Reliability and accuracy of dynamic navigation for zygomatic implant placement

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.

Combined static and dynamic computer-guided surgery for prosthetically driven zygomatic implant placement

OBJECTIVES

To propose and validate a minimally invasive combined static and dynamic computer assisted implant surgery (CAIS) workflow for zygomatic implant (ZI) placement.

METHODS

A combined approach leveraging static CAIS for initial positioning, complemented by dynamic CAIS for real-time control of the angle, depth and width was proposed. Fourteen consecutive patients (age: 60.3±9.8 years; 8 females) seeking ZI-supported restoration were enrolled. A single anatomically and prosthetically driven ZI on either the unilateral zygoma or bilateral zygomata was planned and placed using the proposed approach. The zygomatic anatomy-guided approach (ZAGA) type and the ZI length were recorded. The angular, coronal global, and apical global deviation between the planned and placed positions were measured by overlapping post- and pre-operative cone beam computer tomography. Comparisons were made between the left and right sides across the ZAGA type and ZI length. Statistical significance was set at P<0.05.

RESULTS

22 ZIs were placed using the combined approach and 13 immediate loading prostheses were delivered, with one patient restored 6 months after surgery. The angular deviations and coronal global deviations were 1.99±0.17° and 1.21±0.45 mm, respectively. The median apical global deviation was 1.67 mm (interquartile range [IQR]: 1.11-1.93 mm). No significant differences were found between the left and right sides across the ZAGA type or ZI length. All ZIs remained stable over a median follow-up of 14.5 months (IQR: 7-20 months).

CONCLUSIONS

The proposed combination of static and dynamic CAIS is safe, reliable, accurate, and robust for ZI placement.

CLINICAL SIGNIFICANCE

This pilot study proposed a minimally invasive ZI placement method that combined static and dynamic computer-guided surgery. The implant positioning accuracy achieved using this approach validated its safety, reliability, accuracy, and robustness. The combined approach may reduce the technique sensitivity of ZI placement, facilitating future rehabilitation of severely atrophic or defective maxillae.

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.

ZygoPlanner: A three-stage graphics-based framework for optimal preoperative planning of zygomatic implant placement

Zygomatic implant surgery is an essential treatment option of oral rehabilitation for patients with severe maxillary defect, and preoperative planning is an important approach to enhance the surgical outcomes. However, the current planning still heavily relies on manual interventions, which is labor-intensive, experience-dependent, and poorly reproducible. Therefore, we propose ZygoPlanner, a pioneering efficient preoperative planning framework for zygomatic implantation, which may be the first solution that seamlessly involves the positioning of zygomatic bones, the generation of alternative paths, and the computation of optimal implantation paths. To efficiently achieve robust planning, we developed a graphics-based interpretable method for zygomatic bone positioning leveraging the shape prior knowledge. Meanwhile, a surface-faithful point cloud filling algorithm that works for concave geometries was proposed to populate dense points within the zygomatic bones, facilitating generation of alternative paths. Finally, we innovatively realized a graphical representation of the medical bone-to-implant contact to obtain the optimal results under multiple constraints. Clinical experiments confirmed the superiority of our framework across different scenarios. The source code is available at https://github.com/Haitao-Lee/auto_zygomatic_implantation.

The Rehabilitation of Partially Edentulous Maxilla With Unilateral Zygomatic Implants: A Retrospective Study up to 23 Years Follow-Up

OBJECTIVES

This retrospective study aimed to evaluate the clinical outcomes associated with zygomatic implant (ZI) rehabilitation in partially atrophic edentulous maxillae over a mean follow-up period of more than 10.3 years.

METHODS

All consecutive patients underwent ZI rehabilitation between 1999 and 2020, with a minimum follow-up period of 3 years. The primary outcome was the implant survaival rate. Secondary outcomes included the prosthesis success rate, complications, and Oral Health-Related Quality of Life.

RESULTS

Of the 21 patients, treated with 27 ZIs and 48 conventional implants (CIs), 9 (42.9%) were females. The mean follow-up was 10.3 ± 5.7 years (range 3.2-23.4). ZI and CI survival rates were 100% and 97.9%, respectively, with one CI that failed. Eleven patients received 12 CIs placed in the pterygoid and tuberosity region. Most of the implants (81.33%) were immediately loaded, with 17 patients (80.9%) receiving 21 acrylic bridges. Of the total of 26 definitive prosthesis, the success rate was 96.1%. Local inflammation (n = 2) and soft tissue recession (n = 1) were reported as complications, occurring at a mean follow-up of 4.5 and 3.2 years, respectively. The mean score of the OHIP-14 questionnaire was 1.19 ± 1.99.

CONCLUSIONS

Unilateral ZI rehabilitation was a predictable option for patients with partially atrophic edentulous maxilla who have experienced previous graft or implant failures, or who require immediate loading. Splinting the ZI with CI for restoration appeared to be essential in unilateral ZI treatment. Complications were infrequent and could be managed effectively, with patient-reported outcomes indicating normalization in quality of life.

