Secondary caries is a disease that occurs on the tooth after the filling has been used for a period of time. Second-ary caries is also the main reason for the replacement of dental restorations. Regardless of the material used for fillings, se-condary caries cannot be completely avoided. The proportion of secondary caries is very high after filling in permanent teeth or primary teeth. Secondary caries mainly occurs because of the formation of micro cracks after filling. When the micro crack width exceeds 50?μm, saliva will enter the micro cracks between the filling and tooth tissue. The cariogenic bacteria in the saliva will grow when the environment of micro cracks is appropriate, thereby producing secondary caries. The prevention of secondary caries includes micro crack control, fluoride use, teeth cleaning, tooth decay and gum disease treatment, and regular checkups.

Objective   To observe the effects of Porphyromonas gingivalis (P. gingivalis) ATCC 33277 infection on expression of intercellular adhesion molecule-1 (ICAM-1) in rat vascular smooth muscle cells(VSMC). Methods   An infection model of rat VSMC invaded by P. gingivalis was established in vitro. The mRNA of ICAM-1 was measured through reverse transcription-polymerase chain reaction (RT-PCR). Results   Compared with the control group, an apparent and statistically significant increase in expression of ICAM-1 mRNA was observed after 8, 16, and 24 h in P. gingivals-infected rat VSMC (P<0.05). The expression reached its peak at 16 h. Statistically significant differences were observed in the 8 h group and in the other two experimental groups (P<0.05). Conclusion   Infection of P. gingivals in rat VSMC can cause increased expres-sion of ICAM-1, which may have an important function in the progression of atherosclerosis.

Objective   To compare the shear bond strength(SBS) of cast Co-Cr alloys and selective laser melting(SLM) Co-Cr alloys with those of dental porcelain. Methods  A dental porcelain (Vita) was applied on cast and SLM Co-Cr alloy specimens(n=10). SBS test was conducted, and fracture mode analysis was determined. Student’s t-test by SPSS 13.0 soft- ware was employed to analyze the data. Results   The SLM Co-Cr alloy specimens had lower SBS values than the cast Co-Cr alloy specimens (P>0.05). The metal-porcelain bond strength value of the cast group was (33.11±4.98) MPa, and that of the SLM group was (30.94±5.98) MPa. The specimens in both test groups exhibited mixed failure. Conclusion  The metal-porcelain system processed by SLM exhibit a bond strength that is similar to that of the cast group. This system also display a high precision.

Objective  To investigate the correlation between drinking behavior and polymorphism combination of extracel-lular superoxide dismutase (EC-SOD) and aldehyde dehydrogenase 2 (ALDH2) genes and oral squamous cell carcinoma. Methods   The genetic polymorphisms of EC-SOD and ALDH2 were analyzed by polymorphism-polymerase chain reaction technique in peripheral blood leukocytes of 750 oral squamous cell carcinoma cases and 750 non-cancer controls. Results   The frequencies of EC-SOD (C/G) and ALDH2 variant genotypes were 38.27% and 69.47% in oral squamous cell carcinoma cases and 21.07% and 44.40% in healthy controls, respectively. Statistical tests showed significant difference in the frequencies between the two groups (P<0.01). The risk of oral squamous cell carcinoma with EC-SOD (C/G) was significantly higher than that of controls (OR=2.32). Individuals carrying ALDH2 variant genotypes had high risk of oral squamous cell carcinoma (OR=2.85). Combined analysis of the polymorphisms showed that percentages of EC-SOD (C/G)/ALDH2 variant genotypes in oral squamous cell carcinoma and control groups were 30.67% and 6.80%, respectively (P<0.01). Individuals carrying EC-SOD (C/G)/ALDH2 variant genotypes had high risk of oral squamous cell carcinoma (OR=8.13). The drinking rate of the case group was significantly higher than that in the control group (OR=2.70). Statistical analysis suggested an interaction between drinking and EC-SOD (C/G) and ALDH2 variant genotypes, which increase risk of oral squamous cell carcinoma (OR=25.00). Conclusion   EC-SOD (C/G) and ALDH2 variant genotypes and drinking are the risk factors in oral squamous cell carcinoma, which could carry out a coordinated attack of oral squamous cell carcinoma.

