Advancements in computer-assisted orthognathic surgery: A comprehensive review and clinical application in South Korea.

OBJECTIVES: Orthognathic surgery (OS) has evolved with technological advancements, notably through the implementation of computer-assisted orthognathic surgery (CAOS). This article aims to elucidate various types of CAOS and their efficiency and accuracy, supplemented by a thorough literature review focusing on their clinical applications in South Korea. STUDY SELECTION, DATA, AND SOURCES: A comprehensive search strategy was employed, including systematic reviews, meta-analyses, randomized controlled trials, and observational studies published until December 2023 in the PubMed, MEDLINE, and Google Scholar databases. The literature search was limited to articles written in English. RESULTS: Static CAOS demonstrated high precision, reduced operative time, and high accuracy, suggesting its potential reliability in orthognathic procedures. Dynamic CAOS presented a promising avenue for exploration, showing an accuracy comparable to that of traditional methods. The critical considerations for CAOS include accuracy, time efficiency, and cost-effectiveness. Recent studies have indicated advancements in the time efficiency of static CAOS. Static CAOS requires less equipment and is more cost-effective than dynamic CAOS. CONCLUSIONS: CAOS offers clear advantages over conventional OS in terms of surgical convenience and accuracy in implementing the surgical plan. To achieve recognition as the gold standard method for maxillofacial deformity treatment, CAOS must overcome its limitations and undergo continuous verification via well-designed studies. CLINICAL SIGNIFICANCE: The introduction of CAOS, mainly static CAOS with high precision and reduced surgical time, signifies a notable advancement in OS. However, rigorous studies are warranted to validate CAOS as the gold standard for treating maxillofacial deformities.

A Comparative Analysis of Artificial Intelligence and Manual Methods for Three-Dimensional Anatomical Landmark Identification in Dentofacial Treatment Planning.

With the growing demand for orthognathic surgery and other facial treatments, the accurate identification of anatomical landmarks has become crucial. Recent advancements have shifted towards using three-dimensional radiologic analysis instead of traditional two-dimensional methods, as it allows for more precise treatment planning, primarily relying on direct identification by clinicians. However, manual tracing can be time-consuming, mainly when dealing with a large number of patients. This study compared the accuracy and reliability of identifying anatomical landmarks using artificial intelligence (AI) and manual identification. Thirty patients over 19 years old who underwent pre-orthodontic and orthognathic surgery treatment and had pre-orthodontic three-dimensional radiologic scans were selected. Thirteen anatomical indicators were identified using both AI and manual methods. The landmarks were identified by AI and four experienced clinicians, and multiple ANOVA was performed to analyze the results. The study results revealed minimal significant differences between AI and manual tracing, with a maximum deviation of less than 2.83 mm. This indicates that utilizing AI to identify anatomical landmarks can be a reliable method in planning orthognathic surgery. Our findings suggest that using AI for anatomical landmark identification can enhance treatment accuracy and reliability, ultimately benefiting clinicians and patients.

Customized three-dimensional printed ceramic bone grafts for osseous defects: a prospective randomized study.

Ridge resorption can result in insufficient bone volume for implant surgery, necessitating bone substitutes to restore the resorption area. Recent advances in computer-aided design and manufacturing enable the use of alloplastic bone graft materials with customizable compositions or shapes. This randomized study evaluated the clinical effectiveness of a customized three-dimensional (3D) printed alloplastic bone material. Sixty patients requiring guided bone regeneration for implant installation following tooth extraction due to alveolar bone resorption were recruited at two institutions. The participants were randomly allocated to either a group that received 3D-printed patient-customized bone graft material or a group that received conventional block bone graft material. Implant installation with bone harvesting was performed approximately 5 months after bone grafting. Histological and radiological assessments of the harvested bone area were performed. The experimental group had a significantly higher percent bone volume and a smaller tissue surface than the control group. Bone volume, bone surface, bone surface/volume ratio, bone surface density (bone surface/total volume), and bone mineral density did not differ significantly between groups. Patient-customized bone graft materials offer convenience and reduce patient discomfort. The findings suggest 3D-printed patient-customized bone graft materials could be used as an alternative for simpler bone grafting procedures.

