IMPORTANCE OF ASSESSING THE POSITION OF THE INFRA-ORBITAL FORAMEN IN QUAD ZYGOMA OR UNILATERAL DOUBLE ZYGOMA IMPLANT SURGERY

AIM

Evaluate the frequency of occurrence of extreme inferior positioning of the Infraorbital foramen from the infra-orbital rim that can potentially interfere with the placement of Quad or Unilateral Double Zygomatic implants.

MATERIALS AND METHODS

CBCT scans of 60 patients were read to identify the Infraorbital foramen (IOF)and Infra-orbital rim (IOR). The distances between the two were measured. In cases with increased values, virtual surgical planning was done to evaluate whether two Zygoma implants could be placed in one zygomatic bone.

RESULTS

Two out of the 60 cases showed a more inferior location of the IOF, reducing the amount of bone available , thus rendering quad zygoma or unilateral; double zygomatic implants infeasible.

CONCLUSION

Measurement of the distance of the IOF from the IOR is an important step worth incorporating in Quad Zygoma or unilateral double zygoma implant surgery planning.

Comparison of sinusitis rate after sinus lift procedure and zygomatic implant surgery: a meta-analysis

PURPOSE

To evaluate and compare the reported sinusitis occurrence after the sinus lift procedure and zygomatic implant placement.

METHODS

This meta-analysis has been registered at PROSPERO. Studies were searched on six databases. Two authors screened titles and abstracts and fully analyzed the studies against the inclusion and exclusion criteria. The RoB 2.0 and the ROBINS-I tools were used to assess the quality and risk of bias of the included studies. The random-effects model was used for the meta-analysis. The prevalence of sinusitis was calculated based on the total of patients. Subgroup analysis was performed by sinus lift or zygomatic implant surgery technique.

RESULTS

The search identified 2419 references. After applying the inclusion criteria, 18 sinus lift and 9 zygomatic implant placement studies were considered eligible. The pooled prevalence of sinusitis after sinus lift procedure was 1.11% (95% CI 0.30-2.28). The prevalence after zygomatic implant placement was 3.76% (95% CI 0.12-10.29). In the subgroup analysis, the lateral window approach showed a prevalence of sinusitis of 1.35% (95% CI 0.34-2.8), the transcrestal technique of 0.00% (95% CI 0.00-3.18), and the SALSA technique of 1.20% (95% CI 0.00-5.10). Regarding the techniques for zygomatic implant placement, the sinus slot technique showed a prevalence of 21.62% (95% CI 9.62-36.52) and the intrasinus technique of 4.36% (95% CI 0.33-11.08), and the prevalence after the extrasinus technique was 0.00% (95% CI 0.00-1.22).

CONCLUSION

The sinusitis occurrence rate was higher after zygomatic implant placement than after sinus lift procedure and this occurrence was different depending on the used technique.

Surgical and prosthetic rehabilitation of siblings with Witkop tooth and nail syndrome using zygomatic implants: a familial case series of 3 patients with up to 15-year follow-up

Witkop tooth and nail syndrome is a rare, autosomal dominant type of ectodermal dysplasia that can have significant effects on dentition, including hypoplastic and malformed dentition and significantly atrophic maxillas. Endosseous implants have become one possible solution to replace missing teeth, although their use in areas where bone is sparse becomes challenging. Due to the severe atrophy of the maxillary alveolus, extensive preprosthetic surgeries including orthognathic surgery, extensive bone grafting, and sinus floor augmentations have been recommended prior to placement of endosseous dental implants. Although this treatment has shown favorable outcomes, it requires multiple surgical procedures, contributing to a prolonged treatment course and increased morbidity. An alternative treatment of atrophic maxillas in patients with ectodermal dysplasia includes the use of zygomatic implants. This familial case series discusses 3 siblings, all previously diagnosed with Witkop Syndrome, who underwent comprehensive preprosthetic surgery and prosthetic rehabilitation using zygomatic implants with a follow-up period up to 15 years.

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.

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.

ITI consensus report on zygomatic implants: indications, evaluation of surgical techniques and long-term treatment outcomes

OBJECTIVES

The aim of the ITI Consensus Workshop on zygomatic implants was to provide Consensus Statements and Clinical Recommendations for the use of zygomatic implants.

MATERIALS AND METHODS

Three systematic reviews and one narrative review were written to address focused questions on (1) the indications for the use of zygomatic implants; (2) the survival rates and complications associated with surgery in zygomatic implant placement; (3) long-term survival rates of zygomatic implants and (4) the biomechanical principles involved when zygoma implants are placed under functional loads. Based on the reviews, three working groups then developed Consensus Statements and Clinical Recommendations. These were discussed in a plenary and finalized in Delphi rounds.

