Rehabilitation of Atrophic Maxilla With Immediate Loading of Extrasinus Zygomatic Implant.

Dental implants are used for replacing missing teeth. Placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. Several bone augmentation procedures have been developed to solve this problem. Zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. One to three zygomatic implants can be inserted through the posterior alveolar crest and maxillary sinus to engage the body of the zygomatic bone. A couple of conventional dental implants are also needed in the frontal region of the maxilla to stabilize the prosthesis. The potential main advantages of zygomatic implants could be that in some situations bone grafting may not be needed and a fixed denture could be fitted sooner. Another specific indication for using zygomatic implants could be the need of maxillary reconstruction after maxillectomy in cancer patients. To test the hypothesis of no difference in outcomes between zygomatic implants with and without bone augmenting procedures in comparison with conventional dental implants in augmented bone for severely resorbed maxillae. We searched the Cochrane Oral Health Group's Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and all known zygomatic implant manufacturers were contacted to identify unpublished trials. Most recent search: May 2005. Randomised controlled clinical trials (RCTs) including patients with severely resorbed maxillae who could not be rehabilitated with conventional dental implants, treated with zygomatic implants with and without bone grafts versus patients treated with conventional dental implants in conjunction with bone augmentation procedures having a follow up of at least 1 year. Outcome measures considered were: prosthesis and implant failures, side effects, patient satisfaction and cost effectiveness. Screening of eligible studies, assessment of the methodological quality of trials and data extraction were to be conducted in duplicate and independently by two authors. Results were to be expressed as random-effects models using weighted mean differences for continuous outcomes and risk ratio for dichotomous outcomes with 95% confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors. No RCTs or controlled clinical trials (CCTs) were identified. There is the need for RCTs in this area to assess whether zygomatic implants offer some advantages over alternative bone augmentation techniques for treating atrophic maxillae.

Zygomatic implants for toothless, atrophic posterior maxilla are effective treatment options and it is known that graft use has a positive effect on the zygomatic implant stability with this treatment option. The aim of this study was to evaluate the stress values and their distribution at zygomatic implant-supported prosthetic infrastructure in augmented and non-augmented models. In this study, the three-dimensional finite element method was used and 2 zygomatic implants (47.5 × 4.0 mm), 2 conventional implants (13 × 3.75 mm) and atrophic maxilla with augmented and non-augmented maxillary sinus with prosthetic infrastructure, were modelled. A vertical load of 150 N was applied onto the maxillary model at 4 different regions (#9, #12, #14 and #15). The von Mises stress, which is produced as a result of loading of zygomatic implants and prosthetic infrastructure has been evaluated in augmented and non-augmented models. The highest von Mises stress value for the prosthetic infrastructure was determined in the non-augmented model as a result of the loading to region #9 (MPa 222,886). Consequently, grafting procedures will increase bone support and reduce stresses in the prosthetic substructure, especially in posterior loads in the maxilla with low bone density.

Purpose: The aim of the study was to evaluate and apply a minimal invasive approach for reconstruction of atrophic maxilla using computer-guided implant surgery by zygomatic implants combined with conventional implants. Material and methods: 10 patients with severely atrophic edentulous upper arch were included in this study, each patient had 2 conventional implants placed in the anterior maxilla, and 2 zygomatic implants on either sides placed in the zygomatic bone. In all patients a computer guided approach using a computer guided stent was used for drilling the conventional and zygomatic implants. All patients followed a clinical and radiographic follow up Result: Zygomatic Implants success was 90.0% while conventional implants success was 80.0%. The mean ± standard deviation values of coronal deviation were 3.24 ± 1.9 mm for Zygomatic implants and 2.9 ± 2.5 mm for conventional implant. The mean ± standard deviation values of apical deviation for were 4.2 ± 2.5 mm for zygomatic implants and 2.6 ± 2.5 mm for conventional implants. The mean ± standard deviation values of bone implant contact for zygomatic implant were 19.5 ± 5.3 mm, the bone covering the zygomatic implant laterally were 6 ± 2.3 mm, the minimum distance from the orbit were 5.6 ± 3.2 mm. General satisfactions for the treatment was 8.6. Conclusion: The use of zygomatic implants combined with conventional implants using virtual computer guided planning and surgery was useful for reconstruction of atrophic maxilla allowing an accurate, safe, graft less, less invasive surgery and provided a high patient satisfaction.