Objective   To explore the effect of glimepiride on the glucose uptake as well as glucose transporter (GLUT)-1 and GLUT-3 expression levels of rat mandibular osteoblasts in hyperglycemia. Methods   Primary osteoblasts were isolated and cultured. Then, the cells were placed in an osteogenic medium containing two glucose concentrations (5.5 and 16.5 mmol·L-1), with or without glimepiride (10 μmol·L-1). Glucose uptake was determined by employing 18F-deoxyglucose (18F-FDG) in the cells, and GLUT-1 and GLUT-3 expression levels were evaluated by Western blot analysis. Results   Glucose at 16.5 mmol·L-1 significantly inhibited 18F-FDG uptake and downregulated GLUT-3 protein expression in osteoblasts. Hyperglycemia in-creased GLUT-1 protein expression. Glimepiride significantly increased glucose uptake and upregulated GLUT-1 and GLUT-3. Conclusion   Glimepiride enhance the glucose transporter in rat osteoblasts at two different glucose concentrations.

Objective   To study the effect of peri-implantitis inflammatory microenvironment on the biological function of jaw bone osteoblasts. Methods   Primary mandible osteoblasts from peri-implantitis and normal tissue were isolated and cultured. Third-generation purified osteoblasts were identified and detected. The proliferative activity of osteoblasts was evaluated through MTT assay. Osteocalcin (OCN), Runx2, and collagen?Ⅰ?(Col?Ⅰ) mRNA levels were examined by real-time quantitative poly-merase chain reaction. OCN protein levels were determined by Western blot. Results   After 4 d of culture, the proliferative activity of osteoblasts from peri-implantitis became lower than that of normal tissue (P<0.05). After 7 d of culture, OCN, Runx2, and Col?Ⅰ mRNA expression decreased (P<0.05). The OCN protein levels also decreased (P<0.05). Conclusion   Peri-implantitis inflammatory microenvironment can decrease the proliferation and differentiation activity of mandible osteoblasts.

Objective   To investigate the influence of parathyroid hormone and estrogen on alveolar bone metabolism of castrated female rats. Methods   Sixty-six female Wistar rats which were healthy and 4 months old were divided into two groups, with group SHAM (n=18) and group ovariectomy (OVX) (n=48). After 8 weeks of ovariectomy, the osteoporosis model was confirmed by examing 8 ovariectomized and sham-operated rats. The rest 10 rats in group SHAM were the control group (group A). The rest 40 rats in group OVX were divided into ovariectomized group (group B), ovariectomized and treated with estrogen (group C), ovariectomized and treated with parathyroid hormone (group D), ovariectomized and treated with estrogen and parathyroid hormone (group E) at random with 10 in each group. Group A and B injected physiological saline (1 mL·kg-1), group C injected estradiol benzoate (10 μg·kg-1), group D injected parathyroid hormone (20 μg·kg-1), group E injected parathyroid hormone (20 μg·kg-1) and estradiol benzoate (10 μg·kg-1). The intraperitoneal injection were maken every other day to rats in each group, which continued for 8 weeks. The bone mineral density (BMD), bone histomorphology and serum Ca, P, alkaline phosphatase (ALP) were measured after therapy. Results   After 8 weeks of ovariectomy, the lumbar BMD of ovariectomized rats were significantly declined compared with those of the sham-operated rats (P<0.05). Eight weeks later after the drug use, the BMD, %Tb.Ar, Tb.Th, Tb.N in group C, D, E were slightly elevated compared to group B, espe-cially the group E (P<0.05). Serum calcium and phosphorus values did not change significantly (P>0.05). ALP values in group B was significantly higher than that in group A (P<0.05). Conclusion   Intermittent application of parathyroid hormone in small doses can increase alveolar BMD of castration rats and improve their bone structure. And it can have synergy effects on the treatment of osteoporosis if it is used combining with estrogen.

