Changes in Lactate and Other Ions in Plaque and Saliva after a Fluoride Rinse and Subsequent Sucrose Administration

Abstract

The purpose of this study was to examine plaque and saliva composition after a fluoride rinse and subsequent sucrose application. Fifteen subjects accumulated plaque for 48 h, and then rinsed with a fluoride rinse based on 228 µg/g (ppm) Na₂SiF₆ and some received no rinse. After 60 min, upper and lower buccal molar plaque samples and 1-min saliva samples were collected. The subjects then rinsed with 10% g/g sucrose solution, and 7 and 15 min later, a second and a third set of samples were collected. Plaque fluid and clarified saliva were then recovered from these samples by centrifugation, and the remaining plaque acid extracted. The plaque fluid, centrifuged saliva, and plaque extract samples were then analyzed using micro techniques for pH, free calcium, phosphate, organic acids (plaque fluid and saliva only) and fluoride. Considering both the fluoride rinse and no-rinse groups, the most notable compositional changes in saliva 7 min after the sucrose rinse were pH –0.40 unit, free calcium 0.42 mM, lactate 5.2 mM, phosphate –1.3 mM, and fluoride 2.8 µM; while in plaque fluid, the corresponding changes were pH –1.59 unit, free calcium 1.5 mM, lactate 35 mM, phosphate –1.6 mM and fluoride –26 µM. After sucrose rinsing, undersaturation was found with respect to dicalcium phosphate dihydrate in saliva and plaque fluid and with respect to tooth enamel in some plaque fluid samples. Plaque fluid composition appeared to be strongly influenced by salivary clearance, diffusive loss of ions into the water phase of the rinse, and lower jaw pooling of the sucrose and fluoride components of the rinses. After the experimental rinse, the fluoride concentration in plaque fluid [86 ± 22 mM (upper molar site), 162 ± 150 mM (lower molar site)], saliva (26 ± 18 mM), and whole plaque [99 ± 97 µg/g (upper molar site), 197 ± 412 µg/g (lower molar site)] was comparable to the values in previous studies using this rinse. These very high plaque fluid fluoride concentrations, compared with the ‘no-rinse’ samples, induced an approximately 0.3-unit increase in the plaque fluid pH 7 min after the sucrose rinse, a small decrease (approximately 20%) in lactate production and a modest increase in enamel saturation. Although these changes were all statistically significant, no correlation was found between the decrease in lactate concentration and plaque fluid fluoride, pH or whole plaque fluoride.

Effect of an Essential Oil Mouthrinse, with and without Fluoride, on Plaque Metabolic Acid Production and pH after a Sucrose Challenge

“…Though a previous study has reported that an experimental 228 mg/kg F 'controlled release' F rinse given, as in the current study, 1 h before sucrose rinse significantly reduced lactate production and increased plaque pH [Vogel et al, 2002], no additional suppression of metabolic acids was observed from the 100 mg/kg fluoride in the current study. Previous studies have also found that fluoride did not increase the antiglycolytic effects of antimicrobial rinses [Giertsen and Scheie, 1995].…”

“…Effective suppression of plaque metabolic acid production may be an important approach for prevention or reduction of dental caries and gingivitis. Although fluoride is an effective anticaries agent, the reported clinical effect by fluoride on plaque metabolic activity was somewhat contradictory [Giertsen and Scheie, 1995;Hamilton, 1990;Vogel et al, 2002]. Chlorhexidine-based antimicrobial mouthrinses, however, have been shown to reduce plaque acid production and to increase the postsucrose minimum pH [Giertsen and Scheie, 1995].…”

Intra-Oral Acid Production Associated with Eating Whole or Pulped Raw Fruits

“…The inherent buffering capacity of both plaque [Shellis and Dibdin, 1988] and stimulated saliva [Edgar et al, 1994] also need to be considered in determining the pH achieved, rather than the concentrations of acid anions formed, when assessing the cariogenic potential of a food item in an model system. Here we did not measure plaque acid concentrations but these will be significantly higher than those found in saliva [Vogel et al, 2002]. The clinical relevance of which is that the fall in plaque pH accompanying the production of these acids may persist longer at interproximal sites in particular, since salivary access and consequent dilution and buffering will be limited.…”

“…The major acids produced were lactate and succinate, only low and variable concentrations of formate were detected and the salivary concentration of acetate diminished immediately following consumption of the fruits or the glucose rinse. No other acids were monitored in the saliva although other investigators have quantified the concentrations of other longer chain acids [Luke et al, 1999;Vogel et al, 2002]. The production of lactate occurs when streptococci are exposed to high sugar concentrations and mixed fermentation end products, including acetate, formate and ethanol, are produced in conditions of low sugar concentration [Yamada and Carlsson, 1975].…”

Metabolomic Effects of Xylitol and Fluoride on Plaque Biofilm in Vivo

“…Fluoride inhibits demineralization and promotes remineralization of the tooth surface (ten Cate, 1999;Fejerskov, 2004). Fluoride is also known to inhibit bacterial acid production in vitro (Hamilton, 1990;Marquis, 1990;Jenkins, 1999) and plaque acid production in vivo (Tatevossian, 1990;Vogel et al, 2002). Competitive inhibition by fluoride of enolase, an enzyme in the Embden-Meyerhof-Parnas pathway (the EMP pathway) extracted from Streptococcus mutans and other plaque bacteria (Kaufmann and Bartholmes, 1992;Guha-Chowdhury et al, 1997), suggested that enolase is the target enzyme by fluoride inhibition.…”