates presented were high, and the surgical technique is dependent on the professional experience and the local anatomy. However, it needed additional clinical evidence on bone resorption, esthetic outcomes, and physiological characteristics.

Accuracy assessment of dynamic computer-aided implant placement: a systematic review and meta-analysis

OBJECTIVES

To assess the accuracy of dynamic computer-aided implant surgery (dCAIS) systems when used to place dental implants and to compare its accuracy with static computer-aided implant surgery (sCAIS) systems and freehand implant placement.

MATERIALS AND METHODS

An electronic search was made to identify all relevant studies reporting on the accuracy of dCAIS systems for dental implant placement. The following PICO question was developed: "In patients or artificial models, is dental implant placement accuracy higher when dCAIS systems are used in comparison with sCAIS systems or with freehand placement? The main outcome variable was angular deviation between the central axes of the planned and final position of the implant. The data were extracted in descriptive tables, and a meta-analysis of single means was performed in order to estimate the deviations for each variable using a random-effects model.

RESULTS

Out of 904 potential articles, the 24 selected assessed 9 different dynamic navigation systems. The mean angular and entry 3D global deviations for clinical studies were 3.68° (95% CI: 3.61 to 3.74; I² = 99.4%) and 1.03 mm (95% CI: 1.01 to 1.04; I² = 82.4%), respectively. Lower deviation values were reported in in vitro studies (mean angular deviation of 2.01° (95% CI: 1.95 to 2.07; I² = 99.1%) and mean entry 3D global deviation of 0.46 mm (95% CI: 0.44 to 0.48 ; I² = 98.5%). No significant differences were found between the different dCAIS systems. These systems were significantly more accurate than sCAIS systems (mean difference (MD): -0.86°; 95% CI: -1.35 to -0.36) and freehand implant placement (MD: -4.33°; 95% CI: -5.40 to -3.25).

CONCLUSION

dCAIS systems allow highly accurate implant placement with a mean angular of less than 4°. However, a 2-mm safety margin should be applied, since deviations of more than 1 mm were observed. dCAIS systems increase the implant placement accuracy when compared with freehand implant placement and also seem to slightly decrease the angular deviation in comparison with sCAIS systems.

CLINICAL RELEVANCE

The use of dCAIS could reduce the rate of complications since it allows a highly accurate implant placement.

Dynamic Navigation for Zygomatic Implants: A Case Report about a Protocol with Intraoral Anchored Reference Tool and an Up-To-Date Review of the Available Protocols

Dynamic Navigation is a computer-aided technology that allows the surgeon to track the grip instruments while preparing the implant site in real time based on radiological anatomy and accurate pre-operative planning. The support of this technology to the zygoma implant placement aims to reduce the risks and the errors associated with this complex surgical and prosthetic treatment. Various navigation systems are available to clinicians currently, distinguished by handling, reliability, and the associated economic and biological benefits and disadvantages. The present paper reports on the different protocols of dynamic navigations following a standard workflow in correlation with zygomatic implant supported rehabilitations and describes a case of maxillary atrophy successfully resolved with this technology. An innovative and minimally invasive dynamic navigation system, with the use of an intraoral anchored trust marker plate and a patient reference tool, has been adopted to support the accurate insertion of four zygomatic implants, which rapidly resolved maxillary atrophy from a 75-year-old male system. This approach provided an optimal implant placement accuracy reducing surgical invasiveness.

Computer-Aided Rehabilitation Supported by Zygomatic Implants: A Cohort Study Comparing Atrophic with Oncologic Patients after Five Years of Follow-Up

The aim of this study was to evaluate the survival and clinical success rate, complications, and patients’ quality of life after computer-aided rehabilitation supported by zygomatic implants in cases of severe maxillary atrophy (ten patients) and in bone defects in oncologic patients (ten patients). All patients underwent computer-aided planning and surgery. Seventy-three zygomatic implants were placed. The mean follow-up period was 39.9 months. Implant survival and clinical success rate, the effectiveness of planning the implant length, biological and prosthetic complications, and the quality of life were evaluated. The five-year implant survival rate for patients with maxillary atrophy and oncologic patients was 97.4% and 96.7%, respectively. The prosthetic survival rate was 100%. Two implant failures occurred in the first year. One implant failure was observed in each group. Minor biological and prosthetic complications occurred in both groups without significant differences. All complications were managed without affecting the treatment. The quality of life increased by 71.3% in the atrophic group and by 82.9% in the oncologic group. Zygomatic implant rehabilitation seems to be a reliable technique for patients with maxillary atrophy and for oncologic patients. The three-dimensional computer-aided approach allows the surgeon to plan the surgery and increase its predictability. Early prosthesis loading certainly allows for better functional outcomes.

Automatic robot-world calibration in an optical-navigated surgical robot system and its application for oral implant placement

PURPOSE

Robot-world calibration, used to precisely determine the spatial relation between optical tracker and robot, is regarded as an essential step for optical-navigated surgical robot system to improve the surgical accuracy. However, these methods are complicated with numerous computation. Therefore, a more efficient method of a robot-world calibration is necessary.

METHODS

A fully automatic robot-world calibration was proposed and applied in a surgical robot system for oral implant placement. Making full usage of the movement characteristics of a tandem robot, the least square fitting algorithm was implemented to calculate the relationship between the tool center point of the robot and the robot reference frame, with the robot-world calibration matrix obtained as result.

RESULTS

The experiment was designed to verify the accuracy of the robot-world calibration. The average distance deviation was 1.11 mm, and the average angle deviation was 0.99°. From the animal experiment on the pig maxilla, the entry, apical and angle deviation of the surgical robot system were 1.44 ± 1.01 mm, 1.68 ± 0.76 mm, 1.01 ± 1.06°, respectively.

