Effectiveness of zygomatic-implant fixed rehabilitation for the atrophic edentulous maxilla: protocol for a systematic review and network meta-analysis.

BACKGROUND: Atrophic edentulous maxilla is a debilitating condition caused by the progressive and irreversible bone resorption following loss of teeth, that results in bone of inadequate volume and density. This makes conventional implant therapy extremely challenging without complex reconstructive procedures. Several techniques such as sinus augmentation, short implants, and tilted implants have been used for the rehabilitation of the atrophic maxilla. In recent years, zygomatic implants have emerged as a graftless rehabilitation technique. However, few studies compare zygomatic-implant fixed rehabilitation with other fixed rehabilitation techniques. The existing body of evidence on zygomatic implants is largely based on clinical and disease-oriented outcomes. METHODS: A network meta-analysis (NMA) will be conducted in order to compare the effectiveness of zygomatic-implant fixed rehabilitation with the other rehabilitation techniques. Experimental and observational studies comparing different implant-assisted fixed rehabilitation in adults with atrophic maxilla will be included. The primary and secondary outcomes will be patient's satisfaction and quality of life respectively. Additional outcomes include the implant's survival/success, and biological and prosthetic complications. An electronic search will be performed through various databases for articles in English and French, without time limits. Risk of bias will be assessed using the Revised Cochrane Risk-of-Bias tool for randomized controlled trials, and ROBINS-I for non-randomized and observational studies. Two independent reviewers will screen the titles and abstracts and extract data. Any discrepancy between reviewers will be discussed and resolved through consensus or with the help of a third reviewer. Pairwise meta-analyses will be performed using a random effects model. I2, τ2, transitivity, subgroup/meta-regression analyses will assess and explain heterogeneity and distribution of effect modifiers. A network plot will be created to connect the different interventions directly and indirectly. Interventions will be ranked using the surface under cumulative ranking curve. Confidence in the results of the NMA will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). DISCUSSION: This study will be the first to assess the effectiveness of zygomatic-implant fixed rehabilitation for the atrophic maxilla using NMA. The evidence obtained will aid clinical decision-making and will advance the knowledge of the rehabilitation techniques for the atrophic maxilla. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42023353303.

Dental Versus Zygomatic Implants in the Treatment of Maxillectomy: A Finite Element Analysis.

This study analyzed the stress distributions on zygomatic and dental implants placed in the zygomatic bone, supporting bones, and superstructures under occlusal loads after maxillary reconstruction with obturator prostheses. A total of 12 scenarios of 3-dimensional finite element models were constructed based on computerized tomography scans of a hemimaxillectomy patient. Two obturator prostheses were analyzed for each model. A total force of 600 N was applied from the palatal to buccal bones at an angle of 45°. The maximum and minimum principal stress values for bone and von Mises stress values for dental implants and prostheses were calculated. When zygomatic implants were applied to the defect area, the maximum principal stresses were similar in intensity to the other models; however, the minimum principal stress values were higher than in scenarios without zygomatic implants. In models that used zygomatic implants in the defect area, von Mises stress levels were significantly higher in zygomatic implants than in dental implants. In scenarios where the prosthesis was supported by tissue in the nondefect area, the maximum and minimum principal stress values on cortical bone were higher than in scenarios where implants were applied to defect and nondefect areas. In patients who lack an alveolar crest after maxillectomy, a custom bar-retained prosthesis placed on the dental implant should reduce stress on the zygomatic bone. The stress was higher on zygomatic implants without alveolar crest support than on dental implants.

Round and flat zygomatic implants: effectiveness after a 3­year follow­up non­interventional study.