Accuracy and efficiency of drilling trajectories with augmented reality versus conventional navigation randomized crossover trial

Conventional navigation systems (CNS) in surgery require strong spatial cognitive abilities and hand-eye coordination. Augmented Reality Navigation Systems (ARNS) provide 3D guidance and may overcome these challenges, but their accuracy and efficiency compared to CNS have not been systematically evaluated. In this randomized crossover study with 36 participants from different professional backgrounds (surgeons, students, engineers), drilling accuracy, time and perceived workload were evaluated using ARNS and CNS. For the first time, this study provides compelling evidence that ARNS and CNS have comparable accuracy in translational error. Differences in angle and depth error with ARNS were likely due to limited stereoscopic vision, hardware limitations, and design. Despite this, ARNS was preferred by most participants, including surgeons with prior navigation experience, and demonstrated a significantly better overall user experience. Depending on accuracy requirements, ARNS could serve as a viable alternative to CNS for guided drilling, with potential for future optimization.

From Tradition to Technology: Robotic Artificial Intelligence in Dental Implantology

Dynamic navigation and haptic robotic systems are revolutionizing dentistry by significantly improving implant placement precision, especially in the maxillofacial region where safeguarding nerves, vessels, and vital structures is crucial. This article examines the impact of X-Guide dynamic navigation and Yomi robotics on implant surgery outcomes, comparing these technologies to traditional freehand methods. The X-Guide dynamic navigation system and Yomi robotics have both been proven to enhance accuracy, with both achieving mean deviations of around 1 mm from pre-planned positions. However, the high costs associated with these technologies may limit access for many practitioners. Despite these challenges, both systems facilitate the completion of complex cases with minimal deviations. In addition, their applications are expanding beyond implantology into areas like endodontics, further demonstrating their potential in modern dental practices.

Comparison of robotic system and dynamic navigation for zygomatic implant placement: An in vitro study

OBJECTIVES

To compare the accuracy of robotic and dynamic navigation systems in assisting zygomatic implant (ZI) using an in vitro model experiment.

METHODS

Preoperative cone-beam computed tomography (CBCT) images of patients who underwent ZI treatment between 2011 and 2023 were collected from local databases. Corresponding three-dimensional resin models were printed and assigned to two groups: the robotic and dynamic navigation system groups. Following preoperative plans, ZIs were placed in the models with the assistance of either a robotic or dynamic navigation system. Deviations in the in vitro navigation surgery were measured and compared between the groups.

RESULTS

A total of 110 ZIs were placed in 56 models, with 55 ZIs in each group. No significant differences were observed in entry and angle deviations between the groups (p>0.05). However, the exit deviation in the robotic system group (2.39±1.24 mm) was larger than that in the dynamic navigation group (1.83±1.25 mm) (p<0.05). On the exit side, the Z-axis deviation in the robotic group (left: -0.28±1.43 mm, right: -0.21±1.30 mm) was smaller than that in the dynamic navigation group (left: 0.76±1.11 mm, right: 0.85±1.52 mm) (p<0.05), while no significant differences were found in X- and Y-axis deviations (p>0.05).

CONCLUSIONS

Compared with the dynamic navigation system, the robotic system can effectively prevent ZI overextension. However, its accuracy on the exit side is slightly lower than that of the dynamic navigation system.

CLINICAL SIGNIFICANCE

This preliminary in vitro study showed that the accuracy of the robotic system was slightly inferior to that of the dynamic navigation system in terms of exit deviation when used in ZI placement. Further clinical studies are required to confirm these findings.

A modified protocol merging two published techniques for computer guided zygomatic implants surgery: a technical note

OBJECTIVES

Zygomatic implant surgery can be difficult due to the limited intraoperative visibility of the surgical field and the complex anatomy of the zygomatic bone, which could lead to serious complications. This study aims to assess the accuracy of zygomatic implants placement using computer-guided surgical templates.

MATERIALS AND METHODS

A total of 13 zygomatic implants were placed in four participants. Double-sleeve drill guides were used with the help of computer-guided surgical templates designed with a lateral window. The accuracy was evaluated by measuring the linear deviations regarding the implants' platforms and apices' positions in addition to the angular deviations. Moreover, deviations of both implants from three fixed planes of space were measured.

RESULTS

The mean linear deviation at platforms was 2.44 mm ± 1.57 and at the apices 2.32 mm ± 1 while the mean angular deviation was 3.6˚ ± 1.92. Differences at the entry points were 0.43 ± 1.79 mm, 0.39 ± 1.12 mm, and - 0.54 ± 2.00 mm from the mid-sagittal, horizontal, and coronal planes respectively. Differences at the exit points were - 0.75 ± 1.25 mm, -0.06 ± 1.09 mm, and 0.63 ± 1.24 mm from the same planes respectively. Within all planes, there was no statistically significant difference.

CONCLUSION

Given the limitations of this study, the use of the computer-guided surgical templates augmented by the double sleeve drill guides allowed favorable control over the tip of the long surgical drill away from vital structures during the zygomatic implant osteotomy. It also allowed control over alveolar crest osteotomy and its placement in a favorable prosthetic position. Overall, this protocol should be considered for further research and improvement to allow more predictable surgical outcomes while preventing the occurrence of complications. Before conducting this study, the protocol was reviewed and approved by the Research Ethical Committee of Faculty of Dentistry, Ain Shams University in meeting no. (105), on 15th of July 2020 with the application no.: (FDASU-RecD072029).

