Zygomatic Implants Research Articles

Biomechanical comparison of four treatment models for the totally edentulous maxilla: a finite element analysis

The aim of this study is to evaluate by finite element analysis different techniques of totally edentulous maxilla rehabilitation, considering implants, bone tissue, metallic infra-structure, and prosthetic abutments characteristics, by means of a three-dimensional model. Stress distribution on bone tissue, implants, and abutments was analyzed with four configurations (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants). Greater tension on bone tissue were found around distal implants, in all treatment groups, but not exceeding resistance limits of cortical bone. Von Mises stress was higher on the distal region of distal implants of all-on-four and M-4 techniques. Higher stress concentration was seen on angled abutments of zygomatic implants. The highest values of minimal compression stresses were concentrated on peri implant-bone tissue, especially in the model of All-on-4. Therefore, the present finite element analysis revealed that the four configurations of treatment (six implants axially installed, all-on-four technique, M-4 technique, and four conventional implants with two zygomatic implants) for the totally edentulous maxilla are feasible and safe, from a biomechanical point of view.

Stress Distribution Pattern in Zygomatic Implants Supporting Different Superstructure Materials.

The aim of this study was to assess and compare the stress–strain pattern of zygomatic dental implants supporting different superstructures using 3D finite element analysis (FEA). A model of a tridimensional edentulous maxilla with four dental implants was designed using the computer-aided design (CAD) software. Two standard and two zygomatic implants were positioned to support the U-shaped bar superstructure. In the computer-aided engineering (CAE) software, different materials have been simulated for the superstructure: cobalt–chrome (CoCr) alloy, titanium alloy (Ti), zirconia (Zr), carbon-fiber polymers (CF) and polyetheretherketone (PEEK). An axial load of 500 N was applied in the posterior regions near the zygomatic implants. Considering the mechanical response of the bone tissue, all superstructure materials resulted in homogeneous strain and thus could reconstruct the edentulous maxilla. However, with the aim to reduce the stress in the zygomatic implants and prosthetic screws, stiffer materials, such Zr, CoCr and Ti, appeared to be a preferable option.

Major clinical outcomes for optimization of zygomatic implants: a systematic review

Introduction: In the context of implantology, the rehabilitation of an atrophic maxilla is a challenge. In case of severe resorption, zygomatic implants (ZI) are indicated and loading of the implants is advised at the end of the surgery. Also, quad zygomatic implants have been used as a treatment option for patients with severely resorbed maxilla. Objective: The present study aimed to carry out a systematic review of the main approaches and clinical outcomes of zygomatic implantation in the last ten years. Methods: The present study followed the PRISMA rules and a model of literary review presenting and publishing case series, prospective, retrospective, randomized, double-blind, placebo-controlled trials in humans with a time of the last ten years were selected and analyzed. Results and Conclusion: Under the objective proposed in this study, it was concluded that the ZI has a high 12-year cumulative survival rate, with most failures occurring in the early stages of the postoperative period. Furthermore, the zygomatic bone is a viable site for zygomatic implants and the use of specialized implant planning software is an important tool to achieve predictable results for ZI. Preliminary data one year after loading suggest that immediately loaded ZIs were associated with fewer prosthetic failures, fewer implant failures, and shorter time required for functional loading.

Autogenous bone grafting with conventional implants vs zygomatic implants for atrophic maxillae: a retrospective study of the oral health-related quality of life

IntroductionAutogenous bone grafting (ABG)–combined or not with Le Fort I osteotomy (LFIO)–and zygomatic implants (ZI) are two reliable techniques for the fixed rehabilitation of atrophic maxillae. ZI allow a reduced treatment duration with no need to graft, immediate loading and in principle less morbidity. The aim of this retrospective study was to compare these two protocols on oral health-related quality of life (OHRQoL). We also discussed implant and prosthetic survival rates, and biological complications. Material and methodsAll patients who benefited from ZI or ABG with conventional implants (CI) for a fixed maxillary rehabilitation, from November 2011 to April 2019, were included: 21 patients in the ABG group and 22 in the ZI group. OHRQoL was evaluated postoperatively by OHIP-14 questionnaire. ResultsOHIP-14 median scores were respectively 6.5 (interquartile range [IQR] 2.0–13.0) and 6.0 (IQR 3.0–10.0) without significant difference (p = 0.97). Implant/prosthetic survival rates were 97.9%/100% and 97.1%/95.5%. Biological complications rates were 33.3% and 36.4% without significant difference (p = 0.83). DiscussionThe type of surgery or prosthesis does not seem to affect final OHRQoL, implant and prosthetic survival rates or biological complications rates.

