in general , orthodontic treatment focuses on improving functional occlusion and facial appearance.1 awareness of how facial appearance affects quality of life has rapidly increased the demand for such treatment . in most cases , the motivating factors for undergoing orthodontic treatment are enhanced dental and facial aesthetics and consequently minimized psychosocial problems.2,3 studies of oral health - related quality of life ( ohrqol ) in orthodontics are important because they provide information about therapeutic needs and outcomes as well as long - term oral health improvement.4 they can also ensure better therapeutic choices based on the patient 's perception.5 self - ligating brackets are popular in orthodontics because of their proposed superior properties including low static frictional resistance , full and stable archwire engagement , improved oral hygiene , preserved anchorage , reduced chair time and therapeutic time , and prolonged therapeutic intervals.6,7,8,9 several researchers compared therapeutic efficiency,7 friction,8 speed of archwire changes,9 therapeutic time,10 and initial alignment of the mandibular arch11 between self - ligating and conventional brackets , but the patient 's views were often not considered . further , although studies of pain and discomfort have been performed in orthodontics,12,13,14,15 ohrqol has not been assessed in patients wearing self - ligating and conventional brackets . such an investigation would provide specific information on how orthodontic treatment affects the patient 's physical , social , and psychological well - being in daily activities . it would also improve the patient 's understanding of the potential benefits and drawbacks of treatment.16 the objective of this study was to compare ohrqol of patients wearing conventional , active self - ligating ( asl ) , and passive self - ligating ( psl ) brackets in different therapeutic phases . the null hypothesis was that the prevalence and severity of impacts on ohrqol would not differ among the patients in any therapeutic phase . this randomized controlled clinical trial included 60 malaysian patients who visited the faculty of dentistry , university of malaya , for fixed orthodontic treatment . the inclusion criteria were age 14 - 24 years ; class i , ii , or iii skeletal pattern ; moderate crowding or spacing in the maxillary and mandibular arches ; and no intervention planned with extraoral and other intraoral appliances within the first 6 months of treatment . the exclusion criteria included severe skeletal disharmony requiring orthognathic surgery and presence of syndromes , dental caries , or periodontal disease . all the subjects were given oral healthcare products ( orthodontic toothbrush , fluoride mouthwash , and interdental toothbrush ) and reimbursed for transportation during the study ; they paid only half the total cost of the treatment . ethical approval was obtained from the research ethics committee of the faculty of dentistry , university of malaya [ df ot0803/0024(p ) ] . block randomization was performed by a dental nurse to allocate the subjects to conventional ( victory series ; 3 m unitek , monrovia , ca , usa ) , asl ( in - ovation r ; dentsply gac international , islandia , ny , usa ) , and psl ( damon 3mx ; ormco corporation , orange , ca , usa ) groups . in brief , each patient 's initials were written on a piece of paper , and the paper was randomly placed in one of three boxes representing the bracket systems . it ensured that the subjects had the same probability of being allocated to a group and the groups included an equal number of subjects . ohrqol was measured by using a modified 16-item malaysian version of the oral health impact profile ( ohip-16[m ] ) , adapted from saub et al.17 this instrument was chosen because it is used in most studies of ohrqol in orthodontics . it focuses on the impact of oral health on quality of life via seven domains : " functional limitation , " " physical pain , " " psychological discomfort , " " physical disability , " " psychological disability , " " social disability , " and " handicap . " responses to each item are scored as follows : 1 = never ; 2 = hardly ever ; 3 = occasionally ; 4 = fairly often ; and 5 = very often . for this study , three items were added on the basis of the outcome of a pretest : " problems in speech , " " problems in cleaning , " and " pain . " the item " have you had to spend a lot of money ? " was removed because the patients were mainly schoolchildren funded by their parents . the total score ranged from 16 to 80 , where 16 indicated no impact and 80 indicated the worst impact on ohrqol . each patient received an information sheet about the research and gave written informed consent before responding to the first questionnaire . after examination , diagnosis , and treatment planning , the patients completed the baseline questionnaire to assess ohrqol before any intervention . at the next appointment , activation was performed according to the manufacturers ' specifications at intervals of 4 , 6 , and 8 weeks in the conventional , asl , and psl groups , respectively . immediate and late assessments were conducted in the bonding , first activation , and second activation phases . for the immediate assessment , the questionnaires were given to the patients , and they mailed the completed questionnaires after the visit . the late assessment coincided with the activation appointments , minimizing patient constraints and maximizing compliance ; the patients completed these questionnaires before the subsequent visit . two parameters of ohip-16[m ] were computed according to locker and quionez18 : 
