***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: OBJECTIVE To compare the effectiveness of three applications of silver diammine fluoride ( SDF ) solution at yearly interval and three applications of SDF solution or sodium fluoride ( NaF ) varnish at weekly interval at baseline in arresting active caries  in the primary teeth of preschool children . METHODS Children aged 3 - 4 years ( n = 371 ) who had at least one active caries lesion ( ICDAS codes 3 - 6 ) in their primary teeth were r and omly allocated into three groups : Group 1 - annual application of 30 % SDF solution ; Group 2 - three applications of 30 % SDF at weekly intervals ; and Group 3 - three applications of 5 % NaF varnish at weekly intervals . Follow-up examinations were performed every 6 mo nths by the same masked examiner . RESULTS After 30 months , 309 ( 83 % ) children with 1877 caries lesions remained in the study . For cavitated lesions ( ICDAS code 5 or 6 ) , the caries arrest rate of Group 1 ( 48 % ) was significantly higher than those of Group 2 ( 33 % ) and Group 3 ( 34 % ) , ( p < 0.001 ) . Results of multi-level survival analysis showed that the arrest times of cavitated lesions in both SDF groups ( Groups 1 and 2 ) were significantly shorter than that of the NaF varnish group . For moderate caries lesions without visible dentine ( ICDAS code 3 or 4 ) , the caries arrest rates were 45 % , 44 % and 51 % in Groups 1 , 2 and 3 , respectively ( p > 0.05 ) . Presence of plaque on caries lesion , tooth type and tooth surface type had an influence on caries arrest . CONCLUSION Over a 30-month period , annual applications of SDF solution is more effective than three weekly applications of NaF varnish or SDF solution at baseline in arresting active cavitated dentine caries lesions in primary teeth . CLINICAL SIGNIFICANCE As annual application of SDF solution was found to be more effective than 3 weekly applications of NaF varnish or SDF solution at baseline in arresting active cavitated dentine caries lesions , the former application protocol is preferred for young children who are available for regular caries arrest treatment The recording of multiple interval-censored failure times is common in dental research . Modeling multilevel data has been a difficult task . This paper aims to use the Bayesian approach to analyze a set of multilevel clustered interval-censored data from a clinical study to investigate the effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting active dentin caries in Chinese pre-school children . The time to arrest dentin caries on a surface was measured . A three-level r and om-effects Weibull regression model was used . Analysis was performed with WinBUGS . Results revealed a strong positive correlation ( 0.596 ) among the caries lesions ’ arrest times on different surfaces from the same child . The software WinBUGS made the above complicated estimation simple . In conclusion , the annual application of silver diamine fluoride on caries lesions , and caries removal before the application , were found to shorten the arrest time Correlated or multilevel grouped survival data are common in medical and dental research . Two common approaches to analyze such data are the marginal and the r and om-effects approaches . Models and methods in the literature generally assume that the treatment effect is constant over time . A research er may be interested in study ing whether the treatment effects in a clinical trial vary over time , say fade out gradually . This is of particular clinical value when study ing the long-term effect of a treatment . This paper proposed to extend the r and om effects grouped proportional hazards models by incorporating the possibly time-varying covariate effects into the model in terms of a state-space formulation . The proposed model is very flexible and the estimation can be performed using the MCMC approach with non-informative priors in the Bayesian framework . The method is applied to a data set from a prospect i ve clinical trial investigating the effectiveness of silver diamine fluoride ( SDF ) and sodium fluoride ( NaF ) varnish in arresting active dentin caries in the Chinese preschool children . It is shown that the treatment groups with caries removal prior to the topical fluoride applications are most effective in shortening the arrest times in the first 6-month interval , but their effects fade out rapidly since then . The effects of treatment groups without caries removal prior to topical fluoride application drop at a very slow rate and can be considered as more or less constant over time . The applications of SDF solution is found to be more effective than the applications of NaF vanish Untreated dental caries in Chinese pre-school children is common . This prospect i ve controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries .  Three hundred seventy-five children , aged 3 - 5 years , with carious upper anterior teeth were divided into five groups . Children in the first and second groups received annual applications of silver diamine fluoride solution ( 44,800 ppm F ) . Sodium fluoride varnish ( 22,600 ppm F ) was applied every three months to the lesions of children in the third and fourth groups . For children in the first and third groups , soft carious tissues were removed prior to fluoride application . The fifth group was the control .  Three hundred eight children were followed for 30 months . The respective mean numbers of arrested carious tooth surfaces in the five groups were 2.5 , 2.8 , 1.5 , 1.5 , and 1.3 ( p < 0.001 ) . Silver diamine fluoride was found to be effective in arresting dentin caries in primary anterior teeth in pre-school children OBJECTIVES This study aim ed to compare the effectiveness of three topical fluoride application protocol s in arresting dentine caries in primary teeth of preschool children in a fluori date d area . METHODS Children aged 3 - 4 years who had at least one active dentine caries lesion were r and omly allocated into three intervention groups : Group 1-application of 30 % silver diammine fluoride ( SDF ) solution every 12 months ; Group 2-three applications of 30 % SDF solution at weekly interval at baseline ; and Group 3-three applications of 5 % sodium fluoride ( NaF ) varnish at weekly interval at baseline . A masked examiner carried out follow-up examinations every 6 months to assess whether the treated lesions had become arrested . RESULTS A total of 304 children with 1670 tooth surfaces with dentine caries received treatment at baseline . After 18 months , 275 children ( 91 % ) remained in the study . The caries arrest rates at tooth surface level were 40 % , 35 % and 27 % for Groups 1 , 2 and 3 , respectively ( p<0.001 ) . Result of the multi-level survival analysis showed that the two SDF application protocol s could shorten the time to arrest of dentine caries compared with the NaF application protocol . Presence of plaque on lesion surface , tooth type and tooth surface all had significant effects on caries arrest rates . CONCLUSIONS Annual or three consecutive weekly applications of SDF solution is more effective in arresting dentine caries in primary teeth than three consecutive weekly applications of NaF varnish . CLINICAL SIGNIFICANCE In a water fluori date d area , application of SDF solution , either three weekly applications at baseline or annually , can arrest active dentine caries lesions in primary teeth faster than three weekly applications of NaF varnish at baseline Dental caries in Chinese pre-school children is common , and restorative treatment is not readily available . This prospect i ve controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries . We divided 375 children ( aged 3 - 5 yrs ) with carious upper anterior teeth into five groups . Children in the first and second groups received annual applications of silver diamine fluoride solution ( 44,800 ppm F ) . NaF varnish ( 22,600 ppm F ) was applied every three months onto the lesions of children in the third and fourth groups . For children in the first and third groups , soft carious tissues were removed prior to fluoride application . The fifth group was the control . We followed 341 children for 18 months . The mean numbers of new caries surfaces in the five groups were 0.4 , 0.4 , 0.8 , 0.6 , and 1.2 , respectively ( p = 0.001 ) . The respective mean numbers of arrested carious tooth surfaces were 2.8 , 3.0 , 1.7 , 1.5 , and 1.0 ( p < 0.001 ) 
    Output:
    
When comparing the caries arrest lesions of SDF and NaF , SDF was found to be statistically more effective in dentine caries arrest of primary teeth during the 18 and 30 month clinical examinations .