Fluoride-supplemented milk inhibits acid tolerance in root caries biofilms.

In this study we investigated the effect of fluoride on plaque acid tolerance. The test group consumed 200 ml of milk supplemented with 5 mg F/l as NaF once a day, the milk control group drank 200 ml of unsupplemented milk, and the no-milk control group did not consume milk in this manner. Plaque samples were taken at baseline and after 15 months. The proportion of acid-tolerant bacteria in plaque was estimated using LIVE/DEAD® BacLight™ staining after exposure to pH 3.5 for 2 h. The fluoride group showed a statistically significant decrease in plaque acid tolerance compared to baseline. This study shows that daily intake of fluoride in milk reduces plaque acid tolerance.

Inhibition of enamel lesion formation by fluoridated milk assessed by laser fluorescence--an in vitro study.

The aim of this study was to investigate the effect of fluoridated milk on enamel lesion formation as assessed by laser fluorescence (LF). The material consisted of 18 extracted premolar teeth that were cut in mesial-distal direction and pairwise assigned to either test or control samples in an experimental caries model. The teeth were exposed to a low-pH 5% cellulose gel for 4 h, 5 days per week immediately followed by a 4-h period in either fluoridated (5 ppm, test) or nonfluoridated milk (control). In the meantime, the specimens were stored in pooled human-stimulated whole saliva in room temperature. All teeth were examined by visual inspection with a magnifying glass and by LF readings (DIAGNOdent) at baseline and after 2 and 4 weeks. The baseline LF readings ranged from 3 to 7 with a mean value of 5.6+/-0.9. The mean values increased with time in both groups but the increase was more marked in the control teeth, 8.7+/-2.3 vs 12.8+/-3.3 after 4 weeks, this difference being statistically significant (p<0.01). The visual examination could not distinguish between the test or control samples after 2 and 4 weeks, respectively. The findings indicated that fluoride added to milk may to some extent counteract enamel lesion formation as assessed by LF in an experimental caries model.

Fluoride concentrations in saliva and dental plaque in young children after intake of fluoridated milk.

This study determined fluoride (F) concentrations in whole saliva and dental plaque after intake of fluoridated milk using a randomised crossover experimental design. Eighteen healthy children (6-8 years) were subjected to each of four different 3-day drinking regimens: (a) 200 ml F-free tap water; (b) 200 ml tap water with 1.0 mg F; (c) 200 ml standard milk, and (d) 200 ml standard milk with 1.0 mg F. A washout period of 7 days was organised between the different drinking regimens. All children used F-free toothpaste prior to and during the trial and were instructed to avoid F-rich food and drinks. F concentration in unstimulated whole saliva was determined at baseline and after 15 and 120 min and in plaque samples at baseline and after 2 h. The mean baseline values ranged from 0.01 to 0.02 mg F/l in saliva and between 10.4 and 14.2 mg F/l in dental plaque. A statistically significant (p < 0.05) increase of F was disclosed in saliva 15 min after drinking F-containing milk and water (0.052 and 0.058 mg F/l, respectively). After 2 h, the salivary F(-) concentrations were back to baseline values. In the plaque, however, a statistically significant (p < 0.01) twofold increase was found at 2 h after the intake of fluoridated milk and water, respectively. The results indicate that consumption of fluoridated milk contributes to a F storing process with significantly elevated F concentrations in dental plaque up to 2 h after intake. Further studies are required to determine the 'therapeutic concentration' of F in dental plaque after intake of fluoridated milk.

Effect of quarterly treatments with a chlorhexidine and a fluoride varnish on approximal caries in caries-susceptible teenagers: a 3-year clinical study.

The aim of this study was to compare the effect of two different dental varnishes on approximal caries incidence in teenagers with proven caries susceptibility during a 3-year period. Two hundred 13- to 14-year-old subjects exhibiting at least two approximal enamel caries lesions were selected to take part in the study. One hundred and eighty subjects participated after informed consent and were randomly assigned to two equally sized groups. One group was treated with a fluoride varnish (FV, Fluor Protector) containing 0.1% F every 3rd month and the participants of the other group were treated in the same mode with a chlorhexidine varnish (CV, Cervitec((R))) containing 1% chlorhexidine and 1% thymol. In total, each subject was treated 12 times during the experimental period. Approximal caries including enamel lesions (DMFS(appr)) were recorded from four bitewing radiographs exposed at the start and end of the study. The mean (+/-SD) caries prevalence at baseline was 2.2+/-3.4 in the FV group and 2.5+/-4.0 in the CV group. After 3 years, the average approximal caries incidence was 2.7+/-3.1 and 3.1+/-3.5 in the FV and CV groups, respectively. The differences at baseline and after 3 years were not statistically significant. In conclusion, treatments every 3rd month with either a fluoride- or a chlorhexidine/thymol-containing varnish showed a promising effect with low approximal caries incidence and progression in teenagers with proven caries susceptibility.