Accuracy of Zygomatic Implant Placement Using Task-Autonomous Robotic System or Dynamic Navigation: An In Vitro Study

OBJECTIVES

To evaluate and compare the accuracy of task-autonomous robot-assisted implant surgery (RAIS) and dynamic computer-assisted implant surgery (dCAIS) for zygomatic implant placement.

MATERIALS AND METHODS

Ten atrophic edentulous maxilla models requiring zygomatic implant (ZI) placement were randomly divided into the RAIS and dCAIS groups. Osteotomies and implant placement were performed under the guidance of a task-autonomous robotic system or dynamic navigation system. A total of 20 ZIs were analyzed. The angular, coronal, lateral coronal, coronal depth, apical, lateral apical, and apical depth deviations were measured and analyzed between the two groups. The primary outcome parameters were the angular deviations between the planned and the placed ZIs. Data was subjected to descriptive and comparative statistical analysis. The significance of inter-group differences for continuous variables was assessed with Student's two-sample t-tests, Welch two-sample t-tests, and Mann-Whitney U tests according to the distribution normality and variance homogeneity.

RESULTS

ZI placement deviations were compared between the RAIS and dCAIS groups, showing a mean angular deviation of 0.92 ± 0.40° versus 2.03 ± 0.53° (p < 0.001), a mean (±SD) coronal deviation of 0.48 ± 0.25 mm versus 1.29 ± 0.46 mm (p < 0.001), and a mean apical deviation of 0.88 ± 0.28 mm versus 1.96 ± 0.46 mm (p < 0.001).

CONCLUSIONS

For computer-guided ZI placement, task-autonomous RAIS was superior to dCAIS in terms of accuracy.

Accuracy of robotic-assisted surgery for immediate implant placement in posterior teeth: a retrospective case series

BACKGROUND

Robotic computer-assisted implant surgery (r-CAIS) is a revolutionary innovation in oral implantation; however, the clinical feasibility of r-CAIS for immediate implant placement (IIP) in posterior teeth has not been verified. Thus, this study aimed to evaluate the accuracy of r-CAIS for IIP in posterior tooth regions.

METHODS

Patients with posterior teeth to be extracted and indicated to undergo r-CAIS were evaluated. The patients had positioning markers installed in the oral cavity and underwent cone-beam computed tomography (CBCT). Subsequently, minimally invasive tooth extractions were performed, and an individualised surgical plan was generated in the robotic software. After marker registration, implantation surgery was performed by the robotic arm under the supervision and assistance of the surgeons. Finally, the deviations between the planned and placed implants were evaluated based on preoperative and postoperative CBCT data.

RESULTS

A total of 12 patients were evaluated. No adverse events occurred during the surgery. The mean global coronal, global apical, and angular deviations were 0.46 ± 0.15 mm (95%CI:0.36 to 0.56 mm), 0.46 ± 0.14 mm (95%CI:0.37 to 0.54 mm), and 1.05 ± 0.55° (0.69 to 1.40°), respectively.

CONCLUSIONS

Under the limited conditions of this study, the r-CAIS exhibited high accuracy in posterior teeth IIP surgery. Further multicentre randomised controlled studies are required to confirm the feasibility of this technology.

Factors influencing speech improvement following maxillary complete-arch implant-supported restorations: A retrospective study

OBJECTIVE

This study explored factors affecting speech improvement in patients with an edentulous maxilla after the delivery of a complete-arch implant-supported fixed dental prosthesis (IFDP).

MATERIALS AND METHODS

Patients who had received IFDP for edentulous maxilla were enrolled, and various potential speech improvement-related factors were considered, including patient demographics, anterior residual bone volume, preoperative facial features, preoperative acoustic parameters, and adaptation time. Acoustic analysis and perceptual ratings were used to assess three fricatives [s], [f], and [ɕ]. Correlation and regression analyses were conducted to assess the association between changes in fricatives and potential factors (α = .05).

RESULTS

The study included 50 patients (18 females and 32 males, aged 50.62 ± 15.71 years, range 19-76). Significant correlations were found among the change in the center of gravity (ΔCoG) of [s] and anterior residual bone volume, zygomatic implants number and proportion (p < .05). These correlations were largely mirrored in the perceptual score (ΔPS) changes. After controlling for age, sex, preoperative acoustic parameters, and adaptation time, the ΔCoG and ΔPS of fricatives were mainly correlated with the anterior residual bone volume, preoperative acoustic parameters, and adaptation time.

CONCLUSION

Speech improvements post-IFDP delivery are mainly related to preoperative speech characteristics, anterior residual bone volume, and adaptation time. The residual bone volume's impact on consonants varies with specific articulatory gestures. This study provides insights into forecasting speech outcomes following IFDP restoration and provides recommendations and methods for data collection in developing future prediction models.

Comparison of the accuracy of dynamic navigation and the free hand approaches in the placement of pterygoid implants in the completely edentulous maxilla: An in vitro study

Background/purpose

Pterygoid implant is a promising solution for patients with a partially or fully edentulous atrophic maxilla. However, whether dynamic navigation system will improve the accuracy of pterygoid implant surgery is still unknown. This study aimed to compare the accuracy of dynamic navigation and free-hand approaches in pterygoid implant placement in completely edentulous maxilla models.

