- Email: [email protected]
Quantification of patient compliance with Hawley retainers and removable functional appliances during the retention phase
ORIGINAL ARTICLE
Quantification of patient compliance with Hawley retainers and removable functional appliances during the retention phase Timm Cornelius Schott,a Christoph Schlipf,b Bettina Glasl,c Christian L. Schwarzer,d Joachim Weber,e € rn Ludwigf and Bjo T€ ubingen, Traben-Trarbach, Hameln, Ludwigsburg, and Homburg, Germany
Introduction: The success of retention with removable retainers is highly dependent on efficient patient compliance. The aim of this study was to quantify patient compliance with removable retainers using microelectronic wear-time documentation during the retention phase. Methods: One hundred patients, between 13 and 20 years of age, were retained with removable Hawley retainers and functional appliance retainers after successful multi€bingen, Germany, and in 4 private practices in Germany. Microbracket treatment at the University Hospital of Tu sensors were incorporated into the orthodontic retainers by polymerization, and daily wear time was documented in 15-minute intervals during the retention phase for up to 15 months. Patient compliance was quantified with wear-time documentation. Additionally, the influences of age, sex, place of treatment, device type, and health insurance status on compliance were determined and statistically evaluated. Results: Most study participants complied with the prescribed wear time of 8 hours or more per day. Combined patient data indicated a median wear time of 7.0 hours per day over the evaluation period. Wear-time documentation showed either regular or irregular patterns of compliance. Initial compliance did not usually alter over the retention phase. Compliance was not influenced by device type, but age, sex, place of treatment, and insurance status produced changes in the median wear time of up to 50%. Conclusions: Electronic wear-time documentation of patients' compliance is an easily comprehensible measurement that allows orthodontists to examine the patient's contribution to the success of retention and personalize treatment accordingly. Place of treatment and health insurance status are more closely associated with compliance than are basic patient demographics. (Am J Orthod Dentofacial Orthop 2013;144:533-40)
T
he aim of orthodontic retention is to stabilize the position of the teeth after orthodontic treatment in optimal esthetic and functional positions.1 In the retention phase, the final alignment of the dentition is maintained because the associated soft tissues
a Assistant professor, Department of Orthodontics and Orofacial Orthopedics, Eberhard Karls University, T€ ubingen, Germany. b Postgraduate student, Department of Orthodontics and Orofacial Orthopedics, Eberhard Karls University, T€ ubingen, Germany. c Private practice, Traben-Trarbach, Germany. d Private practice, Hameln, Germany. e Private practice, Ludwigsburg, Germany. f Adjunct professor, Department of Orthodontics, University of Saarland, Homburg, Germany; private practice, Traben-Trarbach, Germany. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Reprint requests to: Timm Cornelius Schott, Department of Orthodontics and Orofacial Orthopedics, University Hospital of Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard Karls University T€ ubingen, Osianderstr 2-8, 72076 T€ ubingen, Germany; e-mail, [email protected]. Submitted, January 2013; revised and accepted, April 2013. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.04.020
remodel at a rate above the baseline,2 and the remodeling process varies among different tissue types.3 Various methods of retention are applied4,5; the main types are the removable Hawley, vacuum-formed, and fixed retainers in the United States.6 In 2010, Hawley retainers were the most commonly used, as reported by active members of the American Association of Orthodontists.7 However, their success is related to patients' compliance. Lack of compliance can destroy the best treatment planning and the most promising treatment strategy. The use of removable retainers means the responsibility for retention lies with the patient. Compliance with removable retainer usage is out of the control of the orthodontist. This can lead to frustration for both practitioners and patients.8 Opinions vary about how many hours the removable retainers should be worn per day.9 It has been reported that more than 50% of patients admitted that they did not wear their retainers as instructed; the most common reasons were discomfort and forgetfulness.10 There are wide variations in the retention regimen used by orthodontists, varying from 533