Survival of conventional dental implants in the edentulous atrophic maxilla in combination with zygomatic implants: a 20-year retrospective study

PurposeImplant-supported prosthetic rehabilitation in the resorbed maxilla is a great challenge. The aim of this study was to determine the survival rate of conventional anterior implants placed in combination with zygomatic implants according to the Brånemark technique, and to identify risk factors for implant failure.MethodsWe collected data retrospectively from 72 consecutive patients who received treatment from 1998 to 2018 at our center, according to Brånemark’s original technique. Kaplan–Meier analysis was conducted to assess survival rate, and a survival regression model was used with the patient as the random factor, applying the Weibull distribution.ResultsA total of 236 maxillary anterior implants were included, with a mean follow-up of 12.1 years. Kaplan–Meier analysis showed overall cumulative survival rates of 95.3% at 1 year, 94.8% at 2 years, 93.0% at 5 years, 90.5% at 10 years, 81.6% at 15 years, and 67.7% at 20 years. Survival regression showed an association between bruxism and implant failure as well as implants bearing an overdenture. Implants with length ≤ 10 mm had a significantly lower survival time. No significant association was found between the number of anterior implants and survival rate.ConclusionsWe found acceptable long-term anterior conventional implant survival. Significant risk factors for failure were bruxism, overdentures, and implants shorter than 10 mm.

Major clinical results of virtual zygomatic implant and assessment of the risk of bias: a systematic review

Introduction: In the context of implantology and severe resorption, zygomatic implants (ZI) are indicated and the procedures can be completed with the placement of a custom-made provisional prosthesis, reducing surgical time and optimizing results. Digital (virtual) optimizations for the ZI were developed in computerized radiology machines that allowed improvements in diagnostic and therapeutic tools. Objective: It was carried out a systematic review of the main considerations and clinical outcomes of using digital tools for the optimization of the virtual zygomatic implant. Methods: The rules of the Systematic Review-PRISMA Platform were followed. The research was carried out from January 2022 to April 2022 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 94 articles were found. In total, 62 articles were fully evaluated and 41 were included and evaluated in this study, and of the total of 41 articles, only 14 articles were developed as the main clinical results of the virtual zygomatic implant. Reducing errors and complications is essential if zygomatic implants are to remain a viable treatment alternative, and further research on a guided approach to their placement is encouraged. The surgical guide system showed accuracy for all variables studied and allowed acceptable and accurate implant placement, regardless of the complexity of the case. Thus, the surgical and prosthetic plan, the position, the emergence, the shape of the implants, the position of the provisional prosthesis, the inter-arch relationships, and the surgical templates were designed in a virtual environment and previously performed by the surgeon in stereolithographic models, allowing the surgical procedure was significantly simplified.

SHORT IMPLANTS IN POSTERIOR JAWS– A LITERATURE REVIEW

One of the greatest challenges that dentists face today is to rehabilitate severe atrophied alveolar ridges in partially and completely edentulous patients with implants. Loss of bone volume at the level of the posterior maxilla and mandible can complicate rehabilitation with implants, since it leads to a reduction in the distance to the maxillary sinus and the inferior alveolar nerve, respectively. Various techniques have been used for many years to avoid damaging these structures, such as alveolar ridge augmentation procedures, bone grafting, tooth nerve transposition, or even zygomatic implants. An alternative to these surgical treatments is the use of short implants in areas where bone availability is reduced.