Current Status of Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) in Maxillofacial Surgery: Should It Be Continued?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has shown potential in maxillofacial surgery owing to its osteoinductive properties. However, concerns about its safety and high cost have limited its widespread use. This review presents the status of rhBMP-2 use in maxillofacial surgery, focusing on its clinical application, efficacy, safety, and limitations. Studies have demonstrated rhBMP-2's potential to reduce donor site morbidity and increase bone height in sinus and ridge augmentation; however, it may not outperform autogenous bone grafts. In medication-related osteonecrosis of the jaw treatment, rhBMP-2 has been applied adjunctively with promising results, although its long-term safety requires further investigation. However, in maxillofacial trauma, its application is limited to the restoration of large defects. Safety concerns include postoperative edema and the theoretical risk of carcinogenesis. Although postoperative edema is manageable, the link between rhBMP-2 and cancer remains unclear. The limitations include the lack of an ideal carrier, the high cost of rhBMP-2, and the absence of an optimal dosing regimen. In conclusion, rhBMP-2 is a promising graft material for maxillofacial surgery. However, it has not yet become the gold standard owing to safety and cost concerns. Further research is required to establish long-term safety, optimize dosing, and develop better carriers.

Patient-specific plates for facial fracture surgery: A retrospective case series.

OBJECTIVES: Surgeons often encounter challenges when treating maxillofacial fractures using conventional methods that involve trimming or bending ready-made titanium plates for open reduction and internal fixation (ORIF) since it can be time-consuming, imprecise, and inconvenient. This retrospective case series aimed to introduce a novel bone reduction method that utilizes virtual planning, patient-specific surgical guides, and titanium plates. METHODS: Seven patients with mandibular symphysis or subcondylar fractures resulting from facial trauma underwent cone-beam computed tomography (CBCT) or facial CT scans, and their medical histories were documented. Virtual surgery was conducted based on three-dimensional (3D) stereolithography images derived from CT scans using the FaceGide software (MegaGen, Daegu, Korea). ORIF was performed using patient-specific surgical guides and plates that were designed, printed, and milled. Radiographic, clinical, and occlusal evaluations were conducted at two weeks and six weeks postoperatively. Subsequently, 3D images from virtual surgery and postoperative CT scans were compared. RESULTS: The comparison of 3D virtual surgery and postoperative images revealed minimal surface differences of less than 1 mm. T-scan evaluations indicated that there were no statistically significant differences between the two- and six-week postoperative assessments. Favorable clinical outcomes were observed. CONCLUSION: This novel method demonstrated stable outcomes in terms of occlusion and healing, with no notable complications. Consequently, this approach may serve as a viable alternative to conventional methods. CLINICAL SIGNIFICANCE: Facial fracture surgery that utilizes patient-specific surgical guides and plates within a digital workflow can facilitate meticulous surgical planning, reducing the risk of complications and minimizing operation time.

Clinical Stability of Bespoke Snowman Plates for Fixation following Sagittal Split Ramus Osteotomy of the Mandible.

Maxillofacial skeletal surgery often involves the use of patient-specific implants. However, errors in obtaining patient data and designing and manufacturing patient-specific plates and guides can occur even with accurate virtual surgery. To address these errors, bespoke Snowman plates were designed to allow movement of the mandible. This study aimed to compare the stability of bespoke four-hole miniplates with that of a bespoke Snowman plate for bilateral sagittal split ramus osteotomy (SSRO), and to present a method to investigate joint cavity changes, as well as superimpose virtual and actual surgical images of the mandible. This retrospective study included 22 patients who met the inclusion criteria and underwent orthognathic surgery at a university hospital between 2015 and 2018. Two groups were formed on the basis of the plates used: a control group with four-hole bespoke plates and a study group with bespoke Snowman plates. Stability was assessed by measuring the condyle-fossa space and superimposing three-dimensional virtual surgery images on postoperative cone-beam computed tomography (CBCT) scans. No significant differences were observed in the condyle-fossa space preoperatively and 1 year postoperatively between the control and study groups. Superimposing virtual surgery and CBCT scans revealed minimal differences in the landmark points, with no variation between groups or timepoints. The use of bespoke Snowman plates for stabilizing the mandible following SSRO exhibited clinical stability and reliability similar to those with bespoke four-hole plates. Additionally, a novel method was introduced to evaluate skeletal stability by separately analyzing the condyle-fossa gap changes and assessing the mandibular position.

