***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 The purpose of this study was to investigate the effect of treatment of m and ibular crowding with self-ligating and conventional brackets on dental arch variables . Fifty-six patients were selected from a pool of subjects satisfying the following inclusion criteria : non- extraction treatment in the m and ibular or maxillary arches , eruption of all m and ibular teeth , no spaces and an irregularity index greater than 2 mm in the m and ibular arch , and no adjunct treatment such as etxra- or intraoral appliances .  The patients were assigned to two groups : one group received treatment with the self-ligating bracket and the other with a conventional edgewise appliance , both with a 0.022 inch slot . Lateral cephalometric radiographs obtained at the beginning ( T1 ) and end ( T2 ) of treatment were used to assess the alteration in m and ibular incisor inclination , and measurements of intercanine and intermolar widths were made on dental casts to investigate changes associated with the correction . The results were analysed with bivariate and multivariate linear regression analysis in order to examine the effect of the bracket systems on arch width or lower incisor inclination , adjusting for the confounding effect of demographic and clinical characteristics . An alignment-induced increase in the proclination of the m and ibular incisors was observed for both groups ; no difference was identified between self-ligating and conventional brackets with respect to this parameter . Likewise , an increase in intercanine and intermolar widths was noted for both bracket groups ; the self-ligating group showed a higher intermolar width increase than the conventional group , whereas the amount of crowding and Angle classification were not significant predictors of post-treatment intermolar width INTRODUCTION The aim of this study was to investigate the duration of m and ibular-crowding alleviation with self-ligating brackets compared with conventional appliances and the accompanying dental effects . METHODS Fifty-four subjects were selected from a pool of patients satisfying the following inclusion criteria : non extraction treatment in the m and ibular or maxillary arches ; eruption of all m and ibular teeth ; no spaces in the m and ibular arch ; irregularity index greater than 2 in the m and ibular arch ; and no therapeutic intervention planned with any extraoral or intraoral appliance . The patients were r and omly assigned to 2 groups : 1 group received treatment with a self-ligating bracket ( Damon 2 , Ormco , Glendora , Calif ) and the other with a conventional edgewise appliance ( Microarch , GAC , Central Islip , NY ) , both with 0.022-in slots . The irregularity index of the m and ibular arch was normalized between the groups , and the time to alignment was estimated in days . Treatment duration was assessed by data modeling with the Cox proportional hazard regression . Lateral cephalometric radiographs were used to assess the alteration of m and ibular incisor position before and after alignment . Measurements of intercanine and intermolar widths were also made on dental casts to determine changes associated with correction . RESULTS AND CONCLUSIONS Overall , no difference in the time required to correct m and ibular crowding with Damon 2 and conventional brackets was observed . For moderate crowding ( irregularity index < 5 ) , however , the self-ligating group had 2.7 times faster correction . This difference was marginally insignificant for subjects with irregularity index scores greater than 5 . Greater crowding prolonged treatment by an additional 20 % for each irregularity index unit . Increases in intercanine and intermolar widths associated with crowding correction regardless of bracket group were noted . The self-ligating group showed a statistically greater intermolar width increase than the conventional group . Also , an alignment-induced increase in the proclination of the m and ibular incisors was observed for both bracket groups , but no difference was found between Damon 2 and conventional brackets for this parameter INTRODUCTION In this r and omized clinical trial , we compared pain levels associated with 2 fixed appliance systems  during initial orthodontic tooth movement . METHODS Sixty-six patients ( 36 female , 30 male ) were r and omly allocated to either a conventional twin bracket ( Tru Straight , Ormco Europe , Amersfoort , The Netherl and s ) or a self-ligating bracket ( Damon 3 , Ormco ) . Both arches were bonded , and a 0.014-in superelastic copper-nickel-titanium archwire was ligated in position . Pain intensity levels were recorded twice a day , over 7 days , by using 10-cm visual analog scales . Patients also recorded whether analgesia was taken . Contact point displacements were measured on study models to calculate Little 's irregularity index . RESULTS Fifty-two patients ( 78.8 % ) completed the trial ( 84.8 % in the Tru Straight group and 72.7 % in the Damon 3 group ) . Patients in the Damon 3 group reported lower mean maximum pain intensity ( P = 0.053 ) and significantly lower mean pain intensity ( P = 0.012 ) than did the Tru Straight patients . Patients who consumed analgesics reported significantly higher mean maximum pain intensity and mean pain intensity than those who did not take analgesia ( P < 0.001 ) . The Damon 3 patients generally reported lower pain intensity than the Tru Straight patients . CONCLUSIONS Although there were wide interindividual variations , in this study , the Damon 3 appliance result ed in lower pain intensity , on average , when compared with the Tru Straight appliance OBJECTIVES To test the hypothesis that the engagement mode of wire to bracket affects the buccolingual inclination of maxillary incisors in extraction and non- extraction treatment with self-ligating and conventional brackets . DESIGN A r and omized clinical trial employing a r and om distribution of variables among the studied population s. SETTING AND SAMPLE POPULATION Private practice of one author . A total of 105 patients followed prospect ively , were divided into two groups based on the inclusion of extraction in the treatment planning . These groups were further divided in two subgroups each , one receiving a self-ligating bracket and the other treated with a conventional Edgewise appliance of the same slot size and prescription . EXPERIMENTAL VARIABLE Difference in the buccolingual inclination of maxillary incisors before and after treatment with the two appliances across the two treatment