IADR Abstract Archives

Fluoride-tolerance Of Actinomyces Acid Production And Its Enhancement By Bicarbonate 

Objectives: Actinomyces, one of the predominant oral bacteria, is associated with various oral diseases, such as root surface caries. It is known that bicarbonate contained in saliva stimulates the growth and the acid production of Actinomyces, while fluoride inhibits the acid production. However, fluoride-sensitivity of Actiomyces acid production and effects of bicarbonate on the fluoride-sensitivity are still unclear. Thus, this study aimed to evaluate the effects of bicarbonate and fluoride on the acid production of Actinomyces naeslundii (An) and Actinomyces oris (Ao) in comparison with Streptococcus mutans (Sm).

Methods: An ATCC 12104, Ao WVU 627 and Sm NCTC 10449 were used. The bacteria were incubated in the reaction mixture containing 10 mM glucose and potassium fluoride (0-90 ppm F) with/without 0.1% ammonium bicarbonate, and the acid production was measured by a pH-stat at pH 7.0 and 5.5.

Results: At pH 7.0, the acid production of An was decreased by 6±16% and 18±9% in the presence of 90-ppm F with/without bicarbonate, respectively, while that of Sm was decreased by 99±1% and 94±4%. At pH 5.5, the acid production was decreased by 21±14% and 24±10% in the presence of 9-ppm F with/without bicarbonate, respectively, while that of Sm was decreased by 79±21% and 88±9%. Ao showed similar results to An. The acid production of Actinomyces were significantly tolerant to fluoride than that of Sm (p<0.05, Tukey test). Furthermore, bicarbonate tended to enhance the fluoride-tolerance of Actinomyces.

Conclusion: This study indicated that, in terms of acid production, Actinomyces was more tolerant to fluoride than Sm both at neutral and acidic pH, and that bicarbonate enhanced the fluoride-tolerance of Actinomyces. Unlike Streptococcus species, Actinomyces species have a bicarbonate-assimilating metabolic pathway, which might be relevant to the enhanced fluoride tolerance in the presence of bicarbonate.


Japanese Division Meeting
2011 Japanese Division Meeting (Hiroshima, Japan)
Hiroshima, Japan
2011

Scientific Groups
  • Kawashima, Junko  ( Tohoku University, Sendai, N/A, Japan )
  • Nakajo, Kazuko  ( Tohoku University Graduate School of Dentistry, Sendai, N/A, Japan )
  • Washio, Jumpei  ( Tohoku University Graduate School of Dentistry, Sendai, N/A, Japan )
  • Shimauchi, Hidetoshi  ( Tohoku University, Sendai, N/A, Japan )
  • Takahashi, Nobuhiro  ( Tohoku University Graduate School of Dentistry, Sendai, N/A, Japan )
    • Microbiology/Immunology