Objective   To analyze the asymmetry of measurements in facial asymmetry patients with skull positioning posterior-anterior radiographs after orthodontic-orthognathic treatment. Methods   Posterior-anterior cephalometric radio-graphy and cephalometric analysis were performed in forty-five patients with different degrees of facial asymmetry. A single sample t-test was conducted to compare the asymmetry of measurements before treatment and individual normal occlusion. The measurement and reference values in facial asymmetry patients who underwent orthodontic-orthognathic treatment were summated by analyzing the correlation coefficient. The paired t-test was employed to compare the difference between the two groups before and after the treatment. Results   Fourteen measurements were significantly different before the treatment and individual normal occlusion (P<0.05). Me[X] exhibited a higher correlation index of Ag[X] in forty-five cases. Twenty-eight patients showed the main asymmetry in the mandibular body, whereas fifteen patients in the ramus. Two patients showed the main asymmetry in both mandibular body and ramus. Fifteen measurements were significantly different before and after the treatment (P<0.05). Conclusion   Facial asymmetry is mainly concentrated in one-third of the surface, primarily manifested in the mandibular body. Orthodontic-orthognathic treatment is preferred when Ag[X] is greater than the minimum reference value of 11.31%, Go[X] is greater than 9.79%, and Me[X] is greater than 5.2 mm.

Objective   To evaluate the orthopedic effect of presurgical nasoalveolar molding (PNAM) devices on the palatal deformities in unilateral complete cleft lip and palate (UCCLP) patients. Methods   Three groups with 19 patients each were studied. All samples in groups A and B were non-syndromic UCCLP children. Group A was treated with PNAM prior to operation. Group B was untreated prior to operation. Samples in group C were normally developed nose and lip palate infants aged three months. The orthotopic palate photos before and after PNAM treatment for group A, as well as pre-operative photos of groups B and group C, were taken and measured. All statistics were analyzed using SPSS 21.0. Results   PNAM treatment significantly increased the AW, AC, and PA of UCCLP patients (P<0.05), whereas CPW, CWA, CWAS, CWAH, PMD, and CA significantly decreased (P<0.05). However, no significant difference was observed with the cases in group C (P<0.05). The AW, CPW, CA, and PA of the patients in group B significantly increased compared with the cases in group A before PNAM treatment (P<0.05). Multivariate analysis of variance indicated that TW had no statistically significant diffe-rence among the three groups (P>0.05). Conclusion   PNAM treatment is a non-surgical early treatment for the effective improvement of palatal primary deformities in UCCLP patients.

Objective   To evaluate the effect of orthognathic surgery in the treatment of condylar osteochondroma. Methods   A total of 12 cases of condylar osteochondroma were treated with Le Fort Ⅰ osteotomy, intraoral vertical ramus osteotomy, sagittal split ramus osteotomy and genioplasty. Results   No recurrence of condylar osteochondroma was observed in all 12 cases two years after the treatments. Facial asymmetry was obviously corrected. Conclusion   The orthognathic surgery me-thods are advantageous in improving facial figure without scar development in the treatment of condylar osteochondroma.

