A microbiological study of dental calculus. I. The microbial flora of mature calculus.

Abstract

The flora of 16 supragingival and 11 subgingival calculus samples from 20 patients was studies using both selective media incubated aerobically and anaerobically. 767 representative isolates, from a total of 1,320 were charaterised and 653 assigned to genera or species.Gram‐positive organisms present in >50% of all samples were Streptococcus sanguis (96%), Streptococcus mitior (93%), Actinomyces naeslundii (78%), Actinomyces israelii (72%), Rothia dentocariosa and Bacterionema matruchotii (70%) and Actinomyces viscosus (67%). the most prevalent Gram‐negative species were Neisseria pharyngis (89%), Selenomonas (80%), Fusobacterium nucleatum (78%), Bacteriodes melaninogenicus and Leptotrichia buccalis (70%), Camylobacter (60%), Veillonella alcalescens and an unidentified Gram‐negative rod (59%) and Eikenella corrodens (56%).The calculus flora was more complex than histological studies had previously suggested, with up to 22 species found in a single sample. there was qualitative similarity with the flora of dental plaque formed at the margin of the gingivae, the chief difference being the absence of Streptococcus mutans and the increased prevalence of Str. sanguis serotype I/II.A. naeslundii, A. viscosus and V. alcalescens were more prevalent in subgingival samples and N. pharyngis, B. melaninogenicus in supragingival. In view of the small number of samples examined these differences may not be highly significant.