RESULTS

A total of 21 Consensus Statements were developed from the systematic reviews. Additionally, the group developed 17 Clinical Recommendations based on the Consensus Statements and the combined expertise of the participants.

CONCLUSIONS

Zygomatic implants are mainly indicated in cases with maxillary bone atrophy or deficiency. Long-term mean zygomatic implant survival was 96.2% [95% CI 93.8; 97.7] over a mean follow-up of 75.4 months (6.3 years) with a follow-up range of 36-141.6 months (3-11.8 years). Immediate loading showed a statistically significant increase in survival over delayed loading. Sinusitis presented with a total prevalence of 14.2% [95% CI 8.8; 22.0] over a mean 65.4 months follow-up, representing the most common complication which may lead to zygomatic implant loss. The international experts suggested clinical recommendations regarding planning, surgery, restoration, outcomes, and the patient's perspective.

Indications for zygomatic implants: a systematic review

PURPOSE

The purpose of this systematic review was to assess the evidence regarding the indications for placement of zygomatic implants to rehabilitate edentulous maxillae.

MATERIAL AND METHODS

A focused question using the PIO format was developed, questioning "in patients in need of an implant-supported rehabilitation of the edentulous maxillae, what are the indications for the use of zygomatic implants''. The primary information analyzed and collected was a clear description of the indication for the use of zygomatic implants.

RESULTS

A total of 1266 records were identified through database searching. The full-text review was conducted for 117 papers, and 10 were selected to be included in this review. Zygomatic implant indications were extreme bone atrophy or deficiency secondary to different factors. The quad zygoma concept (two zygomatic implants bilaterally placed and splinted) was applied to 107 patients, the classic zygoma concept (one zygomatic implant bilaterally placed and splinted to standard anterior implants) was used in 88 patients, and the unilateral concept (one zygomatic implant on one side, splinted with one or more conventional implants) was employed in 14 patients.

CONCLUSIONS

The main indication for the use of zygomatic implants was considered extreme maxillary bone atrophy, resulting from many factors. The clear definition of what was considered "extreme bone atrophy" is not uniquely defined in each paper. Further studies are needed to develop clear indications for zygomatic implants.

Stress Distribution of the Zygomatic Implants in Post-mucormycosis Case: A Finite Element Analysis

Aim

The aim of this study was to assess the stress distribution of the zygomatic implants in maxillectomy cases and to understand the long-term prognosis of this rehabilitation option using finite element analysis.

Materials and Methods

A three-dimensional finite element model was designed using computed tomography of a patient who underwent maxillectomy post-mucormycosis. Zygomatic implants and abutments were designed based on the manufacturer's design. Quad zygomatic implants were placed in the canine and premolar region into the zygomatic bone bilaterally. A prosthesis with an entire complement of teeth extending from the first molar teeth bilaterally was designed and attached to the multiunit abutments and zygomatic implants. Forces were applied to the zygomatic implants at six different locations bilaterally on the prosthesis which included occlusal and laterally directed forces on the central incisor region, canine region, and molar region using von Mises criteria. A three-dimensional finite element analysis was run, and maximum stress distribution was recorded at various loads. Statistical Package for Social Sciences for Windows version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses. Kruskal-Wallis test was used to compare the mean stress values. Multiple comparisons of mean difference in stress values between force applications in implant were done using Dunn's post hoc test.

Results

The maximum stress was observed at the distal head of the implant in the models. Minimum stress was observed at the apex of the implant in the models. The mean stress values based on force application in the bone and fixed prosthesis showed less significance when compared to the zygomatic implants which was statistically significant at p = 0.03.

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.

The severely atrophic maxilla: Decision making with zygomatic and pterygoid dental implants

The severely atrophic maxilla can present with some challenges during treatment planning with communication between those performing the surgical and prosthetic aspects of the treatment as well as communication with the patient as to what is being suggested for treatment. This article simplifies the communication and understanding of treating the severely atrophic maxilla and based on the Bedrossian classification gives a guideline for the surgical approach to be adapted based on the patient residual anatomy.

Zygomatic implant analogue simulation surgery and stereolithographic 3D models

This short communication will share the author's experience and protocols using stereolithographic (SLA) models to simulate zygomatic implant surgery.

