Distal-triangular flap design for impacted mandibular third molars: a randomized controlled trial.

OBJECTIVES: This prospective study was performed to evaluate whether the distal-triangular flap was a practical alternative surgical approach for extracting mandibular third molars. METHODS: Sixty participants with impacted mandibular third molars were randomly divided into three groups: group A, distal-triangular flap; group B, Szmyd flap; and group C, envelope flap. The impacted third molars were extracted by the corresponding flapping method. During a three-month follow-up observation after the extraction, the postoperative pain, swelling, mouth opening, and periodontal status were recorded and analyzed by ANOVA and chi-square tests. RESULTS: The 60 participants had successful extraction and 3-month follow-up observation. No participant suffered from postoperative infections, lower lip disorder, or tongue sensory disorders. No statistical differences were found in the postoperative symptoms and signs of the three flap designs, such as postoperative pain, swelling, mouth opening, and periodontal status (P>0.05). CONCLUSIONS: The distal-triangular flap was as safe and reliable as the Szmyd and envelope flaps but more advantageous because of its convenient operative field exposure and low requirement for the patient's mouth opening. Thus, the distal-triangular flap is one of the alternative flap options for extracting impacted mandibular third molars.

[Clinical study of age-related sensory innervation of the anterior hard palate].

OBJECTIVES: The present study aimed to explore the innervation of the anterior hard palatine and its relationship with individual development stage. Specifically, the effects of anesthesia on patients of different ages were observed, and neurodevelopment in the maxillofacial region was invesitgated. References that are helpful in selecting local anesthesia were provided. METHODS: A total of 182 patients with mixed dentition were randomly divided into the nasopalatine nerve block and greater palatine nerve block groups. Then, 219 patients with permanent dentition were divided into an adolescent group (13-18 years old) and adult group (over 19 years old), all of whom underwent bilateral greater palatine nerve block. Palatal mucosal pain sensation was tested pre- and post-anesthesia with Von Frey hairs. RESULTS: Among the children with mixed dentition, bilateral greater palatine nerve block tended to result in better anesthetic effects than nasopalatine nerve block (P<0.05), except in the incisive papilla. No difference in anesthetic effect was observed between adolescents and adults (P>0.05). The bilateral greater palatine nerve block was more effective in inducing an anesthestic effect in the anterior hard palatine in mixed dentition than in permanent dentition (over 13 years old; P<0.05). CONCLUSIONS: The sensation of the anterior hard palatine seems mainly dominated by the greater palatine nerve until mixed dentition and gradually shifted to the nasopalatine nerve in conjunction with maxillary development and tooth replacement. Hence, the innervation of the anterior hard palatine induce a secondary development during the development of the maxilla.

[Strategy of dental clinics to cope with the epidemic period of infectious diseases based on the experience of corona virus disease outbreak].

The outbreak of corona virus disease (COVID-19) has raised concerns among dentists to develop strategies to prevent infection of dental equipment, materials, and patients during an epidemic period. Strategies following the National Laws and Standards of China and local standards of several provinces for controlling cross-infection and instituting protective measures for medical staff in dental clinics during an epidemic period are discussed. A proposal is put forth for dental clinics that will face similar situations in the future. Further research is warranted to address potential problems that will be encountered under such dire circumstances.

[Prognosis of teeth with external root resorption caused by adjacent impacted teeth].

OBJECTIVE: This study aimed to investigate the prognosis of permanent teeth with external root resorption (ERR) caused by adjacent impacted teeth. METHODS: A total of 75 ERR teeth (permanent teeth) caused by adjacent impacted teeth of 63 patients were included. The prognosis of ERR teeth was analyzed followed by minimally invasive extraction of the adjacent impacted teeth. The time of follow-up was six months. The relationship between prognosis of ERR teeth and patients' age, gender, root number, type of root resorption and degree of root resorption were analyzed. RESULTS: In the 75 ERR teeth, 67 teeth (89.3%) did not show pulpitis symptoms. The clinical outcome was found to be related with age (r=0.330, P<0.05), whereas no relationships with gender, root number, as well as type and degree of root resorption were observed (P>0.05). Pulpitis symptom was not found in ERR teeth of patients under 30 years old. CONCLUSIONS: For ERR teeth caused by adjacent impacted teeth, keeping the pulp vital after surgical removal of impacted teeth is highly probable. Post-operative follow-up instead of preventive root canal therapy of ERR teeth is recommended.

