• Pimpilai Limsomwong D.D.S
• Watcharaporn Tasachan D.D.S., Cert. of Fellowship in Pedodontics, Diplomate, Thai Board of Pediatric Dentistry
• Patchara Pipattanagovit D.D.S., M.Sc. (Microbiology)

Objective The purpose of this study was to compare antimicrobial effect of 500 and 1000 ppm fluoride
dentifrices that distributed in Thailand.

Materials and methods Streptococcus mutans (ATCC 25175), Streptococcus sobrinus (OMZ 176a)
and Lactobacillus casei (IFO 3533) were involved in this study. Fluoride dentifrices brought from the
local market, which six dentifrices were containing 500 ppm fluorides and six dentifrices were containing
1000 ppm fluoride. Supernatants from each were prepared, soluble fluoride ion was analyzed by
fluoride electrode, and bring to test against bacteria in agar plates by agar diffusion method.
The diameter of the bacterial zone of inhibition was measurement by Image Pro Plus^® program (version
4.5) and calculated to bacterial inhibition area. The data were analyzed by SPSS (version 13) to
determine the differences among the means at the significance level of p = 0.05.

Results The results show that there were no significant differences among the mean bacterial
inhibition zone of 500 ppm fluoride dentifrices (p > 0.05). In contrast, there were statistically
significant differences among mean bacterial inhibition zone of 1000 ppm fluoride dentifrices
(p < 0.05). When compare between 500 and 1000 ppm fluoride dentifrices, there was a statistically
significant difference (p < 0.05).

Conclusion 1000 ppm fluoride dentifrices have more antimicrobial effect than 500 ppm fluoride
dentifrices. In addition, the quantity of soluble fluoride ions from fluoride dentifrices has correlation
with antimicrobial effect.

(CU Dent J. 2008;31:385-98)