Zygomatic Implants Research Articles

Case report: utilization of Z-Point fixture "Trans-nasal" implants.

Placement of implants into the trans-nasal bone between the pneumatized maxillary sinus and nasal fossa allows utilization of an extralong implant in this residual bone to augment zygomatic implants placed distal to this for better support of a full arch prosthesis. A typical case is presented with insufficient alveolar height for traditional implant placement in the anterior maxilla following extraction of the dentition related to bone loss resulting from periodontal disease. Review of the anatomy and technique for placement of implants into the Z-point area for trans-nasal implants. This article discusses the utilization of trans-nasal implants into the Z-point and the technique for placement in this residual bone with a case example. The Z-point implant aids in the elimination of the anterior cantilever that may be present due to the most anterior the platform for the zygomatic implant can be placed. Trans-nasal implants should be considered as part of the treatment plan in severely resorbed maxillary arches to allow better implant to spread and load management during functioning.

Zygomatic implant guided rehabilitation based on inverted support technique: a pilot study.

Zygomatic implant insertion surgery is a challenging operation. The primary aim of this pilot study was to assess the accuracy of EZgoma® "Inverted Support Technique" for the zygomatic implant-guided surgery. Secondly, any factors which may affect the surgical protocol results, such as implant-prosthetic virtual plan, surgical model matching, intra or post-operative complications, time rate between surgical procedure and prosthetic loading, zygomatic implant survival rate and implant success rate were analyzed. A total of 20 zygomatic implants were placed in atrophic maxillae of 5 patients. The final position of zygomatic implants after surgery was compared with the pre-operative digitally planned position. The analyzed parameters were zygomatic implants apex and base mean linear distance and zygomatic implants axis mean angular deviation. The comparison was provided by a tridimensional imaging elaboration platform, provided by Geomagic, which allows the overlay of virtual plan STL data with post-operative control CT scan DICOM data. As a result, all the mean values regarding the 20 placed zygomatic implants respected the universally agreed values in guided zygomatic implant surgery: the mean linear distance of the implant platform and of the implant apex were 1.59 mm and 1.62 mm respectively, while the mean angular deviation of the implant axis was equal to 1.74°. One of the patients had mucositis as a post-operative complication. In one patient the anterior wall of the maxillary sinus fractured, and in one zygomatic implant primary stabilization was not achieved. No other complications occurred. As a conclusion, data obtained from this study suggested that guided zygomatic implant rehabilitation may represent a reliable, efficient, rapid, ergonomic, and safe surgical protocol, however further investigations are needed.

Short‐term performance of unilateral zygomatic implants: A case series

AbstractThe aim of this investigation is to contribute to clarify whether zygomatic unilateral implants are a feasible alternative for the rehabilitation of the atrophic maxilla. Six consecutive, unilaterally edentulous patients who received zygomatic implants gave their consent to enter this retrospective observational study. Fixtures were inserted according to the Zygomatic Anatomy‐Guided Approach and loaded with functional screwed restorations. All patients were compliant with their scheduled follow‐up appointments. Six tapered implants were considered, mostly (80%) 4.4 mm diameter 40–50 mm long. These fixtures had been in place for an average of 4.1 years (range: 5–144 months). No implant failures were observed, and continuous fixed‐prosthesis function was achieved throughout the follow‐up period with no loosening or fracture of prosthetic screws. Patients were satisfied with the treatment and experienced only minor complications. Unilateral zygomatic implants seem to be a feasible alternative that diminishes morbidity and treatment times with high‐survival rates for patients with atrophic posterior maxilla.

Minimally Invasive Navigation-Guided Quad Zygomatic Implant Placement: A Comparative In Vitro Study.