 i. prevalence : the percentage of respondents reporting one or more impacts as " very often " or " quite often . " severity : the sum of the response scores of the 16 items , which considers impacts experienced at all frequency levels . i. prevalence : the percentage of respondents reporting one or more impacts as " very often " or " quite often . " severity : the sum of the response scores of the 16 items , which considers impacts experienced at all frequency levels . because items in each domain vary , the scores were standardized to a range of 0 to 100 by using the fayers and machin19 formula : z = x [ 100/(m  ( k - 1 ) ] , where z is the standardized score , x is the summed score , m is the number of items , and k is the response category . therefore , the kruskal - wallis and chi - square tests were used for analyzing continuous and categorical data , respectively . all measurements were analyzed using statistical package for science social version 17.0 ( spss , inc , chicago , il , usa ) . this randomized controlled clinical trial included 60 malaysian patients who visited the faculty of dentistry , university of malaya , for fixed orthodontic treatment . the inclusion criteria were age 14 - 24 years ; class i , ii , or iii skeletal pattern ; moderate crowding or spacing in the maxillary and mandibular arches ; and no intervention planned with extraoral and other intraoral appliances within the first 6 months of treatment . the exclusion criteria included severe skeletal disharmony requiring orthognathic surgery and presence of syndromes , dental caries , or periodontal disease . all the subjects were given oral healthcare products ( orthodontic toothbrush , fluoride mouthwash , and interdental toothbrush ) and reimbursed for transportation during the study ; they paid only half the total cost of the treatment . ethical approval was obtained from the research ethics committee of the faculty of dentistry , university of malaya [ df ot0803/0024(p ) ] . block randomization was performed by a dental nurse to allocate the subjects to conventional ( victory series ; 3 m unitek , monrovia , ca , usa ) , asl ( in - ovation r ; dentsply gac international , islandia , ny , usa ) , and psl ( damon 3mx ; ormco corporation , orange , ca , usa ) groups . in brief , each patient 's initials were written on a piece of paper , and the paper was randomly placed in one of three boxes representing the bracket systems . the process was repeated until all the 60 patients were assigned to a group . it ensured that the subjects had the same probability of being allocated to a group and the groups included an equal number of subjects . ohrqol was measured by using a modified 16-item malaysian version of the oral health impact profile ( ohip-16[m ] ) , adapted from saub et al.17 this instrument was chosen because it is used in most studies of ohrqol in orthodontics . it focuses on the impact of oral health on quality of life via seven domains : " functional limitation , " " physical pain , " " psychological discomfort , " " physical disability , " " psychological disability , " " social disability , " and " handicap . " responses to each item are scored as follows : 1 = never ; 2 = hardly ever ; 3 = occasionally ; 4 = fairly often ; and 5 = very often . for this study , three items were added on the basis of the outcome of a pretest : " problems in speech , " " problems in cleaning , " and " pain . " the item " have you had to spend a lot of money ? " was removed because the patients were mainly schoolchildren funded by their parents . the total score ranged from 16 to 80 , where 16 indicated no impact and 80 indicated the worst impact on ohrqol . each patient received an information sheet about the research and gave written informed consent before responding to the first questionnaire . after examination , diagnosis , and treatment planning , the patients completed the baseline questionnaire to assess ohrqol before any intervention . at the next appointment , activation was performed according to the manufacturers ' specifications at intervals of 4 , 6 , and 8 weeks in the conventional , asl , and psl groups , respectively . immediate and late assessments were conducted in the bonding , first activation , and second activation phases . for the immediate assessment , the questionnaires were given to the patients , and they mailed the completed questionnaires after the visit . the late assessment coincided with the activation appointments , minimizing patient constraints and maximizing compliance ; the patients completed these questionnaires before the subsequent visit . two parameters of ohip-16[m ] were computed according to locker and quionez18 : 