Objective   This study aimed to investigate the duration of gingival healing after the stage Ⅱ surgery of dental implantation for periodontitis patients and to provide clinical guidelines for implant restoration. Methods   Twenty-nine perio-dontitis patients who had implantation surgery and achieved osseointegration were operated with stage Ⅱ surgery (a total of 60 pieces of implants). The height of buccal gingival of each implant was measured twice after the stage Ⅱ surgery. All im-plants were measured at the lowest point of buccal gingival after one week. The implants were randomly divided into four groups according to the schedule of the next test time: group one at one week from the initial test point, group two at two weeks, group three at three weeks, and group four at four weeks. Each group includes 15 pieces of implants. The amount of the buccal gin-gival change in each group between the second and first tests was determined, and the data were analyzed statistically. Results   The amount of gingival change of groups one, two, three, and four was (-0.25±0.66), (-0.04±0.52), (-0.70±0.77), and (-0.74±1.09) mm, respectively. No significant difference was observed between groups one and two in terms of the amount of gingival changes (P>0.05). However, a significant difference was found between groups two and three (P<0.05), and the amount of gingival recession was 0.66?mm. No significant difference was found between groups three and four (P>0.05), and the gingival achieved stability. Conclusion   The gingival recession achieves stability at the fourth week (after 28 d) after stage Ⅱ surgery. At this time, the implant can be restored, and the abutment can be selected according to the amount of gingival change of the periodontitis patient.

Objective   This study aimed to investigate the effects of different tooth preparations on the fracture strength and pattern of failure of teeth with severe wedge-shaped defect restored with post and core crowns. Methods   According to whether the teeth above the wedge-shaped defect was removed (represented by B) or not (represented by A), the ferrule next to the wedge-shaped defect was prepared (represented by D) or not (represented by C), the cast post-and-core was chosen (represented by E) or glass-fiber post and resin core was chosen (represented by F). A total of 64 human mandibular premolar teeth were randomly divided into 8 groups: A1-1 (A+C+E), A1-2 (A+C+F), A2-1 (A+D+E), A2-2 (A+D+F), B1-1 (B+C+E), B1-2 (B+C+F), B2-1 (B+D+E), B2-2 (B+D+F), each group 8 teeth. All the teeth were prepared and restored accordingly and then mounted on an electronic pressure universal testing machine. The maximum fracture strength and the patterns of failure were recorded. Results   1) The fracture strength of GroupA1-1>that of Group B1-1, Group A1-2>Group B1-2, Group B2-1>Group B1-1, and Group B2-1>Group B2-2 with significant differences (P<0.05). 2) The patterns of repairable fracture in Group A1-2 and B1-2 were both 37.5%, and that of the other groups were 0. Furthermore, the difference was significant, and Group A1-2 and B1-2 were higher than other groups. Conclusion   The maintenance of the overhang above the severe wedge-shaped defect aid in the improvement of the fracture strength of the tooth restored with post and core crown. The ferrule of the wedge-shaped defect is not recommended to be prepared. Furthermore, the glass-fiber post and resin core is favorable for the re-repair of the teeth than the cast post and core.

Objective   This study aimed to investigate the expression function of substance P and the formation of osteo-clasts in the periodontal tissues after the inferior alveolar nerve sectioned in rats. Methods   Thirty Wistar male rats were used in the experiment and were divided into six groups (n=5) randomly: 0 d (normal), 3 d, 7 d, 14 d, 21 d, and 28 d. The periodontal tissues were removed from the denervation of the inferior alveolar nerve in rats. The periodontal tissues were checked by para-ffin sections through immunohistochemical staining to trace the expression of substance P and through tratrate resistant acid phosphatase (TRAP) staining to detect the osteoclasts. The average optical density and osteoclast were measured, and the obtained data was statistically analyzed. Results   The expression level of substance P in the first three days decreased signi-ficantly after the inferior alveolar nerve was cut. In addition, the lowest expression level was measured after 7 d. Normal levels in the periodontal tissue were measured after 21 d. In addition, we found that osteoclasts vary proportionally with the changes in substance P. Conclusion   The changes in substance P is positively correlated with the quantity of osteoclasts after the inferior alveolar nerve section. Therefore, we deduce that substance P may regulate the differentiation of osteoclasts formation, and thereby participate in the balancing of aveular bone metabolism.

