***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 
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    Input: In the United Kingdom ( UK ) over the last 10 years , there has been a significant increase in the use of vacuum-formed retainers ( VFRs ) rather than conventional Hawley retainers . There are currently no data to compare the cost-effectiveness of this change in practice . The two aims of this study were to compare ( 1 ) the cost-effectiveness of VFRs and Hawley retainers over 6 months , from the perspective of the National Health Service , orthodontic practice , and the patient and ( 2 ) patient satisfaction in the two retainer groups . A r and omized controlled trial ( RCT ) was carried out in a specialist orthodontic practice . Three hundred and ninety-seven eligible patients were r and omized to one of two retainer groups , and followed up for 6 months . All subjects were invited to complete patient satisfaction question naires . Additional data were collected for the cost analysis from the patient records and national data bases . Descriptive and bivariate analyses were used to compare patient satisfaction between retainer groups . In all , 196 subjects were r and omized to the Hawley group ( mean age 14 years 8 months , 63 per cent female , 37 per cent male ) and 201 to the VFR group ( mean age 15 years , 59 per cent female , 41 per cent male ) .  VFRs were more cost-effective than  Hawley retainers  from all perspectives . The majority of subjects showed a preference for VFRs compared with Hawley retainers . There were also fewer breakages than in the Hawley group Background Retention is an important component of orthodontic treatment ; however , poor compliance with retainer use is often encountered , especially in adolescents . The purpose of this study was to prove the hypothesis that verbal instructions combined with images showing the severe consequences of poor compliance can increase retainer use . Methods This study was a r and omized controlled trial . The sample was recruited from Wenzhou , People ’s Republic of China , between February 2013 and May 2014 , and 326 participants were r and omized into three groups . Patients and parents in Group A ( n=106 ) were given routine retainer wear instructions only ; in Group B ( n=111 ) , images illustrating the severe consequences of poor compliance with Hawley retainer use were shown to patients , combined with routine instructions ; and in Group C ( n=109 ) , images illustrating the severe consequences of poor compliance with Hawley retainer use were shown to patients and parents , combined with routine instructions . Three months after debonding , question naires were used to investigate daily wear time and the reasons for poor compliance . Differences in means between the groups were tested by one-way analysis of variance . Results The mean daily wear time in Group C ( 15.09±4.13 hours ) was significantly greater than in Group A ( 12.37±4.58 hours , P<0.01 ) or Group B ( 13.50±4.22 hours , P<0.05 ) ; the mean daily wear time in Group B was greater than in Group A , but was not significant ( P=0.67 ) . Reasons for nonusage were forgetting to wear the retainer ( 51 % ) and finding the retainer bothersome to frequently insert and remove ( 42 % ) . Conclusion Verbal instructions combined with images showing the severe consequences of poor compliance can increase retainer use . Parents play an important role in compliance with retainer use in adolescent patients INTRODUCTION Intraoral elastics are commonly used in orthodontics and require regular changing to be effective . Unfortunately , poor compliance with elastics is often encountered , especially in adolescents . Intention for an action and its implementation can be improved using " if-then " plans that spell out when , where , and how a set goal , such as elastic wear , can be put into action . Our aim was to determine the effect of if-then plans on compliance with  elastics .  METHODS To identify common barriers to compliance with recommendations concerning elastic wear , semistructured interviews were carried out with 14 adolescent orthodontic patients wearing intraoral elastics full time . Emerging themes were used to develop if-then plans to improve compliance with  elastic wear  . A prospect i ve pilot study assessed the effectiveness of if-then planning aim ed at overcoming the identified barriers on compliance with elastic wear .  