An automated method for assessing condyle head changes in patients with skeletal class II malocclusion based on Cone-beam CT images.

OBJECTIVES: Currently, there is no reliable automated measurement method to study the changes in the condylar process after orthognathic surgery. Therefore, this study proposes an automated method to measure condylar changes in patients with skeletal class II malocclusion following surgical-orthodontic treatment. METHODS: Cone-beam CT (CBCT) scans from 48 patients were segmented using the nnU-Net network for automated maxillary and mandibular delineation. Regions unaffected by orthognathic surgery were selectively cropped. Automated registration yielded condylar displacement and volume calculations, each repeated three times for precision. Logistic regression and linear regression were used to analyse the correlation between condylar position changes at different time points. RESULTS: The Dice score for the automated segmentation of the condyle was 0.971. The intraclass correlation coefficients (ICCs) for all repeated measurements ranged from 0.93 to 1.00. The results of the automated measurement showed that 83.33% of patients exhibited condylar resorption occurring six months or more after surgery. Logistic regression and linear regression indicated a positive correlation between counterclockwise rotation in the pitch plane and condylar resorption (P < .01). And a positive correlation between the rotational angles in both three planes and changes in the condylar volume at six months after surgery (P ≤ .04). CONCLUSIONS: This study's automated method for measuring condylar changes shows excellent repeatability. Skeletal class II malocclusion patients may experience condylar resorption after bimaxillary orthognathic surgery, and this is correlated with counterclockwise rotation in the sagittal plane. ADVANCES IN KNOWLEDGE: This study proposes an innovative multi-step registration method based on CBCT, and establishes an automated approach for quantitatively measuring condyle changes post-orthognathic surgery. This method opens up new possibilities for studying condylar morphology.

Customed 3D-printed Polyetheretherketone (PEEK) Implant for Secondary Salvage Reconstruction of Mandibular Defects: Case Report and Literature Review.

Given the insufficient height of single-barrel fibula and inadequate bone volume of double-barrel vascularized fibula in mandibular reconstruction, it is a better choice to combine the upper full-thickness vascularized fibula with the lower half-thickness nonvascularized fibula. However, the nonvascularized fibula may fail due to complications, affecting the facial shape and occlusal function. Polyetheretherketone is a thermoplastic polymer used for bone defect reconstruction due to its good mechanical properties and biocompatibility. This case report mainly presents a secondary salvage reconstruction of the mandible by using customed 3-dimensional-printing polyetheretherketone, which restored the continuity and symmetry of the mandible, improved the patient's facial shape, and restored functional occlusion through dental implants. After a 28-month follow-up, no complications occurred, and the patient was satisfied with the final restoration.

Application of Patient-Specific PEEK Implant for Aesthetic Considerations in Paranasal Augmentation.

The paranasal area is closely associated with midfacial esthetics. However, there is no special technique available to achieve ideal esthetics paranasal restoration. The present study aims to apply the 3D printed PolyEtherEtherKetone (PEEK) implants as an innovative solution for esthetic paranasal reconstruction. On the basis of the CT scan, the patient-specific PEEK implant and a surgical guiding plate were manufactured aided by a computer. Preoperative and postoperative CBCT data were utilized to evaluate esthetic outcomes. The average follow-up period was 13 months. All patients' wounds healed by first intention. The statistical analysis of preoperative and postoperative esthetic indices revealed light levels of postoperative paranasal depression ( P <0.001) and the wrinkle severity rating scale for nasolabial folds ( P <0.001). Moreover, the nasolabial angle increased ( P <0.05). The established 3D-printing PEEK implanted prosthesis can individually correct the depressed deformity of the paranasal region, and achieve favorable clinical esthetic outcomes.

Application of a surgical guide in the extraction of impacted mesiodentes: a randomized controlled trial.

OBJECTIVE: To explore and evaluate the application of a surgical guide in the extraction of impacted mesiodentes. MATERIALS AND METHODS: Patients with impacted mesiodentes approachable from the labial side of the maxilla were randomly divided into three groups. The surgical guide for group I was made using cone beam computed tomography (CBCT) and dental cast, whereas the surgical guide for group II was only made using CBCT data. Group I and group II were first evaluated to determine whether guide use could accurately locate the cementoenamel junction (CEJ) of the mesiodentes, and the impacted mesiodentes were extracted with the help of the surgical guide. Group III underwent an operation without a guide. For all patients, the preoperative design time, tooth searching time, operation time, complications, and costs were measured. RESULTS: The guides for group I and group II could locate the CEJ of the mesiodentes accurately, with good application effect during the operation. Group I and group II required additional preoperative design time compared with group III. However, the tooth searching time and operation time in groups I and II were significantly reduced compared with those in group III. Group I and group II showed no intraoperative complications, and two cases in group III showed imprecision during localization. The overall cost for group III was higher than that of group I or group II. But group I and group II required extra visits and costs. CONCLUSIONS: Despite some limitations, the surgical guide assisted with mesiodentes extraction and can improve the quality of the operation quality as well as reducing its economic burden, difficulty, and duration. Through proper design, we can create a high-quality surgical guide using only CBCT data. CLINICAL RELEVANCE: The surgical guide can be used as an important assistive tool in alveolar surgery.