Design and biomechanical comparison between classic and new-generation of zygomatic implants – Experimental study

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ZYGOMATIC IMPLANTS MAY IMPROVE QUALITY OF LIFE AND SATISFACTION IN PATIENTS WITH ATROPHIED MAXILLA.

Alberto J, Mariano S, Guerrero-s Y, Pato-mourelo J. Evaluation of Quality of Life And Satisfaction in Patients with Fixed Prostheses on Zygomatic Implants Compared with the All-on-Four Concept: A Prospective Randomized Clinical Study. Int J Environ Res Public Heal. 2021; 18(3426). The Department of Oral Surgery, University of Murcia, Murcia, Spain. Prospective randomized clinical trial.

Dynamic navigation for prosthetically driven zygomatic implant placement in extensive maxillary defects: Results of a prospective case series.

Zygomatic implants (ZIs) that are anchored in remote locations can significantly improve the retention and stability of prosthetic obturation in maxillary defect sites without the need for complex surgical reconstruction. However, ZI placement without alveolar bone guidance is challenging, especially when identifying the ideal three-dimensional location of the "coronal part" of the implant fixture for further rehabilitation. To investigate the feasibility and accuracy of surgical navigation for ZI placement using prosthetically driven plans to treat extensive maxillary defects. Software was used to virtually plan the number and distribution of ZIs for maxillary defect patients according to the existing residual maxillofacial bone. The "coronal part" of the ZI was identified based on the existing maxillodental prosthetic flange, virtually planned infrastructure framework and superstructure. ZI placement was fully guided by surgical navigation. Ten patients were enrolled. One patient had loose reflective spheres, which resulted in an inaccurate back-reflection of the position during navigation. A total of 27 ZIs in the remaining 9 patients were placed uneventfully. The mean of the "coronal part" of the ZI, entry point of the zygomatic bone, apical deviation, and apical angle deviation were 1.50 mm, 1.39 mm, 1.95 mm, and 2.32°, respectively. A Computer-aided design and computer-aided manufacture milled bar and additional attachments were fabricated according to preoperative planning. No osseointegrated implant loss was detected. Six ZIs in three patients received implant surface polishing to reduce soft tissue irritation, and one ZI was submerged. Surgical navigation facilitated the accurate and feasible placement of prosthetically driven ZIs that were preoperatively planned in patients with extensive maxillary defects.

Zygomatic implants using dynamic navigation

Over the decades, surgeons innovated a myriad of methods to assist patients with the replacement of missing teeth with fewer complications and accurate placement. A review of the literature confirmed that zygomatic implants are effective in maxillary reconstruction. Recently, dynamic navigation has proven effective in guiding the insertion of dental implants through the real-time tracking of the surgical instruments during surgery in relation to the planned position on the CBCT of the patients. This method helped improve the accuracy of insertion of dental implants. A prospective randomized control trial was conducted on zygomatic implants inserted using dynamic navigation. A test group and a control group with 20 implants each group were set. In the test group, dynamic navigation guided insertion of zygomatic implants with the reflection of the mucoperiosteal flap was performed. In the control group, flapless insertion of the zygomatic implants was performed. Flapless surgery is associated with less swelling, edema, erythema, and alteration in sensation. The patient could eat and maintain oral hygiene immediately from the very next day. No infections were reported postoperatively. Dynamic navigation-guided insertion of zygomatic implants was effective in maxillary rehabilitation.

Comparison of Extramaxillary Anchored Implants, Tilted Implants, or Sinus Elevation Concepts on Stress Distribution in Atrophic Maxilla: A Finite Element Analysis.

