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 .

Successful Reduction of Unilateral Zygoma Fracture Following Bilateral Malar Reduction Surgery.

Malar reduction surgery can increase its susceptibility to fractures in case of trauma. Patients who had malar reduction surgery and sustained a zygoma fracture pose unique challenges for treatment and management. This is a case of a 28-year-old female patient who presented with a unilateral zygoma fracture following bilateral malar reduction and augmentation rhinoplasty 6 years ago. Physical examination revealed a clicking sound when opening the mouth at the right zygomatic buttress and a depressed preauricular area, suggesting arch fracture. Computed tomography imaging demonstrated a loosened screw at the right zygomatic buttress and a depressed arch fracture. She wanted to remove all plates and treat her right fractured zygoma with absorbable materials. Through the bilateral intraoral incisions, the authors removed the plates and screws and reduced the depression with the Langenbeck elevator through the same right intraoral incision without fixation. The reduction was well-maintained without complications based on postoperative plain x-rays 1 month after surgery. She reported that the pain was mostly gone and that she did not hear any abnormal sounds when opening her mouth after the surgery. In this case, if the zygomaticomaxillary buttress is minimally displaced, but the zygomatic arch fracture is significantly depressed, the authors believe that fracture reduction with only an intraoral incision would be enough to achieve an optimal outcome. If the plates and screws used in the previous malar reduction are not well maintained, it may be necessary to remove them.

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.

Transmalar Kirshner Wire Fixation Under Ultrasound Scanning is Useful for Unstable Zygomatic Arch Fracture Combined With Zygomatic Body Fracture.

Plate fixation to zygomatic arch fractures carries the risk of facial nerve palsy and scarring of the cheek; however, without plate fixation, bone deviation or displacement may reoccur after surgery. Furthermore, zygomatic arch fractures combined with zygomatic body fractures are more postoperatively unstable than single zygomatic arch fractures. Few reports have focused on this combined fracture type, and no consensus has been reached regarding treatment. Because plate fixation for slight deviation of the zygomatic body has little advantage for stabilization, the authors, usually opt for transmalar pinning alone instead of plate fixation at the hospital. This study is a retrospective case series of 7 patients, among 100 zygomatic fractures excluding isolated zygomatic arch fractures, treated using transmalar pinning under ultrasound scanning. The reduction was performed through the oral and temporal incision as a surgical procedure. Under ultrasound observation, a Kirshner wire was inserted into the zygomatic body from the unaffected side while maintaining the reduced position. The wire was removed at an outpatient visit 2 to 3 months following surgery. In all cases, the zygomatic body was of the laterally rotated type, and postoperative morphologic evaluation showed improvement without postoperative complications. Scores were higher in middle-aged and older than in young people. Correction of zygomatic rotation also scored higher than zygomatic arch morphology. Transmalar Kirshner wire fixation under ultrasound observation is a simple and minimally invasive method for zygomatic arch fractures, which avoids the possible complications related to plate fixation.

Volume Redistribution of the Buccal Fat Pad After Reduction Malarplasty.

BACKGROUND: During reduction malarplasty, cheek bulging could be found immediately after zygomatic complex is moved inwards, backwards and upwards. As patient is in the supine position during surgery, the effect of gravity is eliminated, so the only reason for the bulge is the redistribution of the soft tissue in the deep facial spaces. The buccal fat pad, with its main body behind the zygomatic arch and buccal extension in the cheek area, is most likely to be responsible for the bulge. METHODS: 3D buccal extension models were reconstructed from preoperative and long-term follow-up CT images and the volume measured. By comparing the pre- and postoperative 3D models, the shape deviation of the buccal extension and facial soft tissue can be identified. RESULTS: Eleven patients (22 buccal extensions) met the inclusion criteria. Compared with the preoperative buccal extension volume, the postoperative volume increased significantly. By comparing the reconstructed models, the buccal extension volume increase with anteroinferior protrusion can be visually detected, and cheek bulging was clearly identified on the lower face. The bulging area coincided with the projection of the buccal extension on the skin surface. CONCLUSIONS: Reduction malarplasty may cause volume redistribution of the buccal fat pad. Therefore, preoperative assessment of the size of the buccal fat pad based on CT images is recommended. The buccal extension volume increase with anteroinferior protrusion is an important cause of postoperative cheek bulging and should be considered during treatment. 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 .

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.