Materials and methods

Twenty three-dimensional (3D)-printed edentulous maxilla models were assigned to two groups: the dynamic navigation system group and the free-hand group. Two pterygoid implants were planned in the bilateral pterygomaxillary area and then placed in each model. The entry, exit and angle deviations of the pterygoid implants were measured after pre- and post-operative cone-beam CT (CBCT) image fusion. Student's t test and Mann-Whitney U test were used. A P value < 0.05 was considered statistically significant.

Results

A total of 40 pterygoid implants were placed in 20 models. The comparison deviation of the dynamic navigation group and the free-hand group showed a mean (±SD) entry deviation of 0.93 ± 0.46 mm vs. 2.28 ± 1.08 mm (P < 0.001), an exit deviation of 1.37 ± 0.52 mm vs. 3.14 ± 1.82 mm (P < 0.001), and an angle deviation of 2.41 ± 1.24° vs. 10.13 ± 4.68° (P < 0.001). There was no significant difference in the accuracy with regard to the side factors between the navigation group and the free-hand group.

Conclusion

The dynamic navigation system has higher accuracy for pterygoid implant placement in a complete edentulous maxilla than the free-hand approach.

A fully digital planning protocol for dynamic computer-assisted zygomatic implant surgery based on virtual surgery simulation: A dental technique

Dynamic navigation-guided zygomatic implant (ZI) surgery has been a preferred option for achieving optimal prosthetic-driven implant placement. However, during the actual surgical procedure, surgical execution may still be hindered by environmental factors such as mouth opening. A fully digital planning protocol is described that integrated the patient's maxillofacial soft tissue information and virtual surgical handpiece with the drills on the implant planning path to ensure the precise, time-saving, and smooth implementation of dynamic navigation-guided ZI surgery.

A hybrid robotic system for zygomatic implant placement based on mixed reality navigation

BACKGROUNDS

Zygomatic implant (ZI) placement surgery is a viable surgical option for patients with severe maxillary atrophy and insufficient residual maxillary bone. Still, it is difficult and risky due to the long path of ZI placement and the narrow field of vision. Dynamic navigation is a superior solution, but it presents challenges such as requiring operators to have advanced skills and experience. Moreover, the precision and stability of manual implantation remain inadequate. These issues are anticipated to be addressed by implementing robot-assisted surgery and achieved by introducing a mixed reality (MR) navigation-guided hybrid robotic system for ZI placement surgery.

METHODS

This study utilized a hybrid robotic system to perform the ZI placement surgery. Our first step was to reconstruct a virtual 3D model from preoperative cone-beam CT (CBCT) images. We proposed a series of algorithms based on coordinate transformation, which includes image-phantom registration, HoloLens-tracker registration, drill-phantom calibration, and robot-implant calibration, to unify all objects within the same coordinate system. These algorithms enable real-time tracking of the surgical drill's position and orientation relative to the patient phantom. Subsequently, the surgical drill is directed to the entry position, and the planned implantation paths are superimposed on the patient phantom using HoloLens 2 for visualization. Finally, the hybrid robot system performs the processed of drilling, expansion, and placement of ZIs under the guidance of the MR navigation system.

RESULTS

Phantom experiments of ZI placement were conducted using 10 patient phantoms, with a total of 40 ZIs inserted. Out of these, 20 were manually implanted, and the remaining 20 were robotically implanted. Comparisons between the actual implanted ZI paths and the preoperatively planned ZI paths showed that our MR navigation-guided hybrid robotic system achieved a coronal deviation of 0.887 ± 0.213 mm, an apical deviation of 1.201 ± 0.318 mm, and an angular deviation of 3.468 ± 0.339° This demonstrates significantly better accuracy and stability than manual implantation.

CONCLUSION

Our proposed hybrid robotic system enables automated ZI placement surgery guided by MR navigation, achieving greater accuracy and stability compared to manual operations in phantom experiments. Furthermore, this system is expected to apply to animal and cadaveric experiments, to get a good ready for clinical studies.

Long-term survival and complications of Quad Zygoma Protocol with Anatomy-Guided Approach in severely atrophic maxilla: A retrospective follow-up analysis of up to 17 years

INTRODUCTION

The objective of the study was to provide long-term clinical outcomes and complications in the severely atrophic edentulous maxillae treated by means of the quad zygoma protocol (QZP) using the Anatomy-Guided Approach (AGA).

METHODS

This was a retrospective cohort study of all consecutive patients with severely atrophic edentulous maxilla and insufficient bone height and width in the anterior and posterior regions bilaterally, who underwent rehabilitation with the QZP between May 2006 and December 2021. All patients were followed for at least 1 year. All zygomatic implants (ZIs) were placed by the same surgeon. The primary endpoint of the study was the implant survival rate. Secondary endpoints were implant success rate, prosthesis success rate, complications, and Oral Health-Related Quality of Life using the OHIP-14 questionnaire.

RESULTS

A total of 56 patients (men 16, women 40) with 224 ZIs (Nobel Biocare, n = 204; Straumann, n = 16; Southern Implant, n = 4) placement were included with a mean follow-up period 8.8 ± 3.9 years (range, 1.2-17.0). The survival (success) rate was 97.7%. Five ZIs in four patients failed. The mean time between implant placement and failure was 8.6 years (range, 0.5-13.3). All patients received immediate loading with acrylic prosthesis. The successful rates for the definitive prosthesis were 98.2%. Forty-two patients received posterior cantilever for rehabilitation of fixed definitive prosthesis. Local orofacial inflammation (35.7%) and Sinusitis (12.5%) were the most common complications, occurring at a mean follow-up of 10.0 (range, 4.2-14.9) and 10.3 (range, 4.3-16.2) years, respectively. In 48 patients, the mean score of the OHIP-14 questionnaire was 1.7 ± 2.6 with the follow-up period of 9.0 ± 4.1 years.