To determine the von Mises stress values of extramaxillary implants anchored in zygomatic bone, known as zygomatic implants, abutments, superstructures, and principal stress values of bone under occlusal forces and to compare them with tilted implants and sinus elevation concepts. The hypothesis of the study was that there would be higher stress on zygomatic implants under occlusal forces compared with tilted implants and the sinus elevation technique due to the more angled placement of the zygomatic implants. Finite element analysis (FEA) was used to apply a force of 600 N (75 N premolars and 150 N first molar) vertically and at an angle of 20 degrees to the hybrid prosthesis with three different concepts-zygomatic implants, tilted implants, and sinus elevation-in D2 bones in six separate models. The posterior implants were tilted in zygomatic implant models (45 degrees) and tilted implant models (30 degrees). The von Mises and principal stress values formed in the models were compared by FEA. These values were also compared with the physiologic stress limit of the bone. In the zygomatic implant models, the von Mises stress values on both anterior and posterior implants were less than other models under both loading conditions. In addition, the lowest principal stress values were seen in these models. The highest von Mises stress among all models was found to be posterior implants in tilted implant models under oblique loading. In addition, the highest principal stress values were seen at posterior implants in the sinus elevation model under oblique loading. Vertical loading was found to induce less stress than loading at a 30-degree angle. Although zygomatic implants have a more angled placement, the stress values on the bone and implants are lower.

Periorbital infection and fistula after placement of zygomatic implants: a case report and review

Zygomatic implants are a good alternative to severely atrophic maxilla prosthetic treatment, but complications can result from their placement. Skin fistulas are extremely rare complications of zygomatic implants, but it’s management can be challenging. Skin complications can happen when the apex of the zygomatic implant protrudes above the limits of zygomatic bone. To prevent its occurrence, careful planning must be done. The surgeon must control the final position of the implant at the appropriate length carefully. If infection or cutaneous fistula occurs, surgery to cut off the apex of the implant is indicated, either intra- or extra-orally. The aim of this case report was to describe the case of cutaneous fistula after Quad Zygoma treatment of extreme maxillary bone atrophy. A 56-year-old woman developed a left periorbital fistula 4 months after the placement of 4 zygomatic implants. Implant apex was palpable under the skin of zygomatic bone body. We opted for extra-orally cut off the implant tip above the outer cortical of the zygomatic bone. Postoperative course was uneventful and the patient had no more signs and symptoms of infection or fistula.

Three-Dimensional Guided Zygomatic Implant Placement after Maxillectomy.

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

Zygomatic implant: major considerations in the COVID-19 pandemic

Introduction: The dissemination of COVID-19 has presented significant challenges for dentistry. In this context, dental care during the pandemic is challenging due to the high risk of infection. In this scenario of infections and the COVID-19 pandemic, there are huge concerns in dental implant procedures, especially zygomatic implants (ZI), which need to be performed for several reasons, mainly to improve the quality of life of patients. Objective: The present study performed a brief systematic review of zygomatic implantation in the context of the COVID-19 pandemic, to highlight the main challenges and guideline-based safety strategies. Methods: The research was carried out from May 2021 to June 2021 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, following the Systematic Review-PRISMA rules. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: European guidelines and expert opinion showed on the control and prevention of infections in dentistry during the pandemic. As the guidelines were not based on solid evidence, they were supplemented by expert opinion on the control and prevention of infections in dentistry. The type of personal protective equipment provided by the dental team must be appropriate for the procedure and the risk of infection. the American Academy of Implant Dentistry (AAID) points to the issues listed as “What constitutes a dental implant-related emergency?; How should patients be screened and screened?; What personal protective equipment is needed?; How should operators be equipped?; What equipment should be used?; What, when, and how can procedures be performed?” Conclusion: In this current context of general care with dental procedures, especially with ZI, clinical studies show how these safety measures against COVID-19 are important, as ZI involves important surgical management.

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

IntroductionThere 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 methodsConsecutive 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.ResultsTwenty 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.ConclusionsThe 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.

PTERYGOID PLATE IMPLANTS FOR THE REHABILITATION OF THE ATROPHIC POSTERIOR MAXILLA: SURGICAL TECHNIQUE AND REPORT OF CASES.