Investigating the Contraction Pattern of the Zygomaticus Major Muscle and its Clinical Relevance: A Functional MRI Study.

BACKGROUND: Our understanding of facial anatomy has significantly evolved, yet the detailed contraction patterns of facial muscles and their presentation during clinical imaging remain largely unexplored. Understanding the contraction patterns and visual presentation of these muscles, particularly the zygomaticus major could enhance pre-surgical facial assessments and the development of new treatment strategies. METHODS: A total of 34 healthy young individuals (17 female, 17 male) with a mean age of 23.6 (2.4) years [range: 20-30] were investigated regarding the length, thickness, width, and angle of the zygomaticus major muscle in five different facial expressions (i.e., repose, anger, joy, surprise, and sadness) utilizing MR imaging. RESULTS: Joyful expressions caused a reduction in muscle length to 85.6% of its original length and an increase in width (103.4%), thickness (108.4%), and facial angle (2.72°) when compared to that in repose, suggesting isotonic contraction. Conversely, expressions of anger, surprise, and sadness generally led to muscle stretching, seen through changes in length (98.9%, 104.3%, and 102.7%, respectively), width (98.8%, 96.5%, and 99.4%, respectively), and thickness (91.2%, 91.0%, and 102.7%, respectively), with variable alterations in facial angle (0.55°, 1.85°, and 1.00°, respectively) depending on the specific expression. CONCLUSION: This MRI-based study indicates that the zygomaticus major muscle experiences isotonic contraction, characterized by decreased length and increased width and thickness. The findings underline the importance of muscle thickness as a reliable parameter in assessing facial muscle function and offer valuable guidance for practitioners in accurately evaluating muscle performance during different facial expressions. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Prevalence of Zygomatic Air Cell defects in a sample of 6-18-year-old patients in Saudi Arabia and Yemen: a retrospective study.

OBJECTIVES: This study aimed to comprehensively analyze the prevalence and influencing factors of Zygomatic Air Cell Defects (ZACD) among pediatric and adolescent populations in Saudi Arabia and Yemen. MATERIALS AND METHODS: A cross-sectional retrospective study was conducted, utilizing digital panoramic radiographs of dental outpatients aged 6 to 18 years. The data were collected from registered digital databases of dental clinics in Al-Qassim, Saudi Arabia, and an oral and maxillofacial radiology center in Sana'a, Yemen, covering the period from July 2018 to September 2022. The radiographs were evaluated based on inclusion and exclusion criteria, and ZACD was assessed using standardized descriptions. Statistical analysis, including logistic regression, was employed to examine the impact of the associated factors. RESULTS: The study encompassed a total of 3,169 participants, revealing an overall ZACD prevalence of 28.5%. Age emerged as a significant predictor (p ≤ 0.0001), with the likelihood of ZACD increasing as the age of the individual advances. Gender and geographic region did not exhibit statistically significant differences in ZACD prevalence. CONCLUSION: This study provides crucial insights into the prevalence of Zygomatic Air Cell Defects among pediatric and adolescent populations in Saudi Arabia and Yemen. It underscores the prevalence of ZACD and the notable influence of age on its occurrence. Additionally, the research challenges prior notions of gender and regional variations in ZACD prevalence, emphasizing the complexity of the factors involved. Early detection is essential to avoid unwanted complications during any surgical intervention in this area.

The Value of Intraoperative Computed Tomography in the Treatment of Zygomatic Complex Fractures.