Effectiveness of creating digital twins with different digital dentition models and cone-beam computed tomography.

Distortion of dentition may occur in cone-beam computed tomography (CBCT) scans due to artifacts, and further imaging is frequently required to produce digital twins. The use of a plaster model is common; however, it has certain drawbacks. This study aimed to assess the feasibility of different digital dentition models over that of plaster casts. Plaster models, alginate impressions, intraoral scan (IOS) images, and CBCT images of 20 patients were obtained. The desktop model scanner was used to scan the alginate impression twice, five minutes and two hours after impression-making. Using an IOS, the full arch was scanned in segments using CS 3600 and simultaneously with i700 wireless. The digital twins obtained from the alginate impression and IOS were superimposed with those obtained from the plaster cast. The differences and distances at each reference point were measured. Scans of alginate impressions after two hours showed the greatest discrepancies, but these were all less than the CBCT voxel size of 0.39 mm. Alginate impression scans and IOS are suitable supplements to CBCT compared to the plaster model. Accuracy can be improved by scanning the alginate impression within five minutes or by intraoral scanning of the entire arch with segmentation.

Comparative Analysis of Three Facial Scanners for Creating Digital Twins by Focusing on the Difference in Scanning Method.

BACKGROUND: Multi-dimensional facial imaging is increasingly used in hospital clinics. A digital twin of the face can be created by reconstructing three-dimensional (3D) facial images using facial scanners. Therefore, the reliability, strengths, and weaknesses of scanners should be investigated and approved; Methods: Images obtained from three facial scanners (RayFace, MegaGen, and Artec Eva) were compared with cone-beam computed tomography images as the standard. Surface discrepancies were measured and analyzed at 14 specific reference points; Results: All scanners used in this study achieved acceptable results, although only scanner 3 obtained preferable results. Each scanner exhibited weak and strong points because of differences in the scanning methods. Scanner 2 exhibited the best result on the left endocanthion; scanner 1 achieved the best result on the left exocanthion and left alare; and scanner 3 achieved the best result on the left exocanthion (both cheeks); Conclusions: These comparative analysis data can be used when creating digital twins through segmentation, selecting and merging data, or developing a new scanner to overcome all shortcomings.

Fracture and Fatigue of Dental Implants Fixtures and Abutments with a Novel Internal Connection Design: An In Vitro Pilot Study Comparing Three Different Dental Implant Systems.

The aim of this study was to compare the mechanical behaviors of three dental implant fixtures with different abutment connection designs. Three implant systems were studied: the control (BLX implant), test group 1 (TORX++ implant), and test group 2 (IU implant). Three samples from each group were subjected to static compression to fracture tests to determine the maximum fracture load, and twelve samples were exposed to fatigue tests that measured how many cycles the implants could endure before deformation or fracture. Detailed images of the implant-abutment assemblies were obtained using micro-computed tomography imaging, and fractured or deformed areas were observed using a scanning electron microscope (SEM). The mean maximum breaking loads of 578.45 ± 42.46 N, 793.26 ± 57.43 N, and 862.30 ± 74.25 N were obtained for the BLX, TORX++, and IU implants, respectively. All samples in the three groups withstood 5 × 106 cycles at 50% of the nominal peak value, and different fracture points were observed. All abutment connection designs showed suitable mechanical properties for intraoral use. Microscopic differences in the fracture patterns may be due to the differences in the fixture design or abutment connection, and mechanical complications could be prevented by lowering the overload reaching the implant or preventing peri-implantitis.

Effectiveness of cone-beam computed tomography-generated cephalograms using artificial intelligence cephalometric analysis.