PURPOSE: This non-interventional study investigates variations in the type and frequency of late complications linked to novel zygomatic implant designs, installed adhering to the Zygoma Anatomy-Guided Approach (ZAGA) concept, over an extended follow-up period of at least 3 years. METHODS: Consecutive patients presenting indications for treatment with ZIs were treated according to ZAGA recommendations. Implants were immediately loaded. The ORIS success criteria for prosthetic offset, stability, sinus changes and soft-tissue status were used to evaluate the outcome. RESULTS: Twenty patients were treated. Ten patients received two ZIs and regular implants; one received three ZIs plus regular implants, and nine received four ZIs. Fifty-nine ZIs were placed: thirty-six (61%) Straumann ZAGA-Flat implants and twenty-three (39%) Straumann ZAGA-Round implants. Four patients (20%) presented earlier sinus floor discontinuities. Fifteen patients (75%) had prior sinus opacities. Nineteen patients were followed for between 38 and 53 months (mean 46.5 months). One patient dropped out after 20 months. When comparing pre-surgical CBCT with post-surgical CBCT, 84.7% of the sites presented identical or less sinus opacity; nine locations (15%) showed decreased, and another nine increased (15%) post-surgical sinus opacity. Fifty-three ZIs (89.8%) maintained stable soft tissue. Six ZIs had recessions with no signs of infection. ZIs and prosthesis survival rate was 100%. CONCLUSIONS: The study highlights the effectiveness of ZAGA-based zygomatic implant rehabilitations using Round and Flat designs. Despite patient number constraints, minimal changes in the frequency of late complications from the 1-year follow-up were observed. 100% implant and prosthesis survival rate over a mean follow-up of 46.5 months is reported.

Prosthetic rehabilitation of patients with maxillary oncology defects using zygomatic implants.

PURPOSE: Prosthetics for patients after oncological resection of the upper jaw is a complex problem associated with the physiological and anatomical separation of the oral cavity and the nasal/paranasal region. This study reports the clinical results of the use of the zygomatic implants for prosthetic rehabilitation in patients with maxillectomy due to upper jaw tumors. MATERIALS AND METHODS: The study included 16 patients who underwent prosthetic rehabilitation using a zygomatic implant after maxillectomy period from 2021 to 2023. After the tumor was removed, immediate surgical obturators were placed. Main prosthetic rehabilitation was performed 6-12 months after tumor removal, but before that, a temporary obturator was made and used. Six-twelve months after tumor resection, 1-4 zygomatic implants were inserted into the zygomatic bone unilaterally or bilaterally. A total of 42 zygomatic implants were installed, 2 of which were unsuccessful and were removed in 1 patient. The implants were placed using the surgical guide, which was planned and prepared digitally. RESULTS: No postsurgical complications were seen, and the patients were discharged from the hospital after 7-10 days. The patients were able to return to a normal diet (hard food) after just 7 days following surgery, with no further complaints regarding function or pain, apart from the residual edema caused by the intervention. CONCLUSIONS: The use of prostheses fixed on zygomatic implants in patients with maxillary defects is an effective method of prosthodontic rehabilitation in complex clinical cases after maxillectomy.

Image fusion-based low-dose CBCT enhancement method for visualizing miniscrew insertion in the infrazygomatic crest.

Digital dental technology covers oral cone-beam computed tomography (CBCT) image processing and low-dose CBCT dental applications. A low-dose CBCT image enhancement method based on image fusion is proposed to address the need for subzygomatic small screw insertion. Specifically, firstly, a sharpening correction module is proposed, where the CBCT image is sharpened to compensate for the loss of details in the underexposed/over-exposed region. Secondly, a visibility restoration module based on type II fuzzy sets is designed, and a contrast enhancement module using curve transformation is designed. In addition to this, we propose a perceptual fusion module that fuses visibility and contrast of oral CBCT images. As a result, the problems of overexposure/underexposure, low visibility, and low contrast that occur in oral CBCT images can be effectively addressed with consistent interpretability. The proposed algorithm was analyzed in comparison experiments with a variety of algorithms, as well as ablation experiments. After analysis, compared with advanced enhancement algorithms, this algorithm achieved excellent results in low-dose CBCT enhancement and effective observation of subzygomatic small screw implantation. Compared with the best performing method, the evaluation metric is 0.07-2 higher on both datasets. The project can be found at: https://github.com/sunpeipei2024/low-dose-CBCT .

Displacement of Zygomatic Implant in Infratemporal Region in a Case of COVID-19-Associated Mucormycosis.

