Little research has been conducted to evaluate protocols and trends in orthodontic retention. The purpose of this study was to identify the general retention protocols used by orthodontists in the United States. Additionally, our goal was to identify trends in these orthodontic retention protocols by evaluating how they have changed over the past 5 years and how they might continue to change in the next 5 years.
The study was conducted via a 36-question electronic survey (REDCap, Nashville, Tenn) with branching logic on certain questions. The survey was sent to all 9143 practicing members of the American Association of Orthodontists in the United States, and 1632 (18%) responded.
Results and Conclusions
Mean retention protocols of the surveyed population showed predominant use of Hawley or vacuum-formed retainers in the maxillary arch and fixed retention in the mandibular arch. For both arches, there is a current shift away from Hawley retainers and toward vacuum-formed retainers and fixed retention. Respondents who extract fewer teeth reported increased use of fixed retention in the maxillary ( P = 0.041) and mandibular ( P = 0.003) arches. Respondents who extract fewer teeth and use removable retainers were more likely to tell their patients to wear their retainers at night for the rest of their lives ( P = 1.63 × 10 −6 ).
The goal of orthodontic retention is to increase the stability of the dentition after orthodontic treatment. Studies have shown that 40% to 90% of orthodontic patients have unacceptable dental alignment 10 years after treatment. Various methods of retention are in use today. Three main types of retainers used in the United States are Hawley, vacuum-formed, and fixed retainers.
The first of the 2 phases of retention is called the retention phase. In this phase, the final alignment of the dentition is maintained as the associated soft tissues remodel at a rate above the baseline. The length of this remodeling process varies among different associated tissue types. Reorganization of the periodontal ligament occurs over a 3 to 4 month period. The gingival collagen-fiber network takes 4 to 6 months to remodel, and the elastic supracrestal fibers remain deviated for more than 7 months. It is generally accepted that this phase is completed within a year of debonding.
The second phase of retention, called the postretention phase, begins when increased remodeling of the supporting tissues after orthodontic treatment is complete and lasts the rest of the patient’s life. During this extended period of time, teeth are subjected to variable muscular forces acting on the periodontium with associated modeling and remodeling. The goal of the postretention phase is to maintain the alignment of the dentition regardless of changing forces. It is generally accepted that patients need to wear retainers for less time per day during the postretention phase compared with the retention phase.
A Cochrane Review of orthodontic retention reported that, “There are insufficient data on which to base our clinical practices on retention present . . . Given that the vast majority of orthodontic patients undergo a phase of retention, this vital area of orthodontic research should be given priority in the near future.”
Little research has been published that addresses patient compliance with orthodontic retainers. An Australian study in 2005 concluded that there is a strong positive relationship between maxillary retainer compliance and patient-reported appliance comfort.
A survey conducted at the University of Kentucky in 2008 evaluated patient compliance with orthodontic retainers. The authors found that the patient’s age, sex, amount of time since debonding, understanding of proper compliance, and retainer type all significantly influenced patient compliance. It was also found that patients were more compliant with vacuum-formed retainers than Hawley retainers initially after debonding. However, compliance decreased at a much faster rate with vacuum-formed retainers than with Hawley retainers. As a result, patients were more compliant overall with Hawley retainers than with vacuum-formed retainers. Finally, this study found that very few patients wore their retainers as instructed at 5 years after debonding.
A review of the literature yielded 3 studies that evaluated retention protocols in Australia and New Zealand, the United Kingdom, and the Netherlands. Preferred methods of retention varied among the providers in these countries. Orthodontists in Australia and New Zealand preferred vacuum-formed retainers for the maxillary arch and fixed retention for the mandibular arch. Private practices in the United Kingdom preferred a combination of vacuum-formed retainers and fixed retention. Orthodontists in the Netherlands preferred fixed retention for both arches. The wide variations in the data of these studies support the position of the Cochrane review that practice guidelines are needed for orthodontic retention.
Keim et al conducted surveys regarding orthodontic trends over the past 25 years in the United States. They found that between 1986 and 2008 there was an increase in the use of vacuum-formed and fixed retainers as the preferred retainer types. During this same time period, they also found a corresponding decrease in the use of Hawley retainers. These authors reported an increase in lifelong retention protocols among US orthodontists during this time period.
A recent study by Valiathan and Hughes surveyed 2000 members of the American Association of Orthodontists (AAO) in the United States regarding orthodontic retention; they received 658 responses. The survey asked for the orthodontists’ most popular retention modality for each arch. Just over 58% of respondents preferred the Hawley retainer for the maxillary arch, and 40.2% preferred the fixed lingual retainer for the mandibular arch. Commentary responding to this study in the American Journal of Orthodontics and Dentofacial Orthopedics suggested that it would be of interest to determine “why orthodontists retain as they do.” Specifically, the reader feedback called for the study of a possible relationship among practicing orthodontists between their preferred retention protocols and their decisions on extractions.
The purpose of this study was to identify the general retention protocols used by US orthodontists via a census survey. Multiple variables were tested for possible associations, including type and duration of instructed retainer wear, practice of phase 1 treatment, and extraction rate. An additional goal was to identify how these protocols have changed over the past 5 years and how they might continue to change over the next 5 years.
