***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: Aim To describe the occurrence of  dental caries at the person , tooth and tooth surface level from childhood to early mid-life . Background No studies have reported on age and caries experience in a population -based sample through the first half of life . Methods Prospect i ve cohort study of a complete birth cohort ( n = 1,037 ) born in 1972/73 in Dunedin , New Zeal and .  Dental examinations were conducted at ages 5 , 9 , 15 , 18 , 26 , 32 and 38 , and participation rates remained high . Surface-level caries data were collected at each age ( WHO basic methods ) . Statistical analyses and graphing of data were undertaken using Intercooled Stata Version 10 . Results Data are presented on dental caries experience in the permanent dentition at ages 9 , 15 , 18 , 26 , 32 and 38 . Percentile curves are charted and reported for person-level caries experience . Data are also presented on the number of decayed teeth and tooth surfaces , ( including root surfaces at age 38 ) , as a function of the number of teeth and surfaces present , respectively . Across the cohort , the number of tooth surfaces affected by dental caries increased by approximately 0.8 surfaces per year ( on average ) , while the percentage of at-risk tooth surfaces affected by caries increased by approximately 0.5 % per year , with negligible variation in that rate throughout the observation period . Conclusion These unique data show clearly that dental caries continues as a disease of adulthood , remaining important beyond childhood and adolescence and that rates of dental caries over time remain relatively constant 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 We conducted a parallel group r and omized controlled trial of children initially aged 2 to 3 y who were caries free , to prevent the children becoming caries active over the subsequent 36 mo . The setting was 22 dental practice s in Northern Irel and , and children were r and omly assigned by a clinical trials unit ( CTU ) ( using computer-generated r and om numbers , with allocation concealed from the dental practice until each child was recruited ) to the intervention ( 22,600-ppm fluoride varnish , toothbrush , 50-mL tube of 1,450 ppm fluoride toothpaste , and st and ardized , evidence -based prevention advice ) or advice-only control at 6-monthly intervals . The primary outcome measure was conversion from caries-free to caries-active states . Secondary outcome measures were number of decayed , missing , or filled teeth ( dmfs ) in caries-active children , number of episodes of pain , and number of extracted teeth . Adverse reactions were recorded . Calibrated external examiners , blinded to the child ’s study group , assessed the status of the children at baseline and after 3 y. In total , 1,248 children ( 624 r and omized to each group ) were recruited , and 1,096 ( 549 intervention , 547 control ) were included in the final analyses . Eighty-seven percent of intervention and 86 % of control children attended every 6-mo visit ( P = 0.77 ) . A total of 187 ( 34 % ) in the intervention group converted to caries active compared to 213 ( 39 % ) in the control group ( odds ratio , 0.81 ; 95 % confidence interval , 0.64–1.04 ; P = 0.11 ) . Mean dmfs of those with caries in the intervention group was 7.2 compared to 9.6 in the control group ( P = 0.007 ) . There was no significant difference in the number of episodes of pain between groups ( P = 0.81 ) or in the number of teeth extracted in caries-active children ( P = 0.95 ) . Ten children in the intervention group had adverse reactions of a minor nature . This well-conducted trial failed to demonstrate that the intervention kept children caries free , but there was evidence that once children get caries , it slowed down its progression ( EudraCT No : 2009 - 010725 - 39 ; IS RCT N : IS RCT N36180119 ) Aim : This was to determine the increment of caries from 12 to 18 years of age and to explore the possibility of predicting caries increment in this period based on the caries experience at age12 years . Study design : Prospect i ve longitudinal survey . Methods : A sample of 12-year-old children ( n = 159 ) were examined in 1993 and 70 % of them re-examined at 18 years of age .  Bitewing radiographs were taken and a diagnostic system using five caries grade s ( D1−D5 ) was used at both ages . Children at risk were defined as those who developed manifest caries lesions ( D3−5FS ) on approximal surfaces during the follow-up period . Possible predictors were analysed by calculation of sensitivity , specificity , and actual proportion of the population at risk . Results : The mean caries increment ( D1−5MFS ) from 12 to 18 years of age was 4.2 ( SD±9.1 ) . The percentage of  caries-free adolescents at 12 and 18 years of age was 10 % and 1 % respectively ; 25 % had either a reversal or no increment in caries experience while the D1−5MFS increased in 65 % of the adolescents . Of the increment of manifest lesions ( D3−5FS ) , 18 % were located in incisors/canines , 40 % in premolars , 26 % in first molars and 16 % in second molars . Premolars had the largest proportion of the approximal surfaces with manifest caries increment . The best predictors of children at risk of approximal caries increment ( D3−5FS ) were caries experience ( D1−5FS ) on the approximal surfaces of premolars and second molars at the age of 12 years . The individuals that developed four or more manifest lesions on approximal surfaces between 12 and 18 years were the easiest to predict ( sensitivity + specificity = 175 % ) . Conclusions : There was a considerable increment of manifest caries lesions from 12 to 18 years of age in all tooth groups . The best predictors for increment of manifest caries on approximal surfaces during the age period were approximal caries in premolars and second molars at the age of 12 years All field studies have unequivocally reported significant reductions in dental caries occurrence associated with the use of chewing gum containing xylitol . No other xylitol products besides chewing gum have so far been tested in field trials . A 5-year follow-up study with 2- or 3-year xylitol consumption periods began in Estonia in 1994 with 740 10-year-old children in 12 schools