Patient-reported outcomes in patients with severe maxillary bone atrophy restored with zygomatic implant-supported complete dental prostheses: a systematic review

Introduction and Objective: Zygomatic implants (ZI) offer a good and predictable alternative to reconstructive procedures of atrophic maxillae. The main objetive of this systematic review was to assess the effect of rehabilitation with zygomatic implants on patient's quality of life (QLP) using Patient Reported Outcomes Measures (PROMs).Materials and Methods: This review followed PRISMA guidelines. An automated electronic search was conducted in four databases supplemented by a manual search for relevant articles published until the end of January 2021. The Cochrane Collaboration Risk of Bias tool and the Newcastle-Ottawa Quality Assessment Scale were used to assess the quality of evidence in the studies reviewed.Results: General findings of this systematic review showed substantial increases in Oral health-related quality of life (OHRQoL) among patients restored with ZI and high scores in terms of general satisfaction, especially in chewing ability and esthetics. An overall survival rate of ZI was 98.3% after a mean follow-up time of 46.5 months was observed. Occurrence of 13.1% biological complications and 1.8% technical complications were reported.Conclusions: Patients rehabilitated with zygomatic implant-supported complete dental prostheses showed substantial improvements in OHRQoL and general satisfaction with the treatment received.

Round and flat zygomatic implants: effectiveness after a 1-year follow-up non-interventional study

INTRODUCTION

There are few zygomatic implants (ZI) designs available. The objective of this non-interventional study was to report the effectiveness of two new site-specific ZI, selected and placed following the zygoma anatomy-guided approach (ZAGA).

MATERIALS AND METHODS

Consecutive patients presenting indications for rehabilitation using ZI were treated according to ZAGA Concept recommendations. Implants were immediately loaded following the manufacturer's instructions. Success criteria regarding prosthetic offset, rhino-sinus status, soft tissue condition, and implant stability were additionally used as outcome parameters.

RESULTS

Twenty patients were followed for a period of 12 to 28 months (average 18.8 months). Ten received 2 ZI plus regular anterior implants; One received 3 ZI plus regular implants and nine received 4 ZI. In total, 59 ZI were placed, 34 (58%) Straumann ZAGA-Flat design, and 25 (42%) ZAGA-Round. Forty-nine percent of the sites were classified as ZAGA-4 type and 27% as ZAGA-2. Four patients (20%) presented discontinuities of the sinus-nose floor before surgery and 15 patients (75%) presented previous sinus opacities. All implants bar one reached more than 45 N.cm of insertion torque. No surgical complications were observed. After 1 year, the modified Lund-Mackay score was negative in 17 patients. Seventeen sites in 11 patients exhibited decreased opacity when pre-surgical imaging was compared to 1-year post-surgical CBCT. All implants and prostheses remained stable and in function.

CONCLUSIONS

The study concluded 100% implant/prosthesis survival rates and low complication levels. Within the limitations of the sample and observation period, results suggest that even in cases of extremely resorbed maxillae (as per cases in this study), ZAGA-Flat and ZAGA-Round ZI are viable treatment options when restoring atrophic maxillae following the ZAGA protocol.

Changing trends in the microvascular reconstruction and oral rehabilitation following maxillary cancer

Purpose

The maxillectomy defect is complex and the best means to achieve optimal reconstruction, and dental rehabilitation is a source of debate. The refinements in zygomatic implant techniques have altered the means and speed by which rehabilitation can be achieved and has also influenced the choice regarding ideal flap reconstruction. The aim of this study is to report on how the method of reconstruction and oral rehabilitation of the maxilla has changed since 1994 in our Institution, and to reflect on case mix and survival.

Methods

Consecutive head and neck oncology cases involving maxillary resections over a 27-year period between January 1994 and November 2020 were identified from hospital records and previous studies. Case note review focussed on clinical characteristics, reconstruction, prosthetic rehabilitation, and survival.

Results

There were 186 patients and the tumour sites were: alveolus for 56% (104), hard palate for 19% (35), maxillary sinus for 18% (34) and nasal for 7% (13). 52% (97) were Brown class 2 defects. Forty-five patients were managed by obturation and 78% (142/183) had free tissue transfer. The main flaps used were radial (52), anterolateral thigh (27), DCIA (22), scapula (13) and fibula (11). There were significant changes over time regarding reconstruction type, use of primary implants, type of dental restoration, and length of hospital stay. Overall survival after 24 months was 64% (SE 4%) and after 60 months was 42% (SE 4%).

Conclusion

These data reflect a shift in the reconstruction of the maxillary defect afforded by the utilisation of zygomatic implants.

Attitudes regarding zygomatic implant surgical and prosthodontic techniques-a cohort questionnaire study

BACKGROUND

Zygomatic implant (ZI) surgery and restoration is a complex procedure, requiring experienced clinicians to execute with success. This study assessed the opinion and clinical experiences of a cohort of practitioners involved in provision of zygomatic implant treatment on aspects of the surgical and prosthodontic procedures.

METHOD

A survey was distributed among all 176 delegates attending 'Zygomatic 2019' International Conference in the UK, and all delegates completed the survey.

RESULTS

The respondents were clinicians from both prosthodontic and surgical specialties, with a range of experience. Strong agreements were found regarding the use of specific implant designs dependent on the anatomical situation, and that fixed restorations should be used where possible. There was limited agreement between respondents regarding surgical approaches to ZI treatment.

