***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The objective of this research was to evaluate the anticaries effectiveness of a low-dose ( 500 ppm F , low-NaF ) sodium fluoride dentifrice , a high-dose ( 2,800 ppm F , high-NaF ) sodium fluoride dentifrice and an experimental 0.454 % stabilized stannous fluoride ( 1,100 ppm F ) with sodium hexametaphosphate ( SnF2-HMP ) dentifrice , each relative to a st and ard 1,100 ppm F sodium fluoride positive control dentifrice . Subjects ( n = 955 , with ∼239 per group ) with a mean age of 10.6 ( ∼9–12 years ) were r and omly assigned to one of four dentifrice treatments . Two calibrated examiners independently measured visual-tactile caries as DMFS that was supplemented with a radiographic examination at baseline , 12 months and 24 months for each subject . Generally similar results were independently observed by both examiners at the conclusion of the 2-year study period . Considering all subjects that attended at least 60 % of the supervised brushing sessions , statistically significantly less caries was observed in the high-NaF group compared to the control group . Similarly , statistically significantly less caries was observed in the SnF2-HMP group as compared to the control group . Differences in caries increments between the low-NaF and control groups were not statistically significant . One of the examiners observed these same statistically significant differences after 1 year . In conclusion , the results of this clinical trial indicated that while no difference in caries increments was observed between the low-NaF and control groups , both the high-NaF and the SnF2-HMP groups experienced significantly fewer lesions than the control group PURPOSE To assess whether the anti-caries effectiveness of three concentrations of fluoride dentifrice ( placebo , 500 ppm F- and 1450 ppm F- ) could be differentiated with small sample sizes in short time frames . MATERIAL S AND METHODS A controlled fluoride ( F ) dose-response study was conducted in concurrence with a supervised school oral hygiene regimen to assess whether dentifrices with increasing fluoride levels could be differentiated with small sample sizes in short time frames . The study was a r and omized , double-blind study conducted for a period of 21 months . Subjects ( N = 657 with approximately 219 per group ) were r and omized to placebo dentifrice , 500 ppm F- dentifrice or 1450 ppm F- dentifrice treatments for the first 9 months of the study . Subjects in the placebo group were then switched to either 500 ppm F- or 1450 ppm F- dentifrice for the remainder of the study , while subjects in the fluoride groups continued with their original treatment assignments . A calibrated examiner measured visual-tactile caries as DMFS that was supplemented with a radiographic examination at baseline , 9 months and 21 months for each subject . RESULTS The mean caries increments at 9 months were 0.35 surfaces , 0.34 surfaces , and 1.28 surfaces for the 1450 ppm F- , 500 ppm F- , and placebo groups , respectively . The mean caries increments at 21 months were 0.21 surfaces , 0.26 surfaces , 1.75 surfaces and 1.90 surfaces for the 1450 ppm F- , 500 ppm F- , placebo/1450 ppm F- , and placebo/500 ppm F- groups , respectively . The 500 ppm F- and 1450 ppm F- fluoride dentifrices delivered statistically significantly ( P < 0.05 ) lower DMFS scores than the placebo control dentifrice at 9 months , while at 21 months the 500 ppm F- and 1450 ppm F- fluoride dentifrices delivered statistically significantly lower DMFS scores as compared to the both the placebo/500 ppm F- and the placebo/1450 ppm F- dentifrice groups . There was no evidence of a dose response ( 1450 ppm F- < 500 ppm F- ) at 9 months or at 21 months . In this study , the effectiveness of the two fluoride dentifrices was observed at 9 months and these outcomes were still present at 21 months , confirming that caries benefits can be observed in time frames as short as 9 months with approximately 200 subjects per treatment group Since there is no consensus on the anticaries effectiveness of low-fluoride ( F ) dentifrice , this r and omized clinical trial evaluated its effect in children at different caries activity status . One hundred and twenty 2- to 4-year-old children , half with and half without active caries lesions , were r and omly divided into 2 groups which used 500- or 1,100-µg F/g ( NaF ) dentifrices during 1 year  . Caries progression or regression were evaluated as the number