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immediate night-only wear of retainers to 3 to 6 months of full-time wear followed by night-only wear. Hawley retainers worn only at night were shown to be equally effective at reducing relapse as were the same retainers worn full time for 6 months and only nightly thereafter.11 The results of previously published studies about wear time and compliance were based only on selfreporting of compliance with questionnaires and not objective experimentally determined wear times.12,13 In practice, most orthodontists develop their own retention protocol based on either what they were taught in residency or their clinical experience. With no method of objectively determining whether patients follow the prescribed wear time, orthodontists cannot assess whether unsatisfactory changes in tooth position are caused by poor compliance or by an ineffective retainer. New technologies for the objective measurement of wear time using microsensors incorporated into removable retainers now make experimental quantification of patient compliance possible.14,15 Wear-time measurement and documentation can be performed simply and routinely by staff in an orthodontic office.16,17 The overarching purposes of this study were to quantify removable retainer compliance during the first retention phase and to evaluate the potential association of compliance with several demographic, clinical, and social variables such as age, sex, retainer type, place of treatment, and type of health insurance. A further aim was to determine how much patient compliance can realistically be expected during treatment with removable retainers. MATERIAL AND METHODS
One hundred patients (52 male, 48 female) recruited between January 2011 and June 2012 participated in the study, based on the following inclusion criteria: age between 13 and 20 years, no syndromic illnesses, completed active orthodontic treatment with an indication for use of a removable retainer with a microsensor completely incorporated by polymerization, wear time of 3 or more months after the introduction of the device, and checkup appointments at least every 100 days. The mean patient age at the start of treatment was 15.46 years (range, 13-20 years). Wear-time documentation and follow-up were variable, depending on when the patients were recruited to the study; however, all patients had at least 90 days of wear-time documentation. Representative compliance measured by the wearing times of 15 randomly selected patients with different periods of long-duration therapy are documented in
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Table I. Fifteen randomly selected subjects demonstrate the different monthly wear times during treatment with removable retainers Treatment months 1-3
Patient Subject 47 33 17 75 80 65 25 43 36 11 18 41 7 13 31
Sex F F F M M M M M F M F F F M M
Age (y) 18.1 15.3 18.1 15.7 16.1 15.7 16.7 17.5 14.9 14.5 18.2 15.2 13.2 13.5 13.6
9.0 5.9 7.7 2.6 3.2 2.1 11.2 12.1 4.0 6.7 8.5 9.0 9.0 8.7 8.7
4-6
7-9
10-12
Median wear time (h) 9.2 9.0 6.9 8.1 8.3 9.0 4.4 4.0 2.6 10.8 11.8 7.0 5.8 8.6 7.2 8.2 6.5 9.1 9.8 9.4 10.0 9.7 9.2 10.0 10.1
9.2 9.2
5.1 8.1 6.7 9.1 9.1 8.4
F, Female; M, male.
Table I. Twenty-six patients were treated at the Department of Orthodontics at the University Hospital of T€ ubingen, and 74 patients were treated in independent specialist practices in Germany. There were no significant differences in age and sex of the patient groups from the different locations. However, the health insurance status was different among the patients. Statutory health insurance in Germany through sickness funds is compulsory for workers whose gross income does not exceed a certain threshold, for unemployed persons, and for certain other population groups. Employees with incomes above the threshold can opt into a voluntary sickness fund (private health insurance), which is more expensive but offers additional benefits. About 88% of the subjects were covered by the statutory health insurance (74% obligatory, 14% voluntarily).18 No patient was excluded from the study during the treatment period. Written patient consent and that of the parent or legal guardian when necessary was obtained for the incorporation of the wear-time sensor and subsequent data evaluation. The study was approved by the ethics commission of the University of T€ ubingen (project number 339/2012B01). The influences of the following parameters on wear times were evaluated: age, sex, type of retention device (Hawley retainer or functional appliance retainer), place of treatment (university hospital or private orthodontic practice), and health insurance status (statutory health insurance or private health insurance).
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TheraMon software (version 2.1.0.13).14 The actual measured temperature of the oral cavity was transformed by the software to wear times, distinguishing wear times from nonwearing times. The software identified possible temperature manipulations by the patients as abnormal, with conspicuous measurement values highlighted with the built-in detailed analysis. Data processed by the dental staff were displayed as wear-time graphics (Figs 2-4). Statistical analysis
Fig 1. Retention devices with integrated TheraMonsensor: A, Hawley retainer; B, functional appliance retainer.
