By three-dimensional finite element analysis,the present research inquired about the stress on the surface of alveolar bone of mandibular incisor with different level of bone loss under different loadings. For the mandibular incisor without bone loss, the maximums of the von Mises stress under vertical and 15 degree oblique loading were 13.171 and 14.315 MPa respectively, both located in the apical region, and the lingual displacement of the tooth were 0.056 and 0.197mm respectively; under 30 degree oblique loading, the maximum of the von Mises stress was 15.262 MPa, located not only in the apical region but also on the crest, and the lingual displacement of the tooth was 0.324 mm. However, when vertical loading was applied on the mandibular incisor with half of the alveolar bone loss, the maximum of the stress increased significantly, located in the apical regions. And under oblique loadings, the value of the stress of this model increased dramatically,being three to five times over that of mandibular incisor without bone loss. Both of them concentrated on the crest. The scope of its distribution decreased from area to point. The significant lingual displacement happened, amounting to 2.850 mm. So when the loss of alveolar bone is not less than half,occlusal adjustment and splinting should be considered during the initial treatment of periodontal disease in order to avoid the significant change of the stress and alleviate the damage to the periodontal tissues.
Alveolar Bone Loss ; physiopathology ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Incisor ; Mandible ; physiopathology ; Mandibular Diseases ; physiopathology ; Stress, Mechanical

Objective To study the periodontal status and risk factors for periodontitis in periodontitis patients at different ages in wuhan. Methods From January 2007 to March 2008, the cross-sectional survey on periodontal conditions of 493 physical examinees in Wuhan city was carried out with random cluster sampling method. 458 cases of them were in accordance with the inclusive criteria and were stratified into two groups: young and middle-aged adults (aged 30-59 years) and old adults (aged 60 years and over). A case-control study was carried out in the periodontitis cases group (n=280) and the control group (n=178). Database was created by SQSERVER2000 and SPSS11.0 was used for statistical analysis. The relationship of periodontitis with age, gender, nation, educational background, diabetes mellitus, smoking, drinking, mental pressure and oral hygiene habits were analyzed by univariate and multivariate logistic regression analysis. Results The prevalence of periodontitis was 61.1% (280/458). Univariate analysis revealed that age, educational background, diabetes mellitus, smoking and oral hygiene habits were related factors for periodontitis (OR:0.44, 2.27, 3.44, 1.75, 9.82, P<0.05 or P<0.01). Meanwhile, multivariate analysis showed that suffering from diabetes mellitu and low educational background were the independent risk factors for periodontitis (OR=2.66, 1.95, all P<0.05). After stratification by age, multivariate logistic regression analysis showed that there was no correlation between diabetes mellitus and periodontitis prevalence in young and middle-aged adults and diabetes mellitus was a risk factor for periodontitis in old adults(OR=6.91, 95%CI: 1.27～37.42). Conclusions There are many risk factors for periodontitis and diabetes plays a major role in the development of periodontitis in old adults.

Objective: To investigate the efficacy and safety of the new investigational drug pegylated interferon α-2b (Peg-IFN-α-2b) (Y shape, 40 kD) injection (180 µg/week) combined with ribavirin in the treatment of patients with genotype 1/6 chronic hepatitis C (CHC), with standard-dose Peg-IFN-α-2a combined with ribavirin as a positive control. Methods: A multicenter, randomized, open-label, and positive-controlled phase III clinical trial was performed. Eligible patients with genotype 1/6 CHC were screened out and randomly divided into Peg-IFN-α-2b(Y shape, 40kD) group and Peg-IFN-α-2a group at a ratio of 2:1. The patients in both groups were given oral ribavirin for 48 weeks in addition and then followed up for 24 weeks after drug withdrawal. Abbott Real Time HCV Genotype II was used to determine HCV genotype, and Cobas TaqMan quantitative real-time PCR was used to measure HCV RNA level at 0, 4, 12, 24, 48, and 72 weeks. Adverse events were recorded in detail. The primary efficacy endpoint was sustained virological response (SVR), and a non-inferiority test was also performed. Results: A total of 561 patients with genotype 1/6 CHC were enrolled, among whom 529 received treatment; 90.9% of these patients had genotype 1 CHC. The data of the full analysis set showed that SVR rate was 69.80% (95% CI 65.00%-74.60%) in the trial group and 74.16% (95% CI 67.73%-80.59%) in the control group (P = 0.297 0). The data of the per protocol set (PPS) showed that SVR rate was 80.63% (95% CI 76.04%-85.23%) in the trial group and 81.33% (95% CI 75.10%-87.57%) in the control group (P = 0.849 8), and the 95% CI of rate difference conformed to the non-inferiority standard. The analysis of the PPS population showed that of all subjects, 47.9% achieved rapid virologic response, with a positive predictive value of 93.8%. The incidence rate of adverse events was 96.30% in the trial group and 94.94% in the control group, and the incidence rate of serious adverse events was 5.13% in the trail group and 5.06% in the control group. Conclusion In the regimen of Peg-IFN-α combined with ribavirin for the treatment of genotype 1/6 CHC, the new investigational drug Peg-IFN-α-2b(Y shape, 40 kD) has comparable clinical effect and safety to the control drug Peg-IFN-α-2a.