Case-control study of microbial infection and analysis of influencing factors on stress-bearing areas of denture bases in middle-aged and elderly

Objective To investigate the change of microbial component ratio in denture base bearing area of middle-aged and elderly, and to analyze the factors associated with Candida albicans infection. Methods A total of 72 patients were selected from January to September in 2017. They were randomly divided into two groups:36 elderly patients not wearing denture (group A) and 36 patients wearing denture (group B). Their saliva and plaque were collected and cultured. Candida and anaerobion species were identified. Univariate and Logistic regression were used to explain factors predisposing to Candida infection. Results Among the 72 patients, there were 206 strains of microbe, among which 176 were anaerobes, including 82 in group A and 94 in group B; 30 were Candida albicans, of which 8 in group A and 22 in group B. The ratio of the two groups of Candida albicans, Bacterium melanoma and and Lactobacillus in the group B was significantly higher than that in the group A (P<0.05), and the difference between the two groups was statistically significant. The ratio of Streptococcus mutans in group B was significantly lower than that in group A, and the difference between the two groups was statistically significant (P<0.05). There was no significant difference between the constituent groups of Porphyromonas gingivalis (P>0.05). Single factor analysis confirmed the correlation between smoking, wear denture at night, denture hygiene, service life of denture and Candida albicans detection, and the differences were statistically significant (P<0.05). Multi factor Logistic regression analysis showed that the main factors affecting Candida albicans infection were smoking, night wearing denture, denture hygiene and service life of denture. Conclusion The number of Candida albicans in middle-aged and elderly patients wearing dentures was significantly higher than that in elderly patients without denture. Night wearing denture and denture hygiene were the most important factors affecting Candida albicans infection, more likely to cause denture stomatitis.