Lateral cephalograms and related analysis constitute representative methods for orthodontic treatment. However, since conventional cephalometric radiographs display a three-dimensional structure on a two-dimensional plane, inaccuracies may be produced when quantitative evaluation is required. Cone-beam computed tomography (CBCT) has minimal image distortion, and important parts can be observed without overlapping. It provides a high-resolution three-dimensional image at a relatively low dose and cost, but still shows a higher dose than a lateral cephalogram. It is especially true for children who are more susceptible to radiation doses and often have difficult diagnoses. A conventional lateral cephalometric radiograph can be obtained by reconstructing the Digital Imaging and Communications in Medicine data obtained from CBCT. This study evaluated the applicability and consistency of lateral cephalograms generated by CBCT using an artificial intelligence analysis program. Group I comprised conventional lateral cephalometric radiographs, group II comprised lateral cephalometric radiographs generated from CBCT using OnDemand 3D, and group III comprised lateral cephalometric radiographs generated from CBCT using Invivo5. All measurements in the three groups showed non-significant results. Therefore, a CBCT scan and artificial intelligence programs are efficient means when performing orthodontic analysis on pediatric or orthodontic patients for orthodontic diagnosis and planning.

Finite Element Analysis of a New Non-Engaging Abutment System for Three-Unit Implant-Supported Fixed Dental Prostheses.

(1) Background: The stability of implants plays a significant role in the success of osseointegration. The stability of the connection between the fixture and the abutment is one of the critical factors affecting osseointegration. When restoring multiple, non-parallel, and splinted implants, achieving a passive fit can be complicated and challenging. A new EZ post non-engaging abutment system of the BlueDiamond® (BD) implant allows a wide connection angle while achieving a passive prosthesis fit. This study aimed to confirm the new abutment system's clinical applicability by evaluating its biomechanical characteristics using finite element analysis (FEA). (2) Methods: The implant-supported fixed three-unit dental prostheses model was reproduced for two groups of AnyOne® (AO) and BD implants using FEA. The loading conditions were a preload of 200 N in the first step and loads of 100 N (axial), 100 N (15°), or 30 N (45°) in the second step. (3) Results: The peak Von Mises stress (PVMS) value of the fixture in the BD group was more than twice that in the AO group. In contrast, the PVMS values of the abutment and abutment screws were lower in the BD group than in the AO group. The AO group revealed higher maximal principal stress (MPS) values than that of the BD group in the cortical bone, cancellous bone, and crown. The average stress of the outer surface of the abutment was lower in the AO group than in the BD group. The stress distribution for the inner surface of the fixture confirmed that the BD group displayed a lower stress distribution than the AO group under axial and 15° loads; however, the average stress was 1.5 times higher at the 45° load. The stress values of the entire surface where the cortical and cancellous bone were in contact with the fixture were measured. The AO group showed a higher stress value than the BD group in both cortical and cancellous bone. (4) Conclusions: In the AO group, the PVMS value of the fixture and the stress distribution at the contact surface between the fixture and the abutment were lower than those of the BD group, suggesting that the stability of the fixture would be high. However, due to the high stress in the fastening area of the abutment and abutment screw, the risk of abutment fracture in the AO group is higher than that of the BD group. Therefore, the new EZ post non-engaging abutment of the BD implant can be used without any problems in clinics, similar to the non-engaging abutment of the AO implant, which has been widely used in clinical practice.

Three-Dimensional Digital Image Analysis of Skeletal and Soft Tissue Points A and B after Orthodontic Treatment with Premolar Extraction in Bimaxillary Protrusive Patients.

