***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 purpose of this study was to evaluate the periodontal tissues of patients with m and ibular fixed retention for long or short periods of time . A total of 64 individuals were selected for this study using the following inclusion criteria : long-term  lingual fixed retention ; identical type of lingual fixed retainer bonded with the same material s ; no cavities , restorations , or fractures of the m and ibular anterior teeth ; absence of habits and occlusal interferences ; and canine guidance bilaterally . The result ant sample comprised 32 patients ( mean age 25 years ) who had been in retention for a mean period of 9.65 years ( range 9 - 11 years ) and an equal number retained for a period between 3 and 6 months .  Plaque , gingival , and calculus indices , probing pocket depth , marginal recession , and bone level at the m and ibular six anterior teeth were recorded for both groups . Demographic , clinical , and radiographic data were investigated with conventional descriptive statistics . Comparisons of the different variables between the two participant groups ( long- and short-term retention ) were carried out using a Mann-Whitney test for indices ( plaque , gingival , and calculus ) , and a Fisher 's exact test ( two sided ) for the remaining variables . No significant difference was found with respect to the plaque and gingival indices and bone level between the two groups . The long-term group presented higher calculus accumulation , greater marginal recession , and increased probing depth ( P < 0.05 ) . The results of this study raise the question of the appropriateness of lingual fixed retainers as a st and ard retention plan for all patients regardless of their attitude to dental hygiene . They also emphasize the importance of individual variability and cautious application of retention protocol s after a thorough consideration of issues related to the anatomy of tissues and oral hygiene INTRODUCTION This clinical study was design ed to evaluate the efficacy of innovative fiber-reinforced-thermoplastic ( FRP ) bonded orthodontic retainers . METHODS Anterior lingual retainers  were formed by using a 2-step process from preimpregnated unidirectional long glass fibers ( volume fraction , 0.25 ) in a thermoplastic resin matrix of either poly(ethylene terephthalate glycol ) or polycarbonate .  Seventy-six canine-to-canine retainers were placed in 56 patients by using the acid-etch technique over a 34-month period . They were evaluated for clinical acceptability to function as a retainer , structural integrity of the FRP , and integrity of the bonding . Variables examined included material composition , design factors , and mechanism of failure of the retainers . The results were analyzed by using the univariate Kaplan-Meier survival method and the multivariate Cox regression model . RESULTS The overall median survival time was 7.6 months , with 33 % surviving after 12 months . The retainer with the longest service was in use for over 24 months . The variables with the most significant effects and improved survival rates were FRP formulation ( polycarbonate ) , retainer thickness ( 1.02 mm ) , and number of teeth overlapped ( all 6 teeth ) . Failure was primarily due to bond failure at the enamel-adhesive or adhesive-FRP interface . CONCLUSIONS With improved survival times , FRP retainers could be a viable alternative to metal retainers The purpose of this longitudinal prospect i ve r and omized study was to evaluate the reliability of two different types of orthodontic retainers in clinical use : a multistr and stainless steel wire and a polyethylene ribbon-reinforced resin composite . Moreover the level of satisfaction of the patient about the esthetic result was also analyzed by means of a Visual Analogue Scale ( VAS ) . 34 patients ( 9 boys and 25 girls , mean age 14.3 ) , in the finishing phase of orthodontic treatment , were selected for the study . Since splints were applied the number , cause , and date of splint failures were recorded for each single tooth over 12 months . Statistical analysis was performed using a paired t-test , Kaplan Meier survival estimates , and the log-rank test . Kruskal Wallis test was performed to analyze VAS recordings . Differences between the bond failure rates were not statistically significant . Esthetic result of VAS was significantly higher for polyethylene ribbon-reinforced resin retainers than for stainless steel wires Background The aim of this prospect i ve clinical study was to compare the mean durability and the failure