Twelve participants were r and omized equally into study and control groups ; the study group received information about if-then planning . The participants were asked to collect used elastics  , and counts of these were used to assess compliance . RESULTS A wide range of motivational and volitional factors were described by the interviewed participants , including the perceived benefits of elastics , cues to remember , pain , eating , social situations , sports , loss of elastics , and breakages . Compliance with elastic wear  was highly variable among patients . The study group returned more used elastics  , suggesting increased compliance , but the difference was not significant . CONCLUSIONS The use of if-then plans might improve compliance with elastic wear when compared with routine clinical instructions Both r and omized and nonr and omized studies are integral to orthodontic research and practice because they permit evaluation of relationships between exposures and outcomes , allowing the efficacy , effectiveness , and safety of interventions to be assessed . These design s allow clinical decisions to be informed . Nonr and omized design s include nonr and omized clinical trials , cohort studies , case-control studies , cross-sectional studies , case series , and ecological studies . There is debate surrounding the optimal research design ; however , both r and omized and nonr and omized design s are important to build a broad , informative evidence base . The design s are therefore complementary , with unique advantages and limitations . The applicability of either approach hinges on the clinical question posed , the feasibility of study ing it , and ethical considerations Early treatment for Class II malocclusion is frequently undertaken with the objective of correcting skeletal disproportion by altering the growth pattern . Because the majority of previous studies of growth modification for Class II malocclusion have been based on retrospective record review s , the efficacy of such an approach has not been well established . In this controlled clinical trial , patients in the mixed dentition with overjet > or = 7 mm were r and omly assigned to either early treatment with headgear , or modified bionator , or to observation . All patients were observed for 15 months with no other appliances used during this phase of the trial . The three groups , who were equivalent initially , experienced statistically significant differences ( p < 0.01 ) in skeletal change . There was considerable variation in the pattern of change within all three groups , with about 80 % of the treated children responding favorably . Although patients in both early treatment groups had approximately the same reduction in Class II severity , as reflected by change in the ANB angle , the mechanism of this change was different . The headgear group showed restricted forward movement of the maxilla , and the functional appliance group showed a greater increase in m and ibular length . The permanence of these skeletal changes and their impact on the subsequent treatment remains to be evaluated Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more In the first phase of a r and omized clinical trial of early versus late Class II treatment , statistically significant differences were observed between the treatment and observation groups . However , there were wide variations in response . The change in jaw relationship ( categorized as the annualized reduction in ANB angle ) was favorable or highly favorable in 76 % of the headgear , 83 % of the functional appliance , and 31 % of control ( observation only ) groups . The patient 's initial skeletal severity , age/maturity at the outset of treatment , growth pattern , and cooperation with treatment were examined as possible influences on early growth modification treatment . Correlations between the annualized change in the ANB angle and any of the possible influences were close to zero and not statistically significant . We conclude that there is little to be gained from precisely timing early treatment to specific age/maturity markers and that a favorable reduction in Class II skeletal problems can occur for patients in a broad range of skeletal severity and growth patterns . Cooperation , measured as the number of hours of reported wear , or the clinical assessment of compliance , explained little of the variation in treatment response . The wide variation in growth seen in the untreated patients highlights the importance of well-controlled studies if clinicians are to improve their ability to select children with the greatest chances of a favorable treatment response INTRODUCTION The aim of this study was to compare the effectiveness of Twin-block and Dynamax appliances for the treatment of Class II Division 1 malocclusion . METHODS This was a r and omized controlled trial involving 32 boys and 32 girls aged 10 to 14 years with Class II Division 1 malocclusion . They were r and omly allocated to either the Dynamax appliance group or the Twin-block appliance group . Treatment was provided by 4 clinicians at 2 centers . Records were taken at the start and the end of the functional phase and after all treatment . In addition , incisal overjet , the number of appliance breakages , and adverse events or side effects of the treatment were recorded at each patient visit . RESULTS The data monitoring committee in an interim analysis at 18 