of lesions becoming active/cavities or inactive , respectively . The anticaries effect of the low-F dentifrice was similar to the conventional F dentifrice when used by caries-inactive children . However , in children with active caries lesions the low-F dentifrice was less effective than the 1,100-µg F/g dentifrice in controlling the progression of lesions . The data suggest that the child caries activity may be taken into account to recommend a low-F dentifrice The determination of anticarious effects of topically administered fluorine compounds is usually based on short-time cross-sectional or longitudinal studies . In a comparison made for a period of more than seven years the anticarious effects of amine fluorides administered to selected groups of test subjects have been studied under controlled clinical experimental conditions The purpose of the present study was to evaluate the effect of fluoride upon the stain-inducing capacity of chlorhexidine . Ninety-one children , 13 years of age , volunteered for the experiment . Three test dentifrices were used , containing 0.1 % NaF , 0.1 % NaF + 2 % chlorhexidine , and 2 % chlorhexidine respectively . The experiment was carried out as a double-blind test , and the degree of staining was recorded after 1 and 2 years . Four methods were used for stain scoring . The results after 1 year showed that chlorhexidine  induced less stain when applied together with fluoride than when applied alone . After 2 years this difference disappeared , indicating that fluoride only retarded chlorhexidine-induced staining of teeth A double-blind , clinical trial involving 923 children and extending over 4 years was carried out on the Isle of Wight . It investigated the additional protection against dental caries result ing when The 2-year caries increments of fifth to seventh grade students ( mean age 11.7 years ) residing in two fluoride-deficient communities ( A 3-year , double-blind caries trial was conducted to evaluate the caries-reducing effect of a modified technique to use toothpaste . At the outset , 369 children , 4 years of age , were r and omly assigned to four groups . At the end of the study , when the children were 7 years old , 281 ( 76 % ) had completed the trial . Two of the groups ( test groups , n = 131 ) were given the following instructions regarding ' toothpaste technique ' : ( 1 ) to spread the paste evenly on the teeth prior to brushing , ( 2 ) not to expectorate more than necessary during brushing , ( 3 ) to filter the remaining dentifrice foam in the dentition , together with a sip of water , by active cheek movements for 1 min before expectorating , and ( 4 ) not to carry out any further water rinsings afterwards , and not to eat or drink for 2 h after brushing . The children in the other two groups ( control groups , n = 150 ) were not given any instruction how to use the dentifrice and how to rinse after the brushing , but were , as the children in the test groups , encouraged to use the test dentifrice and to brush their teeth twice daily . Two commercial fluoride dentifrices ( A and B ) were compared : one of the test groups and one of the control groups used each product . Approximal carious lesions were scored on bite-wing radiographs at baseline and at the end of the study on the distal surface of the first and on the mesial surface of the second primary molars . No difference in caries increment was found between toothpastes A and B. The children in the two test groups developed a mean of 1.14 new dfs during the 3 years compared to 1.55 in the two control groups ( p < 0.05 ) . Thus , the results indicate that the modified toothpaste technique reduced approximal caries  in preschool children by an average of 26 % In the present study , 2,087 fifth- grade rs ( mean age : 12 years ) from two cohorts entered a 3-year clinical toothpaste trial . The study subjects were r and omly allocated to two groups : one group was a positive control using a 0.83 % NaFPO3 toothpaste , while the other group brushed with a test toothpaste containing 1.77 % KAl(SO4 ) . Both toothpastes were used unsupervised at home . One set of bite-wing radiographs was obtained at the beginning of the trial and another at the 3-year follow-up . Clinical registration s of caries were performed by the municipal dentists responsible for the child 's dental care . After 3 years , the mean caries increment was significantly higher in the group using the aluminum-containing toothpaste measured both clinical ly and