Interdental caries incidence and progression in relation to mutans streptococci suppression after chlorhexidine-thymol varnish treatments in schoolchildren.

The aim of this study was to evaluate interdental caries incidence and progression in relation to the effect of antibacterial varnish treatments in schoolchildren anticipated at caries risk. After a screening procedure, 110 healthy children (8-10 years) with moderate and high counts of salivary mutans streptococci (MS) were invited to join a 2-year longitudinal study. At baseline, MS were enumerated at all mesial interdental sites of the first permanent molars with a chair-side technique. The children were then treated 3 times within 2 weeks by interdental spot applications with a 1% chlorhexidine/thymol-containing varnish (Cervitec). Follow-up samples of saliva and plaque were collected 1, 3, 6, and 12 months after onset of treat. Caries prevalence, incidence and progression of the selected approximal surfaces were scored from bitewing radiographs exposed at baseline and after 2 years. Sixty-three children of the same age formed a non-varnish-treated reference group. Reduction of caries incidence and progression was dearly dependent on the outcome of the antibacterial treatment. A significantly (P< 0.01) higher progression score was found among children who exhibited a less marked suppression of interdental MS levels compared with those with high suppression and the children of the reference group. The results suggest that a suppression of MS in interdental plaque may be an important event to prevent and arrest approximal caries development in schoolchildren at risk. Monitoring the effect of antibacterial agents in a site-specific way could therefore be advocated.

Fluoride concentration in whole saliva and separate gland secretions in schoolchildren after intake of fluoridated milk.

Fluoride concentration in whole saliva and in separate gland secretions was studied after a 7-day fluoridated milk regimen (1mg F per day) in 12 healthy schoolchildren aged 10-13 years. A 2-week fluoride-free run-in period preceded the tests in order to establish the endogenous baseline levels. Unstimulated and stimulated whole saliva and stimulated parotid and submandibular-sublingual saliva were collected at 1, 3, 6, 12 and 24h after F-milk ingestion, and fluoride concentrations were determined with an ion-selective electrode. Typical time-dependent excretion curves were obtained in all collected secretions. The fluoride levels were significantly elevated 1 and 3h in whole saliva and up to 6h in the gland secretions after intake of fluoridated milk when compared to baseline values. When acid-stimulated, the submandibular-sublingual glands were the major contributors of fluoride in the oral cavity. In conclusion, the results of this study demonstrate that fluoride ingested with milk is excreted through the salivary glands, indicating that the bioavailability of fluoride from milk equals that of other vehicles.

Effect of toothpicks with and without fluoride on De- and remineralization of enamel and dentine in situ.

The aim of this investigation was to study the effect of the interproximal use of fluoride (F)-impregnated and non-impregnated birch toothpicks on the degree of de- and remineralization of enamel and dentine in situ. Ten volunteers with complete dentures in the upper jaw participated. Each subject had four specimens: (1) sound enamel, (2) demineralized enamel, (3) sound dentine and (4) demineralized dentine; placed pairwise at two approximal sites (15/16 and 25/26) of the maxillary prosthesis. The study involved three test periods (A, B and C), each lasting 4 weeks. In A, the subjects used F toothpicks (impregnated in 4% NaF) and, in B, nonimpregnated toothpicks 3 times daily. During period C, no toothpicks were used. Dentifrice or other F-containing products were not allowed during the 4-week periods. Transversal microradiography was used to determine lesion depth (ld) and mineral loss (DeltaZ). The results revealed that all the sound samples lost mineral during the three experimental periods; DeltaZ for both enamel and dentine was less for A and B compared with C (p<0.01) and less for A compared with B and C for dentine (p<0.05, p<0.01). The demineralized samples also lost mineral, apart from dentine, during periods A and B, i.e. when F-impregnated and non-impregnated toothpicks were used; ld for enamel and DeltaZ for dentine were less for A compared with C (p<0.05). Four weeks' use of toothpicks, especially F-impregnated toothpicks, thus reduces the demineralization of enamel and dentine at approximal sites in situ.