 i. prevalence : the percentage of respondents reporting one or more impacts as " very often " or " quite often . " severity : the sum of the response scores of the 16 items , which considers impacts experienced at all frequency levels . i. prevalence : the percentage of respondents reporting one or more impacts as " very often " or " quite often . severity : the sum of the response scores of the 16 items , which considers impacts experienced at all frequency levels . because items in each domain vary , the scores were standardized to a range of 0 to 100 by using the fayers and machin19 formula : z = x [ 100/(m  ( k - 1 ) ] , where z is the standardized score , x is the summed score , m is the number of items , and k is the response category . therefore , the kruskal - wallis and chi - square tests were used for analyzing continuous and categorical data , respectively . all measurements were analyzed using statistical package for science social version 17.0 ( spss , inc , chicago , il , usa ) . the response rate was 100% and all the subjects completed the questionnaires in all the therapeutic phases ( figure 2 ) . the groups did not show significant differences in age , gender , and educational level ( table 1 ) . they also did not show significant differences in the prevalence and severity of impacts on ohrqol at the baseline and immediate and late assessments ( table 2 ) . the immediate impacts were more prevalent and severe than the late impacts in all the therapeutic phases regardless of the group . the bonding phase had the greatest effect ; the psl and asl groups showed more immediate and late impacts , respectively , whereas the conventional group showed impacts in both the assessments . the conventional group showed more immediate impacts after the second activation , whereas the psl and asl groups had more late impacts in this phase . similar ohip-16[m ] domains ( " physical disability , " " functional limitation , " " physical pain , " and " psychological discomfort " ) were affected in the therapeutic phases ( table 3 ) . the " social disability " and " handicap " domains were the least affected in all the groups . significant differences in the prevalence of " physical pain " and severity of " social disability " were noted at the late assessment of the second activation phase , with the psl group showing the highest values . significant differences were also observed in the severity of " food stuck between teeth " and " lack of self - confidence " at the late assessment of the bonding phase ( table 4 ) . further , the prevalence of " difficulties in chewing " and severity of " avoided going out " and " difficulty in performing daily activities " showed significant differences at the late assessment of the second activation phase . the psl group had the most severe impacts according to the ohip-16[m ] items in this phase . in this study , the absence of significant differences in the prevalence and severity of impacts on ohrqol in any therapeutic phase among the groups proves our hypothesis . in this study , the prevalence of impacts was quite high ( 65 - 75% ) at the baseline . this value is higher than that ( slightly over 50% ) found by saub and locker20 in malaysian adults . the difference was expected because the present subjects were patients with malocclusion who requested treatment . in the bonding phase , major et al.21 compared the shape of in - ovation and damon q brackets and found that damon q brackets ( ormco corporation , orange , ca , usa ) are more rectangular , with nearly 90-degree corners between the slot bottom and the walls . damon q brackets are a more compatible and sophisticated version of damon 3mx brackets . as damon 3mx brackets are relatively bulky , the patients wearing these brackets may have felt more uncomfortable and had greater difficulty in cleaning their teeth than the other patients . interestingly , the subjects bonded with conventional brackets had the highest severity score , indicating poorer ohrqol than those with self - ligating brackets . the tension and compression of the periodontal ligament during orthodontic treatment cause pain.22 this situation would be more apparent in patients with conventional brackets because of elastomeric ligatures , which produce friction that causes pain , when compared with self - ligating brackets , which are frictionless . such pain will affect eating abilities , as reflected by the most affected domain ( " physical pain " ) in the present study . although elastomeric ligatures reportedly have force decay tendencies , the failure load remained comparably high ( 67% ) in situ even after 6 weeks.23 the late assessment of the bonding phase was performed after 4 weeks , so the effect of elastomeric ligation would still have been perceptible . the lower prevalence of impacts of self - ligating brackets may be attributable to the adaptation to the relatively bulky brackets and frictionless system . the questionnaires in the psl and asl groups were administered at 8- and 6-week intervals , respectively , which would have allowed the subjects to adapt to the situation . immediate assessment after the first activation showed that self - ligating brackets had higher prevalence of impacts than the conventional group . in this phase , the archwire was drastically changed from a small round one ( 0.014 inch copper - nickel - titanium ) to a larger rectangular one ( 0.014  0.025 inch copper - nickel - titanium ) in the psl group . an increase in wire size would increase static frictional resistance,6 which can cause pain and discomfort . therefore , use of