Aim. To investigate the effect of changes in incisor tip, apex movement, and inclination on skeletal points A and B and characterize changes in skeletal points A and B to the soft tissue points A and B after incisor retraction in Angle Class I bimaxillary dentoalveolar protrusion. Methods. Twenty-two patients with Angle Class I bimaxillary dentoalveolar protrusion treated with four first premolar extractions were included in this study. The displacement of skeletal and soft tissue points A and B was measured using cone-beam computed tomography (CBCT) using a three-dimensional coordinate system. The movement of the upper and lower incisors was also measured using CBCT-synthesized lateral cephalograms. Results. Changes in the incisal tip, apex, and inclination after retraction did not significantly affect the position of points A and B in any direction (x, y, z). Linear regression analysis showed a statistically significant relationship between skeletal point A and soft tissue point A on the anteroposterior axis (z). Skeletal point A moved forward by 0.07 mm, and soft tissue point A moved forward by 0.38 mm, establishing a ratio of 0.18: 1 (r = 0.554, p < 0.01). Conclusion. The positional complexion of the skeletal points A and B was not directly influenced by changes in the incisor tip, apex, and inclination. Although the results suggest that soft tissue point A follows the anteroposterior position of skeletal point A, its clinical significance is suspected. Thus, hard and soft tissue analysis should be considered in treatment planning.

Enhanced Bone Regeneration in Variable-Type Biphasic Ceramic Phosphate Scaffolds Using rhBMP-2.

Our aim was to investigate the bone regeneration capacity of powder-type biphasic ceramic scaffold (BCP powder), block-type BCP (BCP block), and collagen-added block-type BCP (BCP collagen) with different concentrations of recombinant human bone morphogenetic protein 2 (rhBMP-2) in an animal model. Four rabbits were assigned to each of the following groups: no graft + rhBMP-2 (0.1/0.2 mg/mL), BCP powder + rhBMP-2 (0.1/0.2 mg/mL), BCP block + rhBMP-2 (0.1/0.2 mg/mL), and BCP collagen + rhBMP-2 (0.1/0.2 mg/mL), i.e., a total of 32 rabbits. Polycarbonate tubes (Φ 7 mm × 5 mm) for supporting scaffolds were fixed into a 7 mm round border. Subsequently, 0.1 mL of rhBMP-2 solutions with different concentrations was injected into the tubes. Both radiological and histomorphometric analyses showed that osteogenesis was not enhanced by increasing the concentration of rhBMP-2 in all groups at both 3 and 6 weeks. Radiological analysis showed that bone formation was higher in the BCP collagen group than in the BCP powder and BCP block groups at both rhBMP-2 concentrations at 3 weeks. rhBMP-2 enhanced bone formation; however, as the concentration increased, bone formation could not be enhanced infinitely. Collagen-added alloplastic graft material may be useful for mediating rapid bone formation in initial stages.

Bone Regeneration of a 3D-Printed Alloplastic and Particulate Xenogenic Graft with rhBMP-2.

This study aimed to evaluate the bone regeneration capacity of a customized alloplastic material and xenograft with recombinant human bone morphogenetic protein-2 (rhBMP-2). We prepared hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic bone blocks made using a 3D printing system and added rhBMP-2 to both materials. In eight beagle dogs, a total of 32 defects were created on the lower jaws. The defective sites of the negative control group were left untreated (N group; 8 defects), and those in the positive control group were filled with particle-type Bio-Oss (P group; 12 defects). The defect sites in the experimental group were filled with 3D-printed synthetic bone blocks (3D group; 12 defects). Radiographic and histological evaluations were performed after healing periods of 6 and 12 weeks and showed no significant difference in new bone formation and total bone between the P and 3D groups. The 3D-printed custom HA/TCP graft with rhBMP-2 showed bone regeneration effects similar to that of particulate Bio-Oss with rhBMP-2. Through further study and development, the application of 3D-printed customized alloplastic grafts will be extended to various fields of bone regeneration.

Clinical Significance of Intraoperative Exposure of Inferior Alveolar Nerve during Surgical Extraction of the Mandibular Third Molar in Nerve Injury.

