IADR Abstract Archives

Reduction in Oral MS Ratios by Nano-Hydroxyapatite: a Clinical Trial

Objectives: Recent microbiotic studies in cariology and periodontitis implicate a disproportionately high level of pathogens in the oral flora in the incidence of disease. Oral disinfectants, which kill both physiological and pathogenic bacteria, do not restore the balance, and long-term antibiotics use can give rise to resistant strains. We previously showed that nanocrystal hydroxyapatite (ncHA) selectively removes mutans streptococci from the oral cavity in a Dental Drug Delivery System (3DS). Here we clinically investigated its effect on the ratio of mutans streptococci to total streptococci (MS ratio) in a subject's mouth.

Methods: After assessment of their MS ratio following in-office tooth cleaning (=starting point), 60 volunteers received either an ncHA paste or a placebo paste containing dicalcium phosphate dehydrate (30 subjects per group). Subjects applied a drug-retainer containing a small amount of the test paste to their upper and lower teeth for 5 minutes daily following nighttime brushing for 1 week. MS ratios were then assessed by culture techniques from saliva samples collected at 1 week, then 1, 2, 6 and 12 months after use of the test paste, and the effect of each paste was statistically evaluated.

Results: Median MS ratios of the group using ncHA paste, measured at starting point, 1 week, then 1, 2 and 6 months after using the paste were respectively 2.94E-3, 2.72E-3, 2.28E-3, 1.50E-3 and 1.38E-3. Linear regression analyses confirmed a high correlation between use of the ncHA paste and MS ratio decrease (R2=0.72). In contrast, no such correlation between paste use and MS ratios in the placebo group was found (R2=0.39). Moreover, at 2 months after using the paste, a significant difference in MS ratio between the two groups was confirmed (P<0.01).

Conclusion: Clinical testing showed ncHA reduces subjects’ MS ratio, and therefore may help restore balance to flora in the oral cavity.

IADR/AADR/CADR General Session
2013 IADR/AADR/CADR General Session (Seattle, Washington)
Seattle, Washington
Cariology Research - Microbiological Studies / Biofilm
  • Senpuku, Hidenobu  ( National Institute of Infectious Diseases, Tokyo, N/A, Japan )
  • Fujimaru, Takeshi  ( Sangi Co.,Ltd, Tokyo, N/A, Japan )
  • Arakawa, Tadayoshi  ( Sangi Co.,Ltd, Tokyo, N/A, Japan )
  • Ishizaki, Tsutomu  ( Sangi Co.,Ltd, Tokyo, N/A, Japan )
  • Hayman, Roslyn  ( Sangi Co.,Ltd, Tokyo, N/A, Japan )
  • Kono, Yoshiharu  ( Nihon University School of Dentistry at Matsudo, Chiba, N/A, Japan )
  • Sekine, Satoko  ( Nihon University School of Dentistry at Matsudo, Chiba, N/A, Japan )
  • Suzuki, Hideaki  ( Nihon University School of Dentistry at Matsudo, Matsudo, , Japan )
  • Ikemi, Takuji  ( Nihon University School of Dentistry at Matsudo, Chiba, N/A, Japan )
  • Oral Session
    Keynote Address; Novel Antibiofilm Therapies