groups ( extraction and non- extraction ) . OUTCOME MEASURE Angular measurements of the Sella-Nasion and Nasion-A point to maxillary incisor axis . RESULTS No difference was found in the mean difference of the two angles measured for the two bracket groups studied . CONCLUSION Self-ligating brackets seem to be equally efficient in delivering torque to maxillary incisors relative to conventional brackets in extraction and non- extraction cases INTRODUCTION In this prospect i ve clinical study , we assessed the relative speed of archwire changes , comparing self-ligating brackets with conventional elastomeric ligation methods , and further assessed this in relation to the stage of orthodontic treatment represented by different wire sizes and types . METHODS The time taken to remove and ligate  archwires for 131 consecutive patients treated with either self-ligating or conventional brackets  was prospect ively assessed . The study was carried out in the orthodontic department of a district general hospital in the United Kingdom . The main outcome measure was the time to remove or place elastomeric ligatures or open/close self-ligating brackets for 2 matched groups of fixed appliance patients : Damon2 self-ligating bracket ( SDS Ormco , Orange , Calif ) and a conventional mini-twin bracket ( Orthos , SDS Ormco ) . The relative effects of various wire sizes and material s on ligation times were investigated . The study was carried out by 1 operator experienced in the use of self-ligating and conventional brackets . RESULTS The Damon2 self-ligating system had a significantly shorter mean archwire ligation time for both placing ( P < .001 ) and removing ( P < .01 ) wires compared with the conventional elastomeric system .  Ligation of an archwire was approximately twice as quick with the self-ligating system . Opening a Damon slide was on average 1 second quicker per bracket than removing an elastic from the mini-twin brackets , and closing a slide was 2 seconds faster per bracket . This difference in ligation time between the Damon2 and the conventional mini-twin brackets became more marked for larger wire sizes used in later treatment stages . CONCLUSIONS The type of bracket and the size of wire used are statistically significant predictors for speed of ligation and chairside time . The self-ligating system offered quicker and arguably more efficient wire removal and placement for most orthodontic treatment stages INTRODUCTION The aim of this study was to compare the rate of en-masse space closure with sliding mechanics between passive self-ligating SmartClip brackets ( 3 M Unitek , Monrovia , Calif ) and conventional twin brackets ligated with stainless steel ligatures . METHODS Nineteen patients including 20 arches participated in this prospect i ve trial with 0.018-in slot brackets . All patients had first premolar extraction s in at least 1 arch , with the second premolar and the first molar distal to the extraction site bonded with SmartClip brackets on 1 side and conventional twin brackets on the other . The sides were alternated with each consecutive patient . Space closure was achieved on 0.016 x 0.022-in stainless steel wires with nickel-titanium coil springs activated 6 to 9 mm . The patients were recalled every 5 weeks until 1 side had closed . The distances from the mesial aspect of the canine bracket to the distal aspect of the first molar bracket were recorded before and after space closure , and an average rate of space closure per month was calculated . RESULTS Thirteen patients completed the trial ( 14 arches ) ; the median rates of tooth movement for the SmartClip bracket side ( 1.1 mm per month ) and the conventional twin bracket side ( 1.2 mm per month ) were not significantly different ( P = .86 ) . CONCLUSIONS There was no significant difference in the rate of en-masse space closure between passive SmartClip brackets and conventional twin brackets tied with stainless steel ligatures INTRODUCTION Enamel decalcification is a common problem in orthodontics . The objectives of this r and omized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types , self-ligating ( SL ) vs elastomeric ligating ( E ) , and to determine whether adenosine triphosphate (ATP)-driven bioluminescence could be used for rapid assessment of bacterial load in plaque . METHODS Patients ( ages , 11 - 17 years ) were bonded with SL and E brackets  in 14 maxillary and 12 m and ibular arches by using a split-mouth design . Recall visits were at 1 and 5 weeks after bonding . Plaque specimens were assayed for oral bacteria and subjected to ATP-driven bioluminescence determinations with a luciferin-based assay . RESULTS In most patients , teeth bonded with SL attachments had fewer bacteria in plaque than did teeth bonded with E brackets . At 1 and 5 weeks after bonding , the means for SL vs E brackets were statistically lower for total bacteria and oral streptococci ( P < 0.05 ) . ATP bioluminescence values were statistically correlated to the total oral bacteria and oral streptococci , with correlation coefficients of 0.895 and 0.843 , respectively . CONCLUSIONS SL appliances promote reduced retention of oral bacteria , and ATP bioluminescence might be a useful tool in the rapid quantification of bacterial load and the assessment of oral hygiene during orthodontic treatment The objective of this study was to compare the effectiveness and comfort of Damon 2 brackets and conventional twin brackets during initial alignment . Sixty consecutive patients participated in a split mouth design . One side of the lower arch was bonded with the Damon 2 bracket and the other with a conventional twin bracket . The sides were alternated with each consecutive patient . The irregularity index ( II ) was measured for each half of the arch at baseline , at 10 weeks at the first archwire change , and at another 10 weeks at the second archwire change . Any difference in discomfort was assessed within the first few days of archwire placement and again at the first archwire change . Comfort on the lips , preferred 
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Meta- analysis of the influence of bracket type on subjective pain experience failed to demonstrate a significant advantage for either type of appliance .
Statistical analysis of other outcomes was unfeasible because of inadequate method ological design and heterogenous design s. CONCLUSIONS At this stage there is insufficient high- quality evidence to support the use of self-ligating fixed orthodontic appliances over conventional appliance systems or vice versa