Purpose: Zygomatic implants (ZIs) have been considered a reliable alternative treatment for patients with maxillary atrophy and/or maxillary defects. The use of a navigation system for assisting ZI placement could be a reliable approach for enhancing accuracy and safety. The purpose of this in vitro study was to evaluate the accuracy of a new dynamic surgical navigation system with its minimally invasive registration guide for quad zygomatic implant placement in comparison with a gold standard navigation approach. Materials and Methods: A total of 40 zygomatic implants were placed in 10 3D-printed models based on the CBCT scans of edentulous patients. For registration, a surgical registration guide with a quick response plate was used for the test group, and five hemispheric cavities as registered miniscrews in the intraoral area were used for the control group. In each model, a split-mouth approach was employed (two ZIs in bilateral zygomata) to test both systems. After ZI placement, a CBCT scan was performed and merged with pre-interventional planning. The deviations between planned and placed implants were calculated as offset basis, offset apical, and angular deviation and compared between the systems. Results: The offset basis, offset apical, and angular deviation were 1.43 ± 0.55 mm, 1.81 ± 0.68 mm, and 2.32 ± 1.59 degrees in the test group, respectively. For the control group, values of 1.48 ± 0.57 mm, 1.76 ± 0.62 mm, and 2.57 ± 1.51 degrees were measured without significant differences between groups (all P < .05). The accuracy of ZI positions (anterior and posterior) were measured without significant differences between groups. Conclusion: Two navigation systems with different registration techniques seem to achieve comparable acceptable accuracy for dynamic navigation of zygomatic implant placement. With the test group system, additional pre-interventional radiologic imaging and invasive fiducial marker insertion could be avoided.

Comparison of Stress Distribution Among Standard Dental Implants Placed in Grafted Bone, Zygomatic Implants, and Subperiosteal Implants in the Atrophic Edentulous Maxilla: 3D Finite Element Analysis.

Purpose: To compare the biomechanical behaviors of different surgical options that are preferred for implant-supported fixed prosthetic rehabilitation of the atrophic edentulous maxilla. Materials and Methods: A 3D finite element analysis (FEA) model was generated from the computed tomography data of a patient with an atrophic edentulous maxilla. Four scenarios were created in the atrophic maxilla. In model 1, the maxilla was reconstructed with an onlay bone graft harvested from the anterior iliac crest, and sinus augmentation procedures were performed. Standard dental implants were placed in the lateral incisor, first premolar, and first molar regions on each side. In model 2, the anterior part of the atrophic maxilla was reconstructed with an onlay bone graft harvested from the mandibular ramus, and zygomatic implants were placed in the posterior part of the maxilla. In models 3 and 4, two-piece subperiosteal implants made of titanium and polyether ether ketone (PEEK) materials, respectively, were placed in the atrophic maxilla. All implants were loaded with 150-N and 50-N forces in vertical and lateral directions, respectively. Stress accumulation on bones, implants, abutments, and prosthetic frameworks was investigated. Results: The tensile stress in both cortical and trabecular bone was highest in the iliac bone grafting group under vertical loading. The compressive stress in both cortical and trabecular bone was the highest in the PEEK subperiosteal implant model, and the compressive stress value on the trabecular bone exceeded the strength of the trabecular bone. The highest von Mises stress in the implants was obtained in the iliac bone grafting group under vertical loading. The highest stress value in the abutments was detected for the titanium subperiosteal implant. The highest von Mises stress in the prosthetic framework was detected in the titanium subperiosteal implant group, under both vertical and lateral loading. Conclusion: Based on the stress accumulation results of the four different scenarios, it can be seen that there is no ideal treatment modality for the fixed implant-supported prosthetic rehabilitation of the atrophic edentulous maxilla. Various intraoperative and prosthetic modifications are suggested to decrease the risk of biomechanical complications during long-term follow-up.

Outcomes of Zygomatic Implants Combined with Anterior Regular Implants: A Retrospective Analysis with a Mean Follow-up Time of 36 Months.