CONCLUSIONS

The rehabilitation of severely atrophic edentulous maxilla using the QZP has shown a predictable and high survival rate in the long term. The implementation of an immediate loading protocol offers potential benefits in stabilizing ZIs with cross-arch stabilization. Moreover, the use of a posterior cantilever in reconstruction can effectively establish functional occlusion through well-distributed ZIs, eliminating the need for additional implant placement.

Peri-zygomatic complications on zygomatic implants with or without penetrating the external surface of zygoma: A 2-year retrospective study

OBJECTIVES

The main purpose of this retrospective study was to assess the difference in the incidence of peri-zygomatic complications (PZCs) when zygomatic implants (ZIs) penetrate or do not penetrate the external surface of zygoma.

MATERIALS AND METHODS

This study included 32 patients with edentulous maxillae or potentially edentulous maxillae undergo zygomatic implantation. The patients were divided into the penetration group (P-group) and the non-penetration group (N-group) according to whether the apex of implants penetrated the external surface of zygoma in postoperative CBCT. The extension length, the penetration section of the implants, and the skin thickness at the corresponding position were simultaneously measured. Clinical follow-up was conducted regularly until 2 years after surgery. The occurrence of PZCs (including peri-zygomatic infection, skin numbness, non-infectious pain, and foreign body sensation) was recorded. A mixed effect logistic model was used to compare the difference of complication rate between the P-group and the N-group, and odds ratio (OR) was calculated. Then identify the impact of the extension length, penetration section and skin thickness in P-group with the same model.

RESULTS

A total of 71 ZIs were implanted in 32 patients, including 37 implants in the P-group and 34 implants in the N-group. During the 2-year follow-up, a total of 13 implants occurred PZCs, with an overall complication rate of 18.3%. Thereinto, the incidence rate was 29.7% in the P-group, and 5.9% in the N-group (OR = 6.77). In P-group, there was a significant difference in complication rate of different extension lengths, while the penetration section and skin thickness had no statistical significance on the complication rate.

CONCLUSION

Under the limitation of this study, to minimize the risk of PZCs, ZI should be placed in a manner that avoids the apex penetrating the external surface of the zygoma.

Stepwise osteotomy protocol for zygomatic implant placement under navigation in patients with extra-sinus trajectory

This technical note describes a stepwise osteotomy for zygomatic implant placement with an extra-sinus trajectory under navigation using virtual markers for registration. The stepwise osteotomy protocol divides the trajectory of the zygomatic implant osteotomy into three consecutive co-axial components. The aim is to achieve better control of the osteotomy under navigation and to minimize or eliminate any intermittent free-hand drilling. The stepwise osteotomy protocol facilitates the use of shorter drills to finish the zygomatic implant osteotomy at the entry location before switching back to the long drill to complete the whole osteotomy. This protocol has been applied in a patient and the preliminary result is promising. However, the clinical effectiveness of this approach requires further investigation in prospective clinical studies.

Longitudinal reactions of maxillary sinus in patients treated with multiple zygomatic implants: A modified radiographic evaluation with clinical follow-up

OBJECTIVES

To investigate the effects of zygomatic implant placement on the maxillary sinus using radiographic and clinical indicators.

METHODS

Patients with an atrophic maxilla who underwent zygomatic implant placement were included. The thickness and morphology of the Schneiderian membrane (SM), infundibular obstruction, and posterior bone wall of the maxillary sinus were analyzed. The generalized estimating equation and chi-square tests were performed to compare the measurements.

RESULTS

Fifty patients with 100 maxillary sinuses were included. In total, 148 zygomatic implants and 105 regular implants were placed in the maxilla. Overall, the mean pre- and postoperative SM thickness was 2.79 ± 3.26 mm and 3.97 ± 5.45 mm, respectively (p = 0.063). In sinuses with two zygomatic implants, the SM thickness increased significantly from 2.12 ± 2.14 mm preoperatively to 4.07 ± 6.14 mm postoperatively (p = 0.026). The number of sinuses with type IV morphology (fully radiopaque) increased from zero preoperatively to six (13%) postoperatively. Sinuses with a single zygomatic implant showed no difference in the pre- and postoperative SM thickness. Postoperatively, six sinuses had infundibulum obstructions. Postoperative osteitis of the bilateral sinuses was found in two patients.

CONCLUSIONS

We have proposed a new imaging evaluation method and system for evaluating the maxillary sinus response. Preoperative infundibulum obstruction combined with mucosal thickening and double zygomatic implant placement are more likely to induce postoperative maxillary sinus mucositis and osteitis.

Feasibility and accuracy of a task-autonomous robot for zygomatic implant placement

STATEMENT OF PROBLEM

Zygomatic implants (ZIs) should be placed accurately as planned preoperatively to minimize complications and maximize the use of the remaining bone. Current digital techniques such as static guides and dynamic navigation are affected by human error; therefore, new techniques are required to improve the accuracy of ZI placement.