The efficiency of semiannual silane fluoride varnish applications: a two-year clinical study in preschool children.

OBJECTIVE: The aim of this two-year community demonstration trial was to study the caries inhibitory effects of semiannual applications of a fluoride varnish in preschool children. METHODS: Twenty-four public dental health clinics in the county of Halland, Sweden, with 5,137 preschool children, 4 and 5 years of age, were matched and equally allocated to a fluoride varnish group (n = 2,535) and a reference group (n = 2,602). The children in the fluoride varnish group were treated every six months with topical applications of a silane fluoride varnish, Fluor Protector (0.1% F), while no fluoride varnish was used in the reference group. Both groups received a basic preventive program at annual checkups consisting of dietary counseling and instructions to parents to brush their children's teeth at least once daily with fluoridated dentifrice. Caries data were collected by clinical examinations at baseline and after one and two years. RESULTS: Caries prevalence at baseline did not differ significantly between the groups. After two years, the mean caries incidence was low and no statistical difference was found in the total number of carious and filled surfaces (dfs) between the two groups. However, the incidence of approximal lesions (dfsa) was significantly lower (P < .05) in the fluoride varnish group than the reference group. Children in the fluoride varnish group with dfs scores of 1-4 and > or = 5 at the start of the study exhibited a statistically significant (P < .05) reduction in approximal caries incidence of 19 percent and 25 percent, respectively, when compared with the reference group. CONCLUSION: Preschool children 4 and 5 years of age with clinical caries who receive semiannual applications of a silane fluoride varnish containing 0.1 percent F experience a reduced incidence of approximal caries over two years.

Effect of semi-annual applications of a chlorhexidine/fluoride varnish mixture on approximal caries incidence in schoolchildren. A three-year radiographic study.

Development and progression of approximal caries is still difficult to prevent and control even in societies with declining caries prevalence. In this study, a test group of 115 12-yr old children were treated semi-annually with a mixture (1:1) of a varnish containing 0.1% F (Fluor Protector) and 1.0% chlorhexidine (Cervitec). A reference group of 104 children received fluoride varnish treatment (Fluor Protector) semi-annually. Approximal caries was recorded from bitewing radiographs at baseline and after 3 yr. At baseline, total decayed and filled surfaces (DFS) including enamel caries were 1.79+/-2.36 in the reference group and 2.0+/-2.77 in the test group. After 3 yr, the mean approximal caries incidence including enamel caries was 3.01+/-3.74 and 3.78+/-4.32, respectively. The differences at baseline as well as after 3 yr were not statistically significant. The results showed that both groups had a comparatively low incidence of approximal caries during the experimental period, and suggest that a mixture of fluoride and antibacterial varnish had no additional preventive effect on approximal caries incidence compared with fluoride varnish treatments alone.

Fluoride concentration in the approximal area after using toothpicks and other fluoride-containing products.

The aim of this work was to study the fluoride (F) concentration in the approximal area after using toothpicks and other F-containing products. The exposure time was standardised to 2 min. 24 subjects participated, divided into 4 groups, with 6 individuals per group. In 3 of the groups, the following 4 products were compared: (1) a toothpick impregnated in 4% NaF; (2) a dentifrice containing 0.32% NaF; (3) a mouthrinse solution containing 0.025% NaF; (4) a tablet containing 0.55 mg NaF. In the 4th group, 3 commercial F toothpicks and 2 F dental flosses were compared. In all 4 groups, the F concentration was determined up to 60 min at 4 approximal sites. On each sampling occasion, 3 triangle-shaped paper points were used, absorbing 3 x 1 microl. In general, the toothpick gave similar or somewhat higher F concentrations in the approximal area than the dentifrice, mouthrinse solution and tablet. Comparing the various commercial toothpicks and dental flosses, 2 of the toothpicks gave higher approximal F concentrations than the other 3 products. When comparing the series in which the very first sample was collected from 2-20 min after the F treatment, it was found that the sampling procedure itself reduced the subsequent approximal F concentration. The main conclusion from this study is that an F-impregnated toothpick is a promising vehicle for delivery of fluoride to the approximal area.