at baseline examinations . For the study , 3 clusters each including 3 - 5 schools were formed on the basis of baseline caries experience . The products were used under the supervision of the teachers 3 times per day during school days but not during weekends or during the 3-month summer holiday . The daily dose of xylitol was 5 g in all groups . The children were examined every year in September by two experienced clinicians . Dental caries was recorded according to WHO criteria . After 3 years , all xylitol groups showed a highly significant 35%-60 % reduction in caries incident , compared with the corresponding control groups . The differences between c and ies , between c and ies and chewing gum , and between 2- and 3-year users in the xylitol groups were non- systematic , indicating no trends between the groups . The results suggest that not only xylitol chewing gum but also xylitol c and ies are effective in caries prevention , and that a school-based delivery system seems to offer a practical way to distribute and control the use of the xylitol products A parallel-r and omized controlled trial on caries-preventive strategies was conducted in a general dental practice with a mixed socioeconomic background patient population . The aim of this study was to test the hypothesis that , compared to regular care consisting of check-ups twice a year with professional fluoride applications and pit and fissure sealants in all permanent molars , a larger caries-preventive effect can be achieved by following a non-operative caries treatment and prevention ( NOCTP ) strategy or by following , in addition to regular care , an increased number of professional topical fluoride applications ( IPFA ) . A total of 230 children ( 6.0 years ± 3 months of age ) were r and omly assigned to the two experimental groups or the control group . After 3 years , 179 participants remained in the study ( 54 NOCTP , 62 IPFA and 63 control ) . The children were examined at baseline and at 3 years by the same experienced examiner , who was blinded for the allocation of the children . Caries was scored clinical ly at the D3 level . Per protocol analysis revealed a mean DMFS increment after 3 years of 0.15 ( 95 % CI -0.05 to 0.35 ) for NOCTP , 0.34 ( 95 % CI 0.11 to 0.54 ) for IPFA and 0.47 ( 95 % CI 0.26 to 0.68 ) for the control group . To account for missing data , multiple imputation was used , after which the mean DMFS increment was 0.11 ( 95 % CI -0.05 to 0.27 ) for NOCTP , 0.29 ( 95 % CI 0.11 to 0.46 ) for IPFA and 0.40 ( 95 % CI 0.21 to 0.55 ) for the control group . Testing the differences with independent sample s t test revealed a lower caries increment in the NOCTP group compared to the control group . ANCOVA was used to correct for differences in baseline dmfs , socioeconomic status and perceived dental hygiene burden . The ΔDMFS effect size between the NOCTP and the control group dropped , losing statistical significance ( p = 0.06 ) . Although the results in this study are promising , it has yet to be established in a larger study whether NOCTP has the ability to be effective in regular dental practice with a mixed socioeconomic status population OBJECTIVE Xylitol studies suggest caries reductions in the order of 50 % . Based on animal/microbial studies , erythritol potentially has caries-preventive properties . However , clinical studies are required to confirm this . The aim of the study was to investigate the additional caries-preventive effect of xylitol/maltitol and erythritol/maltitol lozenges delivered at school , relative to controls receiving comprehensive prevention , in a low-caries prevalence population . METHODS A 4-year , cluster-r and omized , double-blinded clinical trial . Five hundred and seventy-nine 10-year-old consenting subjects from 21 schools were r and omly assigned to one of five groups . Four groups used the lozenges on school days , in three teacher-supervised sessions daily , over 1 or 2 years . The daily amount was 4.7 g/4.6 g for xylitol/maltitol and 4.5 g/4.2 g for erythritol/maltitol . The groups received free examinations and care in the public health centre . Four hundred and ninety-six children were analysed . The main outcome measure was dentin caries increment based on a clinical examination at 4 years since the start . The groups were compared in relation to the increment using hierarchical logistic regression to adjust for potential clustering . RESULTS Use of xylitol/maltitol or erythritol/maltitol lozenges did not result in caries reduction . A strong relationship between baseline caries prevalence and the 4-year increment was observed ( OR = 7.38 ; 95 % CI : 3.78 - 14.41 ) . CONCLUSIONS The results suggest that in relatively low-caries conditions the school-based use of xylitol/maltitol or erythritol/maltitol lozenges would not have additional caries-preventive effect when compared with comprehensive prevention The question has been raised whether low-caries children regularly using fluoride toothpaste will benefit from the professional application of additional fluoride gel . To investigate the caries-reducing effect of semi-annually-applied neutral 1 % sodium fluoride gel , we carried out a double-blind r and omized controlled clinical trial ( n = 594 ) in a child population , initially aged 9.5–11.5 years , with baseline caries experience of D3MFS = 0 ( decayed , missing , and filled tooth surfaces of permanent teeth ) . The mean number of tooth surfaces saved from caries development by fluoride gel application after 4 years was 0.2 D3MFS ( SE = 0.17 ) . The preventive fraction ( PF ) showed a mean relative effect of professionally applied fluoride gel of 18 % . The cariostatic effect of the fluoride gel on pits and fissures would have been influenced by the sealant strategy in the study . Professionally applied fluoride gel showed no statistically significant effect on mean D3MFS score in low-caries 9.5 
    Output:
    
Meta-regression analyses showed that the methods of individual studies influenced pooled caries incidence rates and increments in DMFS and DMFT .
This should be taken into account in planning and evaluation of oral health care services .
However , the caries incidence rate is promising for prediction of future caries increments in population