Objective   To examine the role of lactoferrin (LF) on Toll like receptor 4 (TLR4) stimulated by lipopolysaccharide (LPS) in human periodontal ligament cells (hPDLCs). Methods   Primary hPDLCs were cultured by tissue block enzymolytic method. Cells obtained from four passages were identified and used in this experiment. Cells without stimulation served as the controls and cells treated with LPS (0.1 μg·mL-1) comprised the LPS group. The LPS+LF group was pretreated with LPS (0.1 μg·mL-1) for 2 h, and then treated with LF (10 μg·mL-1). Four hours after LF stimulation, the mRNA expression levels of TLR4 were examined by real-time quantitative polymerase chain reaction (RT-PCR). The protein expression of TLR4 was observed by cell immunofluorescence staining after LF stimulation of 24 hours. Results   TLR4 mRNA expression in the LPS+LF group was significantly more decreased than that in the LPS group (P<0.05), but exhibited no difference with that in the control group (P>0.05). Cell immunofluorescence staining showed that the protein expression of TLR4 in the LPS+LF group was significantly more decreased than that in the LPS group (P<0.05), but exhibited no difference with that in the con-trol group (P>0.05). Conclusion   LF can decrease the expression of TLR4 stimulated by LPS in hPDLCs, thus presenting potential application for controlling the TLR4 immune pathway of periodontitis.

Objective   To observe the changes in subgingival microflora before and after Er: YAG laser treatment on dia-betic patients with periodontitis, and to compare with the subgingival microflora of chronic periodontitis. Methods   Subgingival plaque of 13 pairs of teeth (26 sites) was selected from type 2 diabetic patients at pretreatment, one month post-treatment, and three months post-treatment. Subgingival plaque was also obtained from 11 cases of moderate to severe chronic periodon-titis with similar severity of periodontitis. The DNA of the subgingival plaque samples was extracted. Whole bacterial 16S rDNA gene fragments separated by denaturing gradient gel electrophoresis. Specific DNA bands were then chosen for retrieval and sequencing. Results   The gene sequencing results of the special DNA bands of subgingival plaque samples show that the pathogenic bacteria of both diabetic periodontitis and simple chronic periodontitis were Prevotella intermedia and Tannerella forsythia, respectively. The composition of the subgingival microflora before and after laser treatment changed. Some DNA bands, including that of Tannerella forsythia, disappeared or weakened one month after treatment. A new strip appeared, which belonged to Actinomyces sp. Conclusion   The profiles of the subgingival microflora changed after treatment, and one month was indicated as an important stage. Er: YAG laser may have an important function in delaying microflora recolonization.

Objective   This investigation aimed to examine how buccal mucosa microbiome succeeds in a healthy population with different ages and dentition stages. Methods   Twenty-five subjects were recruited and subdivided into five groups: pri-mary dentition group, mixed dentition group, adolescent group, adult group, and elderly group. Individual mucosal microbiota was obtained by gently scraping both sides of the buccal mucosa with a cotton swab. Microbial diversity was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Results   1) The composition of buccal mucosa microbiota has great intra-individual divergence. 2) The average band numbers of the primary dentition group, mixed dentition group, adolescent group, adult group, and elderly group were 21.2±4.0, 17.8±3.9, 15.8±4.3, 16.8±3.7, and 22.2±6.5, respectively. No between-group differences was observed (P>0.05), indicating that predominant strains in the oral cavity may be stable throughout an individual’s lifetime. 3) The Shannon indices of primary dentition group, mixed dentition group, adolescent group, adult group, and elderly group were 1.73±0.2, 1.43±0.1, 1.05±0.2, 1.45±0.2, and 1.63±0.3, respectively. A significant between-group difference was observed (P=0.003), indicating that the microbial diversity of the buccal mucosa decreases from childhood through adolescence, but increases from adult through senescence. 4) The clustering analysis showed that most of the samples in the same group clustered together, indicating higher intra-group community structure similarity. Conclusion   Composition of the buccal mucosa microbiota was different among age groups. Adolescence may be an essential turning point of microbial ecology succession throughout life.