The extreme maxillary atrophy that indicates the use of zygomatic implants (ZI) is associated with resorptive changes in both alveolar and basal bone, and prevents direct placement of conventional endosseous implants. Therefore, using conventional criteria to describe implant success/failure is not sensible for ZI. Moreover, protocols for the rehabilitation of the atrophic maxilla using ZI have been continuously evolving to overcome initial shortcomings of early initial shortcomings of early techniques. The current zygomatic approach is relatively new, especially if the head of the ZI is located in an extra-maxillary buccal position to the alveolar crest with no alveolar bone around its perimeter. The zygomatic-related rehabilitation protocol differs from conventional implant therapy with respect to biomechanics, clinical procedures, outcomes, and eventual complications such as soft tissue incompetence or recession that may lead to recurrent sinus/soft tissue infections and aesthetic patient complaints. Currently, the way in which results and complications of ZI are reported in the scientific literature is inconsistent and lacks a standardized approach. Specific criteria to describe success/survival of ZI, including a standardized way to report on rhinosinus pathology associated with ZI, is necessary. The aim of this chapter is to critically review success criteria used for conventional and zygomatic implants. Finally, a revisited Zygomatic Success Code describing specific criteria to score the outcome of a rehabilitation anchored on ZI is proposed. The authors use the ORIS acronym to name four specific criteria to systematically describe the outcome of ZI rehabilitation: Offset: evaluation of prosthetic success based on the final positioning of the zygomatic implant with respect to the middle of the alveolar crest in the horizontal dimension. Rhinosinus status report: a pre, and postsurgical cone-beam computed tomography comparative approach to evaluating whether sinuses are healthy; a clinical questionnaire where “yes” and “no” answers can be given. Infection permanence related to dehiscence: an evaluation of soft tissue signs of infection or dehiscence on a grading scale based on reference photographs. Stability report: accepting as success some mobility until dis-osseointegration signs of rotation or apical pain present.

One of the most critical complications that can occur after placing zygomatic implants is the accidental penetration of the patient's eye socket by a drill or implant. This article aims to find some relationships between the anatomical features of the lower orbital wall, different configuration of zygomatic implants, and other factors when planning the placement of zygomatic implants. A total of 81 patients underwent zygomatic implant procedures, receiving different combinations of implants. These included four zygomatic implants along with one or two conventional implants (Group I), four zygomatic implants alone (Group II), two zygomatic implants paired with four conventional implants (Group III), or three zygomatic implants alongside one or two conventional implants (Group IV). The aim of the study was to describe the complications and clinical outcomes of treatment in 81 patients who received zygomatic implants. The following parameters were statistically significant between all four groups of patients: height and distance of two zygomatic implants in the zygomatic bone; surgery type and duration; the distance between zygomatic implants in the zygomatic bone; and zygomatic orbital floor (ZOF) classification at the left side showed significant differences; intramaxillary insertion of zygomatic implants reduced the rupture of Schneiderian's membrane; the average of zygomatic implants' length in all groups was 42.8mm. Not damaging the ZOF is profoundly important for preventing orbital damage during osteotomy for zygomatic implants and should be measured before every surgery.

Rehabilitation of Reabsorbed Maxillae With Implants in Buttresses in Patients With Combination Syndrome

Bone Reformation: Contemporary Bone Augmentation Procedures in Oral and Maxillofacial Implant Surgery

The first patient treated with zygomatic implants in Hong Kong presented with a partial maxillectomy defect after tumor resection and required unilateral reconstruction. Two zygomatic implants were installed on the same side together with two conventional implants to provide support for a fixed prosthesis. Since this first patient was treated successfully in 1999, we have employed zygomatic implants to reconstruct several hundreds of patients presenting with an atrophic edentulous maxilla in addition to a few oncology patients who received a maxillectomy. In the UK, our experience extended from patients with severe maxillary atrophy to oncology patients with extreme problems requiring unique customized solutions. Along the way, we encountered various difficulties when treating these patient groups, and sought solutions to the problems we encountered, such as the palatal location of the head of the zygomatic implants, bulky prostheses, maxillary sinusitis, and tissue recession with exposure of the threaded shaft of the implant, all well-recognized issues associated with zygomatic implant treatment. In the last two decades, the authors have modified Branemark’s original zygomatic implant protocol in several ways in order to minimize problems and optimize outcomes. These modifications included adoption of an immediate loading protocol to restore patients’ oral function as early as possible, incorporating an extended open sinus lift procedure to keep the zygomatic implant external to the maxillary sinus, customization of zygomatic implants to suit patients’ individual needs, optimal positioning of the zygomatic implants for better biomechanics, and guided surgery to better control the zygomatic implant osteotomy. In this chapter, these innovative modifications and optimizations is presented along with some of the evolving features of newer commercially available implants.

Severe atrophy of the maxilla can be due to various factors such as tumor resection, generalized aggressive periodontitis, genetic disorders or syndromes. Fabrication of a prosthesis with adequate retention and stability for patients with an atrophic edentulous maxilla presents a significant challenge. Treatment concepts with zygomatic implants have evolved as an alternative for bone augmentation procedures. This review describes the restoration of the maxillary dentition using four zygomatic implants (quad zygomatic implant technique). Within the limitations of this observation, we can state that full mouth rehabilitation with quadruple zygomatic implant technique can definitely be considered as a viable treatment option treating patients with atrophic maxillae. However, studies with more follow-up time and controlled clinical trials should be done in order to document the longevity of this treatment modality.

