***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 study was to investigate the effect of bracket type ( conventional and self-ligating ) on the levels of Streptococcus mutans and total bacterial counts in whole saliva of orthodontic patients . Thirty-two male and female patients were selected using the following inclusion criteria : adolescents ( mean age 13.6 years , range 11 - 17 years ) , fixed appliances in both arches , non-smoker , and no reported oral habits . Demographic and oral hygiene characteristics were determined for each subject . The patients were subdivided into two groups with r and om allocation of bracket type ( conventional or self-ligating ) . An initial saliva sample was obtained before the initiation of treatment ( T1 ) and a second sample 2 - 3 months following appliance bonding ( T2 ) . Salivary S. mutans and total bacteria were enumerated and analysed after growth in culture . The demographic and clinical characteristics of the sample s were analysed with a t- or chi-square test , where applicable , to assess the r and om allocation of bracket group to participants . The results of S. mutans and total facultative bacterial counts were log transformed and statistically analysed with analysis of covariance with bracket ( conventional versus self-ligating ) as the categorical variable and initial total bacterial counts or initial S. mutans levels serving as the covariate . No difference was found in the demographics and oral hygiene indices between the two groups , verifying the r and om assignment of brackets to the population sample . The levels of S. mutans in whole saliva of orthodontically treated patients do not seem to be significantly different between conventional and self-ligating brackets . The pre-treatment levels of S. mutans are significant predictors of the levels of S. mutans after placement of orthodontic appliances , while this was not the case for total bacterial counts OBJECTIVE To determine the effects of fixed orthodontic appliances on periodontal health and microbiological composition of subgingival dental plaque . MATERIAL AND METHODS This prospect i ve longitudinal self-controlled study was conducted on 32 adolescents ( 13 males , 19 females ) , who were scheduled for fixed orthodontic treatment between 2002 and 2005 .  Dental plaque accumulation , gingival inflammation and pocket probing depth were measured at the mesio-vestibular angle of the examined group of teeth followed by collection of subgingival dental plaque sample s in the same points . These periodontal indices and microbiological parameters were determined prior to the placement of fixed appliances and 1 , 3 and 6 months after the beginning of orthodontic treatment . RESULTS All values of both clinical and microbiological parameters started to increase after the placement of fixed appliances . Maximum values were reached 3 months after fixed appliance placement followed by their decrease in the last registration period of 6 months after the placement of fixed appliances . CONCLUSIONS Treatment with fixed appliances in adolescents may transitionally increase the values of all periodontal indices and stimulate the growth of periodontopathogenic bacteria , but without destructive effects on deep periodontal tissues The aim of this study was to determine the influence of oral hygiene instruction ( OHI ) on oral hygiene status and on the reduction of inducing bacteria ( Streptococcus mutans and Lactobacillus spp . ) in 30 subjects ( 12 males and 18 females ) with an age range from 10 to 14 years . The patients were instructed on how to carry out effective oral hygiene close to brackets and ligatures , and in the use of dental floss for cleaning spaces around brackets , between the teeth and under archwires . The  plaque index ( PI ) was used to measure oral hygiene status , and the level of S. mutans and Lactobacillus spp . was determined using the colour reaction time test before and after 1 month of OHI . Statistical analysis included a Student 's t-test and chi-square test . The results showed that OHI significantly improved oral hygiene . The percentage of patients with a PI exceeding 1 decreased from 23.3 to 10 per cent and for those with a PI below 0.1 it increased from 20 to 60 per cent . The level of S. mutans and Lactobacillus spp . was not reduced . The percentage of subjects with excessive levels of S. mutans ( above 10(6 ) bacteria in 1 ml of saliva ) decreased after OHI but only from 73.3 to 70 per cent . For Lactobacillus spp . , a level above 10(5 ) of bacteria in 1 ml of saliva was found for all subjects at both time points . Patients with fixed appliances , trained in scrupulous tooth cleaning , remain at risk of developing caries and should be carefully monitored OBJECTIVE To evaluate the effects of fixed orthodontic treatment with steel-ligated conventional brackets and self-ligating brackets  on halitosis and periodontal health .  