title: Recovery of Acid Production in Streptococcus mutans Biofilms after Short-Term Fluoride Treatment.
abstract: Fluoride is commonly used as an ingredient of topical oral hygiene measures. Despite the anti-acidogenic activities of fluoride against cariogenic biofilms, the recovery of the biofilms from fluoride damage is unclear. Herein, we investigated the recovery of acid production in Streptococcus mutans biofilms after short-term or during periodic 1-min fluoride treatments. For this study, 46-hour-old S. mutans biofilms were treated with fluoride (0-2,000 ppm F-) for 1-8 min and then incubated in saliva for 0-100 min. The 74-hour-old biofilms were also periodically treated with the fluoride concentration during biofilm formation (1 min/treatment). Changes in acidogenicity and viability were determined via pH drop and colony-forming unit assays, respectively. In this study, acid production after a 1-min fluoride treatment was recovered as saliva incubation time increased, which followed a linear pattern of concentration dependence (R = 0.99, R2 = 0.98). The recovery pattern was in a biphasic pattern, with an initial rapid rate followed by a second slow recovery. Furthermore, recovery from fluoride damage was retarded in a concentration-dependent manner as treatment time increased. In periodic 1-min fluoride treatments, acid production in the biofilms was not diminished during the non-fluoride treatment period; however, it was reduced in a concentration-dependent manner during the fluoride treatment period. The viability of the biofilm cells did not change, even at high fluoride concentrations. Collectively, our results suggest that brief fluoride treatment does not sustain anti-acidogenic activity against S. mutans in biofilms since the damage is recoverable with time.
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Institute of Oral Bioscience and BK 21 Plus Program, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Minh-Huy
authors.initials: MH
authors.lastname: Dang
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Jung
authors.forename: Dae-Woo
authors.initials: DW
authors.lastname: Lee
authors.forename: Kwang-Yeob
authors.initials: KY
authors.lastname: Song
authors.forename: Jae-Gyu
authors.initials: JG
authors.lastname: Jeon
mesh_terms: D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002327:Cariostatic Agents / Q000494:pharmacology*; D003731:Dental Caries / Q000382:microbiology* / Q000628:therapy; D005460:Fluorides, Topical / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability / Q000187:drug effects; D009910:Oral Hygiene; D012463:Saliva / Q000382:microbiology; D013295:Streptococcus mutans / Q000187:drug effects*; D013997:Time Factors
chemical_list: D002327:Cariostatic Agents; D005460:Fluorides, Topical