Investigation on the association of periodontitis and its risk factors among officeholders in Wuhan city / 中华老年医学杂志

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.

Three-dimensional finite element analysis of the stress of mandibular incisor with different level of alveolar bone / 生物医学工程学杂志

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.

Polymerase chain reaction analysis of the clonality of Porphyromonas gingivalis and collagenase gene / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the genotypic characterization of Porphyromonas gingivalis (Pg) and the heterogeneity of a potential virulence factor-PrtC.</p><p><b>METHODS</b>Arbitrarily primed polymerase chain reaction (AP-PCR) was applied to 80 Pg strains isolated from 24 unrelated Chinese periodontitis patients. PCR reaction was used to detect a fragment of the collagenase gene (PrtC gene). To evaluate the sequence heterogeneity of the Pg PrtC genes, sequence analysis of four PrtC gene of clinical isolates was performed.</p><p><b>RESULTS</b>Random primer OPA-05 and OPA-17 distinguished 7 AP-PCR profiles (I through VII). The majority of the strains belonged to type VII which accounted for 25.8%. A 548bp fragment of PrtC gene was detected from 24 clinical strains. The PCR products were verified by the restriction endonucleases PstI and PvuI. Sequence analysis showed 4 PrtC genes were heterogeneous in their nucleotide composition and differed from reference strain Pg 53977.</p><p><b>CONCLUSIONS</b>The results demonstrated genetic diversity existed among these clinical strains isolated from Chinese periodontitis patients and the PrtC genes are heterogeneous in their nucleotide sequence.</p>