PURPOSE

The purpose of this clinical study was to assess the feasibility and accuracy of a task-autonomous robot for ZI placement.

MATERIAL AND METHODS

Patients indicated for ZI placement were enrolled, and an appropriate surgical positioning piece was selected based on the presence of natural teeth in the maxilla. Preoperative cone beam computed tomography (CBCT) scanning was performed with the surgical positioning piece, and virtual implant design and socket preparation procedures were initiated. Implant socket preparation and placement were automatically performed by the robot according to the preoperative plan under the supervision of the surgeon. Postoperative CBCT scanning was performed to evaluate deviations between the virtual and actual implants. All quantitative data were expressed as standardized descriptive statistics (mean, standard deviation, minimum, maximum, and 95% confidence interval [CI]). The Shapiro-Wilk test was used to assess the normal distribution of all variables (α=.05).

RESULTS

Six participants were enrolled, and 8 ZIs were inserted. No intraoperative or postoperative complications were observed. Robotic ZI placement showed a global coronal deviation of 0.97 mm (95% CI: 0.55 to 1.39 mm), a global apical deviation of 1.27 mm (95% CI: 0.71 to 1.83 mm), and an angular deviation of 1.48 degrees (95% CI: 0.97 to 2.00 degrees).

CONCLUSIONS

Task-autonomous robots can be used for ZI placement with satisfactory accuracy. Robotic ZI surgery can be an alternative to static guidance and dynamic navigation to improve the accuracy of implant placement.

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.

Integrating a mouth opening assessment of virtual patients to prevent intraoperative challenges during treatment

Template-guided implant surgery in the posterior region or zygomatic implant surgery using dynamic navigation systems is often hindered if a patient has limited mouth opening. To overcome the problem, the authors have proposed a novel digital protocol that integrates the use of a facial scan for the assessment of the maximal mouth opening of a virtual patient to assist in preoperative planning, thereby minimizing the likelihood of intraoperative obstruction of the surgical site. The proposed method is cost effective and can be easily used in clinical practice.

The accuracy of dynamic computer assisted implant surgery in fully edentulous jaws: A retrospective case series

OBJECTIVES

To evaluate the accuracy of implant placement using a dynamic navigation system in fully edentulous jaws and to analyze the influence of implant distribution on implant position accuracy.

MATERIALS AND METHODS

Edentulous patients who received implant placement using a dynamic navigation system were included. Four to six mini screws were placed in the edentulous jaw under local anesthesia as fiducial markers. Then patients received CBCT scans. Virtual implant positions were designed in the planning software based on CBCT data. Under local anesthesia, implants were inserted under the guidance of the dynamic navigation system. CBCTs were taken following implant placement. The deviation between the actual and planned implant positions was measured by comparing the pre- and postsurgery CBCT.

RESULTS

A total of 13 edentulous patients with 13 edentulous maxillae and 7 edentulous mandibles were included, and 108 implants were placed. The average linear deviations at the implant entry point and apex were 1.08 ± 0.52 mm and 1.15 ± 0.60 mm, respectively. The average angular deviation was 2.85 ± 1.20°. No significant difference was detected in linear and angular deviations between the maxillary and mandibular implants, neither between the anterior and posterior implants.

CONCLUSIONS

The dynamic navigation system provides high accuracy for implant placement in fully edentulous jaws, while the distribution of the implants showed little impact on implant position accuracy.

Semi-autonomous two-stage dental robotic technique for zygomatic implants: An in vitro study

OBJECTIVE

To assess the feasibility and accuracy of a semi-autonomous two-stage dental robotic technique for zygomatic implants.

METHODS

Twenty-six zygomatic implants were designed and randomly divided into two groups using 10 three-dimensionally printed resin models with severe maxillary atrophy. In one group, the conventional drilling technique was used, in the other group, the drilling process for the alveolar ridge section (first stage) was completed, after which drilling for the zygoma section (second stage) was done. Based on preoperative planning combined with postoperative cone-beam computed tomography (CBCT), coronal, apical, depth, and angle deviations were measured. Zygomatic implant placement technique-related deviations (sinus slot, intrasinus, and extrasinus) were also recorded and analyzed.

RESULTS

The two-stage technical group's coronal, apical, depth, and angle deviations were 0.57 ± 0.19 mm, 1.07 ± 0.48 mm, 0.30 ± 0.38 mm, and 0.91 ± 0.51°, respectively. The accuracy of the two-stage technique was significantly higher than that of the conventional one-stage technique (p < 0.05). The apical deviation in the intrasinus group was 1.12 ± 0.56 mm, which was significantly better than that in the other two groups (p < 0.05). The angle deviation in the sinus slot group was 1.96 ± 0.83°, which was significantly worse than that in the other two groups (p < 0.05).

CONCLUSION

Using the semi-autonomous two-stage dental robotic technique for zygomatic implants is feasible and is more accurate than using the conventional one-stage technique.

CLINICAL SIGNIFICANCE

The two-stage technique enabled the semi-autonomous robot to overcome the mouth-opening restriction for zygomatic implants and improved accuracy.

