title: Effects of mutans streptococci, Actinomyces species and Porphyromonas gingivalis on collagen degradation.
abstract: BACKGROUND
  While Streptococcus mutans and Actinomyces spp are considered to be major pathogenic microorganisms of root caries, their roles in the degradation of organic matrix components of human root dentin need clarification.
  
  
  METHODS
  Ten laboratory strains and 11 clinical isolates of mutans streptococci and Actinomyces species, and positive bacterial or purified enzyme controls (Porphyromonas gingivalis whole cell lysates, trypsin or clostridial collagenase) were used to establish the degradation of azocollagen (AC), insoluble type I collagen (IC) or human dentin collagen (DC) from dentin powder in two types of experiments investigating collagenolytic activity either during or after bacterial growth. Ultraviolet-irradiated dentin powder and gamma-irradiated IC were used to assess the collagenolytic activity of test strains during bacterial growth. AC, IC and acid-treated dentin powder were used to determine the collagenolytic activity of sonicated bacterial whole cells and cell-free culture supernatants recovered from test strains after growth. Hydroxyproline or spectrophotometric assays were used to analyze the level of degraded collagen.
  
  
  RESULTS
  Data from this study showed that in contrast to the positive controls, none of the laboratory strains or clinical isolates elicited significant degradation of AC, IC or DC.
  
  
  CONCLUSIONS
  Results indicated that mutans streptococci and Actinomyces species had no significant collagenolytic activity, but may be involved in the root caries process through other mechanisms. In addition, proteolytic enzymes from other oral bacteria such as Porphyromonas gingivalis or from host cells such as neutrophils may also participate in the pathogenesis of root caries.
authors.affiliation: Division of Periodontology, National Yang-Ming University, Taipei, Taiwan, ROC.
authors.forename: S Z
authors.initials: SZ
authors.lastname: Dung
mesh_terms: D000190:Actinomyces / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003094:Collagen / Q000378:metabolism*; D003731:Dental Caries / Q000382:microbiology*; D003804:Dentin / Q000378:metabolism*; D006801:Humans; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D013295:Streptococcus mutans / Q000378:metabolism*
chemical_list: D003094:Collagen