[Relationship between prognosis and different surgical treatments of zygomatic defects: A retrospective study].

OBJECTIVE: To evaluate the effect and summarize the characteristics of different treatment methods in repairing zygomatic defect. METHODS: A total of 37 patients with zygomatic defect were reviewed in the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from August 2012 to August 2019. According to the anatomical scope of defect, the zygomatic defects were divided into four categories: Class 0, the defect did not involve changes in zygomatic structure or continuity, only deficiency in thickness or projection; Class Ⅰ, defect was located in the zygomatic body or involved only one process; Class Ⅱ, a single defect involved two processes; Class Ⅲa, referred to a single defect involving three processes and above; Class Ⅲb, referred to zygomatic defects associated with large maxillary defects. The etiology, defect time, defect size and characteristics of zygomatic defects, the repair and reconstruction methods, and postoperative complications were collected and analyzed. Postoperative computed tomography (CT) data were collected to evaluate the outcome of zygomatic protrusion. Chromatographic analysis was used to assess the postoperative stability. RESULTS: Among the causes of defects, 25 cases (67.57%) were caused by trauma, and 11 cases (29.73%) were of surgical defects following tumor resection. We performed autologous bone grafts in 19 cases, 6 cases underwent vascularized tissue flap, 5 cases underwent external implants alone, and 7 cases underwent vascularized tissue flap combined with external implants. After the recovery of the affected side, the average difference of the zygomatic projection between the navigation group and the non-navigation group was 0.45 mm (0.20-2.50 mm) and 1.60 mm (0.10-2.90 mm), with a significant difference (P=0.045). Two patients repaired with titanium mesh combined with anterolateral thigh flap had obvious deformation or fracture of titanium mesh; 2 patients with customized casting prosthesis had infection after surgery and fetched out the prosthesis finally. CONCLUSION: Autologous free grafts or alloplastic materials may be used in cases without significant structural changes. Pedicle skull flap or vascularized bone tissue flap is recommended for zygomatic bone defects with bone pillar destruction, chronic inflammation, oral and nasal communication or significant soft tissue insufficiency. Titanium mesh can be used to repair a large defect of zygomatic bone, and it is suggested to combine with vascularized bone flap transplantation.

[Three-dimensional finite element analysis of traumatic mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures].

OBJECTIVE: To analyze the biomechanical mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures using finite element analysis (FEA). METHODS: Maxillofacial CT scans and temporomandibular joint (TMJ) MRI were performed on a young male with normal mandible, no wisdom teeth and no history of TMJ diseases. The three-dimensional finite element model of mandible was established by Mimics and ANSYS based on the CT and MRI data. The stress distributions of mandible with different angles of traumatic loads applied on the symphyseal region were analyzed. Besides, two models with or without disc, two working conditions in occlusal or non-occlusal status were established, respectively, and the differences of stress distribution between them were compared. RESULTS: A three-dimensional finite element model of mandible including TMJ was established successfully with the geometry and mechanical properties to reproduce a normal mandibular structure. Following a blow to the mandibular symphysis with different angles, stress concentration areas were mainly located at condyle, anterior border of ramus and symphyseal region under all conditions. The maximum equivalent stress always appeared on condylar articular surface. As the angle between the external force and the horizontal plane gradually increased from 0° to 60°, the stress on the mandible gradually concentrated to symphysis and bilateral condyle. However, when the angle between the external force and the horizontal plane exceeded 60°, the stress tended to disperse to other parts of the mandible. Compared with the condition without simulating the disc, the stress distribution of articular surface and condylar neck decreased significantly when the disc was present. Compared with non-occlusal status, the stress on the mandible in occlusal status mainly distributed on the occlusal surface, and no stress concentration was found in other parts of the mandible. CONCLUSION: When the direction of external force is 60° from the horizontal plane, the stress distribution mainly concentrates on symphyseal region and bilateral condylar surface, which explains the occurrence of symphyseal fracture and intracapsular condylar fracture. The stress distribution of condyle (including articular surface and condylar neck) decreases significantly in the presence of arti-cular disc and in stable occlusal status when mandibular symphysis is under traumatic force.

[Application of computer-aided virtual mandibular position in the simultaneous treatment of children with temporomandibular joint ankylosis and jaw deformity].