MATERIAL S AND METHODS Sixty patients , at the permanent dentition stage aged 12 to 18 years , who had Angle Class I malocclusion with mild-to-moderate crowding were r and omly selected . Inclusion criteria were nonsmokers , without systematic disease , and no use of antibiotics and oral mouth rinses during the 2-month period before the study . The patients were subdivided into three groups r and omly : the group treated with conventional brackets ( group 1 , n = 20 ) ligated with steel ligature wires , the group treated with self-ligating brackets ( group 2 , n = 20 ) , and the control group ( group 3 , n = 20 ) . The periodontal records were obtained 1 week before bonding ( T1 ) , immediately before bonding ( T2 ) , 1 week after bonding ( T3 ) , 4 weeks after bonding ( T4 ) , and 8 weeks after bonding ( T5 ) . Measurements of the control group were repeated within the same periods . The volatile sulfur components determining halitosis were measured with the Halimeter at T2 , T3 , T4 , and T5 . A two-way repeated measures of analysis of variance ( ANOVA ) was used to compare the groups statistically . RESULTS No statistically significant group × time interactions were found for plaque index , gingival index , pocket depth , bleeding on probing , and halitosis , which means three independent groups change like each other by time . The risk of tongue coating index ( TCI ) being 2 was 10.2 times higher at T1 than at T5 ( P < .001 ) . Therefore , the probability of higher TCI was decreased by time in all groups . CONCLUSIONS The self-ligating brackets do not have an advantage over conventional brackets with respect to periodontal status and halitosis This article introduces the approach of GRADE to rating  quality of evidence .  GRADE specifies four categories-high , moderate , low , and very low-that are applied to a body of evidence , not to individual studies . In the context of a systematic review , quality reflects our confidence that the estimates of the effect are correct . In the context of recommendations , quality reflects our confidence that the effect estimates are adequate to support a particular recommendation . R and omized trials begin as high- quality evidence , observational studies as low quality . " Quality " as used in GRADE means more than risk of bias and so may also be compromised by imprecision , inconsistency , indirectness of study results , and publication bias . In addition , several factors can increase our confidence in an estimate of effect . GRADE provides a systematic approach for considering and reporting each of these factors . GRADE separates the process of assessing quality of evidence from the process of making recommendations . Judgments about the strength of a recommendation depend on more than just the quality of evidence OBJECTIVE To determine the effect of bracket type on  halitosis , periodontal status , and microbial colonization . MATERIAL S AND METHODS Forty-six patients scheduled for fixed orthodontic treatment ( age 11 - 16 years ) were selected from the orthodontic department of Suleyman Demirel University . Patients were divided into two groups with r and om distribution of brackets ; 23 patients were treated with self-ligating brackets ( group SLBs ) , the others with conventional brackets ( group CBs ) . Halitosis measurements and periodontal and microbial records were obtained before the placement of brackets ( T0 ) , 1 week later ( T1 ) , and 5 weeks after bonding ( T2 ) . Periodontal parameters , including plaque index ( PI ) , gingival index ( GI ) , and bleeding on probing index ( BOP ) , were obtained from all the bonded teeth . Halitosis measurements were performed at the same time . Microbial sample s were obtained from the buccal surfaces of all the bonded teeth . Data were analyzed by using a repeated-measurement analysis of variance test for the comparison of parameters between groups and times . RESULTS Periodontal parameters and halitosis results were higher in the CBs group than in the SLBs group ( P<.05 ) . In the SLBs group , halitosis and BOP values revealed no pronounced changes between T1 and T2 ( P>.05 ) . Intra- and intergroup comparisons showed that there were no statistically significant differences for microbial colonization between all the time intervals ( P>.05 ) . CONCLUSION Bracket type has an effect on halitosis and periodontal status . Therefore , self-ligating brackets may be advised in order to prevent patients from developing halitosis and to increase the likelihood of good oral hygiene during orthodontic treatment A longitudinal and transverse study has been carried out on 22 orthodontic patients during their first year of treatment to assess levels of plaque control and gingival inflammation . The scores were of full data and the patients r and omly arranged on a split mouth cross-over design to study the effects of patient oral care and selective tooth cleaning on levels of oral health . The results are analysed in respect of upper fixed , lower fixed and upper removable appliances , comparing and contrasting quadrants that have been treated differently . Plaque levels appear constant , whereas levels of gingival inflammation are consistently worse during treatment but only in certain areas of the mouth . Levels of plaque and gingivitis are well controlled . There appears to be no hygiene disadvantage to an upper removable appliance when compared with an upper fixed appliance though the effect differs in relation to the tooth aspect considered . The significance of the findings is discussed The presence of clinical ly detectable areas of decalcification ( observable as whitened areas ) following the removal of orthodontic appliances is well recognized . The aim of the present study was to determine quantitatively the amount of demineralization and the ability of commercially available products to inhibit or reverse orthodontically related demineralization .  