Purpose: To retrospectively evaluate the clinical outcomes of immediately loaded zygomatic implants combined with anterior regular implants (hybrid zygoma) for the fixed rehabilitation of atrophic maxillae. Materials and Methods: A total of 18 patients were enrolled in this study and treated with the hybrid zygoma concept by an experienced surgeon. Follow-up visits were planned after 1 week, 3 weeks, 4 months, 6 months, then annually. At the last follow-up appointment (mean: 36 months after surgery; range: 24 to 52 months), the prostheses were unscrewed and the implants and peri-implant tissues were examined. The primary outcome evaluated was implant success. Following the criteria proposed by Aparicio et al, implant success was classified in five grades, with grade I representing the best condition and grade V representing a failure. At the annual check-up, patients were asked to fill out a questionnaire to evaluate their satisfaction with their oral rehabilitation. Results: A total of 80 implants (34 zygomatic and 46 regular) were inserted. One zygomatic implant was lost in one patient, and two regular implants failed in two other patients. Of the zygomatic implants, 24 (70.6%) presented a success grade I, 9 (26.5%) a success grade II, and 1 (2.9%) a grade V. Sinusitis was the most common biologic complication, occurring in two patients (5.6%). Two patients showed unilateral upper lip paresthesia that was persistent at the last follow-up appointment. According to the annual follow-up visit questionnaire data, 72%, 89%, and 94% of patients declared that they were satisfied with their phonetic ability, chewing ability, and esthetics, respectively. Conclusion: Although zygomatic implants combined with anterior regular implants present a higher risk of complications than traditional implantology, they allow for immediately loaded full-arch fixed rehabilitation of patients with advanced atrophy of the posterior maxilla, which provides satisfactory chewing ability, esthetics, and phonetics.

Assessment of the content and quality of YouTube videos related zygomatic implants: A content-quality analysis.

This study aimed to evaluate the content and quality of YouTube videos of zygomatic implants. According to Google Trends (2021), "zygomatic implant" was the most preferred keyword related to the topic. Therefore, in this study "zygomatic implant" was used as a keyword for the video search. Demographic characteristics such as the number of views, likes/dislikes, comments, video duration, number of days after upload, uploaders, and target audiences of the videos were evaluated. To evaluate the accuracy and content quality of videos (available from YouTube), the video information and quality index (VIQI) and global quality scale (GQS) were used. Statistical analyses were performed using the Kruskal-Wallis test, Mann-Whitney U test, chi-square test, Fisher's exact chi-square test, Yates continuity correction, and Spearman correlation analysis (p < 0.05). A total of 151 videos were searched; 90 met all inclusion criteria. According to the video content score, 78.9% of the videos were identified as low content, 20% as moderate, and 1.1% as high content. There was no statistical difference between the groups in video demographic characteristics (p> 0.001). Conversely, information flow, accuracy of information, video quality and precision, and total VIQI scores were statistically different between the groups. The moderate-content group had a higher GQS score than the low-content group (p < 0.001). The videos were mainly uploaded (40%) from hospitals and universities. Most videos were targeted toward professionals (46.75%). Low-content videos had higher ratings than the moderate- and high-content videos. Most YouTube videos on zygomatic implants showed low-content quality. This implies that YouTube is not a reliable source of information on zygomatic implants. Dentists, prosthodontists, and oral and maxillofacial surgeons should be aware of the content of video-sharing platforms and take responsibility for enriching video content.

Three-dimensional finite element analysis of zygomatic implants for rehabilitation of patients with a severely atrophic maxilla

Statement of problemStresses applied to zygomatic implants have been determined to be transferred mainly to the zygomatic bone; however, consensus regarding the stress distribution pattern in the bone surrounding zygomatic implants has not yet been reached. PurposeThe purpose of this 3-dimensional (3D) finite element analysis (FEA) study was to visually compare the stress distribution pattern in 2 different zygomatic implant treatment modalities and evaluate the effect of masseter musculature involvement. Material and methodsA 3D FEA craniofacial model was constructed from the computed tomography (CT) data of a selected patient with a severely atrophic edentulous maxilla. Modeled zygomatic and conventional implants were inserted into the craniofacial model supporting a prosthesis superstructure. Two types of treatment were considered in the study: 2 zygomatic implants placed bilaterally or 2 zygomatic implants placed in conjunction with at least 2 conventional implants at the anterior maxilla. The models were loaded with a vertical force of 150 N, a lateral force of 50 N, and a distributed occlusal force of 300 N applied to the insertion area of the masseter muscle. The stresses on and deformations of the bones and implants were then observed and compared with and without the involvement of the musculature component. ResultsThe stresses were distributed efficiently along the vertical and horizontal facial buttresses, as in the dentate skull; however, a difference in distribution pattern was observed when the models were loaded without applying the muscle component. The maximum deformation of bones surrounding the implants occurred in the abutment connection of the conventional anterior implant in the model with an additional conventional anterior implant. ConclusionsThe FEA revealed the stresses were distributed efficiently along the vertical and horizontal facial buttresses, as in the dentate skull. However, the stresses in both models were concentrated in the zygomatic bone when incorporating the muscle component. Therefore, incorporating muscular force into FEA studies could affect the analysis result.

