No abstract

Within the limits of this pilot study, the use of the low-power He-Ne laser as an adjunct to non-surgical periodontal therapy in patients with moderate to advanced chronic periodontitis did not seem to provide additional clinical benefit.

The aim of this study was to determine the presence or absence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults and to examine the A. actinomycetemcomitans isolates from positive subjects with regard to the serotype distribution, presence of the leukotoxin gene lktA and the promoter for the leukotoxin operon as well as the incidence of phage Aa phi 23. Sixty subjects, working in a knitting factory in the Province of Guangzhou, People's Republic of China, were investigated. Subgingival microbial samples were taken from both upper first molars. They were cultured both anaerobically and in 5% CO2. P. gingivalis was found in 33 subjects. On average, it constituted 7% of the total anaerobic cultivable counts. A. actinomycetemcomitans was detected in 37 subjects of which seven yielded counts > 10(5). Twenty-one subjects were positive for both organisms. A. actinomycetemcomitans serotype a was found in 9 subjects, serotype c was found in 23 and serotype e in 5. A. actinomycetemcomitans serotypes b and d were not detected in any subjects. Presence of the leukotoxin gene lktA was demonstrated for all A. actinomycetemcomitans isolates; however, none of the A. actinomycetemcomitans strains from the present study had a deletion in the promoter region of the leukotoxin operon. The results of this investigation show a high frequency of the putative periodontal pathogens P. gingivalis and A. actinomycetemcomitans and corroborate the concept that there is variation in virulence and pathogenic potential among isolates from different subjects.

The aim of this study was to compare the predominant cultivable bacterial flora in supragingival plaque samples of Chinese "rapid" and "slow" plaque formers, using the experimental gingivitis model. 11 Chinese subjects (5 "rapid" and 6 "slow" plaque formers) were selected from 49 healthy young adults. The selection was based on the plaque index on the buccal surfaces of all the canines, premolars and 1st molars after 3-days without plaque control. The 11 subjects began a 14-day on oral hygiene period after prophylaxis. Plaque samples were collected on day 1, day 3, day 7 and day 14 from the buccal surface of upper right canine, 2nd premolar, 1st premolar and 1st molar, respectively. The samples were then dispensed into a tryptic soy broth, and cultured anaerobically to obtain pure isolates which were then identified by conventional means. Results showed similar trends in plaque development in the two groups; gram-positive bacteria were the predominant cultivable species ("rapid": 71-37%; "slow": 53-63%) and gram-negative species increased in proportion to the plaque age ("rapid": 9-47%, "slow": 13-28%). "Rapid" plaque formers showed a statistically significant higher percentage of gram-negative rods (38%) than the "slow" group (17%) in the 14-day samples. The difference in the proportions of other groups of bacteria between the "rapid" and "slow" plaque formers were also found to be statistically significant using the MANOVA test (p = 0.0162). Most of the cultivable gram-negative rods belonged to Fusobacterium and Capnocytophaga species. Besides the quantitative difference observed clinically, there seems to be a qualitative difference in the cultivable flora between subjects with different rates of plaque formation.

The tagging SNP rs17611 of the C5 gene and smoking may be associated with periodontitis among the Hong Kong Chinese population.