BACKGROUND: Due to the complex anatomical morphology and lack of anatomic markers on the surface of zygomatic complex (ZMC), the treatment results of ZMC fractures are often suboptimal. PURPOSE: The study aimed to evaluate the effectiveness of intraoperative computed tomography (ICT) in the treatment of unilateral ZMC fractures, and further study the feasibility of ICT to replace early postoperative Computed Tomography (CT). STUDY DESIGN, SETTING, AND SAMPLE: The investigators designed a retrospective cohort study. Adult patients who underwent surgery with unilateral ZMC fractures were enrolled. PREDICTOR VARIABLE: According to whether intraoperative CT was used, the subjects were divided into the ICT group and the control group (without ICT). MAIN OUTCOME VARIABLES: Five distances and 3 angles representing bilateral ZMC symmetry were main outcome variables. The differences of outcome variables were compared between the 2 groups and the indices of ICT group were further compared with their postoperative indices. COVARIATES: Demographics (eg age), etiology (eg traffic injury), dysfunction (eg diplopia), and surgical approach (eg vestibular incision) were collected as covariates while we conducted clinical investigation, examination, and implementation. ANALYSES: The data were analyzed using independent-samples t test, paired-samples t test, Mann-Whitney U test, and χ2 test. P value < .05 was considered statistically significant. RESULTS: A total of 60 patients (18 to 59 years) were enrolled in this study. All median values of the measurements in the ICT group were smaller than those in the control group, and the differences of horizontal displacement distance (0.56 vs 1.02 mm), anteroposterior displacement distance (1.69 vs 2.34 mm, 0.90 vs 2.35 mm), horizontal angle of bilateral zygomatic arch (2.31 vs 4.19°), and horizontal angle of bilateral zygomatic process (1.77 vs 2.94°) were significantly different between the 2 groups with P value < .05. Moreover, there was no statistically significant difference in all indices between the intraoperatively and postoperatively injured sides in the ICT group. CONCLUSIONS: ICT can improve the treatment outcomes of ZMC fractures by evaluating the fracture reduction adequacy during surgery. Moreover, ICT can replace early postoperative CT.

A Novel Technique for the Correction of Unilateral Craniofacial Fibrous Dysplasia Using Multiplanar Sequential Cutting Guides.

In this unique case report, the authors have described a new method for the correction of unilateral craniofacial fibrous dysplasia by using sequential cutting guides. Due to the complex 3-dimensional anatomy of zygoma, it needs to be chiseled in multiple planes to mimic the normal contralateral side. To achieve this, 3 different guides were used one after the other to perform osteotomies in different planes and remove the excess fibrous bone.

Precise Coronoidectomy and Zygomatic Arch Reduction for Unilateral Hyperplasia of the Coronoid Process (Jacob's Disease) via Computer-aided Design and Manufacture.

Jacob disease is the new formation of a pseudo-joint between both of enlarged coronoid process and even zygomatic arch. A 23-year-old female patient with facial asymmetry and limited mouth opening was reported. Computed tomography images showed the classic symptom of Jacob disease with a mushroom-shaped tumor mass from the coronoid process a pseudoarthrosis joint with zygomatic arch. Coronoidectomy and zygomatic arch reduction were planned to operate based on computer-aided design/computer-aided manufacturing. During the actual operation, the excision of coronoid process and reconstruction of zygomatic arch were all navigated by 3-dimensional-printed surgical templates as designed through an intraoral approach. As a result, the enlarged coronoid process was smoothly removed without sequela and mouth opening along with facial symmetry were successfully improved. The authors suggested that computer-aided design/computer-aided manufacturing should be considered as an auxiliary technique to shorten operation time and enhance surgical accuracy.

Treatment of Sagittal Fracture of the Zygomatic Arch Root.

A sagittal fracture at the temporal root of the zygomatic arch (ZAR) often occurs as a component of zygomaticomaxillary complex (ZMC) fractures. However, this area is difficult to access, and anchorage is limited due to the unstable structure around it. Therefore, a preauricular approach using single-screw fixation is proposed, and this study reports its results and usefulness. Forty-four patients with sagittal fractures of ZAR occurring with ZMC fractures were evaluated from 2012 to 2021. Open reduction and internal fixation were performed on all patients with ZMC fractures. Closed reduction using Dingman incision and external finger pressure in group A (indirect approach; 30 patients) and single-screw fixation using a preauricular approach in group B (direct approach; 14 patients) were performed to address sagittal fractures in ZAR. For single-screw fixation, the additional mean operation time was 11.34±3.25 minutes. On postoperative 3-dimensional computed tomography and plain radiographs, group B showed more accurate reduction and less deformity and trismus ( P <0.05). Moreover, a normal diet was initiated more quickly in group B than in group A ( P <0.05). Some cases in group A showed nonunion or malunion. This study revealed that a direct approach (group B) toward sagittal fractures of ZAR is recommended due to more accurate results and fewer complications than those observed with the indirect approach (group A). Moreover, the total operation time and complications may be lesser than those with the bicoronal approach.

Application of Computer-Assisted Preoperative Planning in Treating Congenital Bilateral Zygomatico-Maxillo-Mandibular Fusion: A Case Report and Literature Review.