Zygomatic Implants Research: A Scientometric Analysis from 1990 to 2021

Zygomatic implants imply the use of the zygoma as the implant anchorage and have been proposed as a valuable alternative to the invasive classical procedures in cases of severe maxillary atrophy. Despite the numerous manuscripts published in this field, a quantitative analysis of the research products to infer the trends and the status identification of this specific issue was missing, as well as an objective map of this area. Thus, the present scientometric study analyzed all the research papers published within the interval 1990–2021 that included the keyword “zygomatic implants”. Research papers containing the keywords “zygomatic implants” were collected using Web of Science and analyzed with Cytoscape 3.7.2 and Sci software. A total of 654 studies were published between 1990 and 2020, reaching up to 11639 citations in total, with a mean of 17.8 citations per research study. Data show that the number of publications per year is rapidly increasing, as well as the sum of citations per year. While the USA was identified as the most productive country in this field, followed by Italy, Spain, and Brazil, the National Natural Science Foundation of China stands up as the major funding agency, followed by the National Institutes of Health (NIH) in the USA and the United States Department of Health and Human Services. The analysis of the keywords showed that “zygomatic fractures” represents the most common word within this field, with “complications” as the most recent keyword and “screws” as the keyword used for the longest time. The map of science representing the authors and their collaborations highlighted the existence of multiple small-size research groups that contribute to scientific production, forming highly clustered structures that do not collaborate between them. The present scientometric analysis demonstrates the rising interest in using the zygomatic implants technique as an alternative to the classical ones. The obtained data suggest that the scientific community involved in the study of such a field is highly fragmented, emphasizing the lack of communication among the scientists and research groups.

A Novel Method to Rehabilitate Post-mucormycosis Maxillectomy Defect by Using Patient-Specific Zygoma Implant.

During second wave of COVID pandemic, India faced heavy surge of mucormycosis. Treatment option for these patients included either total or partial maxillectomy with primary closure. Rehabilitation of these patients became challenging because of their age and size of defect. The purpose of the present study is to present a new digital technique for the fabrication of patient-specific zygoma implants (PSI) and to report on its survival and complication rates. Total 21 patients who had undergone either partial or total maxillectomy after mucormycosis and who were disease-free clinically and radiographically for 6 or more months post-resection were rehabilitated using patient-specific zygoma implant. CT scan was obtained for all patients post-maxillectomy for evaluation of existing bone condition. Exocad software was used for virtual surgical planning of zygoma implant considering surgical and prosthetic technicality to achieve goal of maximum functionality and sustainability. All the patients were followed up after 15, 30, 45 and 90days and there after every month for evaluation of soft tissue healing, infection, dehiscence, loosening of prosthesis, eating efficiency and aesthetic. Follow-up period for all 15 patients was in the range of 6-12months. In case of post-mucor maxillectomy patients, use of PSI offers the advantages of minimal bone augmentation, reduction in time required to restore lost function, and reduced financial burden of multiple procedures. Therefore, PSI may represent a valid alternative treatment for the prosthetic restoration of post-mucor maxillectomy patients.

Comparative analysis of biomechanical response between zygomatic implant and Facco technique through the three-dimensional finite element method.