radiographically A 3-year , double-blind , r and omized caries trial was conducted to evaluate the relative anticaries efficacy of four sodium fluoride dentifrices containing 250 ppm fluoride , 1,000 ppm fluoride in combination with 1 % disodium 1-hydroxyethylidene-1.1-bisphosphonate ( HEBP ) , and 1,000 ppm fluoride in combination with 1 % disodium azacycloheptylidene-2.2-bisphosphonate ( AHBP ) . As a positive control , a monofluorophosphate dentifrice ( 1,000 ppm fluoride ) was used . At outset 1,161 Icel and ic children , 11 and 12 years of age , were r and omly assigned to one of the five treatment groups and 1,035 subjects completed the trial . After 3 years of unsupervised brushing , the dentifrice containing 250 ppm fluoride was significantly less effective in controlling the caries increment . The combination of sodium fluoride and AHBP was significantly more effective than the positive control OBJECTIVE To assess the impact of a programme regularly supplying free fluoride toothpaste to children on the prevalence and severity of fluorosis and other developmental defects of enamel . DESIGN R and omised , controlled , parallel three-group clinical trial . Two groups received toothpaste containing either 440 or 1450 ppm F ; the third group received no intervention .  Children were supplied with  toothpaste  and advice on its use from the age of 12 months until they were 5 - 6 years old . The participants were a sub sample of those involved in a study that considered the caries benefits of providing free fluoride toothpaste . They were eligible if they completed the main study , lived in four of the nine districts involved and attended schools with 6 or more eligible participants . SETTING Children from the north west of Engl and consuming drinking water containing less than 0.1 ppm F were examined in primary schools . PARTICIPANTS 3731 children completed the main study . Of the 1833 children in the four selected districts , 927 were from schools with six or more participants . METHOD Digital images encompassing the upper and lower anterior sextants were taken of each child when they were 8 - 9 years old . MAIN OUTCOME MEASURES Developmental defects of enamel and dental fluorosis ( TF index ) were recorded on upper central incisors from wet and dry images . RESULTS A total of 703 children were included in the data analysis . In the 1450 ppm F ( n=218 ) , 440 ppm F ( n = 226 ) and control ( n = 259 ) groups the prevalence of dental fluorosis ( TF > 0 ) was 17 % , 15 % and 12 % for the wet ( p > 0.05 ) and 26 % , 24 % and 25 % for the dry ( p > 0.05 ) photographs respectively . The prevalence of TF scores 2 or 3 ( highest score ) was 5 % , 4 % and 2 % and for the wet ( p > 0.05 ) and 7 % , 4 % and 5 % for the dry ( p > 0.05 ) photographs respectively . All subjects identified with TF score 3 were found in the group using the 1450 ppm F toothpaste ( 3 wet and 4 dry ) and there were statistically significant differences between the three groups for both wet ( p = 0.03 ) and dry photographs ( p < 0.01 ) . However , the pairwise comparisons between the groups failed to attain statistical significance . The highest prevalence and severity of demarcated opacities was seen in the control group and for the wet photographs the difference between the three groups attained statistical significance ( p = 0.04 ) . For both the wet and dry photographs the prevalence of any enamel defects ( including fluorosis ) and large demarcated or TF score 3 was similar for the three groups ( p > 0.05 ) . CONCLUSION Previously it has been reported that only the provision of 1450 ppm F toothpaste provides anticaries benefits in a programme of this type . This benefit is accompanied by a slight increase in prevalence of TF score 3 but not the overall preval 
    Output:
    
There is some evidence of a dose response relationship in that the PF increased as the fluoride concentration increased from the baseline although this was not always statistically significant .
The effect of  fluoride toothpaste also increased with baseline level of D(M)FS and supervised brushing , though this did not reach statistical significance .
This review confirms the benefits of using fluoride toothpaste in preventing caries in children and adolescents when compared to placebo , but only significantly for fluoride concentrations of 1000 ppm and above .
The relative caries preventive effects of fluoride toothpastes of different concentrations increase with higher fluoride concentration .