Comparison of the efficacy of three different chlorhexidine preparations in decreasing the levels of mutans streptococci in saliva and interdental plaque.

The aim of the present study was to evaluate and compare the effects of three different chlorhexidine (CHX)-containing preparations on mutans streptococci (MS) levels in interdental plaque and whole saliva. Ninety-three healthy school-children (8-10 years old) with high scores of salivary MS were selected by a screening procedure and randomised into three equally sized groups. MS were enumerated at all mesial interdental sites of the first permanent molars with aid of a modified chairside technique. The patients were then treated three times within 2 weeks with either a 1% CHX/thymol-containing varnish (group A) or a 1% CHX gel (group B), or they were subjected to daily supervised toothbrushing with a 0.4% CHX dentifrice for 1 month (group C). Follow-up samples of saliva and plaque from the interdental sites were collected 1 and 3 months after termination of treatment. A statistically significant reduction of MS levels in saliva and interdental plaque was found in all groups after 1 month. The CHX-containing dentifrice (group C) was the most effective method in reducing MS levels in saliva, and a significantly stronger (p < 0.05) suppression was found after 1 and 3 months when compared with the gel and the varnish forms. The gel (group B) tended to be slightly more effective than the varnish (group A). In the interdental plaque, the reduction of MS was less marked than in the saliva, and the three groups exhibited MS reductions of similar magnitude (20%) and duration, persisting up to 3 months. However, a high proportion (approximately 50%) of all interdental sites were relatively unaffected by the treatments. In conclusion, our results suggest that the interdental MS colonisation was difficult to combat, irrespective of CHX preparation and method, while the salivary levels were more easily affected. Daily tooth-brushing with a CHX-containing dentifrice was more effective in reducing MS in saliva compared with the gel or varnish applications.

Approximal caries development following intensive fluoride mouthrinsing in teenagers. A 3-year radiographic study.

Caries development on approximal surfaces was studied in 139 adolescents for a period of 3 yr. A test group was randomly sampled (n=69) and subjected to a new intensive mode of fluoride (F) mouthrinsings using 10 ml of 0.045% NaF neutral solution once a day for 3 d, twice a year in all, i.e., 6 rinses per year. A control group (n = 70) rinsed in a similar mode using fluoride-free tap water. The two groups received the same basic prophylactic program during the trial. Detection of approximal caries lesions and fillings was based on bitewing radiographs at baseline and after 3 yr. The test group developed an average of 2.75 + 4.76 (mean +/- SD) approximal DFS compared with 3.21 + 4.74 DFS in the control group (n.s.). However, among those teenagers who were caries free (DFS = 0) at baseline, the incidence of approximal carious and filled surfaces was 1.76+/-4.52 in the F-rinsing group (n = 26) compared with 2.76+/-5.01 DFS in the control group (n = 32), a 36% caries reduction which was statistically significant. The intensified mouthrinsing procedure seems to be a promising prophylactic mode for collective caries prevention.

Effect of different chlorhexidine varnish regimens on mutans streptococci levels in interdental plaque and saliva.

The aim of the present study was to evaluate and compare the effects of an intensive and a monthly mode of antibacterial varnish application on the levels of mutans streptococci (MS) in interdental plaque and whole saliva. Eighty-eight healthy schoolchildren (11-13 years) with high scores of salivary MS were selected by a screening procedure and randomised into two groups, MS were enumerated at all mesial interdental sites of the first permanent molars with the aid of a modified chair-side technique, disclosing a total of 161 sites with moderate or high colonisation levels. The subjects were treated with a 1% chlorhexidine-thymol-containing varnish (Cervitec) either in an intensive mode (IM) with 3 applications within a 2-week period or in a monthly mode (MM) during a 3-month period. The varnish was applied with a miniball burnisher after the teeth had been cleaned interdentally with dental floss and dried with air. Follow-up samples of saliva and plaque from the interdental areas were collected after 1, 3 and 6 months. Both groups exhibited a statistically significant (p > 0.05) reduction of interdental MS after 1 month when compared with baseline. An eliminated MS growth appeared more frequently following the IM compared with the MM. After 3 months, a significant reduction compared with baseline was still found in the IM group but not in the MM group. No reduction was found in either group after 6 months. MS levels in saliva were mainly unaffected at the follow-up samplings, with the exception of a slight reduction in the IM group after 1 month. In conclusion, the results suggest that an intensive mode of chlorhexidine-thymol varnish application is more effective against interdental MS than the monthly mode of application. Bacterial growth should be monitored in a site-specific way, since interdental reductions were not adequately reflected in whole saliva samples.

