***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: Background Dental caries incidence in adults is similar to that in children and adolescents , but few caries preventive agents have been evaluated for effectiveness in adults population s. In addition , dentists direct fewer preventive services to their adult patients .  Xylitol , an over-the-counter sweetener , has shown some potential as a caries preventive agent , but the evidence for its effectiveness is not yet conclusive and is based largely on studies in child population s. Methods / Design X-ACT is a three-year , multi-center , placebo controlled , double-blind , r and omized clinical trial that tests the effects of daily use of xylitol lozenges versus placebo lozenges on the prevention of adult caries . The trial has r and omized 691 participants ( ages 21 - 80 ) to the two arms . The primary outcome is the increment of cavitated lesions . Discussion This trial should help resolve the overall issue of the effectiveness of xylitol in preventing caries by contributing evidence with a low risk of bias . Just as importantly , the trial will provide much-needed information about the effectiveness of a promising caries prevention agent in adults . An effective xylitol-based caries prevention intervention would represent an easily disseminated method to extend caries prevention to individuals not receiving caries preventive treatment in the dental office . Trial Registration Clinical Trials . Gov OBJECTIVES The aim of this 3-year community intervention trial was to determine the caries preventive effect of sugar-substituted chewing gum among Lithuanian school children , and to assess compliance with the instructions for gum use . METHODS A total of 602 children , aged 9 - 14 years , from 28 school classes in five secondary schools in Kaunas , Lithuania , were given a baseline clinical and radiographic caries examination . The schools were r and omly allocated to receive one of the following interventions : sorbitol/carbamide gum ; sorbitol gum ; xylitol gum ; control gum ; and no gum . Children in the four active intervention groups were asked to chew at least five pieces of gum per day , preferably after meals . The children were reexamined clinical ly after 1 , 2 and 3 years , and radiographically after 3 years . Self-reported compliance was monitored anonymously four times during the study . RESULTS A total of 432 children were available at the 3-year clinical follow-up examination . The crude mean 3-year caries increments ( DMFS -- all stages of lesion formation ) were 11.8 for the sorbitol/carbamide gum group ; 9.0 for the sorbitol gum group ; 8.1 for the xylitol gum group ; 8.3 for the control gum group ; and 12.4 for the no gum group . The adjusted 3-year caries increments were statistically significantly lower in the sorbitol gum group , the xylitol gum group and the control gum group than in the no gum group , whereas no statistically significant difference was seen between the no gum group and the sorbitol/carbamide gum group . Adjusted 3-year caries increments in the xylitol gum group and the sorbitol gum group did not differ statistically significantly from the caries increments in the control gum group . Compliance with the study protocol was better in School C ( xylitol gum ) than in the other schools . In all schools , compliance decreased over time . CONCLUSION The results indicate that the caries preventive effect of chewing sugar-free gum is related to the chewing process itself rather than being an effect of gum sweeteners or additives , such as polyols and carbamide Introduction Controversy surrounds decisions on whether to repair or replace defective dental restorations . The concept of built-in obsolescence , ie periodic replacement of dental restorations , is largely accepted as the modus oper and i if not the default mode in restorative care . In this article we examine the current best available evidence underpinning the effectiveness of replacement versus repair of direct amalgam and resin composite restorations .  Method This article builds on two recent Cochrane systematic review s which have reported on the evidence base supporting the effectiveness of replacement versus repair of amalgam and direct resin composites  and translates the results of their research conclusions into recommendations for the dental clinician . Results As no relevant r and omised controlled trials ( RCTs ) were identified in either of these systematic review s , the evidence regarding the effectiveness of repair versus replacement of amalgam and composite restorations  is weak and incomplete . The evidence as it currently st and s seems to favour repair over replacement , but this is insufficient to make firm recommendations . Conclusion In view of the absence of high level evidence there is a need for further well design ed RCTs . To add value to the evidence base these trials should be conducted in a general practice setting which will strengthen the generalisability and applicability of the research conclusions and enable dentists and patients to make informed decisions BACKGROUND Although caries is prevalent in adults , investigators have tested few preventive therapies in adult population s. In a r and omized controlled trial , the authors evaluated the effectiveness of xylitol lozenges in preventing caries in adults at elevated risk of developing caries . METHODS The Xylitol for Adult Caries Trial ( X-ACT ) was a three-site placebo-controlled r and omized trial . Participants ( n = 691 ) aged 21 through 80 years consumed five 1.0-gram xylitol or placebo lozenges daily for 33 months . They underwent clinical examinations at baseline and at 12 , 24 and 33 months . RESULTS Xylitol lozenges reduced the caries increment 10 percent . This reduction , which represented less than one-third of a surface per year , was not statistically significant . There was no indication of a dose-response effect . CONCLUSIONS Daily use of xylitol lozenges did not result in a statistically or clinical ly significant reduction in  33-month caries increment among adults at an elevated