Effect of an antibacterial varnish on lactic acid production in plaque adjacent to fixed orthodontic appliances.

The effect of an antibacterial varnish on lactic acid concentration in suspensions of early supragingival plaque collected adjacent to fixed orthodontic brackets was evaluated in 25 adolescents using a double-blind split-mouth design with a placebo varnish control. The test varnish contained 1% chlorhexidine and 1% thymol as active ingredients. Both varnishes were applied on two occasions within 3 days and plaque was subsequently collected at 3, 7 and 30 days after the first treatment. The samples were evaluated for total viable counts (TVC) and the proportion of mutans streptococci. Acid fermentation in suspensions was induced by glucose and L(+)-lactic acid concentrations were determined enzymatically after a 30-min incubation period. The test varnish did not affect TVC but reduced the proportion of mutans streptococci significantly at the 7-day follow-up (P<0.05). The concentration of lactic acid was reduced by approximately 20% on the 3- and 7-day follow-ups (P<0.05). The results suggest that the chlorhexidine/thymol-containing varnish may to some extent reduce the viability and metabolic activity of susceptible oral bacteria in suspensions of early supragingival plaque.

Dental plaque mass and acid production activity of the microbiota on teeth.

With the purpose of elucidating the effect of dental plaque thickness on the acid production activity in dental plaque, we studied the prevalence of acid anions in dental plaque of children harbouring different amount of plaque on their teeth. On two occasions, the occurrence of plaque on the dentition was scored (Silness-Löe's index), and plaque on available smooth surfaces was collected and the wet weight determined. On the first occasion, the amount of acid anions in resting plaque, and on the second occasion, the acid anions of sucrose-exposed plaque were analysed with isotachophoresis. Mean value of plaque wet weights per individual dentition was 11.7 +/- 9.0 mg (first occasion) and 11.1 +/- 8.9 mg (second occasion). Dominating anions in resting plaque were acetate < propionate < lactate and in sucrose-exposed plaque lactate < acetate < propionate. The microbial acid production activity (acid anion per mg wet plaque weight) decreased with increasing weights of the plaque mass. The findings illustrate the cellular glycolytic metabolism of plaque microorganisms in thin and thick plaque, being a consequence of the diverse environmental condition existing in these ecosystems.

Acid formation in sucrose-exposed dental plaque in relation to caries incidence in schoolchildren.

The aim was to investigate the composition and concentration of organic acids produced by plaque bacteria in vivo and its possible relation to caries development in schoolchildren. Sucrose-exposed pooled plaque from 25 healthy teenagers was collected and the levels of Streptococcus mutans and lactobacilli were estimated. The acid anions were analysed with isotachophoresis. The prevalence and incidence of dental caries during a 2-year period was recorded. Depending on the amount of plaque collected, the subjects were divided into a low (n = 12) and a high (n = 13) plaque weight group. The dominating anions in sucrose exposed plaque were lactate, acetate and propionate. For the entire study group, no association was found between the total acid concentration and caries development but for the participants with low plaque weight a positive relationship (P < 0.01) was disclosed. No correlation was found between the concentrations of acids and the number of lactobacilli or Streptococcus mutans. The present results did not suggest that the acidogenicity of sugar-exposed pooled plaque samples was a suitable indicator of caries activity in teenagers.

On the pH-lowering potential of lactobacilli and mutans streptococci from dental plaque related to the prevalence of caries.

The common method used today to identify persons at risk of dental caries is to estimate the numbers of cariogenic bacteria such as lactobacilli and mutans streptococci in saliva or plaque samples taken from the patient. However, the value of these bacterial counts for explaining and predicting individuals at risk of caries has not been powerful enough. Evaluating one virulence factor such as the acidogenicity of these bacteria might increase their explanatory values for caries. Sixty children aged 14-15 yrs participated in this study. Smooth surface caries and restorations were registered and total plaque samples collected. Counts of lactobacilli and mutans streptococci were estimated, and the pH-lowering potential of both bacteria was measured in an adapted glucose broth. The results showed a weak association between dental caries and lactobacilli, but in the subgroup with this bacterium the explanatory value increased to 14% and in the subgroup with a strong pH-lowering potential it was as high as 27%. For mutans streptococci the associations were weak in all groups.

Number of mutans streptococci or lactobacilli in a total dental plaque sample does not explain the variation in caries better than the numbers in stimulated whole saliva.

For practical reasons the numbers of mutans streptococci (MS) and lactobacilli (LB) in plaque are commonly estimated from saliva samples. The saliva counts are considered to be a reasonable indicator of the entire dentition's total microbial load. However, the value of salivary counts for explaining and predicting caries have been found to be low. There was therefore reason to compare the relationships between caries on the one hand and, on the other, the number of MS or LB in plaque and in saliva, respectively, in order to assess their relative merits for explaining the variation in caries, both in a total material and in subgroups with less favourable oral hygiene. Sixty children aged 14-15 years participated in the study. Caries and plaque were registered and the number of MS and LB was estimated in total plaque and in stimulated saliva samples. The results showed that the number of MS or LB in plaque did not explain the variation in caries to a greater degree than did the salivary counts. For both bacteria the explanatory values increased, as expected, in subgroups with less favourable oral hygiene, but not even at this higher level of explanation was there any difference between plaque and saliva. The LB count was a stronger explanatory variable than the MS count. It was concluded that the number of MS and LB, estimated in total plaque as well as in saliva samples, is not a useful tool in prediction.

Anomalies in the permanent dentition and other oral findings in 29 individuals with Laurence-Moon-Bardet-Biedl syndrome.

This paper reports a clinical and roentgenological examination of the teeth, jaws and saliva of 29 Scandinavian individuals with Laurence-Moon-Bardet-Biedl (LMBB) syndrome, whose cardinal signs are retinal dystrophy, polydactyly, obesity, hypogenitalism and mental retardation. All subjects had at least three of these signs, including retinal dystrophy. Compared with normal subjects, the group had statistically significantly higher frequencies of hypodontia, small teeth and short roots. In addition, the saliva showed a buffering capacity higher than normal. In conclusion, there seem to exist disturbances of both dental and skeletal formation in the LMBB syndrome.

Tissue plasminogen activator (t-PA) and placental plasminogen activator inhibitor (PAI-2) in gingival fluid from 8-9-year-old children.

High concentrations of tissue plasminogen activator (t-PA) and placental type plasminogen activator inhibitor (PAI-2) have previously been found in gingival crevicular fluid (GCF) of adults. In the present study, the levels were examined in 16 children aged 8-9 yr. Sampling of GCF was performed with small disks of Millipore-filter. t-PA and PAI-2 were analyzed with enzyme-linked immunosorbent assays with low method errors. The mean concentration of t-PA was slightly higher than in adults, while the mean PAI-2-concentration was slightly lower. An intraindividual study comparing healthy and inflamed sites in the children showed slightly higher concentrations in GCF from inflamed sites. No change was observed in the balance between t-PA and PAI-2.