Reconstruction of maxillary defects can be carried out using a variety of treatment modalities. The choice of modality depends on numerous factors, including the size and extent of the defect, patient characteristics, and existing comorbidities. One of the various options is reconstruction and rehabilitation using a fixed prosthesis supported over a zygomatic implant. In maxillectomy cases, a zygomatic implant can be used to improve the retention of the obturator prosthesis, as the loss of alveolar bone makes it impossible to use conventional endosseous implants. Although zygomatic implants are reported to have high success rates, they are not free of complication. We hereby present a rare complication associated with the placement of a zygomatic implant in a patient with COVID-19-associated mucormycosis who underwent operation. This rare complication has never been reported before. This case report also highlights on the management of complications involving displacement of a zygomatic implant in the infratemporal region.

Consideration of the diameter of superficial temporal arteries related to filler injections in the temporal region.

BACKGROUND: The concavity of the temple due to adipose tissue atrophy from aging accentuates the zygomatic arch and lateral orbital rim, leading to an aged appearance. The use of hyaluronic acid filler in the temporal region has gained popularity due to its procedural simplicity and consistent outcomes. OBJECTIVE: To evaluate the safety of administering hyaluronic acid filler in the temporal region concerning the frontal branch of the superficial temporal artery, which is at risk of injury. METHODS: Empirical observations were conducted on the internal diameter of the frontal branch of the superficial temporal artery, a critical anatomical site for potential injury. RESULTS: A significant proportion of the artery segments exhibited an internal diameter below 1 mm. Given that the outer diameter of an 18-gauge cannula is 1.27 mm, this method can be considered a relatively secure approach for enhancing the temporal region. CONCLUSION: The use of an 18-gauge cannula for hyaluronic acid filler administration in the temporal region appears to be a safe and effective method, with the potential risk to the frontal branch of the superficial temporal artery being minimal.

Guided placement of zygomatic implants in head and neck cancer patients: implant survival and patient outcomes at 1-3 years of follow-up.

Zygomatic implants (ZI) are a valuable option for supporting an obturator prosthesis after maxillary resection. This study was performed to assess the clinical outcomes of a digitally validated guided technique for ZI placement, followed by immediate prosthetic obturation. The primary objective was to evaluate implant survival, while the secondary objective was to assess patient-reported quality of life post-rehabilitation. Twelve patients treated for head and neck cancer received a total of 36 ZI after ablative surgery. The mean duration of ZI follow-up was 30.1 months. The survival rate of ZI placed in non-irradiated patients was 100%, while it was 85% in irradiated patients. Patient-reported outcomes were evaluated using the Liverpool Oral Rehabilitation Questionnaire (LORQv3) and the University of Washington Quality of Life Questionnaire (UW-QOL v4). Most patients reported satisfactory outcomes in the oral function domain of the LORQv3 (mean score 17.7 ± 4.5; possible range 12-48, with lower scores indicating better outcomes). Regarding the UW-QOL v4, the swallowing and chewing domains had the highest scores (mean 97.5 ± 8.7 and 95.8 ± 14.4, respectively; maximum possible score of 100). In conclusion, this treatment approach improves function and quality of life after maxillary ablative surgery. However, irradiated patients showed a noticeable trend of higher implant failure, and this was influenced by tumour position and size impacting the radiation dose to the zygomatic bone.

Retrospective comparison of two different miniscrew-supported molar distalization methods applied in the buccal and palatal regions.

BACKGROUND: To compare dentofacial effects of distalization with miniscrew-supported pendulum and infrazygomatic crest miniscrews. METHODS: The study included 36 patients whose lateral cephalometric radiographs were obtained before (T0) and after (T1) distalization. Patients were divided into two groups according to the treatment methods: 1) distalization with miniscrew-supported pendulum (MSP) (n = 19; 14 girls and 5 boys; mean age 16.9 ± 1.46 years) and 2) distalization with infrazygomatic crest (IZC) miniscrews (n = 17; 8 girls and 9 boys; mean age 17.0 ± 1.68 years). Dental, skeletal and soft tissue measurements were performed on lateral cephalograms taken from individuals. RESULTS: A significant molar distalization was achieved both in the MSP group (3.52 ± 0.76 mm at 8.71 ± 2.02 months) and the IZC group (3.5 ± 0.74 mm at 9.7 ± 2.5 months) (P < 0.001 for both). Premolar distalization was significantly lower in the MSP group (1.73 ± 1.09 mm) than in the IZC group (2.81 ± 0.79 mm) (P < 0.01). Significant molar tipping was observed in both groups (P < 0.001), while no significant difference was found between the groups (P > 0.05). Retrusion of maxillary incisors were significantly higher in the IZC group (2.75 mm) than in the MSP group (0.98 mm) (P < 0.01). A significant difference was found between the two groups with regard to the changes in overjet and overbite (P < 0.05). CONCLUSIONS: Both distalization methods were found to be effective in achieving a Class I molar relationship in patients with Class II malocclusion.