months after the start of the trial found significantly greater overjet reduction in the Twin-block group than in the Dynamax group and more breakages and adverse events with the Dynamax appliance . As a result , treatment with the Dynamax appliance was terminated , and those patients completed treatment with the Twin-block or a fixed appliance . Regression analysis showed a statistically significant difference in the performance over time between the Twin-block and Dynamax appliances in terms of reduction in overjet , with the Twin-block appliance performing significantly better than the Dynamax . The incidence of adverse events was greater in the Dynamax group ( 82 % ) than in the Twin-block group ( 16 % ) , with a statistically significant difference ( P < 0.001 ) between the 2 groups . CONCLUSIONS The Twin-block appliance was more effective than the Dynamax appliance when overjet was evaluated and the Dynamax appliance patients reported greater incidence of adverse events with their appliance than those who were treated with the Twin-block appliance 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 The aim of this controlled trial was to identify and quantify skeletal , soft tissue and dental changes during treatment , and immediately post-treatment with Twin Block ( TB ) or Dynamax appliance using the techniques of three-dimensional (3D)optical surface laser scanning , cephalometric , and clinical measurements . Sixty-two Caucasian subjects , 36 males aged 11 - 14 years and 26 females aged 10 - 13 years were enrolled in the study . The patients were placed in two groups , matched for gender and age and subsequently allocated r and omly for treatment with either a TB or Dynamax appliance . Active treatment lasted 9 months followed by 3 months ' post-treatment observation . Laser scanning and clinical measurements were taken at 3-monthly intervals and final cephalometric records after 12 months . Statistical analysis was performed using Wilcoxon 's matched-pairs signed-rank tests . The non-compliance rates were the same for both groups ( 9 per cent ) , but a greater incidence of breakages was found in the Dynamax group . The TB was found to produce slightly more antero-posterior skeletal change , median ANB reduction , TB=2 degrees , Dynamax 1.1 degree ( P=0.006 ) , and similar forward movements of the chin and was associated with larger increases in the vertical facial dimension , median total anterior face height increase ; TB=3.2 mm , Dynamax = 2.8 mm ( P=0.03 ) . The soft tissue vertical cephalometric increases were 3.6 mm with the TB , 2.0 mm with the Dynamax ( P=0.036 ) , and with laser scanning 5.05 and 2.6 mm , respectively , a difference which is likely to be more clinical ly relevant . The median post-treatment changes in soft tissue pogonion were -0.65 mm in the TB and + 0.22 mm in the Dynamax group . The optical surface scanning mark and measure system is a valid method for quantifying soft tissue changes The aim of this study was to evaluate the effectiveness of Herbst and Twin-block appliances for established Class II Division I malocclusion . The study was a multicenter , r and omized clinical trial carried out in orthodontic departments in the United Kingdom . A total of 215 patients ( aged 11 - 14 years ) were r and omized to receive treatment with either the Herbst or the Twin-block appliance .  Treatment with the Herbst appliance result ed in a lower failure-to-complete rate for the functional appliance phase of treatment ( 12.9 % ) than did treatment with Twin-block ( 33.6 % ) . There were no differences in treatment time between appliances , but significantly more appointments ( 3 ) were needed for repair of the Herbst appliance than for the Twin-block . There were no differences in skeletal and dental changes between the appliances ; however , the final occlusal result and skeletal discrepancy were better for girls than for boys . Because of the high cooperation rates of patients using it , the Herbst appliance could be the appliance of choice for treating adolescents with Class II Division 1 malocclusion . The trade-off for use of the Herbst is more appointments for appliance repair The aim of this study was to evaluate the effectiveness of a fixed Twin-block appliance by using a study with a prospect i ve cohort design . Thirty-two children were included in the study over a 2-year period .  Cephalometric data were analyzed with the Pancherz cephalometric analysis . Study models were analyzed with the PAR index , 
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Conclusions : Compliance with removable orthodontic appliances and adjuncts is suboptimal , and patients routinely overestimate duration of wear .
HighlightsSuboptimal compliance is typical with all types of orthodontic appliances .
Actual wear time is approximately 5 hours per day less than stipulated .
Overreporting of appliance wear was found with all types of appliances .