The placement of zygomatic implants is an alternative used for rehabilitation of edentulous patients with atrophic maxilla. However, the complexity of the various techniques suggested in the literature requires high skill from surgeons. Aim: The objective of this research was to compare the biomechanical performance of traditional technique of zygomatic implant placement in relation to a new proposal, the Facco technique, through finite element analysis. A three-dimensional geometric model of the maxilla was input into computer-aided design software (Rhinoceros version 4.0 SR8). STL file of the geometric models of implants and components supplied by the company Implacil De Bortoli was converted to volumetric solids through reverse engineering by RhinoResurf software (Rhinoceros version 4.0 SR8). Three groups were modeled: traditional technique, Facco technique without frictional contact and Facco technique with frictional contact, following the recommended position in each technique for implant placement. All models received a maxillary bar. Groups were exported to the computer-aided engineering software ANYSYS 19.2, in step format. Mechanical static structural analysis was requested with occlusal load of 120N. All elements were considered isotropic, homogeneous, and linearly elastic. Contacts were considered ideal and system fixation was considered at the bone tissue base. There is similarity between the techniques. Microdeformation values capable of generating undesirable bone resorption were not observed in both techniques. Highest values in the posterior region of Facco technique were computed at the angle of part B close to the posterior implant. Biomechanical behaviors of the two evaluated zygomatic implant techniques are similar. Prosthetic abutment (pilar Z) modifies the distribution of stresses over the zygomatic implant body. Highest stress peak was found in the pilar Z, but it is within acceptable physiological limits. Key words:Atrophic maxilla, zygomatic implants, surgical techniques, pilar Z, dental implants.

The Use of Zygomatic Implants in Severe Maxillary Atrophy: A Systematic and Meta-Analysis Review of Randomised Clinical Trials

The Use of Zygomatic Implants in Severe Maxillary Atrophy: A Systematic and Meta-Analysis Review of Randomised Clinical Trials

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

ObjectivesThe assessment of the accuracy of flapless placement of zygomatic implants in edentulous maxilla using dynamic navigation. MethodsA 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. ResultsOsseointegration 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. ConclusionsFlapless placement of zygomatic implants guided by dynamic navigation offered satisfactory safety and accuracy. Clinical significanceThis 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.

P-66186951-371 - Conventional implants instead of zygomatic implants? An effective alternative: Review of a case.

P-66186951-371 - Conventional implants instead of zygomatic implants? An effective alternative: Review of a case.

A Novel Method to Achieve Preferable Bone-to-Implant Contact Area of Zygomatic Implants in Rehabilitation of Severely Atrophied Maxilla.

Purpose: To propose and evaluate a novel method for achieving a favorable bone-to-implant contact (BIC) area for zygomatic implants (ZIs). Materials and Methods: Patients who needed ZIs to restore a severely atrophied maxilla were recruited. In preoperative virtual planning, an algorithm was utilized to find the ZI trajectory that would achieve the largest BIC area with a predefined entry point on the alveolar ridge. The surgery was conducted according to the preoperative plan with the assistance of real-time navigation. Area BIC (A-BIC), linear BIC (L-BIC), distance from implant to infraorbital margin (DIO), distance from implant to infratemporal fossa (DIT), implant exit section, and deviation of the real-time navigated surgery were measured and compared between the preoperative plan and the placed ZIs. The patients were followed up for 6 months. Results: Overall, 11 patients with 21 ZIs were included. The A-BICs and L-BICs were significantly higher in the preoperative plan than in the placed implants (P < .05). Meanwhile, there were no significant differences in DIO or DIT. The planned-placed deviation was 2.31 ± 1.26 mm for the entry, 3.41 ± 1.77 mm for the exit, and 3.06 ± 1.68 degrees for the angle. All ZIs survived to the 6-month follow-up. Conclusion: This novel method can virtually calculate the trajectory of ZIs and transfer the preoperative plan to surgery to acquire a favorable BIC area. The actual positions of placed ZIs were slightly deviated from the ideal due to navigation errors.

A Comparative Finite Element Analysis of ‘Hexa-Zygomatic’ Implants vs Conventional Quad Zygomatic Implants for The Rehabilitation of Bilateral Maxillectomy Defects

Restoration of bilateral maxillectomy defects is inherently challenging. Zygomatic implants are one of the non-bone grafting solutions for restoration of such defects which require minimum armamentarium and are widely available. The Quad Zygomatic Implants have a long track record in maxillectomy defects secondary to cancer ablative surgeries. In the current scenario, they are being used in COVID associated mucormycosis maxillectomy defects. Since there is a paucity in literature on the use of zygomatic implants in the above-mentioned malady, we have used finite element analysis to assess the longevity of the Quad Zygomatic Implants concept and the newer Hexa Zygomatic Implants concept for these types of cases. The finite element analysis showed similar results for both the concepts on simulation which leads to the conclusion whereas both are viable treatment modalities. The Quad Zygomatic Implants concept is the more economically favourable and practical solution. As this a finite element analysis study, clinical based studies with long follow-up may shed light on a more conclusive clinical outcomes.