Accuracy of a Novel Semi-Autonomous Robotic-Assisted Surgery System for Single Implant Placement: a Case Series

OBJECTIVE

This study aimed to evaluate the accuracy of dental implant placement at single-tooth sites using a novel semi-autonomous robotic-assisted surgery system (sa-RASS).

METHODS

Patients with single missing teeth were included. Cone-beam computed tomography (CBCT) was performed prior to surgery using a U-shaped silicone tube to develop a virtual implant placement and drilling plan. The sa-RASS was used for implant osteotomy and placement in conjunction with a surgeon. Cone-beam computed tomography data were utilised to evaluate deviations between planned and placed implants using a three-dimensional Slicer software. Data were analysed using the t-test and analysis of variance. Statistical significance was considered at P<0.05.

RESULTS

Nineteen implants were placed using the sa-RASS. No adverse events or complications were observed during the surgery. Mean ± standard deviations between planned and postoperative implant positions were 0.90 ± 0.41 mm at the platform, 1.04 ± 0.47 mm at the apex, and 3.37 ± 1.51° for angulation. In a lateral direction, deviations were 0.72 ± 0.38 mm and 0.88 ± 0.47 mm at the platform and apex, respectively. Deviations in depth were all <1mm at both the platform (0.46 ± 0.33 mm) and apex (0.45 ± 0.32 mm). The apex deviation was greater than that at the platform (p = 0.036 < 0.05), mainly in the lateral distance (p = 0.037 < 0.05).

CONCLUSIONS

The current study illustrate that this robotic implant system is sufficiently accurate for single-tooth implant placement.

CLINICAL SIGNIFICANCE

This study provides significant evidence to support the use of sa-RASS as a potential alternative to static guided surgery and dynamic navigation, in dental implant surgery.

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.

Autonomous dental robotic surgery for zygomatic implants: A two-stage technique

Zygomatic implants (ZIs) can be a treatment option for patients with severe atrophy in the maxilla, but deviation during ZI placement could lead to serious complications. Surgical guides and dynamic navigation have been used to improve the accuracy of ZI placement, but both techniques are subject to human error. A 2-stage technique is described that enabled an autonomous dental robot to overcome mouth-opening restrictions for ZI placement. The technique enables the complete digitalization of ZI placement, further improving the accuracy of the drilling process.

Cost-effectiveness of the Flapless Insertion of Zygomatic Implants Using Dynamic Navigation - A Retrospective Study

Introduction

Zygomatic implants are an effective solution for rehabilitation of edentulous atrophic maxillae. However, the conventional technique of zygomatic implant placement is invasive, requires a longer healing period and is economically cumbersome. Therefore, the flapless technique of insertion of zygomatic implants using dynamic navigation system has been introduced. This study aims to compare the cost-effectiveness of flapless insertion of zygomatic implants using dynamic navigation to the conventional flap technique.

Materials and Methods

The study participants were divided into two groups: Group A (n = 20) included patients treated by flapless insertion of zygomatic implants using dynamic navigation and Group B (n = 20) included patients treated with zygomatic implants using the flap technique. An analysis of the effectiveness of the implants was done using the concept of quality-adjusted prosthesis years, and an analysis of the costs was done by evaluating the treatment costs at each step. The data were collected, and analysis was done using IBM SPSS software. The Kruskal-Wallis rank-sum test was employed to analyse variations in costs and effects between the two groups.

Results

The study showed that the distribution of costs varies across both the categories of the procedure. Group B shows lesser cost-effectiveness as compared to Group A.

Conclusion

The technique of flapless insertion of zygomatic implants is cost-effective. However, further studies considering factors such as time and cost of productivity evaluating the cost-effectiveness should be conducted.

A deep learning-based automatic segmentation of zygomatic bones from cone-beam computed tomography images: A proof of concept

OBJECTIVES

To investigate the efficiency and accuracy of a deep learning-based automatic segmentation method for zygomatic bones from cone-beam computed tomography (CBCT) images.

METHODS

One hundred thirty CBCT scans were included and randomly divided into three subsets (training, validation, and test) in a 6:2:2 ratio. A deep learning-based model was developed, and it included a classification network and a segmentation network, where an edge supervision module was added to increase the attention of the edges of zygomatic bones. Attention maps were generated by the Grad-CAM and Guided Grad-CAM algorithms to improve the interpretability of the model. The performance of the model was then compared with that of four dentists on 10 CBCT scans from the test dataset. A p value <.05 was considered statistically significant.

RESULTS

The accuracy of the classification network was 99.64%. The Dice coefficient (Dice) of the deep learning-based model for the test dataset was 92.34 ± 2.04%, the average surface distance (ASD) was 0.1 ± 0.15 mm, and the 95% Hausdorff distance (HD) was 0.98 ± 0.42 mm. The model required 17.03 seconds on average to segment zygomatic bones, whereas this task took 49.3 minutes for dentists to complete. The Dice score of the model for the 10 CBCT scans was 93.2 ± 1.3%, while that of the dentists was 90.37 ± 3.32%.

CONCLUSIONS

The proposed deep learning-based model could segment zygomatic bones with high accuracy and efficiency compared with those of dentists.

CLINICAL SIGNIFICANCE

The proposed automatic segmentation model for zygomatic bone could generate an accurate 3D model for the preoperative digital planning of zygoma reconstruction, orbital surgery, zygomatic implant surgery, and orthodontics.