Congenital fusion of the jaws (syngnathia) is a rare facial malformation with an unknown etiology. This disease may vary in severity with adhesion of soft tissue and bony fusion. It can be anterior fusion, unilateral or bilateral fusion, and complete fusion. The main problem of these patients is the difficulty of airway maintenance and feeding, and the most common postoperative complication is the relapse of bony fusion. Here, we report a young male patient with bony syngnathia, involving bilateral fusion of the ascending ramus and body of the mandible with the maxillary complex. We performed bone isolation by computer-assisted preoperative planning and used an insertional temporalis flap to fix the wound surface to prevent refusion of bone.

Anatomical Basis for Malar Augmentation Injection With the Zygomatic Ligamentous System.

BACKGROUND: The malar augmentation injection has gained popularity in recent years, but the exact location of each injection site has not been clearly identified. OBJECTIVE: To discover ideal injection sites by comprehensively considering the distributions of ligaments, muscles, and vessels. MATERIALS AND METHODS: Eighteen cadaver heads were dissected to investigate the zygomatic ligamentous system and to measure the position of muscles. Sixty-six cadaver heads were subjected to computed tomographic scanning and three-dimensional vessel reconstruction. Radiological evaluation of the fillers was performed before and after experimental injection in one hemiface and dissected to confirm safe delivery. Five patients were enrolled in a prospective clinical study. 2D and 3D photographs were taken before and after the injections for comparison. RESULTS: Site 1 was defined along the zygomatic arch, except the first 1/4 length and the midline of the arch. Site 2 was on the body of the zygoma, superior to the level of the infraorbital foramen and medial to the jugale. Site 3 was defined in the anteromedial midface approximately 30 mm below the lateral canthus. CONCLUSION: Injections at these 3 sites can be performed within the range of the ligaments to achieve effective lifting effects and minimize potential complications.

The Relationship Between Morphometric Measurements, Severity, and Success of Zygomatic Arch Fracture Reduction.

PURPOSE: Identify associations between preoperative radiographic measurements and clinical findings of zygomatic arch fractures and postoperative radiographic measurements. Based on those findings, propose a comprehensive treatment algorithm for the solitary zygomatic arch fracture and combined zygomatic arch-zygomatic complex fracture. METHODS: Retrospective cohort study with patients referred to our department for zygomatic arch fractures between 2013 and 2018. Data analyzed included patient demographics, clinical evaluation, and radiographic information. Predictor variables were preoperative morphometric measurements: the initial latero-lateral (LL) defect was determined by the difference between the preoperative LL distances of the fractured and the healthy arches, LL distance was measured from the midsagittal plane in the cranium to the inner cortex of the most displaced arch segment, initial arch coronoid distances were measured from the medial part of the most dislocated arch fragment to the lateral aspect of the coronoid, and the anterior-posterior telescoping was measured as the distance between the 2 points in the arch that lost continuity and overlapped as a result of the fracture. The outcome was defined as the residual defect. It was calculated as the ratio between the postoperative remaining LL distance and the initial LL defect. RESULTS: A total of 179 cases were enrolled, all involving head residual defects. Statistical analysis was performed only on 149 medially displaced fractures. Results show that an initial LL defect larger than 3.5 mm has an 86.3% chance of remaining with a better residual defect (<84.1%), P = .001. Cases with antero-posterior (AP) telescoping > 1.45 mm showed a 72.4% chance of remaining with a poor residual defect >84% (P = .003). Arch-coronoid initial distance showed little effect on the chance of remaining with a large remining defect (P = .417, CI = 95%) CONCLUSION: Based on our results, we found that morphometric measurements can be used to predict the reduction results and can assist the clinician in choosing the optimal reduction method and thus increasing the success rate.

Zygoma Augmentation With 3D Printed Bioactive Glass-Ceramic Implant.

ABSTRACT: Zygoma, which is located at the middle third of the face, has a significant impact on the facial impression with its volume and prominence. CaO-SiO 2 -P 2 O 5 -B 2 O 3 glass-ceramics (BGS-7) has been reported as a new alternative of nonresorbable bone grafting material, which has bioactivity of inducing human osteoblast between bone and implant, resulting integration to the bone. Furthermore, its chemical characteristics are similar to bone, resulting in radiopacity with no metallic artifact on the radiographic images. With the development of Computer aided design-Computer aided manufacturing technology, BGS-7 can be manufactured into a patient-specific design.During follow-up periods, 3D printed BGS-7 implant did not displace from the initial recipient site. By cone-beam computed tomography evaluation, a gap between bone and BGS-7 was filled with the radiopacity, which implied bony fusion. Consequently, this clinical case shows that the BGS-7 implant could be an effective and safe graft material for zygoma bone defects.