CONCLUSION

The limited agreement found between respondents highlights the varied and conflicting literature available on ZI surgery. High-quality research is required to inform clinicians and assist education.

Extra-long transnasal implants as alternative for Quad Zygoma: Case report

Introduction and importance

The aim of this case report is to present a technical report for rehabilitation of patients with atrophic maxilla with the use of extra-long transnasal implants associated with unilateral zygomatic implants.

Case presentation

The indications, contraindications, planning and surgical procedure are described in order to give surgeons confidence in the management of this surgical approach to how to increase the range of rehabilitative options available to surgeons and patients.

Clinical discussion

Maxillary bone atrophy is a challenge demanding a high degree of experience of dental surgeons who trains themselves to rehabilitate these patients, whose treatment options range from bone grafts through to zygomatic implants. Extensive regions of atrophy require the use of 4 zygomatic implants which, in spite of offering predictability of the treatment, increase the surgical risk, require zygomatic bone with volume for anchoring 2 zygomatic implants. Generally, this bone density is reduced in elderly patients, making apical anchorage of the implants unfeasible.

Conclusion

The case report presented is a feasible alternative for replacing the placement of a second zygomatic implant, thereby diminishing the surgical risk, and making it possible for the technique to be more extensively used and performed by a larger number of surgeons.

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Present a case report with the use of extra-long transnasal implants.

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Alternative for substituting the insertion of a second zygomatic implant.

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Decrease the surgical risk.

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.

A practical approach to orofacial rehabilitation in a patient after inferior maxillectomy and rhinectomy with mono framework construction supported on a zygomatic implant placed in the glabella: a case report

Background

In the field of craniofacial tumor surgery, an adequately performed excision, despite being a life-saving procedure, is only a first step to successful treatment. During such a procedure, the main goal is to completely remove the lesion, paying less attention to factors contributing to future rehabilitation possibilities. One ty 2of the possibilities for prosthetic rehabilitation of such cases is utilizing one-piece implants with bicortical anchorage.

Case presentation

This case report presents a case of a 48-year-old patient with oral squamous cell carcinoma (OSCC). The treatment protocol consisted of radical surgery to remove the tumor, and intraoral and extraoral rehabilitation with a single framework prosthesis anchored with one-piece implants. Moreover, the intraoral stomatognathic deformity was corrected with a fixed implant-retained prosthesis, and the extraoral defect was covered with a removable epithesis.

Conclusions

The use of one-piece implants with bicortical anchorage may be an additional tool in reconstructing maxillofacial defects. Properly executed treatment may improve the esthetics, speech, masticatory function, muscle support, and the overall quality of life of patients with extensive defects in the maxillofacial region.

Factors influencing implant and prosthesis survival in zygomatic implant-supported fixed rehabilitation: a retrospective study

BACKGROUND

The aim of this retrospective study was to evaluate mid-term implant and prosthesis survival in patients with edentulous atrophic maxillae submitted to zygomatic implant-supported fixed rehabilitation and to identify possible related risk factors.

METHODS

Data were collected from records of patients with edentulous atrophic maxillae, in good general health and who were rehabilitated by means of acrylic resin full-arch screw-retained prosthesis supported by at least one zygomatic implant, between the years of 2006-2017. Implant and prosthesis survival rates were calculated. The association between implant and prosthesis loss and quantitative and qualitative variables of interest was verified with t tests and Fisher's exact tests, respectively. For the significant variables in the latter, odds ratio and 95% confidence intervals were additionally calculated.

RESULTS

The sample comprised 66 patients in whom 171 zygomatic implants were placed to support maxillary screw-retained full-arch prostheses. Implant and prosthesis survival rates of 94.15% and 92.4%, respectively, were observed in a mean of 3.6 years of follow-up (up to 11.7 years). Implant loss was 4.33 more likely to occur when adverse events were recorded after the procedure of implant placement (P = 0.026) and 10.31 more likely to occur in implants that had their prosthesis repaired during follow-up visits (P = 0.004). Prosthesis loss was 22.00 times more likely to occur when implants were previously lost (P < 0.001). All prostheses that were considered as failures (i.e. were replaced) had been previously submitted to laboratory repair at some point during follow-up.

CONCLUSIONS

Zygomatic implant rehabilitation demonstrated to be a reliable method with good mid-term results. The occurrence of post-surgical adverse events and need for laboratory repair of the prosthesis were found to be significant risk factors for implant loss. Previous implant loss was significantly associated with prosthesis loss. These risk factors may be prevented by means of detailed planning of the rehabilitation to be carried out, including post-operative care of the patients, so that treatment success using zygomatic implants can be achieved.

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.