Evaluation of surgical techniques in survival rate and complications of zygomatic implants for the rehabilitation of the atrophic edentulous maxilla: a systematic review

PURPOSE

To assess the outcome [zygomatic implant (ZI) survival] and complications of the original surgical technique (OST) and an Anatomy-Guided approach (AGA) in the placement of ZI in patients with severely atrophic maxillae.

METHODS

Two independent reviewers conducted an electronic literature search from January 2000 to August 2022. The inclusion criteria were articles reporting at least five patients with severely atrophic edentulous maxilla undergoing placement OST and/or AGA, with a minimum of 6 months of follow-up. Number of patients, defect characteristics, number of ZI, implant details, surgical technique, survival rate, loading protocol, prosthetic rehabilitation, complications, and follow-up period were compared.

RESULTS

Twenty-four studies comprised 2194 ZI in 918 patients with 41 failures. The ZI survival rate was 90.3-100% in OST and 90.4-100% in AGA. Probability of complications with ZI with OST was as follows: sinusitis, 9.53%; soft tissue infection, 7.50%; paresthesia, 10.78%; oroantral fistulas, 4.58%; and direct surgical complication, 6.91%. With AGA, the presenting complications were as follows: sinusitis, 4.39%; soft tissue infection, 4.35%; paresthesia, 0.55%; oroantral fistulas, 1.71%; and direct surgical complication, 1.60%. The prevalence of immediate loading protocol was 22.3% in OST and 89.6% in the AGA. Due to the heterogeneity of studies, statistical comparison was only possible after the descriptive analysis.

CONCLUSIONS

Based on the current systematic review, placing ZI in severely atrophic edentulous maxillae rehabilitation with the OST and AGA is associated with a high implant survival rate and surgical complications within a minimum of 6 months follow-up. Complications, including sinusitis and soft tissue infection around the implant, are the most common. The utilization of immediate loading protocol is more observed in AGA than in OST.

Accuracy of computer-aided static and dynamic navigation systems in the placement of zygomatic dental implants

BACKGROUND

Zygomatic implants are widely used in the rehabilitation of severely atrophic maxillae, but implant placement is not without risks, and it can potentially cause damage to related anatomical structures. The aim of this study was to perform a comparative analysis of the accuracy of static navigation systems in placing zygomatic dental implants in comparison to dynamic navigation systems.

METHODS

Sixty zygomatic dental implants were randomly allocated to one of three study groups, categorized by which implant placement strategy was used: A: computer-aided static navigation system (n = 20) (GI); B: computer-aided dynamic navigation system (n = 20) (NI); or C: free-hand technique (n = 20) (FHI). For the computer-aided study groups, a preoperative cone-beam computed tomography (CBCT) scan of the existing situation was performed in order to plan the approach to be used during surgery. Four zygomatic dental implants were inserted in each of fifteen polyurethane stereolithographic models (n = 15), with a postoperative CBCT scan taken after the intervention. The pre- and postoperative CBCT scans were then uploaded to a software program used in dental implantology to analyze the angular deviations, apical end point, and coronal entry point. Student's t-test was used to analyze the results.

RESULTS

The results found statistically significant differences in apical end-point deviations between the FHI and NI (p = 0.0053) and FHI and GI (p = 0.0004) groups. There were also statistically significant differences between the angular deviations of the FHI and GI groups (p = 0.0043).

CONCLUSIONS

The manual free-hand technique may enable more accurate placement of zygomatic dental implants than computer-assisted surgical techniques due to the different learning curves required for each zygomatic dental implant placement techniques.

Dynamic navigation for zygomatic implant placement: A randomized clinical study comparing the flapless versus the conventional approach

OBJECTIVES

The assessment of the accuracy of flapless placement of zygomatic implants in edentulous maxilla using dynamic navigation.

METHODS

A randomized controlled trial was carried out on 20 patients. Patients were randomized into two groups, the flapless (Group 1; n=10) and the conventional (Group 2; n=10). In each case two zygomatic implants were inserted under local anaesthesia, one on the right and one on the left side guided by a dynamic navigation system. The surgical procedure was identical in the two groups except for the reflection of the mucoperiosteal flap which was eliminated in the flapless cases. Postoperative CBCT scans were used to assess the accuracy of the placement of zygomatic implants.

RESULTS

Osseointegration was achieved for all the implants, except one case in the flapless group. Statistically significant differences in the accuracy of the position of the zygomatic implants was found between the flapless and the conventional groups, measured at the apex and the entry points of the implants (p < 0.01). The average apical and coronal deviations were 5 mm and 3 mm, respectively; the angular deviation was 6°, and 2 mm vertical apical disparity was detected between the planned and the achieved surgical position. Perforation of the Schneiderian membrane was noted in three cases, one in flapless group and two in the conventional group.

CONCLUSIONS

Flapless placement of zygomatic implants guided by dynamic navigation offered satisfactory safety and accuracy.

CLINICAL SIGNIFICANCE

This is the first clinical trial to prove the feasibility and accuracy of flapless placement of zygomatic implant with minimal morbidity. The study highlights the innovative reflection of the Schneiderian membrane under guided surgical navigation. The procedure can be performed under local anaesthesia, which offers clinical advantages. Adequate training on the use of dynamic navigation is mandatory before its use in clinical cases.