During extraction surgery, the inferior alveolar nerve (IAN) can occasionally be observed in the extraction socket of the mandibular third molar (M3). The purpose of this study was to investigate and compare the incidence of IAN injury in groups with and without intraoperative IAN exposure during surgical extraction of M3, and to identify additional risk factors for the IAN injury in addition to the IAN exposure. A total of 288 cases in 240 patients, who underwent surgical extraction of M3 by a single surgeon, were divided into the exposed group (n = 69) and the unexposed group (n = 219). The surgeon recorded the information regarding the procedure when the clinical observation of IAN exposure was made during the surgery. The incidence of IAN injury after the extraction surgery was significantly higher in the exposed group than in the unexposed group (4.3% versus 0%, p < 0.05). Paresthesia was recognized in three cases of the exposed group, but it showed complete recovery within three postoperative months. No case of permanent paresthesia was detected in both groups. According to the logistic regression, the only significant risk factor of IAN injury in the exposed group was the increase of age (OR 1.108, p < 0.05). Intraoperative IAN exposure during surgical extraction of M3 may show a higher incidence of IAN injury than the case without IAN exposure, representing an incidence of 4.3%. Even if the paresthesia associated with IAN exposure occurs, it is likely to be a temporary injury, and this risk may increase with age.

Various Therapeutic Methods for the Treatment of Medication-Related Osteonecrosis of the Jaw (MRONJ) and Their Limitations: A Narrative Review on New Molecular and Cellular Therapeutic Approaches.

Medication-related osteonecrosis of the jaw (MRONJ) is one of the most interesting diseases in the field of maxillofacial surgery. In addition to bisphosphonates, the use of antiresorptive and antiangiogenic agents is known to be the leading cause. However, the exact pathogenesis of MRONJ has not been established, and various hypotheses have been proposed, such as oxidative stress-related theory. As a result, a definitive treatment protocol for MRONJ has not been identified, while various therapeutic approaches are applied to manage patients with MRONJ. Although the surgical approach to treat osteomyelitis of the jaw has been proven to be most effective, there are limitations, such as recurrence and delayed healing. Many studies and clinical trials are being conducted to develop another effective therapeutic modality. The use of some materials, including platelet concentrates and bone morphogenetic proteins, showed a positive effect on MRONJ. Among them, teriparatide is currently the most promising material, and it has shown encouraging results when applied to patients with MRONJ. Furthermore, cell therapy using mesenchymal stem cells showed promising results, and it can be the new therapeutic approach for the treatment of MRONJ. This review presents various treatment methods for MRONJ and their limitations while investigating newly developed and researched molecular and cellular therapeutic approaches along with a literature review.

Cephalometric Predictors of Future need for Orthognathic Surgery in Korean Patients with Unilateral Cleft Lip and Palate Despite Long-term Use of Facemask with Miniplate.

OBJECTIVE: To investigate the cephalometric predictors of the future need for orthognathic surgery in Korean patients with unilateral cleft lip and palate (UCLP) despite long-term use of facemask with miniplate (FMMP). METHODS: The sample consisted of 53 UCLP patients treated by a single orthodontist using an identical protocol. Lateral cephalograms were taken before commencement of FMMP therapy (T0; mean age, 10.45 years), after FMMP therapy (T1; mean age, 14.72 years), and at follow-up (T2; mean age, 18.68 years). Twenty-eight cephalometric variables were measured. At T2 stage, the subjects were divided into FMMP-Nonsurgery (n = 33, 62.3%) and FMMP-Surgery (n = 20, 37.7%) groups according to cephalometric criteria (point A-nasion-point B [ANB] < -3°; Wits-appraisal < -5 mm; and Harvold unit difference [HUD] > 34 mm for FMMP-Surgery group). Statistical analyses including discrimination analysis were performed. RESULTS: In FMMP-Surgery group, the forward position of the mandible at T0 stage was maintained throughout the whole stages and Class III relationship worsened with significant growth of the mandibular body and ramus and counterclockwise rotation of the maxilla and mandible at the T1 and T2 stages. Six cephalometric variables at T0 stage including ANB, anteroposterior dysplasia indicator, Wits-appraisal, mandibular body length, HUD, and overjet were selected as effective predictors of the future need for surgical intervention to correct sagittal skeletal discrepancies. CONCLUSIONS: Despite long-term use of FMMP therapy, 37.7% of UCLP patients became candidates for orthognathic surgery. Therefore, differential diagnosis is necessary to predict the future need for orthognathic surgery at early age.

