***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: In orthodontics , multiple site observations within patients or multiple observations collected at consecutive time points are often encountered . Clustered design s require larger sample sizes compared to individual r and omized trials and special statistical analyses that account for the fact that observations within clusters are correlated . It is the purpose of this study to assess to what degree clustering effects are considered during design and data analysis in the three major orthodontic journals . The contents of the most recent 24 issues of the American Journal of Orthodontics and Dentofacial Orthopedics ( AJODO ) , Angle Orthodontist ( AO ) , and European Journal of Orthodontics ( EJO ) from December 2010 backwards were h and search ed . Articles with clustering effects and whether the authors accounted for clustering effects were identified . Additionally , information was collected on : involvement of a statistician , single or multicenter study , number of authors in the publication , geographical area , and statistical significance . From the 1584 articles , after exclusions , 1062 were assessed for clustering effects from which 250 ( 23.5 per cent ) were considered to have clustering effects in the design ( kappa = 0.92 , 95 per cent CI : 0.67 - 0.99 for inter rater agreement ) . From the studies with clustering effects only , 63 ( 25.20 per cent ) had indicated accounting for clustering effects . There was evidence that the studies published in the AO have higher odds of accounting for clustering effects [ AO versus AJODO : odds ratio ( OR ) = 2.17 , 95 per cent confidence interval ( CI ) : 1.06 - 4.43 , P = 0.03 ; EJO versus AJODO : OR = 1.90 , 95 per cent CI : 0.84 - 4.24 , non-significant ; and EJO versus AO : OR = 1.15 , 95 per cent CI : 0.57 - 2.33 , non-significant ) . The results of this study indicate that only about a quarter of the studies with clustering effects account for this in statistical data analysis The aim of this longitudinal study was to monitor patients ' microbiological and clinical parameters from bracket placement up to 3 months post-treatment . Twenty-four patients ( 10 males and 14 females , aged 14.6 ± 1.0 years ) were included in this investigation . Microbiology ( sub- and supragingival ) , periodontal probing depth ( PPD ) , bleeding on probing ( BOP ) , and gingival crevicular fluid ( GCF ) flow were assessed at baseline ( T1 ) , at bracket removal ( T2 ) , and 3 months post-treatment ( T3 ) . A statistical comparison was made over time and between the b and ed , bonded , and control sites . Repeated measurements on patients were taken into account by modelling the patients as a r and om factor . Except for PPD and BOP , values were log-transformed before analysis . Corrections for simultaneous hypothesis testing were performed via simulation . The results demonstrated that sub- and supragingival colony-forming units ratio ( CFU ratio aerobe/anaerobe ) decreased significantly ( relatively more anaerobes ) at T2 compared with T1 . Between T2 and T3 no significant increase in CFU ratio was seen , result ing in a significantly lower CFU ratio at T3 compared with T1 for subgingival plaque . The difference concerning supragingival plaque between T3 and T1 was not significant . Clinical parameters PPD , POB , and GCF flow showed a significant increase between T1 and T2 . Between T2 and T3 these variables decreased significantly but remained significantly higher than at T1 [ except for BOP values at the bonded sites ( P = 0.0646 ) ] . Placement of fixed orthodontic appliances has an influence both on microbial and clinical periodontal parameters , which were only partly normalized , 3 months following the removal of the appliances INTRODUCTION The aim of this study was to investigate differences in the periodontal outcomes of palatally displaced canines ( PDC ) exposed with either an open or a closed surgical technique .  METHODS A multicenter , r and omized controlled trial was undertaken in 3 hospitals in the United Kingdom , involving 2 parallel groups . Patients with unilateral PDC were r and omly allocated to receive either an open or a closed surgical exposure .  