risk of developing caries . CLINICAL IMPLICATION S These results suggest that xylitol used as a supplement in adults does not reduce their caries experience significantly Objective : The aim of this study was to test the efficacy of long-term , daily intake of erythritol and xylitol c and y , compared with sorbitol c and y , on the development of enamel and dentin caries lesions . Methods : The study was a double-blind r and omized controlled prospect i ve clinical trial . Altogether 485 primary school children , first- and second- grade rs at baseline , from southeastern Estonia participated in this 3-year intervention . Each child consumed four erythritol , xylitol or sorbitol ( control ) c and ies three times per school day . The daily intake of polyol was about 7.5 g. The International Caries Detection and Assessment System ( ICDAS ) was used in the clinical examinations by four calibrated examiners at baseline and at 12 , 24 and 36 months . Results : The annual examination analyses and the follow-up analyses confirmed that the number of dentin caries teeth and surfaces at 24 months follow-up and surfaces at 36 months follow-up was significantly lower in the mixed dentition in the erythritol group than in the xylitol or control group . Time of enamel/dentin caries lesions to develop and of dentin caries lesions to progress was significantly longer in the erythritol group compared to the sorbitol and xylitol groups . Also the increase in caries score was lower in the erythritol group than in the other groups . Conclusions : In the follow-up examinations , a lower number of dentin caries teeth and surfaces was found in the erythritol group than in the xylitol or control groups . Time to the development of caries lesions was longest in the erythritol group . Trial registration : Clinical Trials.gov Identifier NCT01062633 OBJECTIVES To evaluate the effectiveness of a xylitol pediatric topical oral syrup to reduce the incidence of dental caries among very young children and to evaluate the effect of xylitol in reducing acute otitis media in a subsequent study . DESIGN Double-blind r and omized controlled trial . SETTING Communities in the Republic of the Marshall Isl and s. PARTICIPANTS One hundred eight children aged 9 to 15 months were screened , and 100 were enrolled . Intervention Children were r and omized to receive xylitol topical oral syrup ( administered by their parents ) twice a day ( 2 xylitol [ 4.00-g ] doses and 1 sorbitol dose ) ( Xyl-2 x group ) or thrice per day ( 3 xylitol [ 2.67-g ] doses ) ( Xyl-3x group ) vs a control syrup ( 1 xylitol [ 2.67-g ] dose and 2 sorbitol doses ) ( control group ) . MAIN OUTCOME MEASURES The primary outcome end point of the study was the number of decayed primary teeth . A secondary outcome end point was the incidence of acute otitis media for reporting in a subsequent report . RESULTS Ninety-four children ( mean [ SD ] age , 15.0 [ 2.7 ] months at r and omization ) with at least 1 follow-up examination were included in the intent-to-treat analysis . The mean ( SD ) follow-up period was 10.5 ( 2.2 ) months . Fifteen of 29 of the children in the control group ( 51.7 % ) had tooth decay compared with 13 of 32 children in the Xyl-3x group ( 40.6 % ) and eight of 33 children in the Xyl-2x group ( 24.2 % ) . The mean ( SD ) numbers of decayed teeth were 1.9 ( 2.4 ) in the control group , 1.0 ( 1.4 ) in the Xyl-3x group , and 0.6 ( 1.1 ) in the Xyl-2x group . Compared with the control group , there were significantly fewer decayed teeth in the Xyl-2x group ( relative risk , 0.30 ; 95 % confidence interval , 0.13 - 0.66 ; P = .003 ) and in the Xyl-3x group ( 0.50 ; 0.26 - 0.96 ; P = .04 ) . No statistical difference was noted between the 2 xylitol treatment groups ( P = .22 ) . CONCLUSION Xylitol oral syrup administered topically 2 or 3 times daily at a total daily dose of 8 g was effective in preventing early childhood caries 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 PURPOSE To evaluate the efficacy of a sodium fluoride (NaF)/silica/xylitol dentifrice compared with that of a positive control NaF/silica dentifrice on  caries increments in school children over a 3-year period in an area without an optimal level of fluoride in the drinking water ( mean level < 0.1 ppm ) . MATERIAL S AND METHODS A 3-year , double-blind clinical caries study was conducted in 2,630 children initially aged 8 - 10 years at 17 schools in the San Jose , Costa Rica metropolitan area . Clinical dental examinations were performed at participating schools utilizing portable dental equipment . Caries evaluations employed conventional tactile/visual methodology consisting of artificial light , dental mirrors and single-edge # 23 explorers . Children accepted into the study were stratified by age and sex into two balanced groups within each school , and r and omly assigned to use either a positive control dentifrice containing 0.243 % NaF/silica or a test dentifrice containing 0.234 % NaF/silica/10 % xylitol . Children were instructed to brush with the assigned dentifrice twice daily . Caries evaluations were conducted at baseline , 2 years , and 3 years . RESULTS After 3 years , subjects using the 0.234 % NaF/silica/10 % xylitol dentifrice had statistically significantly reduced decayed/filled surfaces ( DFS ; -12.3 % reduction ; P < or = 0.001 ) and decayed/filled buccal and lingual surfaces ( DFS-BL ; -10.5 % reduction ; P < or = 0/01 ) OBJECTIVE Xylitol studies suggest caries reductions in the order of 50 % . Based on animal/microbial studies , erythritol potentially has caries-preventive properties . 
    Output:
    
AUTHORS ' CONCLUSIONS We found some low quality evidence to suggest that fluoride toothpaste containing xylitol may be more effective than fluoride-only toothpaste for preventing caries in the permanent teeth of children , and that there are no associated adverse-effects from such toothpastes .
The remaining evidence we found is of low to very low quality and is insufficient to determine whether any other xylitol-containing products can prevent caries in infants , older children , or adults