[Research progress on the modification of guided bone regeneration membranes].

Guided bone regeneration (GBR) is an important technique to solve bone defect problems. In this technique, GBR barrier membranes play an irreplaceable role. GBR membranes can act as a barrier protecting fibroblasts from bone defects and promote osteoblast adhesion and proliferation, leading to bone regeneration. GBR barrier membranes should be enhanced because of the disadvantages of collagen membranes, which are extensively applied to the field of GBR. Therefore, various efforts have been devoted to modifying the antibacterial and osteogenic properties of GBR barrier membranes and developing novel materials. This article reviews the research advancements on the modification of GBR barrier membranes and discover future directions for the development of GBR barrier membranes to provide a reference for bone tissue engi-neering and repair.

[Relationship between initial archwire materials and pain at the initial stage of orthodontic treatment: a systematic review and network Meta-analysis].

OBJECTIVE: This review aims to assess the relationship between initial archwire materials and pain at the initial stage of orthodontic treatment. METHODS: On October 1, 2017, seven databases were searched electronically for studies oninitial archwire materials and pain at the initial stage of orthodontic treatment. Quality assessment was performed with bias risk assessment tools suggested by Cochrane's handbook. Data extraction of included studies was also carried out. Network Meta-
analysis was conducted using R 3.4.2 (with JAGS 4.3.0), GeMTC 0.14.3, and STATA 11.0. RESULTS: Five studies with 330 participants were included, comparing four different materials: multi-stranded stainless steel, conventional nickel-titanium, super-elastic nickel-titanium, and thermal heat-activated nickel-titanium. Two studies were at low risk of bias, one was at high risk of bias, and the remaining two were at unclear risk of bias. Network Meta-analysis results showed no statistical differences of pain among the four initial archwire materials at day 1 and day 7. However, the most painless material was most likely to be thermal heat-activated nickel-titanium on rank probability. CONCLUSIONS: On statistical probability, thermal heat-activated nickel-titanium initial arch wires is most likely to cause the least pain at the initial stage of orthodontic treatment, compared with other materials.

[Application of peer-assisted learning in evidence-based dentistry teaching].

PURPOSE: To explore the effects of peer-assisted learning (PAL) for evidence-based dentistry (EBD) teaching. METHODS: Four hundred and eleven students who attended EBD class were randomly classified into PAL group (n=75) and traditional teaching group (n=326) via a ratio of 1:5. Students in traditional teaching group received traditional theoretical teaching; while PAL group received traditional theoretical teaching and group study with tutors introduced and finished study protocols given by the teachers. Teaching effects were evaluated by final examinations, questionnaires and published articles via bibliographic searching. Statistical analysis was carried out with STATA 11.0 software package. RESULTS: In the final examination, students in PAL group had 6.9 higher scores than traditional teaching group (P<0.05). The results of questionnaires showed that students in PAL group had higher interests and contentments in EBD class (P<0.05), and PAL had positive effects on their usage of EBD methodology and involvement in EBD research (P<0.05). In publication of articles, the number and ratios of article publication in PAL group were significantly higher than the traditional group (P<0.05). CONCLUSIONS: PAL has positive effects on EBD teaching.

Angiogenic gene-modified myoblasts promote vascularization during repair of skeletal muscle defects.