The presence of sufficient bone volumes is one of the most important criteria for the success of oral implant osseointegration. Therefore, the rehabilitation of edentulous atrophic maxillae represents the greatest challenge in terms of oral rehabilitation. Techniques such as bone grafts, angled implants, short implants, tuberosity, and pterygoid implants may not always be a viable alternative in the subsequent rehabilitation of the posterior atrophic maxilla. A breakthrough occurred when Brånemark first introduced longer, custom-designed implants inserted into the zygomatic bone to support craniofacial prosthesis in the 1980s. When used in the treatment of atrophic jaws, zygomatic implants provide a safe and effective alternative, with stable long-term results. Objectives: We aimed to retrospectively evaluate zygomatic bone resorption ten years after the placement of zygomatic implants. Methods: A retrospective observational study was designed to evaluate bone resorption over ten years following the placement of zygomatic implants. In a study group of 50 patients, using Hounsfield scales, the area of the zygoma and its bone density were established and evaluated. The NewTom NNT Analysis software (NewTom®, Imola, Italy) was employed to trace the bone and implant limits on CBCT scans. Using this software, the three-dimensional information of the postoperative CBCT image was compared with the ten-year postoperative CBCT image, allowing for the assessment of the zygomatic bone resorption and bone density. Results: Highly significant statistical differences to an alpha level of 0.01 were identified between T0 (pre-op), T1 (12 months), and T2 (120 months) concerning zygomatic bone density, both in the first and in the second quadrants. The post hoc Bonferroni test revealed that significant statistical differences were observed between T0 and the remaining timepoints (T1 and T2), with the latter two exhibiting similar values. Conclusions: The evaluation of the resorption at the level of the zygoma, ten years after the placement of zygomatic implants, reveals that there are no significant losses between the initial and final controls. Therefore, it follows that this type of implant rehabilitation represents a viable alternative approach in patients with bone atrophy of the maxilla, offering a predictable therapeutic solution that enables immediate full function and excellent long-term success rates. However, we must not neglect the potential for future innovations in GBR involving the use of barrier membranes, either resorbable or non-resorbable, and even the application of titanium alveolar customized osteogenic scaffold, in conjunction with autologous bone grafts or biomaterials.

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

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.

Severely resorbed or atrophic maxilla has always posed a problem in terms of conventional implant therapy due to insufficient bone. A new approach to such situations is placing implants in the zygoma. Zygomatic implants are placed in patients with inadequate bone due to resection of the maxilla after surgery or in cases of resorbed maxilla. These are longer implants anchoraged in the zygoma, and present as an alternative to sinus augmentation or bone grafting. Being a technique sensitive procedure extreme care has to be taken during the placement of these implants to obtain promising results. This article reviews the zygomatic implants used in dentistry.

This retrospective study evaluates the survival rates, complications, and patient satisfaction associated with zygomatic implants in severe maxillary atrophy, focusing on 2 approaches: Quad Zygoma (4 zygomatic implants) and Hybrid Zygoma (2 zygomatic and 2 standard implants). A total of 76 patients classified as Cawood Grade VI, treated between 2007 and 2021, were included in this study. The primary outcome measure assessed was implant survival rate, while secondary outcomes included complications, patient satisfaction, and willingness to undergo the procedure again. The study included 69 patients with atrophic maxilla and 8 with tumor resection, receiving a total of 262 zygomatic implants, 220 in the Quad Zygoma group and 42 in the Hybrid Zygoma group. The mean follow-up duration was 67.6 ± 49.7 months. Eight implant failures were recorded (3 early and 5 delayed), resulting in an overall survival rate of 96.9%. Biological complications were observed in 27.6% of patients, with sinusitis in 16 patients and soft tissue issues in 5. Technical complications occurred in 6.5% of cases, including screw fractures and loosening of the screws. A patient satisfaction survey of 40 patients indicated high levels of satisfaction, with most expressing a willingness to undergo the procedure again. In conclusion, Zygomatic implants have been shown to have favorable outcomes in patients with severe upper Maxillary atrophies. Both the Quad and Hybrid techniques have shown promising long-term results. However, some complications can occur due to the implants' proximity to important anatomical areas.

The rehabilitation of atrophic jaws represents a complex challenge, leading to the search for innovative approaches. Conventional procedures, such as sinus lifts, have limitations, driving interest in zygomatic implants. However, complications persist, especially in areas of pronounced concavity. This case report aims to demonstrate the effectiveness of an innovative surgical approach, combining zygomatic and transnasal implants, to overcome anatomical limitations and achieve satisfactory aesthetic and functional results. A 58-year-old female patient, completely toothless, underwent rehabilitation at the Instituto Rosenvaldo Moreira, due to pronounced maxillary atrophy. Two treatment plans were proposed, involving zygomatic and transnasal implants. The surgery, performed in an outpatient setting under intravenous sedation and local anesthesia, included the sequential installation of transnasal and zygomatic implants, with special attention to machining the cervical third to prevent complications. The surgical approach used, combining zygomatic and transnasal implants, proved to be effective in the rehabilitation of the atrophic maxilla. Careful machining helped to avoid complications, demonstrating stability and absence of peri-implant inflammation in the one-year follow-up. This report offers a valuable contribution, highlighting the feasibility and success of this innovative approach in challenging situations of maxillary atrophy in implant dentistry. Keywords: atrophic maxillary; zygomatic implants; macrogeometry of zygomatic implants; machining of threads in zygomatic implants.