Myxofibrosarcoma of the mandible: a case report and review of the literature.

BACKGROUND: Myxofibrosarcoma (MFS) is a soft tissue sarcoma that commonly occurs in late adult life. It is mainly located in the subcutaneous soft tissues of extremities characterized by a high recurrence rate at the original site. MFS of the head and neck is rare, while it occurs in the maxilla and mandible is extremely rare. CASE PRESENTATION: We report a case of MFS of the mandible in a 51-year-old female who presented with a painless gingival swelling and mobile, super-erupted right mandibular second and third molars. Panoramic x-ray and maxillofacial CT revealed an ill-defined radiolucent lesion surrounding the mandibular molars giving a teeth-floating-in-air appearance. Histopathological examination showed scattered spindle and stellate cells with mild atypia distributed in the myxoid stroma. Only a few mitotic figures were identified and no area of tissue necrosis was found. The characteristic thin-walled and curvilinear vasculature were prominent. Immunohistochemistry analysis revealed the tumor cells being positive for vimentin and vascular CD31. CK, S-100, P63, HHF-35 stains were negative. The labeling index of Ki-67 was about 30%. Based on the histopathological and immunohistochemical examinations, the diagnosis of a low-grade MFS was established. This patient underwent a radical segmental excision with a 2-cm margin, supraomohyoid neck dissection and immediate reconstruction of the mandibular continuity defect with a fibular osteocutaneous free flap. This patient has been followed for 20 months to date and has remained disease free. CONCLUSIONS: This report describes a rare case of MFS of the mandible. Recognizing the histopathological features of MFS and applying the appropriate immunohistochemical examinations are crucial in establishing the correct diagnosis. Our case may provide diagnosis and treatment experiences of MFS occurs in the mandible.

Fibular free flap necrosis after mandibular reconstruction surgery with osteoradionecrosis: Establishment and verification of an early warning model.

OBJECTIVE: Fibular free flap necrosis (FFFN) is the most common complication in patients with osteoradionecrosis (ORN) after mandibular reconstruction surgery. However, there are no effective forecasting tools at present. This research is aimed to establish and verify a nomogram model to predict the risk of FFFN after mandibular reconstruction surgery in ORN patients. METHODS: A total of 193 ORN patients with mandibular reconstruction using fibular free flap (150 cases in the model group and 43 cases in the validation group) were enrolled in this study. In the model group, the variables were optimized by lasso regression. Then the prediction model was established by binary logistic regression analysis, and the nomogram was drawn. The bootstrap self-sampling method was used for internal verification. Moreover, 43 cases in the validation group were used for external validation. RESULTS: The results of lasso regression and binary logistic regression analysis showed that the radiotherapy interval (≤2 years), trismus, diabetes, without deep venous anastomoses, and American society of anesthesiologists (ASA) III were the independent risk factors for FFFN after mandibular reconstruction surgery in ORNJ patients (P<0.05). Based on the above-mentioned risk factors, the nomogram model was established. The AUC values of the model group and the validation group were 0.936 and 0.964, respectively. The curve analysis showed that when the probability thresholds of the model group and the validation group were 5.699%∼98.229% and 0.413%∼99.721%, respectively. So the patient's clinical net profit rate was the highest. CONCLUSION: A nomogram combining the factors of radiotherapy interval (≤2 years), trismus, diabetes, without deep venous anastomoses, and ASA III provided a comparatively effective way to predict the risk of FFFN after mandibular reconstruction surgery in ORN patients, which has distinct applied clinical value.

Experts' consensus on precaution and treatment for complications of sagittal split ramus osteotomy.

Sagittal split ramus osteotomy (SSRO) is a versatile orthognathic procedure for correcting mandibular deformities. Various complications can possibly occur when performing SSRO, and it can even cause serious adverse consequences because of the complexity of anatomy and operative procedures. The types of complications and their accompanying clinical manifestations are closely related to the choice of diagnosis and treatment strategies and clinical outcomes. To discuss the causes, prevention, and treatment measures of various common complications of SSRO, domestic orthognathic surgery experts prepared this consensus to increase the awareness of SSRO complications, thereby ensuring safe surgical procedure and good results.

3D-printed PEEK implant for mandibular defects repair - a new method.

