Journal of Dental Research, Vol 75, 1901-1908, Copyright © 1996 by International & American Associations for Dental Research Online Journals
Plaque pH and microflora of dental plaque on sound and carious root surfaces
A. Aamdal-Scheie, W. M. Luan, G. Dahlen and O. Fejerskov
Department of Oral Biology, Faculty of Dentistry, University of Oslo, Norway.
Given the hypothesis that root caries is the result of acid formation by
acidogenic micro-organisms, the present study was performed to relate
sucrose-induced pH response of dental plaque on root surfaces to the
microbial composition of the overlying plaque. Seventeen caries-active
elderly Chinese with poor oral hygiene and with both sound and carious root
surfaces were examined. Plaque pH was measured before and up to one hour
after a controlled sucrose mouthrinse. Plaque samples for microbiologic
analyses were collected from 2 sound and 2 or 3 carious pH-measurement
sites in each subject. The prevalence of the following micro-organisms was
assessed as % of total viable counts on Brucella agar: Prevotella
intermedia, Prevotella melaninogenica, Fusobacterium nucleatum,
Campylobacter rectus, Capnocytophaga spp., Actinomyces viscosus,
Actinomyces naeslundi, Streptococcus spp., S. sanguis, S. mitis, S. mutans,
S. sobrinus, Lactobacillus spp., and Candida spp. There was no difference
in plaque pH response on sound and carious root surfaces. The plaque pH
response was more pronounced in the maxilla than in the mandible for both
sound and carious sites. There was no difference in microbial composition
of dental plaque on sound and carious root surfaces. The pH response to
sucrose was the same regardless of the presence or absence of mutans
streptococci. Our results thus do not readily support the traditional
concept of caries formation.