Efficacy of a chlorhexidine and a chlorhexidine-fluoride varnish mixture to decrease interdental levels of mutans streptococci.

The aim of the present study was to evaluate and compare the efficacy of a chlorhexidine/thymol-containing (CHX) and a chlorhexidine/thymol/fluoride-containing (CHX + F) varnish to decrease interdental levels of mutans streptococci (MS). Eighty-two healthy schoolchildren (11-13 years) with high scores of salivary MS were selected by a screening procedure and randomised into two groups. MS were enumerated at all mesial interdental sites of the first permanent molars with the aid of a modified chair-side technique. The interdental molar and premolar sites were treated with either a 1% CHX varnish (Cervitec) or a 1:1 mixture of the CHX varnish and a fluoride varnish containing 0.1% w/w difluorsilane (Fluor Protector; CHX + F) on two occasions within a 2-week period. The varnishes were applied with a small brush after cleaning with dental floss and drying with air. Follow-up samples from the interdental areas were collected after 1 and 3 months. Both groups exhibited a similar statistically significant (p < 0.05) reduction of interdental MS after 1 month when compared with baseline. After 3 months, a significant reduction (p < 0.05) was still found in the CHX + F varnish group but not in the CHX varnish group. In conclusion, the results suggest that the addition of fluoride to an antibacterial varnish might improve the long-term efficacy in diminishing the cariogenic microbial challenge. Thus, the mixed varnish concept should be further developed and warrants an implementation of clinical studies.

Prediction of caries in pre-school children in relation to fluoride exposure.

The levels of salivary mutans streptococci and caries experience were used as predictors for caries incidence in 3 groups of pre-school children from areas with different levels of natural and topical fluoride exposure. Altogether 1022 children, 4-5 years of age at baseline, were examined according to the WHO-criteria and followed for 2 years. The low fluoride group (n = 374) had a low fluoride level in the piped water and no topical fluoride applications; the F-varnish group (n = 442) had low water fluoride but semiannual topical applications of a fluoride varnish; the optimal fluoride group (n = 206) had an optimal level of fluoride in the drinking water and semiannual F-varnish applications. The number of salivary mutans streptococci was estimated and scored at baseline with the Strip mutans chair-side method. The sampling procedure was repeated in 337 children of the low fluoride group 3 weeks after baseline. In comparison with the low fluoride group, caries incidence was 30% and 60% lower in the F-varnish and the optimal fluoride group respectively. The caries predictive ability decreased with increasing fluoride exposure. The sum of sensitivity and specificity decreased from 151% (65% + 86%) in the low fluoride group to 131% (40% + 91%) in the optimal fluoride group. The positive predictive value was highest (62%) in the low fluoride group. Repeated salivary samplings at baseline did not improve the caries predictive power. The results suggest that the overall fluoride exposure should be taken into account when caries risk assessment strategies for preschool children are developed and implemented.

Caries incidence in relation to salivary mutans streptococci and fluoride varnish applications in preschool children from low- and optimal-fluoride areas.

Caries incidence during a 2-year period was studied in 4- to 5-year-old children from three areas with contrasting levels of natural fluoride (F) in the drinking water and different regimens of topical fluoride varnish applications; group A (n = 448) was from an area with a low level of F (0.1 ppm) and semi-annual applications of fluoride varnish; group B (n = 374) was from a low F area (0.1 ppm) and no fluoride varnish treatments; group C (n = 206) was from an area with optimal F (1.2 ppm) and fluoride varnish treatments. All children were clinically assessed at baseline and after 2 years according to WHO criteria. The number of salivary mutans streptococci was estimated and scored at baseline and after 2 years with the Strip mutans method. The varnish containing 0.1% F was applied every 6 months on all accessible tooth surfaces after cleaning with a pumice paste. Basic preventive care was given to all children and restorative treatment on individual indications. Higher levels (p < 0.05) of salivary mutans streptococci were found in the low-fluoride areas compared to the optimal fluoride area at baseline and after 2 years. The caries incidence (mean dft +/- SD) in the different groups was A: 0.65 +/- 1.40; B: 1.09 +/- 1.85; C: 0.53 +/- 1.09. The difference between group B and groups A and C was statistically significant (p < 0.05). A positive relationship (p < 0.05-0.001) between salivary mutans streptococci scores at baseline and caries incidence was found in all three groups. This study confirms the close association between salivary mutans streptococci and caries incidence in preschool children and suggests a caries-reducing effect of topical applications of the fluoride silane varnish.