All-on-4 Concept With Use Of Zygoma Implants for Rehabilitation in the Severely Atrophied Maxilla With a Definitive Immediate Restoration.

This case report of a 45-year-old patient at initial presentation shows an illustration of the limitations of periodontal maintenance therapy and subsequent implant prosthetic therapy. In close consultation with the patient, treatment strategies were adopted to maximize the preservation of prognostically questionable teeth. Eight years later, the patient had a highly atrophied maxilla that could be successfully restored with implants. This was achieved with 2 zygoma implants and 2 anterior conventional implants, which were immediately loaded according to the All-on-4 concept and immediately provided with a definitive prosthetic restoration. The case report demonstrates to the general practitioner that using zygoma implants in such constellations may offer a solution to achieve a fixed, rapid, and financially acceptable prosthetic rehabilitation.

El reposicionamiento malar. Presentación de una técnica original: punto MM / Malar repositioning. Presentation of an original technique: point MM

El envejecimiento facial es una sinergia compleja de cambios texturales de la piel, hiper- o hipoactividad muscular, reabsorción del tejido graso y resorción ósea. El déficit de volumen resultante, la deflación y la posterior caída del tercio medio facial produce una cara menos atractiva y juvenil. Los procedimientos inyectables en región malar son cada vez más populares y solicitados por los pacientes. El conocimiento de la anatomía de la cara media es fundamental para el inyector. La comprensión de la irrigación facial puede ayudar a disminuir la exposición a la aparición de hematomas y complicaciones vasculares severas. Existen múltiples técnicas de inyección propuestas para el tercio medio, en este artículo presentamos una técnica original, simple, segura y eficaz con resultados satisfactorios y riesgo reducido

Facial aging is a complex synergy of textural skin changes, muscle hyperactivity, fat dysmorphism, bone resorption. The resulting volume deficit and deflation of the mid face produces a less attractive and youthful face. Injectable midface procedures are becoming increasingly popular and requested by patients. Knowledge of the anatomy of the midface is critical for the injector. Understanding the irrigation of the face can help decrease the risk of hematoma and severe vascular complications. There are multiple injection techniques proposed for the middle third, in this article we present a simple, safe and effective technique with satisfactory results and lower risk

Modeling stability post zygomatic fracture reconstruction.

Zygomaticomaxillary complex (ZMC) fracture repair is one of the most common surgical procedures performed in craniomaxillofacial trauma management. Miniplates and screws are used to stabilize the fractured bone using small local incisions, however, these procedures are not infrequently associated with hardware-related post-operative complications. The amount of fixation hardware utilized varies depending on the fracture pattern and surgical judgment, with three-point fixation being the conventionally accepted treatment. However, limited experimental testing and clinical studies have suggested that ZMC stabilization may be achieved with less than three-point fixation. In this study, we utilized a previously developed finite element modeling approach that allows for detailed bone and muscle representation to study the mechanical behavior of the fractured craniomaxillofacial skeleton (CMFS) under one, two, or three-point fixation of the ZMC. Results suggest that using a miniplate along the infraorbital rim in three-point fixation increases the amount of strain and load transfer to this region, rather than offloading the bone. Two-point (zygomaticomaxillary and zygomaticofrontal) fixation yielded strain patterns most similar to the intact CMFS. One-point (zygomaticofrontal) fixation resulted in higher tensile and compressive strains in the zygomaticofrontal region and the zygomatic arch, along with a higher tensile strain on the zygomatic body. These modeling results provide biomechanical evidence for the concept of over-engineering in the stabilization of facial fractures. Furthermore, they support previous suggestions that less than three-point fixation of ZMC fractures may be adequate to achieve uneventful healing.