Vascularization is thought to be a principle obstacle in the reconstruction of skeletal muscle defects. Long-term survival of reconstructed skeletal muscle is dependent on good vascularization. In this study, we upregulated angiogenic gene expression in myoblasts in an attempt to promote vascularization during repair of skeletal muscle defects. Skeletal myoblasts were isolated and expanded from newborn male Sprague-Dawley (SD) rats. The cells were transfected with human vascular endothelial growth factor 165 (VEGF-165) or human stromal cell-derived factor 1 (SDF-1), using Lipofectamine™ 2000 transfection reagent, prior to seeding onto calf collagen scaffolds. Gene and protein overexpression was verified by ELISA, RT-PCR and western blot analysis. Cell-seeded scaffolds were transplanted into back muscle defects in female SD rats. At weeks 2, 4 and 8 after transplantation, Y chromosome detection was used to observe the survival of growth factor-producing cells within the scaffolds in vivo. Capillary density was investigated using microvessel density detection, haematoxylin and eosin (H&E) staining and immunohistochemical staining. We found that vascularization was enhanced by transfected myoblasts compared with non-transfected myoblasts. In addition, VEGF-165 and SDF-1 had a synergistic effect on vascularization during repair of skeletal muscle defects in vivo. In conclusion, we have combined myoblast-seeded collagen sponge with gene therapy, resulting in a promising approach for the construction of well-vascularized skeletal muscle.

Primary tumor prevalence has an impact on the constituent ratio of metastases to the jaw but not on metastatic sites.

This article provides an overview of metastases to jaws (MJ), mainly concerning the differences between American and Chinese patients, and exploring the relationship between the primary tumors' prevalence (PTP) and constituent ratio of MJ. Information concerning of 399 MJ cases in 215 papers, including one new case in our hospital, was subjected to statistic analysis. The main clinical features of MJ, such as constituent ratio of PTP and that of MJ, metastatic sites, treatments, and prognosis were summarized. Breast, lung, kidney, prostate and thyroid (in descending order) were the leading primary sites of MJ. Furthermore, the constituent ratio of MJ was found to be correlated with that of PTP in all subjects including American and Chinese subjects in our study. As to metastatic sites in the mandible, a specific "M" shaped pattern appeared regardless of the tumor type or constituent ratios of MJ were in all subjects. Almost all subjects received traditionally palliative treatments, and the prognosis was quite poor. The PTP had a significant impact on the constituent ratio of MJ. However, it was the properties of the microenvironment rather than characteristics or constituent ratios of tumor cells, that decided the metastatic sites in various tumor subjects.

Intratumoral c-Met expression is associated with vascular endothelial growth factor C expression, lymphangiogenesis, and lymph node metastasis in oral squamous cell carcinoma: implications for use as a prognostic marker.

Hepatocyte growth factor has been identified as a lymphangiogenic factor in experimental animal models. However, the correlation between hepatocyte growth factor or c-Met expression and lymphangiogenesis in human spontaneous tumors has been rarely reported, and the distribution pattern of c-Met on tumor-related lymphatic vessels remains to be further investigated. Lymphatic vessel density, lymphatic invasion, the expression of hepatocyte growth factor, c-Met, and vascular endothelial growth factor C proteins were evaluated by immunohistochemistry in 76 cases of oral squamous cell carcinoma. The distribution of c-Met on lymphatic endothelium was examined. High expression of c-Met in tumor cells was significantly associated with advanced clinical stage (P = .045), high expression of vascular endothelial growth factor-C (P < .001), higher peritumoral lymphatic vessel density (P = .003), higher incidence of peritumoral lymphatic invasion (P = .032), and positive lymph node status (P = .005), in spite of its negative expression on most lymphatic vessels. Patients with high-c-Met expression tumors exhibited shorter overall survival and disease-free survival (P < .001 and P = .010, respectively). Taken together, our results provide indirect evidence for an association and possible regulatory link of c-Met with the lymphangiogenic factor, vascular endothelial growth factor C, and, by extension, with lymphangiogenesis and lymph node metastasis, suggesting important prognostic significance of c-Met for patients with oral squamous cell carcinoma.

Mesenchymal stem cells transduced by stromal cell-derived factor-1α augment ischemic free flaps' survival.