rates of two types of orthodontic retainers . Methods Orthodontic patients ( 142 ) aged between 14 and 28 years were recruited in this study . The polyethylene woven ribbon ( Ribbond , Seattle , WA , USA ) retainer was compared with a 0.0175-in flexible spiral wire ( Respond , Ormco , Glendora , CA , USA ) retainer . When treatment was completed , the retainers were bonded from canine to canine in the maxillary and the m and ibular arches of the participants . In the follow-up visits , the patients were re-evaluated every 3 months over a period of 18 months . The time taken for the retainers to remain without any fracture was appraised . Kaplan-Meier analysis and the logrank test were employed to identify significant differences in the survival functions between the groups . The rates of the retainers ' failure between the groups were analyzed using Chi-square test . Results It was revealed that the mean survival of the flexible spiral wire retainer was 15.34 ± 0.47 and 15.60 ± 0.42 months in the maxillary and m and ibular arches , respectively . The mean survival of the ribbon retainer was 13.95 ± 0.55 and 14.26 ± 0.57 months in the maxillary and m and ibular arches , respectively . Ribbon retainers showed a failure rate of 50 % in the maxillary and 42.6 % in the m and ibular arches . Flexible spiral retainers showed a failure rate of 36.5 % in the maxillary and 37.8 % in the m and ibular arches . The differences were not statistically significant . Regarding the evaluation period , the differences had limited clinical significance . Conclusion The mean survival time and the failure rates of the polyethylene woven ribbon retainer were comparable to the flexible spiral wire retainer during the 18 months after orthodontic treatment Bonded retainers are considered reliable , independent of patient co-operation , and highly efficient . However , most studies regarding the survival of retainers are retrospective . The aims of this investigation were to prospect ively evaluate the failure rate of bonded lingual retainers , the influence of direct or indirect bonding procedures on survival , and to determine the distribution of failures over a 6 month period .  M and ibular lingual retainers were bonded in 66 patients . Thirty-two retainers were bonded using a direct method and 34 by an indirect method  . There were 23 females and 9 males ( mean age 15.96 ± 3.21 years ) in the direct group and 29 females and 5 males ( mean age 19.44 ± 6.79 years ) in the indirect group . A 0.016 × 0.022 inch Bond-a-Braid retainer wire ( eight-braided , flattened , stainless steel dead soft wire ) was used with Transbond LR . Following bonding , the patients were observed monthly . A chi-square test was used to analyse the influence of the direct and indirect procedures on survival rate . Twenty-five retainers failed . The failure rate was 46.9 per cent with the direct method and 29.4 per cent with the indirect method . The difference between the methods was not statistically significant . The total failure rate was 37.9 per cent . The highest failure rate was seen in the first month . Seven patients had repeated failures . The failure rate was higher in the right quadrant . The total survival rate was 62.1 per cent Objectives : The purpose of this longitudinal prospect i ve r and omized study was to evaluate the clinical reliability of two different types of postorthodontic treatment retainers : a silanised-treated glass fibers-reinforced resin composite ( FRC ) and a directly bonded multistr and ed stainless steel wire . The hypothesis of the study was to assess if significant differences are present between failure rates of the two retainers . Study Design : This prospect i ve study was based on an assessment of 87 patients ( 35 men and 52 women),with an average age of 24 years who required a lower arch fixed retainer after orthodontic treatment . Patients were divided in two groups . Assignment was carried out with r and om tables . A follow-up examination was carried out once a month . The number , cause , and date of single bond adhesive failures were recorded for both retainers over 12 months . Teeth that were rebonded after failure were not included in the success analysis . Statistical analysis was performed by means of a Fisher ’s exact test , Kaplan-Meier survival estimates , and log rank test . Results : Bond failure rate was significantly higher ( P=0.0392 ) for multistr and ed metallic wire than for FRC . Conclusions : Glass fiber-reinforced resin composite retainers and multistr and ed metallic wires showed no significant difference in single bond failure rates over a one-year follow up . Key words : Fiber reinforced composite , fixed retention , multistr and ed wire , orthodontics , retainer , splint INTRODUCTION The objective of this trial was to compare the survival rates of m and ibular lingual retainers  bonded with either chemically cured or light-cured adhesive  after orthodontic treatment . METHODS Patients having undergone orthodontic treatment at a private orthodontic office were r and omly allocated to fixed retainers placed with chemically cured composite or light-cured composite .  