OBJECTIVE: To evaluate the feasibility of computer-aided design virtual mandibular position in the simultaneous treatment of children with temporomandibular joint ankylosis (TMJA) and jaw deformity. METHODS: The children with unilateral TMJA were surgically treated from January 2016 to June 2017 in the Department of Oral and Maxillofacial Surgery. The image data of jaw and dentition were imported into the computer software to simulate the surgical procedure. An osteotomy of the affected side was performed to remove ankylosed bone mass. Then the mandible was rotated around the unaffected condyle to eliminate the chin deviation by the virtual plan. An open bite was thus created on the affected side to provide space for vertical midfacial growth. In the virtual mandibular position, the affected ramus was reconstructed with costochondral grafting. Finally, digital occlusal splint was designed and prefabricated by 3D printing. During surgery, temporomandibular joint ankylosis was released and mandibular position was guided in place by the digital occlusal splint. In the new mandibular position, costochondral grafting was completed. After the surgery, the occlusal splint was wired to the mandibular dentition and would be gradually adjusted by grinding off the maxillary side to promote downward growth of the maxilla until the open bite was eliminated. The ramus height and chin deviation were measured before and one week after the surgery to validate the method. Comparisons of the measurements were made by means of a repeatedmeasures analysis of variance (ANOVA) (P=0.05). Pairwise multiple comparisons were conducted using the Bonferroni correction (P=0.05). RESULTS: Five patients were included in this study. Under the guidance of the digital occlusal splint, the mandible could reach the preoperative designed position smoothly in all the cases. The chin deviations were (0.58±0.20) mm in the virtual plan before surgery, and (0.70±0.27) mm after surgery, which were not significant statistically (P>0.05). The ramus heights on the affected side were (48.19±3.20) mm in the virtual plan before surgery, and (48.17±3.62) mm after surgery, which were not significant statistically (P>0.05). CONCLUSION: It is feasible and reliable in the simultaneous treatment of TMJA with jaw deformity under the guidance of virtual mandibular position.

[Application of the submandibular gland for management of stage 3 medication-related osteonecrosis of the mandible].

Objective: To summarize the clinical outcomes of reconstruction plate fixation combined with submandibular gland translocation (A) or reconstruction plate fixation combined with submental island flap and submandibular gland (B) for mandibular stage-3 medication-related osteonecrosis of the jaw (MRONJ). Methods: The clinical data of the patients with stage-3 mandibular MRONJ treated with one of the above mentioned procedures from September 2014 to December 2020 in the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, were retrospectively reviewed. The clinical data included the general data of the patients, the initial mucosal healing rate at the time of 2 weeks postoperatively and follow-up, and the occurrence of complications. Results: A total of 40 patients were treated, including 17 males and 23 females, aged (64.6±8.9) years. Among the patients, 33 were treated with operation A and 7 with operation B. The initial mucosal healing rate was 90% (36/40). Plate fracture occurred in 4 patients. The mean length of the mandibular bony defect was (4.5±1.4) cm (ranged from 2.1 to 8.0 cm). Conclusions: For management of stage-3 mandibular MRONJ, reconstruction plate fixation combined with submandibular gland translocation or with submental island flap and submandibular gland might be one of the effective and reliable options.

[Evaluation of the preliminary clinical effect of flap-raising combined with cortical-perforation technique in tooth extraction cases of patients with potential risk of medication-related osteonecrosis of the jaw].

Objective: To evaluate the preliminary clinical effect of flap-raising and cortical-perforation based extraction method in patients with potential risk of medication-related osteonecrosis of the jaw (MRONJ). Methods: Eighteen patients, who needed teeth extraction in the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from February 2016 to November 2020, with a history of using anti-resorption/anti-angiogenesis medication were included in this retrospective study. According to the characteristics of the patient's medication history, patients were stratified into three categories, low-dose anti-resorption drug group, high-dose anti-resorption drug group, and high-dose anti-resorption combined with anti-angiogenesis targeted drug group. There were 15 females and 3 males, the average age was 62.4 years (range from 27 to 87 years) old. A total of 31 teeth were indicated for extraction due to chronic infection. The flap-raising and cortical-perforation techniques were used to extract the affected teeth, and the patients were followed up closely. By observing the healing status and swelling degree of the mucosa of tooth extraction sites, whether there was a fistula, pus and bone exposure of jaw bone,the healing of the tooth extraction sites were evaluated. Results: Among the 18 patients, there were 9 cases of osteoporosis and 9 cases of malignant tumors. Classified by medication-using history, 10 cases were treated with low-dose anti-resorption drugs, 5 cases were high-dose anti-resorption drugs, and 3 cases were high-dose anti-resorption drugs combined with anti-angiogenesis drugs. A total of 31 teeth of the patients were extracted by flap-raising and cortical-perforation based extraction method. Thirteen patients completed treatment underwent local anesthesia and five cases were performed under general anesthesia. The shortest follow-up period was 3 months with an average of 13.2 months. Seventeen patients recovered well after the tooth extraction. One patient had the mandible exposed at one extraction site one month after the surgery, resulting in MRONJ. Conclusions: In patients with potential risks of MRONJ, the application of flap-raising and cortical-perforation based teeth extraction method could safely and effectively alleviate the dental inflammation in the oral cavity.