The Spatial Relationship Between Coronoid Process and Zygomatic Complex After Reduction Malarplasty.

BACKGROUND: Reduction malarplasty presents challenges in terms of postoperative complications, particularly limited mouth opening. Excessive inward displacement of the zygomatic complex can impinge on the coronoid process resulting in restricted mouth opening. This study aimed to assess the spatial relationship between the coronoid process and the zygomatic complex after reduction malarplasty. METHODS: A retrospective study was conducted, including consecutive patients underwent reduction malarplasty. Radiological measurements were performed before surgery and during the final follow-up, including the coronoid-condylar index, distance between the coronoid process and zygomatic complex, and thickness and density of the temporal and masseter muscles. Clinical and radiographic data were recorded and analyzed. RESULTS: A total of 159 female patients were included with an average age of 28.1 years and a mean follow-up of 6.7 months. The mean coronoid-condylar index was 1:1.4, ranging from 1:0.6 to 1:2.6. Following surgery, the distances between the coronoid process and the anterior zygoma decreased by approximately 1 mm. Additionally, the postoperative distance between the highest point of the coronoid process and the zygomatic arch decreased by around 4 mm horizontally and changed approximately 1 mm vertically. No significant changes were observed in the thickness and density of the temporal and masseter muscles after surgery. CONCLUSIONS: Reduction malarplasty led to a slight decrease in the distance between the coronoid process and the zygoma. The operation generally resulted in proximity between the highest point of the coronoid process and the zygomatic arch. However, we believe that common reduction malarplasty rarely leads to osseous impingement. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Comparison of stress distribution around all-on-four implants of different angulations and zygoma implants: a 7-model finite element analysis.

BACKGROUND: In recent years, zygomatic implants and the all-on-four treatment concept have been increasingly preferred for rehabilitation of atrophic maxillae. However, debate continues regarding the optimal configuration and angulation of the implants. The aim of this study was to analyze the biomechanical stress in implants and peri-implant bone in an edentulous maxilla with zygomatic implants and the all-on-four concept, using multiple implant configurations. METHODS: A total of 7 models consisting different combinations of 4-tilted dental implants and zygomatic implants were included in the study. In each model, a total of 200 N perpendicular to the posterior teeth and 50 N with 45° to the lateral tooth were applied. A finite element analysis was performed for determination of stress distribution on implants and peri-implant bone for each model. RESULTS: Higher stress values were observed in both cortical and trabecular bone around the 45°-tilted posterior implants in all-on-four models when compared to zygomatic implants. In cortical bone, the highest stress was established in an all-on-four model including 45°-tilted posterior implant with 4,346 megapascal (MPa), while the lowest stress was determined in the model including anterior dental implant combined with zygomatic implants with 0.817 MPa. In trabecular bone, the highest stress was determined in an all-on-four model including 30°-tilted posterior implant with 0.872 MPa while the lowest stress was observed in quad-zygoma model with 0.119 MPa. Regarding von Mises values, the highest stress among anterior implants was observed in an all-on-four model including 17° buccally tilted anterior implant with 38.141 MPa, while the lowest was in the including anterior dental implant combined with zygomatic implants with 20,446 MPa. Among posterior implants, the highest von Mises value was observed in the all-on-four model including 30°-tilted posterior implant with 97.002 MPa and the lowest stress was in quad zygoma model with 35.802 MPa. CONCLUSIONS: Within the limits of the present study, the use of zygoma implants may provide benefit in decreasing biomechanical stress around both dental and zygoma implants. Regarding the all-on-four concept, a 17° buccal angulation of anterior implants may not cause a significant stress increase while tilting the posterior implant from 30° to 45° may cause an increase in the stress around these implants.

Three-dimensional Measurement of the Zygomatic-maxillary Complex in the Class III Malocclusion Patients with Maxillary Retrusion.