Objective   To analyze the differences between the oral microbiota of monozygotic and dizygotic twins by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Methods   A total of 20 pairs of twin children were included in this study, in which 10 pairs were monozygotic (MZ) twins, and 10 pairs were dizygotic (DZ) twins. Of the 20 pairs, 10 pairs of twins had primary dentition, and 10 pairs had mixed dentition; 17 children had caries, and 23 children had no caries. Genomic DNA was extracted from saliva samples. The 16s rRNA was amplified and analyzed by PCR-DGGE. The PCR-DGGE band number and Shannon index were calculated. Results   Cluster analysis showed high similarity in the oral bacterial community seen in co-twins. However, no significant difference was seen between MZ and DZ twins. In the primary dentition, the PCR-DGGE band number and Shannon index of children with caries (11.00±1.56, 1.05±0.36) were lower than those of children without caries (14.00±2.74, 1.44±0.37) (P<0.05). In mixed dentition, the PCR-DGGE band number and Shannon index of children with caries (11.88±4.05, 1.18±0.36) were lower than those of children without caries (14.31±5.71, 1.28±0.47), but the differences were not statistically significant (P>0.05). Conclusion   Environmental factors may have a stronger effect on the constitution of oral microbiota in children compared with genetic factors. Children without caries may have a richer microbial diversity compared with children with caries.

Objective   To explore the effects of stress imposed on adenoid cystic carcinoma (ACC), therefore to clarify the molecular basis and mechanism of ACC’s malignant phenotype under the elevated tumor interstitial fluid pressure. Methods   ACC cells were cultured under pressure (103.74 kPa), and were divided into four groups (3 h group, 6 h group, 12 h group, 24 h group) according the pressure time. Untreated ACC2 was as negative control group, untreated ACCM was as positive control group. The level of epidermal growth factor receptor (EGFR) was detected by semiquantitative analysis of immunoche-mistry. Matrix metalloproteinase 9 (MMP9) and EGFR mRNA expression were assessed by reverse transcriptase polymerase chain reaction. EGFR, phosphorylation epidermal growth factor receptor (P-EGFR), MMP9, keratinocyte growth factor (KGF) and phosphorylation extracellular signal-regulated kinase (P-ERK) protein expressions were assessed by Western blot. Results   As the extension of pressure time, the expression of EGFR, P-EGFR, MMP9, KGF, P-ERK in ACC2 gradually increased, which were positive correlation with pressure time, and were higher than that of negative control group. Conclusion   Under the stimulation of pressure, the mRNA and protein levels of adhesion molecules and metastatic relative molecules in ACC2 were sharply elevated.

Objective   The non-specific antitumor immunity effect of 4-1BBL-B7-H3 gene was investigated by establishing an oral squamous cell carcinoma human peripheral blood lymphocyte-severe combined immunodeficient (SCID) mice chimeric model. Methods   Forty mice were randomly divided into five groups. All groups, except the non-immune reconstitution group (group D), had reconstructed human partial immune system. The control group (group A) was injected with Tca8113 cells. The Ad4-1BBL-B7-H3 group (group B) was injected with Tca8113 cells transfected by adenovirus containing 4-1BBL-B7-H3 gene. The empty vector group (group C) was injected with Tca8113 cells transfected by adenovirus containing an empty vector. The non-immune reconstitution group (group D) was injected with Tca8113 cells. The non-tumor group (group E) was injected with PBS. The tumor volumes in each group were measured weekly. Human IgG in blood was obtained through the tail vein and was determined by enzyme-linked immu-nosorbent assay. Human CD3+ and D56+ lymphocytes were assessed by flow cytometry. Model animals were killed on the ninth week. Differences in the expression of the natural killer group 2 member D (NKG2D) and toll-like receptor 2 (TLR2) in tumor tissues of each group were observed by im-munohistochemical method. 4-1BBL-B7-H3 gene expression in mice tumor tissues was detected by reverse transcription polymerase chain reaction (PCR) and the expressions of major histocompatibility complex 1 class related molecule (M1C) A, M1CB, and TLR2 were detected by real-time quantitative PCR. Results   The tumor volumes of group B were remarkably lower than those in the other groups (P<0.05). Human IgG and CD3+ and CD56+ lymphocytes were detected in the peripheral blood of immune-reconstituted mice. These lymphocytes were remarkably higher in group B than those in groups A, C, and E (P<0.05). Higher NKG2D and TLR2 expression were observed in group B tumor than those in the other groups. The stable expression of 4-1BBL-B7-H3 gene in group B was proven. The expression of M1CA, M1CB, and TLR2 were significantly higher in the group B tumor than those in groups A, C, and D (P<0.05). Conclusion   The high 4-1BBL-B7-H3 gene expression in tumor tissues could successfully induce the proliferation of CD3+ and CD56+ lymphocytes. This expression can also directly or indirectly activate TLR2 and up-regulate the expression of NKG2D and its ligands (M1CA and M1CB), which result in an effective antitumor immune response.