Quality of life in patients with lepromatous leprosy in China.

BACKGROUND: Leprosy has an impact on patients' quality of life (QoL). However, there has been no study specifically on the impact of the severest type of leprosy-lepromatous leprosy on QoL. OBJECTIVE: To describe the use of Dermatology Life Quality Index (DLQI) among patients with lepromatous leprosy in China. METHODS: Sixty-four inpatients with lepromatous leprosy of Shangluo hospital and Hanzhong hospital and sixty-four controls (healthy volunteers or patients with other dermatoses) matched for age and gender were asked to complete DLQI questionnaires from 2 September 2008 to 20 December 2008. Extensive data were collected besides DLQI, including demographic data and disease-related characteristics. Absence or presence of disability among patients with lepromatous leprosy was evaluated at the same time. RESULTS: The overall mean DLQI score for lepromatous leprosy (18.78) was higher than that for control (9.00) (P < 0.001). Patients with lepromatous leprosy scored significantly higher for all items (P < 0.001) except Q4 (clothes choice). Controls scored significantly lower for all domains of DLQI. Scores of LL increased markedly with increasing clinical severity, but were not associated with educational level, gender, age and disease duration. The inter-item correlation averaged 0.240 and Cronbach's alpha was 0.759, indicating high internal consistency. CONCLUSIONS: This is the first exclusive study to attempt to measure the impact of lepromatous leprosy on QoL. Lepromatous leprosy has a severe impact on QoL.

[Sagittal fracture of mandibular condyle: a review of 151 cases].

Objective: A retrospective research was made to summarize the clinical characteristics, treatment methods, results of the adult cases with sagittal fracture of mandibular condyle (SFMC). Methods: One hundred and fifty-one cases of hospitalized patients were enrolled. The age, sex, etiology, level of fracture, degree of displacement, associated facial fractures, treatment methods and results were retrospectively analyzed. Results: The patient's age ranged from 16 to 81 years old, with a median age of 38.5 years. The male to female ratio was 2.97∶1. The most involved age group was 20-29 years old [35.1% (53/151)]. Falls [53.6% (81/151)] were the most common cause. According to the classification of He (2009) and Duan (2011), the most common type of SFMC was type A [60.5% (130/215)] and the displacement type [80.9% (174/215)]. Eighty-six point zero percent (185/215) of SFMC were treated by surgery. The surgical rates of type A, B and M fractures were 91.5% (119/130), 79.6% (43/54) and 88.5% (23/26), with significant differences between the groups (P<0.05). The surgical rates of the displacement and dislocation type were 89.7% and 100%, with significant differences. The differences between the fixations of type A, type B and type M fractures were statistically significant. The follow-up results showed that, 78.7% (59/75) of patients treated with surgery had normal occlusion, no joint symptoms and no limited mandibular movement. Patients treated with conservative therapy had good occlusion and an average maximum mouth opening of 36.25 mm with malunion occurred in 5/6 of the condyles. Conclusions: Under appropriate surgical indications, surgical treatment of SFMCs could achieve significantly better outcomes than conservative treatment.

Role of Bone Marrow Stromal Cells in Impaired Bone Repair from BRONJ Osseous Lesions.

Treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ) has posed significant challenges to maxillofacial surgeons because of the poor repair of BRONJ bone defects. Moreover, the pathological mechanisms remain unclear. Bone marrow stromal cells (BMSCs) play key roles during bone repair and bone regeneration. However, the activities of BMSCs derived from BRONJ lesions and the BRONJ lesion boundary, as well as the roles of BMSCs in BRONJ defect repair, are poorly defined. In this study, we found that BMSCs from the central area of the osteonecrotic BRONJ region (center-BRONJ BMSCs) and the peripheral area at the recommended debridement boundary (peri-BRONJ BMSCs) had decreased proliferative ability, self-renewal capacity, and multidifferentiation capacities compared with control BMSCs. Osteoclast-inducing ability was also impaired in BRONJ BMSCs. All of these results suggested that the decreased activities of BRONJ BMSCs, even the BMSCs derived from the BRONJ lesion boundary, might be an important factor leading to insufficient bone repair of BRONJ lesions. This study offers early stage evidence for the use of marrow stromal cells in the treatment of BRONJ.