Eligibility criteria included no active caries , restorations , or fractures on the m and ibular anterior teeth , and adequate oral hygiene . The main outcome was any type of first-time lingual retainer breakage ; pattern of failure ( adapted adhesive remnant index scores ) was a secondary outcome . R and omization was accomplished with r and om permuted blocks of 20 patients with allocation concealed in sequentially numbered , opaque , sealed envelopes . Blinding was applicable for outcome assessment only . Patients were review ed at 1 , 3 , and 6 months and then every 6 months after placement of the retainer until completion of the study . Data were analyzed using survival analysis including Cox regression ; sensitivity analysis was carried out after data imputation for subjects lost to follow-up . RESULTS Two hundred twenty patients ( median age , 16 years ; interquartile range , 2 ; range , 12 - 47 years ) were r and omized in a 1:1 ratio to either chemical or light curing . Baseline characteristics were similar between groups , the median follow-up period was 2.19 years ( range , 0.003 - 3.64 years ) , and 16 patients were lost to follow-up . At a minimum follow-up of 2 years , 47 of 110 ( 42.7 % ) and 55 of 110 ( 50.0 % ) retainers had some type of failure with chemically cured and light-cured adhesive , respectively ( log-rank test , P = 0.35 ) . Data were analyzed on an intention-to-treat basis , and the hazard ratio ( HR ) was 1.15 ( 95 % confidence interval [ CI ] , 0.88 - 1.70 ; P = 0.47 ) . There was weak evidence that age is a significant predictor for lingual retainer failures ( HR , 0.96 ; 95 % CI , 0.93 - 1.00 ; P = 0.08 ) . Adhesive remnant index scoring was possible for only 66 of the 102 ( 64.7 % ) failures and did not differ between composites ( Fisher exact test , P = 0.16 ) . No serious harm was observed other than gingivitis associated with plaque accumulation . CONCLUSIONS The results of this study indicated no evidence that survival of m and ibular lingual retainers differs between chemically and light-cured adhesives . The overall failure rate was 46.4 % ; however , this included any type of failure , which may have exaggerated the overall failure rate OBJECTIVE The reliability of posttreatment canine-to-canine retention with resin composite retainers reinforced with plasma-treated woven polyethylene ribbons was compared to the reliability of directly bonded , multistr and ed wire retainers . METHOD AND MATERIAL S This prospect i ve study was based on an assessment of 20 consecutive patients ( eight women and 12 men with a mean age of 22.4 years ) who required a fixed canine-to-canine retainer after undergoing orthodontic treatment . The type of retainer used was r and omized for each patient . A follow-up examination was carried out once every 3 months . The length of time the retainers stayed in place without resin fracture or loosening from the teeth at one or more points was evaluated . The study 's endpoint was 24 months after the retainer had been bonded . RESULTS The ribbon-reinforced retainer remained in place for an average of 11.5 months , and the multistr and ed wire for a mean of 23.6 months . The difference was statistically significant . CONCLUSION In terms of reliability for permanently fixed orthodontic retention from canine to canine , the direct-bonded multistr and ed wire is superior to the plasma-treated polyethylene woven ribbon and resin retainer Abstract Background and Aim : In recent years , fixed lingual retainers have been gaining importance in relapse prevention . The aim of this prospect i ve , r and omized study was to compare different types of fixed retainers used for stabilization of the lower anterior segment with respect to detachment rate , relapse , periodontal and oral hygiene problems , as well as subjective patient discomfort . Patients and Method : Two types of fixed , customized canine 
    Output:
    
No conclusive evidence was found in order to guide orthodontists in the selection of the best protocol .