An In Vitro Study of the Effect of Fluoridated Milk on Oral Bacterial Biofilms

Abstract

Microcosmic dental plaques were grown in artificial saliva and supplemented with either milk or fluoridated milk. The presence of fluoride in the milk increased the pH of the biofilms and reduced the proportions of streptococci, demonstrating that in this model, fluoridation of milk produces biofilms with reduced cariogenic potential.Caries, one of the most prevalent diseases of humans, results from the production of acids in bacterial biofilms (dental plaques) on the tooth surface which causes localized destruction of the teeth (2). The plaque microflora are diverse, and disease is not due to an exogenous species but to changes in the proportions of members of the resident microflora-in particular, an increase in the levels of mutans streptococci (7). Fluoride continues to be the cornerstone of any caries prevention program and is administered, in many regions of the world, by fluoridation of the water supply (11). Milk fluoridation has been suggested as a possible alternative to water fluoridation, as it is an important foodstuff for children, the primary group when considering caries prevention (16). Although several studies have reported on the clinical benefits of fluoridation, (5, 6), no detailed investigation of its effects on biofilms of oral bacteria under controlled conditions in vitro has yet been published.A considerable amount of information concerning the identity and metabolism of bacteria found in plaque has now been amassed, however, and much in vitro work has involved the use of aqueous suspensions of bacteria rather than the biofilmgrown cells which comprise dental plaque (8). It is well established that many attributes of a bacterium grown in aqueous suspension differ considerably from those found when it is grown in a biofilm (3,17). The existence of differences between biofilm-grown bacteria and aqueous suspensions argues strongly that studies of plaque bacteria should be biofilm based. The purpose of this study was to use a biofilm-based model to determine the effects of fluoridation of milk on the cariogenic potential of dental plaque microcosms grown under conditions similar to those which would exist in vivo.Saliva was used as an inoculum to provide a multi-species biofilm consisting of organisms found in the oral cavity. Saliva was collected from 10 healthy individuals, equal amounts from each person were pooled, and 1-ml aliquots were dispensed into cryovials and stored at Ϫ70°C for subsequent use.Biofilms were grown in a constant-depth film fermentor as described previously (13). The nutrient supply was a mucincontaining artificial saliva which was delivered to the biofilms at a rate of 0.72 liters/day (12). In different experiments, the biofilms were supplemented with either ultra-high-temperature milk (containing 0.03 g of fluoride [Safeway, Hayes, United Kingdom] per ml) or with this milk containing an additional 5.00 g of fluoride per ml (i.e., a total of 5.03 g of fluoride per ml). A total of 200 ml of milk was pulsed into the constant-depth film fermentor at the same time each ...

Demineralization of Dentin by <i>Streptococcus mutans</i> Biofilms Grown in the Constant Depth Film Fermentor

“…These studies demonstrated that CDFF biofilms reflect properties that have been published for dental plaque [Bowden and Li, 1997;Wood et al, 2000] and that CDFF can be used for the initial screening of new antimicrobials under controlled conditions [Kinniment et al, 1996b;Pratten et al, 2000b].…”

Antimicrobial Activity of Fluoride and Its in vivo Importance: Identification of Research Questions

“…Rinsing a saliva-induced biofilm in vitro with a large volume of fluoridated milk (5 ppm fluoride) reduced the numbers of streptococci throughout the biofilm, reaching a 100-fold reduction at the enamel-biofilm interface ( fig. 1) [Pratten et al, 2000]. Unfortunately, the analysis was not sufficiently detailed to predict whether the cariogenic potential of the biofilm would be reduced.…”

“…1. Viable counts of 30-Ìm-thick sections through a 624-hour bacterial biofilm grown in the presence of milk and fluoridated milk [Pratten et al, 2000]. CHX = Chlorhexidine; AmCl = amine chloride; AmF = amine fluoride.…”

The in vitro effect of fluoridated milk in a bacterial biofilm - Enamel model

“…ment of caries lesions. A considerable amount of research has been conducted on investigating the influence of various foods on caries development [22][23][24] It has also been discussed, that milk and milk products may have a cariostatic effect 19,20,25 The cariostatic effect of milk and milk products may be due to their high content of Ca and P ions, the buffer capacity, or to the content of casein phosphopeptides 17,20,26 . However, there has been a controversial discussion about the fluoride availability in milk 27 .…”