Mesenchymal stem cells (MSCs) have the potential for differentiating into vascular endothelial cells. Stromal cell-derived factor-1α (SDF-1α) plays an important role in neovascularization of ischemic flaps. The authors evaluated the feasibility of applying MSCs transduced by SDF-1α gene to the treatment of early and partial ischemic free flaps survival. MSCs were isolated from Lewis rats and cultured in vitro. Recombinant adenovirus encoding SDF-1α gene (Ad-SDF-1α) was transduced into the MSCs. Lewis rats that underwent epigastric free flaps based on medial and lateral branches of superficial inferior epigastric vessels and femoral vessels were equally randomized into 4 groups, and injected with Ad-SDF-1α-transduced MSCs, MSCs, Ad-SDF-1α, and normal saline, respectively. Gene transduction, flaps survival, neovascularization, and expression level of SDF-1a protein were detected. The results showed that Ad-SDF-1α-transduced MSCs expressed higher SDF-1α both in vitro and in vivo, yielded more survival area, and resulted in higher neovascularization than any other groups. Interestingly, the necrotic sites of all free flaps were in the proximal end rather than in the distal end. In conclusion, Ad-SDF-1α-transduced MSCs can increase neovascularization of early and partial ischemic free flaps and augment the surviving areas.

Anterior skull base reconstruction with galeal-frontalis-pericranial flap based on temporalis myofascial flap.

Such a giant anterior skull base mucocele involving the orbito-ethmoido-maxillo-fronto sinuses is a rare case. This patient complained of a right orbital mass for 18 years, and he was recommended to our hospital for treatment. His history, physical examination, laboratory study results, diagnosis, and treatment are reported in detail. In conclusion, we show that modified transcranial pathway and ingenious assistant incision can get the utmost exposure and can obtain a satisfactory aesthetic result and that anterior skull base reconstruction with the galeal-frontalis-pericranial flap based on the temporalis myofascial flap for the first time can successfully prevent life-threatening complications from happening.

Expression of Twist in different subtype of ameloblastomas.

OBJECTIVE: The objective of this study was to investigate the pattern of Twist expression in a series of ameloblastomas, and to study the possible role of Twist in the bone destruction and local invasiveness of ameloblastoma variants. STUDY DESIGN: Immunohistochemical study was performed for Twist protein in 53 ameloblastomas (32 solid/multicystic [SA] and 21 unicystic [UA]). RESULTS: The salient finding was that expression of Twist was related to the histological subtype of tumors, as there was a higher expression in SA (14/32, 43.75%) as compared to UA (4/21, 19.05%) (P < .05). Both nuclei and cytoplasm positivities were detected in positive cases, whereas cytoplasmic staining was diffused and predominant. Cases rich in stromal cells showed a higher percentage of positive cells than those with less stroma. CONCLUSIONS: Our results suggest that Twist expression might be associated with invasion in ameloblastoma variants, and stromal cells might play a regulatory role during tumor development.

[An experimental study on angiogenesis of non-vascularized autogenous bone graft with vascular bundle implantation].

OBJECTIVE: To investigate the effect of vascular bundle implantation in autogenous bone graft on angiogenesis. METHODS: Thirty-six New Zealand white rabbits were evaluated in this study. A portion of bilateral radial bones of a rabbit were removed as free bone grafts, whose periostea were peeled off. In test group, the external maxillary artery bundle was passed through the marrow cavity of the bone. In control group, there was no vascular bundle implantation. Each bone was placed in masseter muscle separately. The rabbits were sacrificed and the specimens were procured at 3 days, 1, 2, 3, 4 and 6 weeks after surgery for histological observation, Chinese ink perfusion and CD34 immunohistochemistry. Microvessel density (MVD) was assessed in order to evaluate angiogenesis of autogenous bone grafts. RESULTS: The bone grafts were found revascularization in 3 days after surgery in the test group, whereas at 2 weeks in the control group. In 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks after surgery, the MVD of test group was significantly higher than that of control group. In 4 weeks after surgery, angiogenesis of test group reached to peak. CONCLUSION: Vascular bundle implantation improved angiogenesis in non-vascularized autogenous bone graft in this study.