Periodontal health was assessed 3 months after removal of fixed appliances . Parameters measured included clinical attachment levels , recession , alveolar bone levels , and clinical crown height . RESULTS Data from 62 participants ( closed , 29 ; open , 33 ) were analyzed . There was no difference between PDC exposed with an open vs a closed surgical technique ( mean difference , 0.1 mm ; 95 % confidence interval [ CI ] , -0.2 - 0.5 ) . There was , however , a statistical difference in mean attachment loss between the operated and unoperated ( contralateral ) canines ( mean difference , 0.5 mm ; 96 % CI , 0.4 - 0.7 ; P < 0.001 ) . Twenty of the 62 subjects had some recession on the palatal aspect of the operated canine , whereas only 4 subjects had some visible root surface on the palatal aspect on the unoperated side ( P = 0.001 ) . CONCLUSIONS There is a periodontal impact when a unilateral PDC is exposed and aligned . This impact is small and unlikely to have clinical relevance in the short term ; however , the long-term significance is unknown . When the open and closed techniques were compared , no difference in periodontal health was found Non-r and omised studies of the effects of interventions are critical to many areas of healthcare evaluation , but their results may be biased . It is therefore important to underst and and appraise their strengths and weaknesses . We developed ROBINS-I ( “ Risk Of Bias In Non-r and omised Studies - of Interventions ” ) , a new tool for evaluating risk of bias in estimates of the comparative effectiveness ( harm or benefit ) of interventions from studies that did not use r and omisation  to allocate units ( individuals or clusters of individuals ) to comparison groups . The tool will be particularly useful to those undertaking systematic review s that include non-r and omised studies INTRODUCTION Our objective was to learn the possible effects of fixed orthodontic therapy on the periodontium of the extraction sites adjacent to canines and first molars . This was a prospect i ve cohort study . METHODS Sixty-two systemically healthy subjects were selected . The study was divided into the period of oral hygiene instructions and the period of active orthodontic treatment . Plaque index , gingival index , probing pocket depth , and clinical attachment loss  were recorded for the canines and first molars at baseline , after 1 month of orthodontic therapy , and every 3 months until the completion of the orthodontic treatment . RESULTS There was a statistically significant increase in all clinical parameters ( plaque index , gingival index , probing pocket depth , and attachment loss ; P < 0.05 ) on the first molars compared with the canines . Significant increases in attachment loss were noted in both the canines ( baseline , 0.06 ± 0.01 mm ; end of treatment , 0.17 ± 0.02 mm ) and the molars ( baseline , 0.07 ± 0.01 mm ; end of treatment , 0.20 ± 0.02 mm ) . CONCLUSIONS Attachment loss can not be explained solely by the effect of plaque or the b and ing of teeth . Other factors such as tooth extraction s adjacent to the canines , tooth movement , and occlusal trauma may have contributing roles in the loss of periodontal support in adolescent patients Prospect i ve registration of systematic review s promotes transparency , helps reduce potential for bias and serves to avoid unintended duplication of review s. Registration offers advantages to many stakeholders in return for modest additional effort from the research ers registering their review AIM To compare undisturbed plaque formation on teeth bonded with different types of orthodontic brackets with non-bonded control teeth , via a de novo plaque growth experiment over a 7-day period . MATERIAL AND METHODS A r and omized controlled trial with split-mouth design was set up enroling 16 dental students . Within each subject sites with Speed(S ) and GAC(G ) , brackets and control sites were followed . Clinical periodontal parameters were recorded at baseline , on days 3 and 7 . Microbiological sample s were taken from the brackets and the teeth on days 3 and 7 . RESULTS Both anaerobe and aerobe colony-forming units ( CFU ) were significantly higher in S-sites than in G-sites ( p=0.0002 , p=0.02 ) . The shift from aerobic to anaerobic species was observed earlier in S-sites than in G-sites . The aerobe/anaerobe CFU ratio was significantly lower in S-sites than in G-sites ( p=0.01 ) . On day 3 , the crevicular fluid flow was significantly higher in S-sites than in control sites ( p=0.01 ) . On day 7 , S-sites and G-sites showed a significantly higher crevicular flow than control sites ( both p<0.0001 ) . More hypertrophy was seen in S- than in G- and control sites ( p=0.05 ) . No