The Pathogenic Bacteria Analysis Of Plaque And Saliva From Susceptible Senile Persons With Root Surface Caries

Root surface caries is one of the dental problems among the dentate oldelderly. Overseas informations revealed that the prevalence of root surface caries was 20% in the 1870s,but in the beginning of the 2000s it has gone up to 70%.Domestic data revealed that the prevalence of root surface caries was 12%～78%. The process of root surface caries is similar to coronal caries. If root surface caries cannot be prevented and treated promptly ,it may become pulposis ,disease of periapical and osteomyelitis of the jaws . Studies on the microbiology of root surface caries were initiated in the 1970s and received some impetus from caries studies in experimental animals where it was shown that strains of Actinomyces from humans could cause root surface caries.There are different theories on the pathogen of root surface caries.Some scholars regarded the relative pathogen as Actinomyces viscosus; Others have suggested that the main pathogen was Streptococcus mutans;And some researches revealed that the main pathogen was Streptococcus mutans and lactobacillus. The main purpose of the present study was to study the pathogens of root surface caries in the elderly. The second purpose was to determine the correlation between numbers of Actinomyces viscosus of saliva from the test group and that of dental plaque. Objective: 1. To study the pathogens of root surface caries in the elderly. 2. To investigate the relationship between root surface caries in susceptible Senile persons and the pathogenic bacteria through quantitative analyses of the dental plaque and saliva samples. To provide experimental data for prevention of root surface caries. 3. To study the correlation between numbers of Actinomyces viscosus of saliva from the test group and that of dental plaque. Materials and Methods: In this study, The test group (DMFS>50)consisted of 35 patients who had root surface caries, and they ranged in age from 55-70 year old. The control group (DMFS<15) included 35 patients with root exposure and no root surface caries.Each patient gave informed consent for dental examination and took standardized samples of dental plaque from root carious lesions and standardized samples of supragingival plaque from sound exposed root surfaces for microbiological culture. One root surface was sampled per subject. Each patient also took samples of saliva for microbiological culture.The samples of saliva and dental plaque were diluted and respectively inoculated to the selective medium.The colony's CFU/ml was recorded.Applying SPSS FOR WINDOWS 10.0 to analyze the data. Result: 1.The positive dectectable rate and counts of Actinomyces viscosus of saliva and dental plaques was significantly higher than those of Streptococcus mutans and lactobacilli from the test group.The positive dectectable rate and counts of Actinomyces viscosus of saliva and dental plaque from the test group was significantly higher than those of saliva and dental plaque from the control group. There was positive correlation between numbers of Actinomyces viscosus of saliva and that of dental plaque from the test group. There were no differences between the positive dectectable rate and counts of Streptococcus mutans of saliva and dental plaque from the test group and those of Streptococcus mutans of saliva and dental plaque from the control group. There were no differences between the positive dectectable rate and counts of lactobacillus of saliva and dental plaque from the test group and those of lactobacillus of saliva and dental plaque from the control group. 2. There is positive correlation between numbers of Actinomyces viscosus of saliva from the test group and that of dental plaque. Conclusions: 1. The results of present study showed that Actinomyces viscosus exist in association with root surface lesions, Streptococcus mutans and lactobacillus don'texist in association with root surface lesions.The main pathogen of root surface caries in the elderly is Actinomyces viscosus. 2. Our findings illustrate that there is positive correlation between numbers of Actinomyces v...