The Volume Difference Along the External Surface of the Zygomatic Bone: A Novel Method of Measuring Zygomatic Bone Asymmetry.

ABSTRACT: This study introduced the volume difference along the external surface (VDAES) of the zygomatic bone as a novel approach to assess zygomatic bone asymmetry and was the first to describe a distinctive, 4-step method of measuring it. VDAES has a potential to be used as an objective tool to evaluate dislocation and can assist surgeons in predicting risks of long-term cosmetic complications in patients with zygomaticomaxillary complex fractures. After having measured 100 healthy study participants, the observed median VDAES was 1.48 cm3 for all study participants, 2.02 cm3 for males, and 1.09 cm3 for females, with the gender difference being significant (P = 0.003). Additional studies are needed to test the hypothesis of whether VDAES is more relevant than conventional methods of clinically evaluating zygomatic bone asymmetry.

Design and Use of a Pair of Computer-Designed Surgical Templates in Reduction of a Comminuted Zygomatic Arch Fracture.

BACKGROUND: Isolated depressed zygomatic arch fractures are often treated with closed reduction. Reduction is usually performed through the Gillies approach or Keen approach. comminuted zygomatic arch fractures generally require open reduction and fixation to achieve good results. This article describes how to use a pair of surgical templates to assist in the fixation of comminuted zygomatic arch fractures with absorbable plates. METHODS: A pair of computer-designed surgical templates were applied to restore the main part of zygomatic arch. Placing a surgical template on the medial side of the zygomatic arch can provide a supporting force and improves the stability of the reduced bone fragments. The lateral template of zygomatic arch limits the excessive uplift of bone fragments. RESULTS AND DISCUSSION: The operation was performed according to the predetermined procedure. Postoperative computed tomography showed satisfactory reduction effect. In conclusion, with the aid of surgical templates, the reduction and fixation of comminuted zygomatic arch fractures can be more easily performed using absorbable plates.

Reduction Malarplasty Using Customized Surgical Stent Based on 3D Virtual Surgery, CAD/CAM, and 3D Printing Technology: Case Series.

ABSTRACT: The zygomatic bone is a structure that protrudes symmetrically on both sides of the midface and plays an important role in the overall aesthetic appearance of the face. Unlike Caucasians, the mesocephalic facial shape is predominant in Asians, and therefore, many people have a relatively laterally developed zygomatic bone. In Asians, when the zygomatic bone is excessively developed, it gives a strong and stubborn image, and aesthetically, many people want to reduce the zygomatic bone because they prefer an oval and slim face.To reduce the excessive zygomatic bone, a reduction malar- plasty through an intraoral and preauricular approach has been performed. Although reducing the zygomatic bone is not a big problem in most cases of symmetric reduction malarplasty, it is not easy to produce surgical results as intended by the surgeon in asymmetric malar patients or patients requiring a three-dimensional (3D) change of zygoma. In addition, because of the mobility of the zygoma segment, it may be difficult to drill holes and fix plate after osteotomy. Moreover, these factors can increase the possibility of malunion or nonunion.In this study, cutting guides made with the aid of 3D virtual surgery, 3D printing, and customized titanium plates manufactured with the computer-aided design/computer-aided manufacturing technology are used for 8 patients to maximize the recovery of 3D symmetry and minimize complications through accurate fixation after surgery. During the surgical procedures, screw hole drilling and osteotomy were performed using a cutting guide, and then, the malar segment was fixed by matching the premade customized plates with the predrilled holes. As a result of checking the accuracy of the surgery by superimposing the postoperative 3D cone beam computed tomography image and virtual surgery data based on the skull base, the 2 images almost overlapped and no significant differences were observed, so it was confirmed that the operation was performed exactly as planned.When using the 3D technology, it is possible to perform a more accurate surgery in patients with asymmetry due to congenital anomalies or trauma as well as simple asymmetry, so it can be concluded that using the 3D technology can overcome the limitations and disadvantages of the conventional method as in the cases in this study. The accurate prediction of soft tissue is still insufficient, and further research is needed to overcome this limitation.