significant differences for bleeding on probing were observed . CONCLUSION Bracket design can have a significant impact on bacterial load and on periodontal parameters The goal of the present study was to measure attachmentlevel changes in patients of 12 - 48 years of age whose maxillary incisors have been intruded during an orthodontic treatment lasting between 9 and 14 months . Clinical parameters such as clinical probing depth , clinical attachment level and bleeding on probing were evaluated . The results show that i ) the intruded teeth gained an average of 0.6 mm of clinical attachment , while the control teeth showed a stable attachment level and ii ) the clinical probing depth remained stable at test and control teeth . It was concluded that orthodontical intrusion of maxillary front teeth in patients with a high level of oral hygiene maintains stable periodontal parameters and may even lead to a small clinical attachment gain The present study evaluated the periodontal conditions in dental students after appliance removal ( mean period 7.16 + /- 3.5 years ) compared with an untreated control group . Twenty-five subjects in the treated group ( 16 females and 9 males : 23.0 + /- 2.04 years ) and 29 in a control group ( 15 females and 14 males : 23.99 + /- 2.46 years ) underwent a periodontal examination : visible plaque index ( VPI ) , gingival bleeding index ( GBI ) , bleeding on probing ( BOP ) , periodontal probing depth ( PPD ) , and clinical attachment loss ( CAL ) of canines , premolars , and b and ed first molars and unb and ed second molars . Statistical analysis was performed using a Mann-Whitney test , a Student 's t-test , and Tukey 's analysis of variance . The level of significance was set at 5 per cent . The median percentage of positive sites for the treated and control groups for VPI ( 1.25 + /- 2.37 and 1.25 + /- 5.45 ) , GBI ( 0.95 + /- 1.81 and 1.23 + /- 2.14 ) , and BOP ( 0.83 + /- 6.45 and 0.83 + /- 3.43 ) did not differ between groups . Mean PPD values were 1.33 + /- 0.19 and 1.34 + /- 0.14 for the treated and 1.40 + /- 0.24 and 1.39 + /- 0.25 for the control group . No intra- or intergroup differences were observed . For the control group , the smallest PPD was at the canines followed by premolars and molars . PPD was less for premolars than molars but similar to the canines in the treated group . No differences in CAL were observed between the examined teeth in the control group . For the treated group , the canines showed lower CAL values than the first molars . The results indicate that the use of orthodontic appliances is not necessarily related to a worsening of periodontal conditions Obesity is a widespread chronic inflammatory disorder characterized by an increased overall disease burden and significant association with periodontitis . The aim of this prospect i ve clinical cohort study was to investigate the effect of obesity on orthodontic tooth movement . Fifty-five adolescent patients ( 27 males , 28 females ) with a mean ( SD ) age of 15.1 ( 1.7 ) years and mean ( SD ) body mass index ( BMI ) of 30.2 ( 3.5 ) kg/m2 in obese and 19.4 ( 2.2 ) kg/m2 in normal-weight groups were followed from start of treatment to completion of tooth alignment with fixed orthodontic appliances . Primary outcome was time taken to complete tooth alignment , while secondary outcomes included rate of tooth movement and change in clinical parameters ( plaque/gingival indices , unstimulated whole-mouth salivary flow rate , gingival crevicular fluid biomarkers ) . Data collection took place at baseline ( start of treatment : appliance placement ) , 1 h and 1 wk following appliance placement , and completion of alignment . Results were analyzed by descriptive statistics followed by generalized estimating equation regression modeling . There were no significant differences between groups in time taken to achieve tooth alignment ( mean [ SD ] 158.7 [ 75.3 ] d ; P = 0.486 ) . However , at 1 wk , initial tooth displacement was significantly increased in the obese group ( P < 0.001 ) , and after adjusting for confounders , obese patients had a significantly higher rate of tooth movement compared with normal-weight patients ( + 0.017 mm/d ; 95 % confidence interval , 0.008–0.025 ; P < 0.0 
    Output:
    
Conclusions According to existing evidence from longitudinal clinical studies orthodontic treatment with fixed appliances has little to no clinical ly relevant effect on periodontal clinical attachment levels .