Ky Zee

Single nucleotide polymorphisms of complement component 5 and periodontitis.

BACKGROUND AND OBJECTIVE Polymorphisms of host defence genes might increase ones risks for periodontitis. This study investigated whether tagging single nucleotide polymorphisms (SNPs) of the gene encoding complement component 5 (C5) are associated with periodontitis in a Hong Kong Chinese population. MATERIAL AND METHODS Eleven tagging SNPs of 229 patients with at least moderate periodontitis and 207 control subjects without periodontitis were genotyped using an i-plexGOLD MassARRAY mass-spectrometry system. RESULTS Genotype AG of SNP rs17611 was more prevalent in the group of periodontitis patients than in the controls (54.6% vs. 41.7%, p = 0.007). The haplotype CGCA of the haplotype block consisting of rs1035029, rs17611, rs25681 and rs992670 was significantly associated with periodontitis in a dominant model (p = 0.001). The SNP rs17611 showed high linkage disequilibrium with rs1035029, rs25681 and rs992670. Smoking was also significantly associated with periodontitis (p = 0.006). CONCLUSION The tagging SNP rs17611 of the C5 gene and smoking may be associated with periodontitis among the Hong Kong Chinese population.

SNPs of Fc-gamma Receptor Genes and Chronic Periodontitis

Genetic polymorphisms of host defense genes might increase risk for periodontitis. This case-control study investigated whether 102 single-nucleotide polymorphisms (SNPs) in Fc gamma receptor (FCGR) genes are associated with chronic periodontitis. Cases were 190 Hong Kong Chinese patients with severe chronic periodontitis, and there were 169 periodontitis-free individuals as controls. Genotype CC and allele C of rs445509 (p < 0.0001, OR = 0.30) of FCGR3A were significantly more prevalent among control individuals than among cases, after adjustment for age, sex, and smoking. Smoking was significantly associated with chronic periodontitis (p = 0.003, OR = 3.35). Within the limitations of this study, SNP rs445509 of FCGR3A seem to be negatively associated, while smoking was positively associated, with severe chronic periodontitis among Hong Kong Chinese.

Oral colonisation by aerobic and facultatively anaerobic Gram-negative rods and yeast in Tibetans living in Lhasa

Sample groups of children (n=50) and adults (n=38) were selected from pools of 207 children, (11-13-year olds from two primary schools) and 94 adults (25-44-year olds from four governmental agencies) who were the subjects of an oral health survey among Tibetans living in Lhasa, Tibet Autonomous Region. Mean ages of the study groups of children (38% females) and adults (61% females) were 11.6+/-0.9 and 37.1+/-6.1 years, respectively. All had lived in Tibet since birth. Oral rinse samples were selective cultured to isolate, quantify and speciate aerobic and facultatively anaerobic Gram-negative rods (using the API 20E kit) and yeasts (using API 20C AUX and API ZYM kits). For children, the isolation rates for oral coliform bacteria and yeasts were 84 and 14%, respectively, for adults, the respective rates were 26 and 40%. The corresponding quantities of coliforms/yeasts for children and adults were 0.4+/-1.6 x 10(3)c.f.u./15.8+/-72.3 and 0.2+/-0.6 x 10(3)c.f.u./57.2+/-137.5c.f.u. per millilitre oral rinse, respectively. Aerobic and facultatively anaerobic Gram-negative rods and Stenotrophomonas maltophilia, a free-living saprophytic and ubiquitous bacterial species of wide geographic distribution, were significantly more frequently recovered from the childrens oral rinses. The isolation rates of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups were similar to those found in similar cohorts from southern China in earlier studies. Randomly amplified polymeric DNA analysis showed that the S. maltophilia spp. isolated from children were of several different clonal types and were school specific. This study shows that the colonisation rate of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups are similar to those in populations living at lower altitudes, the native young, urban Tibetans appear to exhibit a high oral carriage rate of S. maltophilia spp.