Functional reconstruction of large-size mandibular continuity defect is still a major challenge in the oral and maxillofacial surgery due to the unsatisfactory repair effects and various complications. This study aimed to develop a new functional repair method for mandibular defects combined with 3D-printed polyetheretherketone (PEEK) implant and the free vascularized fibula graft, and evaluated the service performance of the implant under whole masticatory motion. The design criteria and workflows of the mandibular reconstruction were established based on the requirements of safety, functionality, and shape consistency. Both the biomechanical behavior and the mechanobiological property of mandibular reconstruction under various masticatory motion were investigated by the finite element analysis. The maximum von Mises stress of each component was lower than the yield strength of the corresponding material and the safety factor was more than 2.3 times, which indicated the security of the repair method can be guaranteed. Moreover, the actual deformation of the reconstruction model was lower than that of the normal mandible under most clenching tasks, which assured the primary stability. More than 80% of the volume elements in the bone graft can obtain effective mechanical stimulation, which benefited to reduce the risks of bone resorption. Finally, the novel repair method was applied in clinic and good clinical performances have been achieved. Compared with the conventional fibular bone graft for surgical mandibular reconstruction, this study provides excellent safety and stability to accomplish the functional reconstruction and aesthetic restoration of the mandible defect.

HLA-DRB1*16:02 is associated with PEG-asparaginase hypersensitivity.

Aim: To evaluate the associations between human leukocyte antigen (HLA)-DRB1 variants and the rs6021191 variant in nuclear factor of activated T cells 2 (NFATC2) with PEG-asparaginase hypersensitivity in children with acute lymphoblastic leukemia (ALL) treated according to the Chinese Children Leukemia Group (CCLG) ALL 2018 protocol. Methods:HLA-DRB1 genotyping was performed using a PCR sequence-based typing (SBT) method. NFATC2 rs6021191 was genotyped applying TaqMan Genotyping Assay. Results: T-ALL and higher risk groups were at higher risk for PEG-asparaginase hypersensitivity. No association was found between NFATC2 rs6021191 and PEG-asparaginase hypersensitivity. HLA-DRB1*16:02 variant was associated with PEG-asparaginase allergy both in univariate and multivariate logistic regression analysis. Conclusion: Our results confirm that variations in HLA-DRB1 might influence the development of asparaginase hypersensitivity.

[Application of digital positioning guide plate in extraction of impacted supernumerary teeth].

OBJECTIVE: To explore the application of digital positioning guide plate in extraction of impacted supernumerary teeth and evaluate its clinical efficacy. METHODS: From March to August, 2019, 30 patients with labial impacted supernumerary teeth treated in the Department of Oral and Maxillofacial Surgery, Stomatological Hospital, Southern Medical University were enrolled in this study. Fifteen of the patients were treated with digital positioning guide plate to remove the impacted supernumerary teeth (test group). According to the CBCT data and the dentition model of the patients, the positioning guide plate was positioned by avoiding the important anatomical structure with the tooth-bone surface as the support to design the soft tissue incision line and bone tissue exposure range. The other 15 patients who were treated without the use of the guide plate for operation served as the control group. The design time, tooth searching time, operation time and complications were compared between the two groups. RESULTS: The positioning guide plate was well attached during the operation and allowed quick location of the supernumerary teeth while helping to expose the supernumerary teeth and avoid the damage of the adjacent important anatomical structures. The pre-operative design time was 50 ± 5 min in the test group and 0 min in the control group. The average time of tooth finding in the test group was 5±2 min, as compared with 10±3 min in the control group (t=15.40, P < 0.01); the average time of operation was significantly shorter in the test group than in the control group (25±4 min vs 45±6 min; t=35.50, P < 0.01). No intraoperative complications occurred in the test group, and slight deviation occurred in one case in the control group. CONCLUSIONS: The application of digital positioning guide plate in extraction of embedded supernumerary teeth can significantly shorten the time of tooth finding, reduce the difficulty of operation, and improve the quality of operation.

Accuracy of virtual surgical planning in two-jaw orthognathic surgery: comparison of planned and actual results.

OBJECTIVE: This study aims to evaluate the accuracy of virtual surgical planning in two-jaw orthognathic surgery via quantitative comparison of preoperative planned and postoperative actual skull models. STUDY DESIGN: Thirty consecutive patients who required two-jaw orthognathic surgery were included. A composite skull model was reconstructed by using Digital Imaging and Communications in Medicine (DICOM) data from spiral computed tomography (CT) and STL (stereolithography) data from surface scanning of the dental arch. LeFort I osteotomy of the maxilla and bilateral sagittal split ramus osteotomy (of the mandible were simulated by using Dolphin Imaging 11.7 Premium (Dolphin Imaging and Management Solutions, Chatsworth, CA). Genioplasty was performed, if indicated. The virtual plan was then transferred to the operation room by using three-dimensional (3-D)-printed surgical templates. Linear and angular differences between virtually simulated and postoperative skull models were evaluated. RESULTS: The virtual surgical planning was successfully transferred to actual surgery with the help of 3-D-printed surgical templates. All patients were satisfied with the postoperative facial profile and occlusion. The overall mean linear difference was 0.81 mm (0.71 mm for the maxilla and 0.91 mm for the mandible); and the overall mean angular difference was 0.95 degrees. CONCLUSIONS: Virtual surgical planning and 3-D-printed surgical templates facilitated the diagnosis, treatment planning, and accurate repositioning of bony segments in two-jaw orthognathic surgery.