Zygomatic implant penetration to the central portion of orbit: a case report

Background

Zygomatic implants have been proposed in literature for atrophic maxillary fixed oral rehabilitations. The aim of the present research was to evaluate, by a clinical and tomography assessment, a surgical complication of a zygomatic implant penetration to the orbit.

Case presentation

A 56 year-old female patient was visited for pain and swelling in the left orbit after a zygomatic implant protocol. The orbit invasion of the zygomatic implant screw was confirmed by the CBCT scan. The patient was treated for surgical implant removal and the peri- and post-operative symptoms were assessed. No neurological complications were reported at the follow-up. The ocular motility and the visual acuity were well maintained. No purulent secretion or inflammatory evidence were reported in the post-operative healing phases.

Conclusion

The penetration of the orbit during a zygomatic implant positioning is a surgical complication that could compromise the sight and movements of the eye. In the present case report, a zygomatic implant removal resulted in an uneventful healing phase with recovery of the eye functions.

Clinical outcome of 302 zygomatic implants in 110 patients with a follow-up between 6 months and 7 years

BACKGROUND

Zygomatic implant surgery is considered as a safe and successful alternative to the conventional implant surgery with bone grafts for patients with severe atrophic maxilla.

PURPOSE

The aim of this retrospective clinical case series was to report clinical outcome of zygomatic implants with a follow-up between 6 months and 7 years.

MATERIALS AND METHODS

A total of 110 patients with 302 zygomatic implants were included in this study. The intra and postoperative complications and survival rate of zygomatic implants were evaluated.

RESULTS

The study included 110 consecutively treated patients with an age range of 21 to 76 years (mean 57.35 years, SD 10.42). The overall zygomatic implant survival rate was 98.34%. There were five implant failures in four patients. One intraoperative and 17 postoperative complications developed in 18 patients. There were no dropouts and the median follow-up of the patients was 41.75 months (with a range of 6-89 months).

CONCLUSIONS

According to the results, in cases of severely atrophic posterior maxilla, zygomatic implant surgery can be considered as an effective and safe alternative to conventional implants and bone grafting procedures.

Frequency and location of the zygomaticofacial foramen and its clinical importance in the placement of zygomatic implants

PURPOSE

Anatomical knowledge of the zygomatic region is important, because the zygomatic nerve and its branches may suffer lesions during surgical procedures in the periorbital region. The position and frequency of zygomaticofacial foramina (ZFF) may vary between individuals, and between one side and the other in the same individual. In the present study, we analysed the presence and location of ZFF, as well as the distance between them and the orbital cavity, in macerated skulls of adult individuals.

METHODS

We examined 287 macerated skulls, of individuals of both sexes, analysing the frequency and location of ZFF and the distance from the ZFF to the margin of the orbital cavity (OC).

RESULTS

Zygomaticofacial foramina are very frequent structures which tend to appear singly. They are generally located in the temporal process of the zygomatic bone, but in many cases, they may be located in the mid portion of the bone. They also tend to appear at the same distance from the OC when left and right sides are compared. Sex was an important factor in determining differences in ZFF; the distance from the ZFF to the margin of the OC was greater in males than in females. Sex, age, side and skin colour did not affect the frequency and location of the ZFF.

CONCLUSION

We consider that the mid portion of the zygomatic bone is the safest place to anchor zygomatic implants (ZI), since ZFF are less frequently located there than in the temporal process of the zygomatic bone.

Extra-Long Nasal Wall-Directed Dental Implants for Maxillary Complete Arch Immediate Function: A Pilot Study

Immediate loading of maxillary denture prostheses in the context of severe bone atrophy is complicated by posterior implant placement, sometimes requiring a complex surgical approach as zygomatic or pterygoid implants. To overcome this complexity, the authors developed an extra-long (20-24 mm) 24-degree angulated platform. It was tested on 33 patients, with 24 patients immediately loaded (72.7%) for a total of 115 implants (46% nasal). All delayed loading implants osseointegrated. Eight bilateral and six unilateral sinus grafts were performed. There were no complications during the follow-up period.

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.

TEN-YEAR follow-up of treatment with zygomatic implants and replacement of hybrid dental prosthesis by ceramic teeth: A case report

The aim of this case report was to show the 10-year follow-up of a zygomatic implant supported rehabilitation treatment to replace the hybrid dental prosthesis with resin teeth - one by one - with ceramic teeth. The complications that occurred were described right from the time when the first implant supported prosthesis with immediate loading was placed, through the fabrication of a personalized dental prosthesis with twelve ceramic crowns, with a view to achieving esthetic excellence and restoring the patient's self-esteem. It was concluded that all patients with zygomatic implants must participate in a preventive maintenance program to assure the predictability of this type of treatment.

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Surgery may occur in the private clinic with local anesthesia and oral sedation.

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Treatments have high success rates, improvement in quality of life.

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All patients must participate in a preventive maintenance program.