Predominant cultivable microflora of supragingival dental plaque in Chinese individuals

The aim of this study was to determine the predominant supragingival cultivable bacterial flora in Chinese individuals, using the experimental gingivitis model. A total of 11 healthy dental students, mean age 22.5 years (range 20-25) were recruited. All were provided with once-a-week dental prophylaxis and oral hygiene reinforcement for 3 weeks to ensure gingival health. In the fourth week, after prophylaxis, the participants entered a 14-day period without any plaque control. A plaque sample was collected at days 1, 3, 7 and 14 from the buccal surface of the upper right canine, second premolar, first premolar and first molar, respectively. Each sample was then dispensed in tryptic soy-broth transport medium and grown anaerobically to obtain pure cultures, which were subsequently identified. Results showed that Gram-positive cocci and rods were the predominant cultivatable species (51-61%) in the samples throughout the 14-day period; with time there was a decreasing percentage of cocci and an increasing percentage of rods. Gram-negative cocci and rods increased in proportion with the plaque age (11-37%). Streptococcus spp. were the predominant Gram-positive cocci while Actinomyces were the predominant Gram-positive rods isolated. Fusobacterium and Capnocytophaga spp. were the two most frequent Gram-negative anaerobic rods cultured. The results compared with those from other analogous studies from the West suggest the possibility of interracial differences in supragingival plaque flora.

An in vivo replica study of microbial colonization in "rapid" and "slow" dental plaque formers.

The aim of the present study was to investigate the morphological features of supragingival plaque development in «rapid» and «slow» plaque formers using the replica technique. Forty‐nine healthy volunteers were screened for their plaque formation rate after 3 days of oral hygiene abstinence using the plaque index (PI). Five subjects with the highest mean PI and six with the lowest mean PI were selected as «rapid» and «slow» plaque formers, respectively. After a series of thorough prophylaxis and oral hygiene instruction, all subjects went through a 14‐day period of no oral hygiene to allow undisturbed plaque formation. Light body silicone elastomeric impressions were taken for the upper right central incisor of each subject on day‐0, 1, 3, 7, and 14. Positive replicas were then poured from the impressions using epoxy resin and observed under a scanning electron microscope. A more complex supragingival plaque structure was seen in the day‐1 and day‐3 replicas of the «rapid» group compared to the «slow» group. From day‐7 to day‐14, during the maturation period of supragingival plaque, no discernible differences were noted between the two groups. Quantitatively, the percentage of plaque coverage on the tooth surfaces was higher in the «rapid» group than in the «slow» group in day‐1 and day‐3 replicas. These observations indicate that the morphological and topographical features of supragingival plaque in «slow» and «rapid» plaque formers differ, especially in the early developmental phase.

Estimation of the gray level variations in soft and hard peri-implant tissue from X-ray images

In the treatment and assessment of periodontal disease periapical films are taken at regular intervals. The films are compared around the region of the implant to monitor the changes that have taken place. A computer-assisted method to automate this process is presented here. To compare two images, a pair of X-ray images are superimposed on top of each other. The images are normalized and transformed to obtain the best fit. These images are subtracted and the difference in pixel values are used as a basis for analysis. A method for improving the alignment accuracy and contrast compensation is highlighted.

Single nucleotide polymorphisms of Fc-gamma receptor genes and periodontitis

Background: The significance of access to dental care on oral conditions in older subjects is limited. We hypothesized that dental care control for aging effects on oral and periodontal conditions. Materials and methods: 1020 randomly selected subjects between age 60 and 96 from the Swedish National Study on Aging and Care Blekinge study received comprehensive medical and dental examinations. Results: Dentate women and men had, on average,18.4 teeth (S.D. ± 7.6), and 18.9 teeth (S.D.±7.5) (P = 0.37) respectively. In the youngest age group with infrequent dental visits 37% had > 20 teeth, and 73% had > 20 teeth if they had annual visits. Among old-old infrequent dental visitors 1.8% had > 20 teeth and 37% had > 20 teeth with annual visits. Across age groups, the overall % bleeding on probing was 23%. When adjusting for age, GLM univariate analysis failed to demonstrate an effect of frequency of dental visits and ABL scores (P = 0.18) but frequent dental visitors had significantly more teeth than infrequent visitors (P = 0.001). Conclusions: Tooth loss and extent of alveolar bone loss increase with age. Frequent dental visits seem to preserve teeth but has no impact on the amounts of deposits, gingival inflammation, or alveolar bone levels.This free journal suppl. entitled: Special Issue: Abstracts of Europerio 6, 4-6 June 2009, Stockholm, SwedenBackground: The periodontal ligament cells (PDL cells) play a key role in the formation of the periodontal ligament but these cells have other functions as well. The PDL cells express estrogen rec ...