Effect of the buccal fat pad in the prevention of zygomatic implant surgery postoperative complications: A pilot study.

Zygomatic implants have been used to treat severe atrophy maxilla. Since its description, the technique has been improved in order to reduce patient morbidity as well as prosthesis rehabilitation time. Despite the improvements in the procedure, zygomatic implant treatments still have complications related to the peri-implant soft-tissue; a probing depth greater than 6 millimeter (mm) and a prevalence of bleeding on probing of 45% have been described. The mobilization of the buccal fat has been used to manage different oral and maxillofacial soft-tissue pathologies. The aim of this study was to assess whether the buccal fat pad might prevent mucosal dehiscence and avoid potential postoperative complications when is placed covering the body part of the zygomatic implants. In this pilot study, 7 patients were enrolled and a total of 28 zygomatic implants were placed and evaluated during a 12-month follow-up period. Surgical sites were randomly divided into two groups before implant placement: control group (A; in which no buccal fat pad was applied) and experimental group (B). Peri-implant soft tissue thickness difference, pain using a Visual Analog Scale (VAS), swelling, hematoma, buccal soft tissue healing and sinusitis, were evaluated. The implant survival rate was determined according the Aparicio success criteria and compared between the control and experimental procedure. A nonstatistical difference was found between groups regarding to pain. The experimental group showed higher soft-tissues thickness (p= 0.03) and the implant survival rate was 100% in both groups. The mobilization of the buccal fat pad to cover the body of the zygomatic implants increases peri-implant soft-tissue thickness, without increasing the postoperative pain.

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

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

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. 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. 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). 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.

Accuracy of zygomatic dental implant placement using computer-aided static and dynamic navigation systems compared with a mixed reality appliance. An in vitro study.

Analyze and compare the accuracy of zygomatic dental implant placement carried out using a static navigation surgery, a dynamic navigation surgery and an augmented reality appliance. Eighty (80) zygomatic dental implants were randomly assigned to one of four study groups: A: static navigation implant surgery (n = 20) (GI); B: dynamic navigation implant surgery (n = 20) (NI); C: augmented reality appliance implant placement (n = 20) (ARI) and D: free hand technique (n = 20) (FHI). A preoperative cone-beam computed tomography (CBCT) scan of the existing situation was performed to plan the surgical approach for the computer assisted implant surgery study groups. Four zygomatic dental implants were placed in anatomical-based polyurethane models (n = 20) manufactured by stereolithography, and a postoperative CBCT scan was taken. Subsequently, the preoperative planning and postoperative CBCT scans were uploaded to dental implant software to analyze the coronal global, apical global, and angular deviations. Results were analyzed using linear regression models with repeated measures to assess the differences according to the group, according to the position, and the interaction between both variables. If statistically significant differences were detected, 2-to-2 comparisons were made between the groups/positions. The results did not show statistically significant differences between the coronal global deviations of GI (5.54 ± 1.72 mm), NI (5.43 ± 2.13 mm), ARI (5.64 ± 1.11 mm) and FHI (4.75 ± 1.58 mm). However, showed statistically significant differences between the apical global deviations of FHI (3.20 ± 1.45 mm) and NI (4.92 ± 1.89 mm) (p = 0.0078), FHI and GI (5.33 ± 2.14 mm) (p = 0.0005) and FHI and ARI (4.88 ± 1.54 mm) (p = 0.0132). In addition, the results showed also statistically significant differences between the angular deviations of FHI (8.47º ± 4.40º) and NI (7.36º ± 4.12º) (p = 0.0086) and between GI (5.30º ± 2.80º) and ARI (9.60º ± 4.25º) (p = 0.0005). Free-hand technique provides greater accuracy of zygomatic dental implant placement than computer-assisted implant surgical techniques, and zygomatic dental implants placed in the anterior region are more accurate than in the posterior region. However, it is an in vitro study and further clinical studies must be conducted to extrapolate the results to the clinical setting. Key words:Implantology, computer assisted implant surgery, image-guided surgery, augmented reality, navigation surgery, zygomatic implants.