3D-Printed Ceramic Bone Scaffolds with Variable Pore Architectures.

This study evaluated the mechanical properties and bone regeneration ability of 3D-printed pure hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic scaffolds with variable pore architectures. A digital light processing (DLP) 3D printer was used to construct block-type scaffolds containing only HA and TCP after the polymer binder was completely removed by heat treatment. The compressive strength and porosity of the blocks with various structures were measured; scaffolds with different pore sizes were implanted in rabbit calvarial models. The animals were observed for eight weeks, and six animals were euthanized in the fourth and eighth weeks. Then, the specimens were evaluated using radiological and histological analyses. Larger scaffold pore sizes resulted in enhanced bone formation after four weeks (p < 0.05). However, in the eighth week, a correlation between pore size and bone formation was not observed (p > 0.05). The findings showed that various pore architectures of HA/TCP scaffolds can be achieved using DLP 3D printing, which can be a valuable tool for optimizing bone-scaffold properties for specific clinical treatments. As the pore size only influenced bone regeneration in the initial stage, further studies are required for pore-size optimization to balance the initial bone regeneration and mechanical strength of the scaffold.

Bioabsorbable Osteofixation Materials for Maxillofacial Bone Surgery: A Review on Polymers and Magnesium-Based Materials.

Clinical application of osteofixation materials is essential in performing maxillofacial surgeries requiring rigid fixation of bone such as trauma surgery, orthognathic surgery, and skeletal reconstruction. In addition to the use of titanium plates and screws, clinical applications and attempts using bioabsorbable materials for osteofixation surgery are increasing with demands to avoid secondary surgery for the removal of plates and screws. Synthetic polymeric plates and screws were developed, reaching satisfactory physical properties comparable to those made with titanium. Although these polymeric materials are actively used in clinical practice, there remain some limitations to be improved. Due to questionable physical strength and cumbersome molding procedures, interests in resorbable metal materials for osteofixation emerged. Magnesium (Mg) gained attention again in the last decade as a new metallic alternative, and numerous animal studies to evaluate the possibility of clinical application of Mg-based materials are being conducted. Thanks to these researches and studies, vascular application of Mg-based biomaterials was successful; however, further studies are required for the clinical application of Mg-based biomaterials for osteofixation, especially in the facial skeleton. The review provides an overview of bioabsorbable osteofixation materials in maxillofacial bone surgery from polymer to Mg.

Quantitative Evaluation of the Postoperative Changes in Nasal Septal Deviation by Diverse Movement of the Maxilla After Le Fort I Osteotomy.

The purposes of this study were to compare the postoperative changes in nasal septal (NS) deviation between total impaction (TI) and anterior elongation (AE) of the maxilla after Le Fort I osteotomy (LF-IO) and to investigate the correlation between the change in NS deviation and the amount of surgical maxillary movement. Twenty-eight patients, who underwent LF-IO and sagittal split osteotomy by a single surgeon, were divided into TI group (N = 13; mean = 1.5 mm) and AE group (N = 15; mean = 1.6 mm). NS deviation was measured using computed tomography and deviation indices before and after surgery at 3 coronal measurement planes (CMP) passing through the nasion, crista galli, and the most anterior point of the sphenoid sinus (MAPS). Then, statistical analysis was performed. The AE group did not have significant changes in any deviation indices after surgery. The TI group; however, exhibited significant increases in the MAPS-CMP and total deviation indices (0.67-1.16 mm, P < 0.01; 5.45-6.43 mm, P < 0.05). The TI group also exhibited a greater increase in the ΔMAPS-CMP deviation index than the AE group (0.49 mm versus 0.06 mm, P < 0.05). The amount of forward movement of the maxilla was positively correlated with the nasion-CMP and total deviation indices (r = 0.422, P < 0.05; r = 0.398, P < 0.05). LF-IO for TI and forward movement can worsen NS deviation posteriorly and anteriorly, respectively. It is necessary to manage the nasal septum and the nasal crest of the maxilla meticulously during LF-IO procedure.