Application of molecularly imprinted polymers to selective removal of clofibric acid from water.

A new molecularly imprinted polymer (MIP) adsorbent for clofibric acid (CA) was prepared by a non-covalent protocol. Characterization of the obtained MIP was achieved by scanning electron microscopy (SEM) and nitrogen sorption. Sorption experimental results showed that the MIP had excellent binding affinity for CA and the adsorption of CA by MIP was well described by pseudo-second-order model. Scatchard plot analysis revealed that two classes of binding sites were formed in the MIP with dissociation constants of 7.52 ± 0.46 mg L(-1) and 114 ± 4.2 mg L(-1), respectively. The selectivity of MIP demonstrated higher affinity for CA over competitive compound than that of non-imprinted polymers (NIP). The MIP synthesized was used to remove CA from spiked surface water and exhibited significant binding affinity towards CA in the presence of total dissolved solids (TDS). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance.

Sorption of carbamazepine from water by magnetic molecularly imprinted polymers based on chitosan-Fe3O4.

A novel magnetic-molecularly imprinted polymer (MMIP) based on chitosan-Fe3O4 has been synthesized for fast separation of carbamazepine (CBZ) from water. During polymerization, the modified chitosan-Fe3O4 was used not only as supporter but also as functional monomer. The properties of obtained MMIP were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectra, thermo-gravimetric analysis and so on. The sorption equilibrium data was well described by Freundlich isotherm model and the increase in the temperature generated an increase in the sorption amount, indicating endothermic nature of adsorption process. Sorption kinetics followed the pseudo-second-order model. The feasibility of selective sorption of CBZ from real water by the MMIP was analyzed by using spiked real water samples. The result showed that the sorption capacity of MMIP has no obvious decrease in different water samples whereas there was obvious decline in the sorption amount of the MNIP.

Synthesis by precipitation polymerization of molecularly imprinted polymer for the selective extraction of diclofenac from water samples.

A molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template, 2-vinylpyridine (2-VP) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and toluene as porogen. The MIP showed outstanding affinity toward DFC in aqueous solution with a binding site capacity (Q(max)) of 324.8 mg/g (1.09 mmol/g) and was used as solid-phase extraction (SPE) material for the quantitative enrichment of DFC in environmental water samples and off-line coupled to a reversed-phase HPLC/DAD. Various parameters including washing solvent, elution solvent and breakthrough volume affecting the extraction efficiency of the polymers have been evaluated to achieve the selective preconcentration of DFC from water samples and to reduce non-specific interactions. Recoveries of DFC extracted from tap water, river water and wastewater samples were higher than 95%, and no significant DFC recovery difference was obtained among the different water matrix. The stability of MIP was tested by consecutive percolation of water sample, and it was shown that the performance of the MIP did not vary even after 30 adsorption and desorption cycles. Furthermore, the MISPE was used for the analysis of DFC in river water and wastewater samples and revealed DFC concentrations of 0.69±0.002 µg/L (n=3) and 0.31±0.004µg/L (n=3), respectively. The results were in good agreement with corresponding LC-MS/MS data.

[Clinical characters, diagnosis and treatment of parapharyngeal region neoplasms: a report of 115 cases].

OBJECTIVE: The aim of this study was to analyze the clinical characters, diagnosis and treatment of primary neoplasms in the parapharyngeal regions. METHODS: A total of 115 cases of primary neoplasms in the parapharyngeal regions were included in this study. RESULTS: Disorders of swallowing, breath or speaking were the common symptoms of neoplasms in parapharyngeal regions. The majority of neoplasms parapharyngeal regions were benign. 46 cases were from the deep lobe of the parotid, and 42 cases were neurogenic. CT or MRI provides useful information such as their sizes, shapes and extents. The relationship between the tumor and vessel was shown using super-selective angiography. All the tumors were resected completely by extra-oral approach through the posteroinferior incision of the mandible. The follow-up was carried out from 1 to 10 years, and the data indicated that 2 patients died, 18 cases were lost, and others had no recurrence. CONCLUSION: CT and/or MRI are essentially useful for diagnosis and presurgical planning. Super-selective angiography can be used if the lesions involved carotid artery. Posteroinferior incision of the mandible is a simple, effective and safe approach for excision of neoplasms parapharyngeal regions.