Twenty orthodontic patients scheduled to have premolars extracted were r and omly divided into four groups -- one control and three test groups . The extracted premolars ( numbering 58 ) were bracketed using an acid-etch composite system ; each patient was given precise oral hygiene instructions and supplied with a sodium fluoride ( 1,100 ppm fluoride ) dentifrice and an orthodontic toothbrush . The control group brushed only with the supplied dentifrice . In addition to brushing with the dentifrice , those in test group I rinsed once each night with a sodium fluoride ( 0.05 % ) mouthrinse ; group II received a weekly topical APF treatment ( 1.2 % fluoride ) ; and Group III received a weekly topical APF treatment and rinsed once each night with the sodium fluoride mouthrinse . All premolars were extracted after 1 calendar month . Mineral profiles were determined on cross-sectioned teeth 50 to 75 micron occlusal and cervical to the brackets , directly underneath the brackets , and 500 micron away from the brackets . The control teeth ( dentifrice only ) demonstrated up to 15 % demineralization to a depth of 50 micron . All of the test teeth produced rehardening and /or inhibition of demineralization ( P less than 0.01 ) . Those in test group III showed a particularly hard outer layer . The study demonstrated that measurable demineralization occurred around orthodontic appliances after only 1 month and this demineralization can be completely inhibited and /or reversed by the use of commercially available fluoride products Fixed or removable orthodontic appliances impede the maintenance of oral hygiene and result in plaque accumulation . Plaque retention surrounding orthodontic appliances leads to enamel demineralization caused by organic acids produced by bacteria in the dental plaque . Many studies have evaluated the effects of fixed orthodontic appliances on microbial flora and periodontal status , but only a few have evaluated the method of ligation as an additional factor . The aim of this study was to determine the changes in microbial flora and periodontal status after orthodontic bonding and to determine whether two different archwire ligation techniques affect these changes . A total of 21 orthodontic patients scheduled for fixed orthodontic treatment were selected for this split-mouth study . Two commonly used auxiliaries ( elastomeric rings and ligature wires ) for tying archwires were tested . Microbial and periodontal records were obtained before bonding ( T0 ) , one week later ( T1 ) , and five weeks after bonding ( T2 ) . Paired t-test and Wilcoxon signed rank test were used to compare the groups statistically . Although , teeth ligated with elastomeric rings exhibited slightly greater numbers of microorganisms than teeth ligated with steel ligature wires , the differences were not statistically significant and could be ignored . The two archwire ligation techniques showed no significant differences in the gingival index , bonded bracket plaque index , or pocket depths of the bonded teeth . However , teeth ligated with elastomeric rings were more prone to bleeding . Therefore , elastomeric ring use is not recommended in patients with poor oral hygiene OBJECTIVE To determine the effect of different bracket design s ( conventional brackets and self-ligating brackets ) on periodontal clinical parameters and periodontal pathogens in subgingival plaque . MATERIAL AND METHODS The following inclusion criteria were used : requirement of orthodontic treatment plan starting with alignment and leveling , good general health , healthy periodontium , no antibiotic therapy in the previous 6 months 
    Output:
    
At 4 - 6 weeks after bracket placement there was no evidence to support the use of either type of bracket for achieving improved plaque- ( PI ) and gingival index ( GI ) .
At 3 - 6 months , there was scarce evidence of greater PI increase for conventional brackets .
GI and pocket depth pooled estimates did not reveal significant differences between the two systems .
Overall , non-significant differences on the periodontal status of adolescents undergoing orthodontic treatment with either conventional or self-ligating brackets  were detected .
CLINICAL SIGNIFICANCE The periodontal status of adolescents undergoing orthodontic treatment is of considerable importance .