Uptake and release of fluoride from birch and lime toothpicks.

Birch and lime toothpicks were impregnated in a 4% sodium fluoride (NaF) solution for different periods of time, viz. 30 s, 30 min and 3 d. After impregnation for 30 min, an average of 4.1 mg NaF per birch toothpick was taken up. The corresponding value for lime toothpicks was 5.1 mg. About 60% of the fluoride (F) was released within 1 h in vitro when the toothpicks were kept in water. In vivo, the concentration of F was determined in whole saliva from five adults during 30 min after using birch toothpicks immersed in a 4% NaF solution. After 2 min, the mean salivary F concentration was 2.7 mM. Impregnation of birch toothpicks in 1, 2 or 3% NaF resulted in lower F concentrations both in vitro and in vivo, with a clear dose-response effect. When comparing the use of a 4% NaF impregnated birch toothpick, a mouthrinse with 10 ml of 0.025% NaF, sucking on a F tablet containing 0.55 mg NaF, and toothbrushing with 1 g of an 0.068% F (as NaF) dentifrice--all procedures carried out in the mouth during 2 min--the highest concentration of F in saliva was obtained after using the fluoridated toothpick. Thus, NaF impregnated birch and lime toothpicks show a quick release of F in vitro as well as in vivo and may be suitable as home care products for prevention of dental caries.

Effect of an antibacterial varnish on mutans streptococci in plaque from enamel adjacent to orthodontic appliances.

The effect of an antibacterial varnish (Cervitec) on the levels of mutans streptococci in plaque adjacent to bonded orthodontic brackets was evaluated in 18 children using a split-mouth technique with a placebo varnish control. The test varnish contained 1% chlorhexidine and 1% thymol as active ingredients. Both varnishes were applied on four occasions during a 3-month period, and plaque was subsequently collected between 1 week and 6 months after the onset of treatment. All teeth involved in the study were carefully examined and clinically assessed for enamel demineralization prior to onset of the fixed appliances and immediately after debonding. The results showed a more frequent growth of mutans streptococci in the dental plaque collected from placebo-treated quadrants as compared with the test quadrants on all sampling occasions. The proportion of mutans streptococci within the plaque microflora was significantly (p < 0.05-0.01) lower on the test sides than on the opposite sides at the 1-week and 1-month examinations. The incidence of incipient enamel lesions around the brackets and along the gingival margin was generally low, and no differences were found between the test and placebo varnish treated quandrants at the time of debonding. The results suggest that mutans streptococci in plaque from orthodontic patients can be suppressed effectively by topical applications of an antibacterial varnish.

Influence of xylitol in dentifrice on salivary microflora of preschool children at caries risk.

The aim was to study whether the use of a xylitol-containing dentifrice could affect the number of mutans streptococci and lactobacilli in preschool children with medium and high initial salivary counts. After screening 147 healthy preschool children, 3-6 years of age, 70 were selected and randomly assigned into two groups for 3-month's use of either a xylitol (9.7%) or a non-xylitol-containing fluoride dentifrice. The parents were trained to brush the teeth of their children twice daily in a standardized manner and the study was carried out double blind. Bacterial levels at screening and after 3 months were enumerated with aid of chair-side methods. No significant differences in mutans streptococci levels or lactobacilli counts after 3 months were obtained, either in comparison to baseline or between the groups. About 50% of all children exhibited unchanged bacterial scores at the end of the test period but more children in the xylitol group disclosed reduced scores of salivary mutans streptococci compared with the non-xylitol group (38% vs 16%). The results suggest that the dose level achieved by using this xylitol-containing dentifrice in preschool children, did not provide sufficient antibacterial action to suppress caries associated microorganisms in the saliva of those with high initial counts.