Reeconstruction of a mandibular defect after bisphosphonate-related osteonecrosis of the jaw.

We describe the reconstruction of a mandible damaged by bisphosphonate-related osteonecrosis of the jaw (BRONJ) using the simple and safe combination of a reconstruction plate and patching with a submandibular gland.

Treatment of traumatic dislocation of the mandibular condyle into the cranial fossa: development of a probable treatment algorithm.

This study summarizes our experience of treating three rare cases of traumatic superior dislocation of the mandibular condyle into the cranial fossa and provides a potential treatment algorithm. Between the years 2002 and 2012, three patients with traumatic superior dislocation of the mandibular condyle into the cranial fossa were admitted to our department. After evaluating the interval from injury to treatment, the associated facial injuries including neurological complications, and the computed tomography imaging findings, an individualized treatment plan was developed for each patient. One patient underwent closed reduction under general anaesthesia. Two patients underwent open reduction with craniotomy and glenoid fossa reconstruction. All three patients were followed up for 1 year. Mouth opening and occlusal function recovered well, but all patients had mandibular deviation during mouth opening. Closed reduction under general anaesthesia, open surgical reduction with craniotomy, and mandibular condylotomy are the three main treatment methods for traumatic superior dislocation of the mandibular condyle into the cranial fossa. The treatment method should be selected on the basis of the interval from injury to treatment, associated facial injuries including neurological complications, and computed tomography imaging findings.

A novel frameshift mutation in the cylindromatosis (CYLD) gene in a Chinese family with multiple familial trichoepithelioma.

Multiple familial trichoepithelioma (MFT) (OMIM: 601606) is an autosomal dominantly inherited disorder characterized by numerous, skin-colored papules and nodules with pilar differentiation. Recently, several mutations in the cylindromatosis (CYLD) gene have been reported in MFT. In this study, a mutation analysis of the CYLD was conducted in a Chinese pedigree of typical MFT. Affected individuals were identified through probands from Shanxi Province, China. Lesional skin biopsy of the proband revealed the typical histopathological characteristics of trichoepithelioma. Individuals belonging to five consecutive generations were similarly affected, which indicated an autosomal dominant inheritance pattern. Genomic DNA was extracted from peripheral blood lymphocytes using standard phenol/chloroform extraction method. All the coding exons (4-20) and exon-intron boundaries of the CYLD gene were amplified by polymerase chain reaction (PCR). Direct sequencing of all PCR products amplified from the complete coding regions of the CYLD gene was performed to identify mutations. Sequencing of the CYLD gene was performed in a further 100 unrelated, unaffected control individuals to exclude the possibility of polymorphism. A novel heterozygous frameshift mutation c.1169_1170delCA (p.Thr390Argfs) was identified in exon 10 of the CYLD gene in the affected family members. This mutation was also detected in unaffected family members, but not in the unrelated, healthy individuals who were also analyzed. Our study expands the database on the CYLD gene mutations in MFT and should be useful in providing genetic counseling and prenatal diagnosis for families affected by MFT.

Decreased osteogenesis in stromal cells from radiolucent zone of human TMJ ankylosis.

We previously hypothesized that the development of traumatic temporomandibular joint (TMJ) ankylosis was similar to that of hypertrophic non-union. Besides similarities in etiology, hypertrophic bone stumps, and long-term development, the radiolucent zone, frequently located in the ankylosed bone, is another common feature. In this study, we demonstrated that the radiolucent zone also contained multilineage potential cells (RZs, radiolucent-zone-related cells) as the non-union tissues. RZs were characterized and compared with mandibular bone marrow stem cells (BMSCs) by analysis of MSC-related markers, colony-forming-unit assays, multipotential differentiation assays, alkaline phosphatase (ALP) activity assays, and cell transplantation in vivo. Both cell types were positive for CD105, CD166, and Stro-1 expression, negative for CD34 and CD45 expression, and exhibited osteogenic, adipogenic, and chondrogenic differentiation potentials. However, compared with mandibular BMSCs, RZs showed lower colony-forming-unit abilities and proliferation rates. The mineralization and bone-forming ability of RZs was weaker than that of mandibular BMSCs, with Runx2 and ALP mRNA expression and ALP activity significantly lower in RZs. All these results suggest that RZs possess the properties of MSCs but lower proliferation and osteogenic differentiation capacity similar to that of stromal cells in hypertrophic non-union tissues.