Horizontal augmentation of the maxillary alveolar ridge to change the prosthetic profile: Clinical and radiological results of a retrospective study

BACKGROUND

In this retrospective study, we aimed to analyze the clinical and radiological results of compensating the long-term deficiencies in hard and soft tissues of edentulous patients by placing dental implants and performing a horizontal ridge augmentation.

MATERIAL AND METHODS

We treated patients with edentulous maxillaries (Cawood-Howell type III or IV) by combining 4 implants, or 6 implants, or using zygomatic and conventional anterior implants as appropriate. Simultaneously, horizontal ridge augmentation was performed by combining autologous bone with Bio-Oss and membranes.

RESULTS

A total of 14 zygomatic and 80 standard implants were used for the rehabilitations in 16 edentulous patients. The success rates were 93.75% and 85.71% for the standard and zygomatic implants, respectively. Also, respective gains of 5.79mm and 3.25mm were obtained at the levels of the midsagittal line and canines, with respective resorption rates of 10% and 8.6% after 20months.

CONCLUSION

The millimeters gained by performing a horizontal augmentation optimizes the relation between the implant position and the prosthetic profile. This allows the different prostheses to be selected and for rehabilitation to be optimized. In this way, mucosal coverage can be avoided and fixed prosthetic design can be enhanced.

The development of non-contact user interface of a surgical navigation system based on multi-LSTM and a phantom experiment for zygomatic implant placement

PURPOSE

Image-guided surgical navigation system (SNS) has proved to be an increasingly important assistance tool for mini-invasive surgery. However, using standard devices such as keyboard and mouse as human-computer interaction (HCI) is a latent vector of infectious medium, causing risks to patients and surgeons. To solve the human-computer interaction problem, we proposed an optimized structure of LSTM based on a depth camera to recognize gestures and applied it to an in-house oral and maxillofacial surgical navigation system (Qin et al. in Int J Comput Assist Radiol Surg 14(2):281-289, 2019).

METHODS

The proposed optimized structure of LSTM named multi-LSTM allows multiple input layers and takes into account the relationships between inputs. To combine the gesture recognition with the SNS, four left-hand signs waving along four directions were designed to correspond to four operations of the mouse, and the motion of right hand was used to control the movement of the cursor. Finally, a phantom study for zygomatic implant placement was conducted to evaluate the feasibility of multi-LSTM as HCI.
 RESULTS: 3D hand trajectories of both wrist and elbow from 10 participants were collected to train the recognition network. Then tenfold cross-validation was performed for judging signs, and the mean accuracy was 96% ± 3%. In the phantom study, four implants were successfully placed, and the average deviations of planned-placed implants were 1.22 mm and 1.70 mm for the entry and end points, respectively, while the angular deviation ranged from 0.4° to 2.9°.

CONCLUSION

The results showed that this non-contact user interface based on multi-LSTM could be used as a promising tool to eliminate the disinfection problem in operation room and alleviate manipulation complexity of surgical navigation system.

Stresses generated by two zygomatic implant placement techniques associated with conventional inclined anterior implants

Purpose

To make a comparative evaluation, by means of the finite element method, of the stress generated on supporting tissues and prosthetic system components, using zygomatic implants with the exteriorized and extramaxillary techniques, and different placement positions, associated either with inclined anterior implants, or those without inclination.

Materials and methods

Eight (8) tridimensional models were created to represent the clinical situations being researched, using the dataset of scanned images of an edentulous model. The implants and prosthetic components were photographed on millimeter paper and inserted into Rhinoceros 3D modeling computer software. From the measurements made on the image, the virtual models were made. The application force was distributed on the occlusal surface of the working side of the left maxillary first molar, first and second premolars, and incisal regions of the central incisor, simulating the occlusal load during mastication, in a total of 150 N.

Results

The extramaxillary technique presented considerable variation in increased tension on the prosthesis screws and bone tissue. In the exteriorized technique, the highest tension values occurred in the region of the ridge, and the lowest, on the zygomatic process; the absence of cantilever reduced the stress on bone tissue in almost all regions.

Conclusion

The exteriorized technique was shown to be more favorable to the distribution of stresses on the micro-unit screws and bone tissue, with the model with zygomatic implant placed in the region of the first molar and inclined anterior implant presenting the best results.

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The extramaxillary technique showed considerable variation in stress increase.

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In the exteriorized technique, the highest stress occurred in the alveolar ridge region.

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The alveolar bone support for zygomatic implants reduced the internal stress generated by the vertical force.

Protocol for mandibular reconstruction with zygomatic implants (zygomatic mandibular implant)

INTRODUCTION

This study describes a modified protocol using transmandibular zygomatic implants with immediate occlusal loading for the comprehensive dental rehabilitation of previously reconstructed mandibular defects and reports preliminary results of this modified protocol.