Metastatic tumors to the oral and maxillofacial region: a retrospective study of 19 cases in West China and review of the Chinese and English literature.

PURPOSE: The aim of this article was to obtain an overview of metastatic tumors to the oral and maxillofacial (OMF) region, especially the differences in the constituent ratios of primary cancers between the United States and China. PATIENTS AND METHODS: Clinical findings of 19 cases encountered in West China Hospital of Stomatology were summarized and the English and Chinese literature were reviewed and analyzed. The main clinical features of OMF metastases were summarized, with an emphasis on primary cancers' constituents. RESULTS: The lung, breast, kidney, liver, and prostate were the top 5 common primary sites of cancer. However, there was a significant difference in the primary cancers' constituents between United States and China (P < .001). The breast, kidney, prostate cancers, and melanoma of skin were more frequent primary cancers in United States than in China, whereas that of the lung, thyroid, liver, esophagus, and the stomach were more common in China than in United States. The proportions of the OMF metastatic lesions originating in the lung, kidney, liver, thyroid, and esophagus in all OMF metastatic tumors were higher than the corresponding primary cancers' prevalent proportions. CONCLUSIONS: The frequency of developing OMF metastasis is not always consistent with primary cancers' prevalence, which suggests that different cancers have different potentiality to develop OMF metastasis. Cancers of the kidney, liver, lung, thyroid, and esophagus were more likely to spread to the OMF region. In general screening of primary cancer, it would be helpful to take into account the metastatic potentiality of different cancers and primary cancers' prevalence in different countries in the case of occult primary.

Cutaneous metastasis from a parotid myoepithelial carcinoma: a case report and review of the literature.

Myoepithelial carcinoma of the parotid gland is a rare salivary gland tumour, and its distant cutaneous metastasis has not been reported to date. Here, we report a case of myoepithelial carcinoma of the left parotid gland, which had metastasised to the skin of the right thorax after parotidectomy and radiotherapy. Diagnosis of the primary and metastatic tumour was based on the clinical findings and was confirmed by immunohistochemistry. A literature review of the clinical features of the skin metastases of parotid malignancies and their related pathological mechanisms is included in this case study. It was noted that myoepithelial carcinoma of the parotid gland has the potential to develop distant skin metastasis, which may be indicative of widespread dissemination and poor prognosis. Attention should be paid to initial treatment of the primary tumour and to emerging cutaneous masses whose location is distant from the primary tumour during follow up.

[Cancer stem cells: its existence, proliferation and differentiation in an adenoid cystic carcinoma cell line].

OBJECTIVE: To investigate the evidences of the presence of tumor stem cells and its impact on the tumorigenesis of adenoid cystic carcinoma cell (ACC)-2 cell line by analyzing the biologic characteristics of different sub-clones of adenoid cystic carcinoma cell line. METHODS: In vitro individual cell culture was employed to observe the proliferating character of ACC-2 cells. The expression of CD44(+) and CD24(-) of ACC-2 cells were investigated by immunohistochemical. Immunomagnetic isolation of different phenotype of ACC-2 cells, followed by cell culture, was used to study the proliferating abilities of different clusters of the cell line. The hetero-transplanted tumor mold was established using BALB/C nude mice by subcutaneous injection of tumor cells. The tumorigenic and differentiating properties of the different cluster were investigated. RESULTS: Only 4.41% of cultured ACC-2 cell had ability of division, proliferation and establishment of cell clone. CD44(+)-CD24(-) cluster accounted for about 8.1% of total ACC-2 cells, among which, 25.71% cells could divide and proliferate. All of CD44 and CD44(+)-CD24(+) cells were failure to be eternal alive in the condition of in vitro individual cell culture. According to the results of in vivo tumorigenic study, the minimal cell quantity to develop a subcutaneous transplanted tumor by CD44(+)-CD24(-) cells was 1 x 10(3), where as the needed cell amount were 1 x 10(5) and 1 x 10(4) as to non-isolated ACC-2 cells and CD44(+) cells, respectively. The CD44(-) and CD44(+)-CD24(+) did not develop transplanted tumors. CD44(+)-CD24(-) ACC-2 cell could differentiate into cells of other phenotypes. CONCLUSIONS: CD44(+)-CD24(-) ACC-2 cells consist of a very small portion of all ACC-2 cells (about 4%). They have remarkable proliferating ability and can bear special phenotypes, The tumorogenic ability of CD44(+)-CD24(-) cells are stronger than that of CD44(+) and non-isolated ACC-2 cells. Eliminating of this cluster from ACC-2 would actually deprive the tumorogenic ability of the cell line.