Objective   To construct a 3D finite-element model of the craniofacial complex with the original DICOM data of CT and to investigate the preliminary biomechanical characteristics with different directions and magnitudes of retractive forces to the maxilla of rhesus monkeys. Methods   A male rhesus monkey with mixed dentition was used. Spiral CT was performed to establish a 3D finite-element model of the craniofacial complex. The ANSYS 12.1 software was used to ana-lyze craniofacial complex displacement. Results   Each landmark showed larger displacement with increasing force value. The displacement values and force size exhibited a linear relationship. In the x-axis direction, all displacements were small. In the y-axis direction, all displacements showed significantly higher changes with increasing force value displacement. In the z-axis direction, the A-point and ANS point moved downward, but PNS moved upward. Conclusion   Loading retractive force resultes in an apparent backward and clockwise rotation on the maxilla with no obvious effects on the width of the upper jaw.

Ossifying fibromyxoid tumor is an uncommon neoplasm with uncertain histogenesis. This tumor is usually characterized by a small, painless mass in the subcutaneous tissue or limb muscles. In this case, an ossifying fibromyxoid tumor of the mandible was reported, and relevant literature was reviewed.

Deep vein thrombosis is a common complication after orthopedic, gynecological, and obstetric operations. However, instances of this complication after oral and maxillofacial surgeries have been rarely reported. We report a case with odontogenic keratocyst in the jaw that gained left lower extremity venous thrombosis after operation, and discuss the risk factors and prevention of lower extremity venous thrombosis through literature review.

Anterior mandibular fracture, which includes symphyseal and parasymphyseal mandibular fractures, is one of the most common types of fracture in clinical work, and is usually associated with condyle fracture. This type of fracture predisposes the patients to facial widening, malocclusion, and ankylosis when not properly and timely treated because of the influence of its anatomic structure. This article reviews the characteristics, complication, diagnosis, and therapy of this type of fracture.

Objective   This study aimed to improve students’ ability in practical and theoretical courses of oral health education and to promote students’ learning interest and initiative. Methods   Fourth-year students of the oral medical pro-fession from 2006 to 2008 at Weifang Medical University were chosen as research objects for oral health education to explore the experimental teaching reform. The students were divided into test and control groups, with the test group using the “speak out” way of teaching and the control group using the traditional teaching method. Results of after-class evaluation of the test group, as well as final examination and practice examination of the two groups, were analyzed and compared. Results   After-class evaluation results of the test group showed that the “speak out” teaching method was recognized by the students and improved students’ ability to understand oral health education. The final examination and practice examination results showed that the score of the test group was higher than that of the control group (P<0.01). Conclusion   “Speak out” teaching methods can improve students’ ability for oral health education, in accordance with the trend of teaching reform.