MATERIALS AND METHODS

Fifteen patients (6 female and 9 male), with a mean of age 40.26 years (range 12 to 68 years), had previously undergone immediate mandibular reconstruction using either autologous bone grafting, bone transport, or microvascular free-flap reconstruction for a variety of diagnoses. Transmandibular zygomatic implants were subsequently placed, depending on the type of defect. Implant stability was evaluated by insertion torque, percussion testing, and the implant stability quotient (ISQ). The patients were rehabilitated with an immediate provisional prosthesis. All patients' records included pre and postoperative clinical examination, radiographs, CT scan, and photographic analysis. All patients were followed for a minimum of 36 months.

RESULTS

All patients were dentally rehabilitated immediately with functional and esthetic hybrid dentures based on either acrylic or porcelain on a metal framework. Among all cases of transmandibular zygomatic implants, the ISQ was greater than 75, which allowed immediate prosthetic loading. The zygomatic implants were considered to be successful if they were asymptomatic with no clinical mobility and no sign of infection. We have also added new indications for placement of transmandibular implants in cases of sequelae of gunshot trauma, dentoalveolar defects, and complications of orthognathic surgery, partially edentulous and/or failure of prior mandibular reconstruction.

CONCLUSIONS

The zygomatic implant is an excellent immediate loading option for mandibular dental rehabilitation among patients with mandibular defects. According to our observation, immediate occlusal loading of transmandibular zygomatic implants has a very good potential for success.

Maxillary zygomatic hexagonal implant system (MZH system) for severe resorption: a new technique

INTRODUCTION

The biomechanical demands of the severely resorbed maxilla have prompted the search for alternative points of anchorage for zygomatic implants that allows stabilizing a prosthesis in young patients (30 years old or more) for restitution of function and form. The purpose of this study is to describe the protocol of zygomatic hexagonal implants in patients with severe maxillary bone resorption.

MATERIALS AND METHODS

Ten patients with severe maxillary resorption were treated with hexagonal implants system, they were evaluated at the preoperative and the postoperative periods for a minimal of 24 months, and the evaluation was clinical and trough conventional radiographs and CT scans. Six implants according to prosthetic prior planning were placed in each patient. Anteroposterior severely resorbed maxilla was evidence. Patients were rehabilitated with immediate provisional prosthesis. Ten days after surgery, definitive prosthesis metal structures were designed and adapted.

RESULTS

Force distribution and load concentration were balanced; adjustment of the metal bar was passive. Correction of skeletal relationship was evident. No fatigue in the later additions in controls was observable. No complications were found in the immediate postoperative period and late (6-24 months), no patients dropped out from the study, and all were followed up to 24 months.

CONCLUSIONS

The zygomatic hexagonal implants' protocol guarantees barrier function, biomechanical stability, load distribution, and preventing fatigue bone/implant interface, which allows distributing of the forces through the pillars, anterior masticatory load reduction, and correcting the skeletal class III type which occurs in patients with severe resorption.

Evaluation of satisfaction of individuals rehabilitated with zygomatic implants as regards anesthetic and sedative procedure: A prospective cohort study

PURPOSE

To evaluate the satisfaction of individuals with atrophic maxilla, rehabilitated with fixed dental prostheses, anchored on zygomatic implants, with variables being the anesthetic procedure: general anesthesia, or local with sedation.

MATERIALS AND METHODS

By means of the clinical record charts from the Training Course in Advanced Hospital Surgeries for Implant Dentists conducted at the Campinas-SP unit of the São Leopoldo Mandic School of Dentistry, 30 individuals were randomly selected. They had zygomatic implant placement surgeries performed, and were rehabilitated with fixed implant supported complete dentures, between the years 2005 and 2011. One group of 15 individuals underwent surgery in hospital, under general anesthesia. The other 15 were treated in the post-graduation clinic at the School of Dentistry, under local anesthesia and sedation.

RESULTS

From the emotional point of view, the Wilcoxon test revealed that irrespective of the anesthesia procedure used, at the beginning of treatment, the emotional condition of individuals differed from that verified after conclusion of the treatment (p < 0.0001).

CONCLUSION

There was no difference between the two groups as regards the anesthetic procedure. General satisfaction was high; there was emotional improvement after conclusion of the treatment, thus improving the quality of life.

The zygomatic implant perforated (ZIP) flap: a new technique for combined surgical reconstruction and rapid fixed dental rehabilitation following low-level maxillectomy

This aim of this report is to describe the development and evolution of a new surgical technique for the immediate surgical reconstruction and rapid post-operative prosthodontic rehabilitation with a fixed dental prosthesis following low-level maxillectomy for malignant disease.