Introduction: The rehabilitation of the atrophic posterior maxilla with dental implants is a challenging procedure due to various limitations. Low bone quality and quantity, the anatomy of the maxillary sinus and inaccessibility to the area, are the most frequent obstacles that surgeons have to overcome. Several surgical techniques have been used as a solution to this problem, such as sinus lift augmentation procedures with bone graft, guided bone regeneration, tilted implants, short implants, zygomatic implants and pterygoid plate implants. This case report presents the placement of implants in the pterygomaxillary region, aiming to restore the partially edentulous posterior maxilla in two patients, without any additional surgical procedures. The aim was to place a fixed dental prosthesis using a minimum invasive surgical protocol. The usual surgical technique had to be modified because of the anatomical limits encountered in that region, as the quality of bone and the extent of the maxillary sinus. A 30 years follow up is presented. Conclusion: In view of the clinical case follow up and the literature review that only minor surgical complications have been reported, it is concluded that pterygoid implants are a valid and safe solution for the rehabilitation of the edentulous posterior maxilla avoiding more invasive surgical procedures.

Zygomatic implants– Changing face of implant dentistry

Conventional implants cannot be placed in patients with severe atrophied maxilla resulting in insufficient amount of bone remaining for anchorage. Routinely, grafts were the preferred technique. But the drawbacks associated with this procedure, Branemark proposed surgical /prosthetic rehabilitation with zygomatic implants to overcome them. This review aims to address the criteria for placement, surgical and prosthodontics procedure, outcome evaluation and complications arising with zygomatic implants.

Melolabial interpolated island flap for reconstruction of an anterior oronasal fistula after horseshoe Le Fort I osteotomy with iliac bone grafts interposition - A case report.

IntroductionHorseshoe Le Fort I osteotomy (HLFO) in combination with iliac bone grafts interposition is an established and very effective procedure for reconstructing the severely atrophic maxilla. However potential complications connected to this method, such as oronasal fistula (ONF), have not been described in the literature to date.Case presentationWe report the case of a female patient with severe atrophy of the edentulous maxillary alveolar ridge with type 2 diabetes (T2D). Initially, a sinus floor augmentation was performed, followed by a failed placement of dental implants. Afterwards, HLFO with simultaneous interposition of iliac bone grafts was conducted. Subsequently, an oronasal communication occurred in the antral maxilla. As several local flaps had not achieved sufficient results, a melolabial interpolated island flap was carried out, yielding satisfactory results.DiscussionFailed implant treatment or bone augmentation procedures in combination with T2D may have resulted in significant tissue irritation and subsequent wound healing complications in the antral maxilla, leading to an ONF.ConclusionIn this case, an ONF occurring after HLFO was described for the first time. The melolabial interpolated island flap proved to be an outstanding long-term solution for the management of an anterior ONF occurring after HLFO over a period of 10 years. Less invasive treatment options including zygomatic implants should be taken into consideration for the treatment of such patients.

Extramaxillary Zygomatic Implant Coverage with a Pedicled Buccal Fat Pad Flap Through a Tunnel Approach: A Prospective Case Series.

To describe the benefits of covering the extrasinusal length of extramaxillary zygomatic implants with a pedicled buccal fat pad flap through a tunnel approach. Four extramaxillary zygomatic implants were placed in 10 patients and loaded immediately with an acrylic provisional fixed prosthesis. The extrasinusal length of every implant was covered with a pedicled buccal fat pad flap. Study variables were implant survival rate, peri-implant soft tissue recession (PISTR), peri-implant soft tissue condition (PISTC), modified Bleeding Index (mBI), and suppuration. The statistical analysis comprised the Brunner-Langer model of longitudinal data for each variable and the analysis of variance to assess main effects and interactions. All the zygomatic implants showed osseointegration, resulting in a survival rate of 100%. The PISTR was evaluated after surgery (T0) and after 12 months (T1), statistically significant differences being observed (P = .014). Recession also depended on specific implant positioning; zygomatic implants in the anterior were found to have a higher risk of recession vs implants in the posterior (P = .065). The PISTC was assessed at T0 and T1, and no statistically significant changes were observed (P = .718). Bleeding on probing was present in 10% of the implants at T0 and in 15% at T1, the difference being nonsignificant (P = .317). The use of a pedicled buccal fat pad flap to cover the extrasinusal length of extramaxillary zygomatic implants appears to reduce the risk of soft tissue recession and exposure of the implant surface to the oral cavity.