CONCLUSION

The surgical robot system for oral implant placement with our robot-world calibration maintains a high precision. Besides, the operation range of the surgical tool is no longer limited by the visual range of the optical tracking device. Hence, it is unnecessary to adjust the optical tracking device for the planned implant trajectories to different positions and directions.

A novel extraoral registration method for a dynamic navigation system guiding zygomatic implant placement in patients with maxillectomy defects

Zygomatic implants (ZIs) are used for the oral rehabilitation of patients with maxillectomy defects as an alternative to extensive bone grafting surgeries. New technologies such as computer-assisted navigation systems can improve the accuracy and safety of ZI placement. The intraoral anchorage of fiducial markers necessary for navigation registration is not possible in the case of a severe maxillary defect and lack of residual bone. This technical note presents a novel extraoral registration method for a dynamic navigation system guiding ZI placement in patients with maxillectomy defects. Titanium microscrews were inserted in the mastoid process, supraorbital ridge, and posterior zygomatic arch as registration markers. The mean fiducial registration error (FRE) was 0.53 ± 0.20 and the deviations between the planned and placed ZIs were 1.56 ± 0.54 mm (entry point), 1.87 ± 0.63 mm (exit point), and 2.52 ± 0.84° (angulation). The study results indicate that the placement of fiducial markers at extraoral sites can be used as a registration technique to overcome anatomical limitations in patients after maxillectomy, with a clinically acceptable registration accuracy.

Quad Zygoma: Technique and Realities

Four zygomatic implants may be used in patients with severe maxillary atrophy for rehabilitation with a fixed or removable prosthesis. Immediate loading is also typically performed, providing patients with a less invasive and more efficient solution for rehabilitation. Options for immediate loading are presented. The indications, contraindications, procedure, and complications are reviewed. Appropriate treatment planning and work-up are highlighted, as they are required for success in conjunction with advanced surgical skill. Scientific evidence, although lacking in quantity, suggests that the quad zygoma approach offers a predictable solution for the challenge of severe maxillary atrophy; high implant survival rates are noted.

Augmented reality for dental implantology: a pilot clinical report of two cases

BACKGROUND

Despite the limited number of articles dedicated to its use, augmented reality (AR) is an emerging technology that has shown to have increasing applications in multiple different medical sectors. These include, but are not limited to, the Maxillo-facial and Dentistry disciplines of medicine. In these medical specialties, the focus of AR technology is to achieve a more visible surgical field during an operation. Currently, this goal is brought about by an accurate display of either static or dynamic diagnostic images via the use of a visor or specific glasses. The objective of this study is to evaluate the feasibility of using a virtual display for dynamic navigation via AR. The secondary outcome is to evaluate if the use of this technology could affect the accuracy of dynamic navigation.

CASE PRESENTATION

Two patients, both needing implant rehabilitation in the upper premolar area, were treated with flapless surgery. Prior to the procedure itself, the position of the implant was virtually planned and placed for each of the patients using their previous scans. This placement preparation contributed to a dynamic navigation system that was displayed on AR glasses. This, in turn, allowed for the use of a computer-aided/image-guided procedure to occur. Dedicated software for surface superimposition was then used to match the planned position of the implant and the real one obtained from the postoperative scan. Accuracies, using this procedure were evaluated by way of measuring the deviation between real and planned positions of the implants. For both surgeries it was possible to proceed using the AR technology as planned. The deviations for the first implant were 0.53 mm at the entry point and 0.50 mm at the apical point and for the second implant were 0.46 mm at the entry point and 0.48 mm at the apical point. The angular deviations were respectively 3.05° and 2.19°.

CONCLUSIONS

From the results of this pilot study, it seems that AR can be useful in dental implantology for displaying dynamic navigation systems. While this technology did not seem to noticeably affect the accuracy of the procedure, specific software applications should further optimize the results.

Long-term Schneiderian membrane thickness changes following zygomatic implant placement: A retrospective radiographic analysis using cone beam computed tomography

OBJECTIVES

The purpose of this retrospective study was to evaluate the long-term changes in the thickness of Schneiderian membranes after zygomatic implant placement using cone beam computed tomography (CBCT).

MATERIAL AND METHODS

Twenty-five consecutive patients were included in this study. All the patients underwent bilateral zygomatic implant placement. Schneiderian membrane thickness (SMT) in 49 maxillary sinuses (one sinus was not included because of early loss of the zygomatic implants) was measured using CBCT before and at least 1 year after zygomatic implant placement. Ostium patency of each sinus was also evaluated and recorded.

RESULTS

In total, 84 zygomatic implants and 30 regular implants were placed in included patients. Two unilateral maxillary zygomatic implants in one patient were removed 2 months after implant placement. The SMT increased from 1.03 mm (inter-quartile range: 1.57 mm) to 1.33 mm (inter-quartile range: 1.98 mm) after a median follow-up time of 23.00 months (inter-quartile range: 14 months), and the difference was statistically significant. Before zygomatic implant insertion, 24.5% (12/49) of sinuses had SMT greater than 2 mm, whereas this value was 28.6% (14/49) after zygomatic implant placement. The percentage of sinuses observed with ostium patency also increased from 2.0% (1/49) to 12.2% (6/49).

CONCLUSIONS

Chronic Schneiderian membrane thickening could result from zygomatic implant insertion. Intensive postoperative care and clinical and radiographic monitoring are recommended after zygomatic implant placement.