Material and methods
The study was conducted via an online, 36-question survey (REDCap, Nashville, Tennessee) with branching logic where appropriate. The AAO approved the survey before sending it to its US members, excluding residents and graduate students (approximately 9143 orthodontists). The survey was sent twice, with the second mailing 3 weeks after the first mailing. The survey concluded approximately 2 months after the initial mailing, when virtually all responses had ceased. Statistical analysis was conducted to identify trends ( P <0.05) in the responses by using chi-square tests, analysis of variance (ANOVA), and linear regression, when appropriate.
One thousand six hundred thirty-two responses were received (18%). Thirty-nine percent of the respondents were certified by the American Board of Orthodontics, and 61% were uncertified. The respondents were evenly allocated in their number of years in practice; 83% of the respondents were men.
A summary of the data from this study is presented in Tables I and II . Average protocols reported are as follows ( Fig 1 ): Hawley retainers were the most frequently used retainer type for the maxillary arch (47%), followed closely by vacuum-formed retainers (41%). Fixed retention (11%) was used much less frequently. In the mandibular arch, fixed retention (42%) was used most frequently, followed by an even distribution of Hawley retainers (29%) and vacuum-formed retainers (29%). Just over half (53%) of the responding orthodontists believed that their patients were more compliant with vacuum-formed retainers than with Hawleys, whereas only 6% believed the reverse to be true. Forty-one percent of our sample believed that there was no difference in compliance between the 2 retainer types ( Fig 2 ).
|What is your gender?||Male = 83% Female = 17%|
|When did you graduate from your orthodontic residency program?||Before 1970 = 6%|
|1970-1980 = 20%|
|1980-1990 = 25%|
|1990-2000 = 25%|
|2000-present = 24%|
|Are you certified by the American Board of Orthodontics?||Yes = 39%|
|No = 61%|
|Do you use Phase I treatment in your practice?||Yes = 94%|
|No = 6%|
|What percentage of patients in your practice receive extractions as part of their treatment plan?||Less than 1/4th = 76%|
|Between 1/4th and 1/2 = 22.5%|
|Between 1/2 and 3/4th = 1.5%|
|More than 3/4ths = 0%|
|Do you practice a post-retention phase of retainer wear? (Do you have patients continue to wear retainers after the hard and soft tissues have completed remodeling following orthodontic therapy?)||Yes = 99%|
|No = 1%|
|Does your post-retention phase last the rest of the patient’s file?||Yes = 82%|
|No = 18%|
|Does whether or not a patient received extractions as part of their orthodontic therapy influence the type of retainer that you will give a patient?||Yes = 46%|
|No = 54%|
|Do you charge for retainer checks?||Yes = 11%|
|No = 89%|
|With which of the following types of retainers do you believe patients are more complaint?||VFR = 53%|
|Hawley = 6%|
|No Difference = 41%|
|Do you believe that a patient’s age influences their retainer compliance?||Yes = 86%|
|No = 14%|
|How many hours per day do you require patients to wear their retainers during the retention phase of treatment? (0-24 hours)||1362||3.4||17.1||19.4||24.0||5.8|
|How long does your retention phase last? (0-1 year)||1362||0.0||0.8||1.0||1.0||0.3|
|How many hours per day do you require patients to wear their retainers during the post-retention phase of treatment? (0-24 hours)||1109||0.0||8.6||8.2||24.0||2.9|
|How long does your post-retention phase last? (0-6 year)||171||0.0||3.4||3.2||6.0||1.6|
|What percentage of your patient population receives Hawley retainers for the maxillary arch?||1362||0.0||53.6||60.0||100.0||36.7|
|What percentage of your patient population receives vacuum-form retainers for the maxillary arch?||1362||0.0||47.5||45.0||100.0||37.1|
|What percentage of your patient population receives fixed retention for the maxillary arch?||1362||0.0||13.0||5.0||100.0||22.7|
|What percentage of your patient population receives Hawley retainers for the mandibular arch?||1362||0.0||32.6||15.0||100.0||34.9|
|What percentage of your patient population receives vacuum-form retainer for the mandibular arch?||1362||0.0||32.7||11.0||100.0||36.4|
|What percentage of your patient population receives fixed retention for the mandibular arch?||1362||0.0||48.0||40.0||100.0||39.4|
|What percentage of your patient population receives a fiberotomy following treatment?||1362||0.0||4.1||1.0||100.0||10.2|
|How long do your patients continue to return to your practice for scheduled retainer check appointments? (0-10 + years)||1362||0.0||2.9||2.3||10.0||2.2|
|How often do your patients return for retainer checks? (0-6 times per year)||1362||0.0||2.1||1.9||6.0||1.3|
|How long after debonding do you begin charging for retainer checks? (0-4 years)||127||0.0||1.2||1.0||4.0||18.4|
|When you charge for retainer checks, what is the average fee charged? ($0-200)||138||0.0||52.9||26.5||196.0||1.0|
|What percentage of patients do you believe to be compliant with your retention protocols six months following bebonding?||1362||1.0||69.4||75.0||100.0||17.5|
|What percentage of patients do your believe to be complaint with your retention protocols one year following debonding?||1362||2.0||57.5||60.0||100.0||20.5|
|What percentage of patients do you believe to be compliant with your retention protocols three years following debonding?||1362||0.0||39.4||38.0||100.0||21.5|
|What percentage of patients do you believe to be complaint with your retention protocols five years following debonding?||1362||0.0||29.8||25.0||100.0||21.5|