The technique involves the use of a zygomatic oncology implant perforated micro-vascular soft tissue flap (ZIP flap) for the primary management of maxillary malignancy with surgical closure of the resultant maxillary defect and the installation of osseointegrated support for a zygomatic implant-supported maxillary fixed dental prosthesis.

The use of this technique facilitates extremely rapid oral and dental rehabilitation within a few weeks of resective surgery, providing rapid return to function and restoring appearance following low-level maxillary resection, even in cases where radiotherapy is required as an adjuvant treatment post-operatively. The ZIP flap technique has been adopted as a standard procedure in the unit for the management of low-level maxillary malignancy, and this report provides a detailed step-by-step approach to treatment and discusses modifications developed over the treatment of an initial cohort of patients.

Quadruple zygomatic implants supported rehabilitation in failed maxillary bone reconstruction

Extreme atrophy of the jaws constitutes a challenge for maxillofacial surgeons. The technique involving Le Fort I osteotomy, bone grafting, and endosseous implants remains the gold standard treatment for class V and class VI atrophy of the maxilla. As severe maxillary atrophy is associated to impaired microvascularization of overlying soft tissues, reconstruction using vascularized free fibula flaps together with endosseous implants is one of the possible treatment plans. When this approach fails, however, retreating these patients using traditional techniques often proves unsatisfactory. This study outlines our clinical experience with full-arch zygoma implant-supported prosthetic rehabilitation to treat severe atrophic maxilla following failure of strategies including multiple Le Fort I procedures or vascularized free fibular flaps.

Endoscopically-Assisted Zygomatic Implant Placement: A Novel Approach

BACKGROUND

Zygomatic implants (ZIs) have been proposed as a valid alternative to advance bone-grafting procedures in the rehabilitation of the severe atrophied upper maxilla, with a reported overall success rate of more than 95 %. Otherwise, the use of the endoscope has been described for the treatment of maxillofacial trauma, orthognatic surgical procedures, sinonasal pathology, salivary gland disease, and TMJ internal derangement. A careful identification of anatomical landmarks is of utmost importance while trying to avoid potential complications during the insertion of ZIs. Several approaches for ZI insertion have been reported, such as the classical approach; the sinus slot technique; and the exteriorized approach.

MATERIALS AND METHODS

The authors first introduce in the literature the endoscopically-assisted approach for the insertion of ZIs in the extremely severe atrophic maxilla.

RESULTS

Optimal results in terms of ZIs positioning with no damage to surrounding structures were obtained.

CONCLUSIONS

By means of this new technique the surgeon may minimize the risk of complications related to the damage of neighbouring anatomic structures, such as orbital disruption or infraorbitary nerve damage, while ensuring an adequate drill positioning and angulation for the placement of one or two implants into the zygomatic bone.

Prosthetic improvement of pronounced buccally positioned zygomatic implants: a clinical report

This report presents a prosthetic technique for the improvement of surgically positioned, buccally placed zygomatic implants with the use of custom abutments for improved retention screw position and an esthetic implant reconstruction. The patient presented four zygomatic implants with pronounced buccal inclination. The anterior implants were inclined toward the location where the anterior artificial teeth should be placed during rehabilitation. As the manufacturer does not provide angulated abutments, we attempted the waxing and overcasting of a prosthetic abutment, repositioning the access holes of the prosthetic screws to a more palatal position. This clinical report demonstrates that abutment customization could be an interesting way to relocate the access holes of the prosthetic screws in cases of zygomatic implants with pronounced buccal inclination.

Treatment of atrophic maxilla with zygomatic implants in 29 consecutives patients

Atrophic maxilla is a common condition in older population; some treatments are proposed with bone reconstruction or zygomatic implant. Long-term follow up show the efficiencies of zygomatic implant but limited data are associated to consecutive patient. The aim of this study was to evaluate retrospectively the zygomatic implants performed consecutively in 29 patients. Data from clinical records of 29 patients treated with zygomatic implants were analyzed; were include patient with at least 10 month of prosthetic function. Four surgeons realized all surgeries using local anesthesia with a slot technique on local anesthesia; the variables analyzed were implant survival, complications, prosthetic load and satisfaction of patient; data collection was analyzed by descriptive statistic and chi-square test with p<0.05 for significance statistical. 67 zygomatic implants and 84 conventional implants were installed in patients between 35 and 69 year old being 18 (62%) female and 11 (38%) male.The main indication was the case of severe alveolar resorption in 21 cases (72.41%), followed by failures in maxillary reconstruction with bone graft in 4 (13.79%). The implant success was 79.1% and the immediate or delayed load was not associated to statistical difference (p=0.104). The main complication was the loss of osseointegration and mucositis. Analogue Visual Scale (AVS) for satisfaction show acceptable esthetic and function. Finally we conclude that zygomatic implant present adequate survivor and a good response of patient; important complication can be present in a learn curve for this surgery.