Positive Correlation Between Sulphate-Reducing Bacteria Prevalence and Periodontal Health

Sulphate-reducing bacteria (SRB) represent a group of anaerobic microorganisms that release, during dissimilatory sulphate reduction, large amounts of hydrogen sulphide, a toxic volatile compound. Objectives: This study aimed to determine if there was any statistical evidence for the implication of these bacteria as potential aetiological agents of periodontal diseases. Methods: Samples of dental biofilms were taken from periodontal pockets and tongues of 58 patients divided in 3 groups: periodontitis (1), gingivitis (2) and healthy (3). The samples were cultured in anaerobiosis for 3 weeks on a medium specific for SRB growth (Biomérieux®: France). The occurrence of SRB was then ascertained from the formation of a typical black precipitate of ferrous sulphide in the enrichment culture. Results: In periodontal samples, SRB prevalences were 82,6 % in group 1, 69,6 % in group 2 and 16,7 % in group 3 which showed a reduction of the SRB occurrence at the same time as a decrease of periodontal disease severity. These differences were only statistically significant between the healthy group and the two others (p= 0,0002 between groups 1 and 3; p= 0,004 between groups 2 and 3). There was no statistical difference between the groups 1 and 2 (p= 0,29). These observations significate that SRB prevalence is statistically correlated with periodontal health and that this correlation does not depend on periodontal disease severity. Moreover we found that SRB prevalence in gingival sulci was 64,9 % and 77,1 % on tongue samples of the same 58 patients. This difference was significant (p= 0,02). Conclusions: This study do give account of the possible implication of SRB in the aetiology of periodontal diseases. It also demonstrates a high SRB prevalence on tongues of patients more than in periodontal pockets leading one to believe that this niche could contribute to sulci colonization or halitosis aetiology.