[Effect of mechanical stimulation on the expression of E-cadherin/cateninin complex in salivary adenoid cystic carcinoma].

OBJECTIVE: To investigate the effects of cyclic biaxial mechanical stimulation on adhesion of salivary adenoid cystic carcinoma(SACC) extracellular matrix (ECM) and expression of E-cadherin/cateninin complex in the SACC high metastasis cell lines ACC-M, SACC low metastasis cells line ACC-2, we observed the functions of mechanical stimulation in the adhesion of SACC cell-ECM and investigate the mechanism in the adhesion of ACC. METHODS: Mechanical stimulation were applied to the cells for periods of 1, 3 and 6 hours every day, lasting for 2 days. The amplitude of mechanical stimulation applied to the cells were 1000, 4000 micro strain, at a frequency of 3 Hz. Unstrained cells were used as control. The expression of E-cadherin/cateninin complex on the cell of ACC-M, ACC-2 were studied with laser scanning confocal microscope and image analysis. SACC cell-ECM adhesion was assayed by MTT technique. RESULTS: The results showed that expressions of alpha, beta, gamma-cateninin on the cell of ACC-2 were obviously higher than that ACC-M and E-cadherin on the cell of ACC-M were obviously higher than that ACC-2 without mechanical stimulation. Mechanical stimulation can change the expression of E-cadherin/cateninin complex on the cell of ACC-2 and ACC-M with time. The results also showed that cell-ECM adhesion on the cell of ACC-2 were obviously higher than that of ACC-M without mechanical stimulation. Mechanical stimulation can change the cell-ECM adhesion of ACC-2 and ACC-M with time. CONCLUSION: Mechanical stimulation can change the adhesion of the SACC cell-ECM and expression of E-cadherin/cateninin complex of the SACC cell. We think it played an important role in metastasis of the cancer.

[The combination of VEGF-C expressing vector and the detection of expression in Tca8113 cell].

OBJECTIVE: To investigate the functional expression of a truncated VEGF-C gene in mammalian cells. METHODS: A truncated VEGF-C cDNA (with 5'-terminal cleaved between residues 207/208) was used to construct a pcDNA3.1(+)-VEGF-C recombined plasmid, which was cloned into a lingual SCC cell line (Tca8113) by lipid-mediated transfection. The expression of VEGF-C was detected by Western blotting and immunohistochemical staining. RESULTS: The VEGF-C fragment was successfully ligated into the pcDNA3.1(+) between EcoR I and Xho I multiclone sites. By Western blotting, the relative molecular mass 53 x 10(3) and 29 x 10(3) forms of VEGF-C were detected in cell lysates of VEGF-C transfected cells (VcTca), while the relative molecular mass 29 x 10(3) form of VEGF-C presented the only band in culture media. According to immunohistochemistry, the VcTca cells showed intensive cytoplasm positive reaction to VEGF-C, whereas faint reaction was found in non-transfected cells and pcDNA3.1(+) mock transfected cells. CONCLUSION: The results indicated that the truncated VEGF-C cDNA was sufficient for expression, secretion and activation when it was transfected into Tca8113 cell.