rectangular archwire might have had a greater impact . however , again , the conventional group had more severe impacts , which may have been caused by the strain from elastomeric ligatures . furthermore , the archwire in the conventional group was slightly larger ( 0.016 inch copper - nickel - titanium ) in this phase than in the bonding phase ( 0.014 inch copper - nickel - titanium ) . all the three bracket systems caused almost similar prevalence and severity of late impacts on " psychological discomfort " and " physical disability . " studies have shown that perceived pain peaks at around 24 hours after the placement of archwire , with reducing levels subsequently.24,25,26 this also suggests better adaptation of all patients to appliances , a phenomenon known as " learning experiences of treatment."27 at the second activation , the archwire for conventional and asl brackets was changed from round ( 0.016 inch ) to rectangular ( 0.016  0.022 inch ) copper - nickel - titanium . meanwhile , in the psl group , the shape of the archwire was the same ( i.e. , rectangular ) but a larger dimension was used ( from 0.014  0.025 inch to 0.018  0.025 inch copper - nickel - titanium ) . in this phase although this was the first instance where rectangular archwire was inserted in both the conventional and the asl groups , elastomeric ligatures in the conventional group could have complicated the situation . further , the prevalence of late impacts was higher in the psl group and the domains mostly affected were " physical pain " and " psychological discomfort , " with " food stuck in between teeth " being the most common effect reported . the larger archwire in the psl group could have caused food to become trapped between the archwire and the teeth , causing discomfort . the severity of impacts was the highest in the asl group , which could be due to the sustained friction in this system , compared with conventional brackets , which might show forced decay of elastomeric ligatures . strict inclusion and exclusion criteria were used to optimize group homogeneity , because factors such as age and severity of malocclusion play a role in the reporting of impacts on ohrqol.28,29 block randomization was performed to ensure an equal number of subjects per group , because pooling of eligible patients would have been time consuming given the stringent inclusion criteria . although the small number of participants in each group could cause bias , the operator had no control over the responses , so the bias may not be significant . further , the bracket systems in this study had different manufacturer - specified therapeutic intervals , which could have introduced bias , because a longer interval would have allowed adaptation to the appliance and thus affected the reporting of ohrqol . the sample was initially planned to ensure 30 patients per group , as proposed by roscoe.30 however , because of the stringent inclusion criteria and required therapeutic time , only 20 patients could be recruited in each group . the estimated statistical power by the post - hoc test was 74% for a sample size of 60 , divided into three groups , with medium effect . these findings would be useful when clinicians want to modify the standard protocol of the manufacturers , such as the archwire sequences or therapeutic intervals , to achieve patient comfort , as long as treatment is not jeopardized . they could also be applied when explaining the therapeutic phases , especially the initial one , and selecting the optimal bracket system based on the patient 's preference .
objectivethe aim of this randomized controlled clinical trial was to compare oral health - related quality of life ( ohrqol ) of patients treated with conventional , active self - ligating ( asl ) , and passive self - ligating ( psl ) brackets in different therapeutic phases.methodssixty patients ( mean age 18.3 years ; 29 males and 31 females ) requiring orthodontic treatment were randomly and equally assigned to receive conventional ( victory series ) , asl ( in - ovation r ) , or psl ( damon 3mx ) brackets . 
 ohrqol was measured with a self - administered modified 16-item malaysian version of the oral health impact profile for immediate ( soon after the visit ) and late ( just before the subsequent visit ) assessments of the bonding and activation phases . 
 data were analyzed with the kruskal - wallis and chi - square tests.resultsthe psl and asl groups showed more immediate and late impacts in the bonding phase , respectively ; the conventional group was affected in both the assessments . 
 the first activation phase had similar impacts in the groups . 
 after the second activation , the conventional group showed more immediate impacts , whereas the psl and asl groups had more late impacts . 
 the commonly affected domains were " physical disability , " " functional limitation , " " physical pain , " and " psychological discomfort . " 
 no significant differences in the prevalence and severity of immediate and late impacts on ohrqol of the patients were noted in any therapeutic phase.conclusionsno bracket system seems to ensure superior ohrqol . 
 this information could be useful for explaining the therapeutic phases , especially the initial one , and selecting the optimal bracket system based on the patient 's preference .