This study investigated the anatomic features of the zygomatic-maxillary complex in patients with maxillary retrusion without clefts. Individuals were grouped, and craniofacial measurements were performed for 21 individuals with skeletal Class III malocclusion with maxillary retrusion (CIII) and 48 individuals from the control group (CG). We evaluated the predetermined hard-tissue and soft-tissue points of the facial profile in each group. Independent sample t -tests were performed to determine the differences between groups (significance set at P <0.05). Multiple points on the midface, including the most posterior point on the contour of the maxillary alveolar process, lowest point of the zygomaticomaxillary suture, furthest point to the zygomatic self-base plane, superior point in the infraorbital foramen, and lowest point of the inferior margin of the orbit to the coronal plane were smaller in CIII than in CG (all P <0.05). The soft tissue thickness in these regions was significantly increased compared with that in the normal group. In summary, for class III malocclusion patients with maxillary retrusion, the deficiency in the midface gradually decreased going upward, with the deficiency at the maxillary alveolar level being the most serious. To some extent, soft tissues compensate for the deficiencies in the facial skeleton, and standard Le Fort I osteotomy advancement was sufficient to achieve a harmonious appearance.

Evaluation of Bone Thickness and Density Values in Resistance Regions in Rapid Maxillary Expansion Using Computed Tomography.

OBJECTIVES: This study used computed tomography (CT) to compare the bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures that are resistant to rapid maxillary expansion (RME) treatment according to age, sex, and cervical vertebrae maturation (CVM) stage. METHODS: The study included 200 paranasal sinus records obtained for medical diagnosis and examination in a radiology clinic. The records provided data on 110 males and 90 females aged between 4 and 28 years. Bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures were measured using CT imaging. The correlations of bone thickness and density values with the variables of age, sex, and CVM stage were evaluated. RESULTS: No statistically significant difference was revealed between the bone thickness values around the zygomaticomaxillary and zygomaticotemporal sutures and age, sex, CVM stage, and the right and left regions of the same individual ( P >0.05). A strong correlation was identified between Hounsfield units (Hu) values on bone density in all 3 regions and age and sex ( P <0.001). No correlation was found between the CVM stage and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures ( P >0.05). CONCLUSIONS: The Hu values of the records from females were higher than those of males in all age groups. It was observed that with increasing age, bone density values increased in all 3 regions, and thus circummaxillary region's Hu value increased.

Rotation of a Part of the Composite Flap for Simultaneous Gonion Reduction and Malar Augmentation During Rhytidectomy in Asians.

BACKGROUND: The desired facial shape that Asians aim to achieve through plastic surgery differs from that of westerners. OBJECTIVES: The author facilitates facial volume deflation by using the rotation of a part of the composite flap to the malar area resulting in volumetric augmentation during rhytidectomy; simultaneously, a volumetric reduction was implemented in the gonion. METHODS: Extended deep plane rhytidectomy with the rotation of a part of the composite flap was performed in 49 patients, whereas extended deep plane rhytidectomy without the rotation of a part of the composite flap was performed in 20 patients. For the results, the satisfaction survey of the surgery was conducted in all patients and by 2 surgeons during a follow-up visit 12 months later. To assess the surgical outcome objectively, the author used the Allergan photometric midface volume deficit scale to measure the midface volume. The midface contour and degree of projection were analyzed using lateral view photographs of the patients. The measurement of segment CM (distance between the lateral canthus and mouth corner) and segment MA (distance from segment CM to the most protruding malar area) was performed. RESULTS: The patients who underwent extended deep plane rhytidectomy with the rotation of a part of the composite flap reported higher overall satisfaction and achieved more favorable results, as evaluated by the 2 aesthetic surgeons (P < 0.05). The scores on the Allergan photometric midface volume deficit scale showed a significant increase before and after the surgery in both groups (P < 0.05), also as evaluated by the 2 aesthetic surgeons. However, the change in scores was found to be higher in the extended deep plane rhytidectomy with the rotation of a part of the composite flap group. The midface contour and degree of projection showed an increase of 20.6% on the right face and 22.7% on the left face, respectively (P < 0.001). CONCLUSION: Using the rotation of a part of the composite flap during rhytidectomy resulted in overall satisfactory outcomes for all patients. Based on these findings, it can be concluded that the use of this surgical method is beneficial and effective.