Hawley retainers in both jaws were used in 71 patients, and functional appliance retainers in 29 patients (Fig 1). The devices were made with Orthocryl (Dentaurum, Ispringen, Germany) according to standard procedures. It was advised that the device should be worn by the patient for a minimum of 8 hours a day. The patients were informed that longer daily wear times were favorable because they could positively influence the outcome of the retention phase. The TheraMon-Sensor (Handelsagentur Gschladt, Hargelsberg, Austria, or Forestadent, Pforzheim, Germany) was used in this study because it offers significant advantages compared with the Smart Retainer, as described by Schott and G€ oz.15 The microsensor was completely embedded in the polymer matrix of the maxillary removable Hawley retainer and the functional appliance retainers without difficulty (Fig 1).19 The nondetachable sensors did not affect the comfort of the retainer. During the entire treatment, the ambient temperature was measured by the sensor every 15 minutes and saved in its integral memory, together with the time and the date. At regular checkup appointments, the recorded data were transmitted outside the oral cavity to a computer within seconds via the TheraMon reading station using radio-frequency identification technology and processed with the proprietary
Statistical analysis of the data was performed with SPSS for Windows (version 20; IBM SPSS, Chicago, Ill). The data distribution was tested for normality using the Shapiro-Wilks t test. Because the mean wear times were mostly not normally distributed, minimum, 25th percentile, median, 75th percentile, and maximum values were used as statistical indexes, and nonparametric tests were used for data analysis. The mean monthly wear times of each group are shown in boxplots (Fig 5), and the summarized mean wear times over a 3month period are presented in Table II. The MannWhitney U test was used to investigate the differences in wear times between the groups. The alpha level was set at 0.05. Thus, P #0.05 was considered significant. RESULTS
The median monthly wear time was only 7.0 hours in all patient groups. Two sets of wear-time documentation presented in Figure 2 show characteristic patterns of wearing behavior. Figure 2, A, shows that a patient wore a Hawley retention device for a mean of 7.7 hours daily over the entire 15-month retention phase, but with mean monthly wear times ranging between 4.9 and 10.4 hours. In contrast to patients with high but fluctuating mean compliance, other patients had high and regular compliance. Figure 2, B, illustrates 12 months of wear times for another patient in this group who wore a Hawley device regularly over the retention period for a mean of 9.0 hours (8.8-9.9) daily. Low monthly wear times usually resulted from the retainer's not being worn for several days or being worn for only a few hours each day, as illustrated in Figure 3. In this example, the sum of the daily hours from which the mean wear time was calculated for the third month was only 4.9 hours (see Fig 2, A). The graphic shows that the retainer was not worn on 11 days, was only worn for less than 3.5 hours on 4 days, and was worn for 9 to 10 hours daily on only 9 days. An evaluation of the wear-time documentation from all study participants over the first 3 months
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Fig 2. Characteristic median wear times (hours): A, fluctuating over 15 months; B, regularly over 12 months.
Fig 3. An illustration of the sum of the daily hours from which a mean wear time for the third month with only 4.9 hours median wear time (red dots) was calculated in Figure 2, A. Daily wear time is indicated by the purple line, and prescribed wear time by the horizontal blue bar.
demonstrated that 60% of patients wore the retainer for a mean of less than 8 hours daily, 25% wore it between 8 and 10 hours daily, and 15% wore it for more than 10 hours daily. The 15 patients listed in Table I were chosen
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from the data set using a randomization list to illustrate the characteristic patterns of wear. The patterns show that participants usually maintained the same wear behavior demonstrated during the first 3 months for
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Fig 4. Detailed analysis of 1 day of the wear time in Figure 3, showing the measured temperature over time.
the entire treatment period. The mean monthly wear times altered during the retention phase by up to 1.7 hours. Most patients' compliance improved slightly, and it worsened in only a few. Only a few participants showed mean monthly wear time fluctuations of more than 1.7 hours. These data representations can be used by dental staff for high-resolution insight into patient behavior. For instance, using the wear-time graphic in Figure 3 and the detailed analysis (Fig 4), they could determine that on October 19, 2011, the patient had a documented wear time of 14 of 24 hours, and that the retainer was worn from 18:45 to 5:45 (11 hours) continuously, during the day from 14:15 to 14:45 (0.5 hour), and from 16:15 to 17:45 (1.5 hours), providing an additional 2 hours of daytime wear. To better understand the factors influencing compliance, we evaluated how age, sex, place of treatment, device type, and health insurance status were associated with compliance in 100 study participants during the first 3 months of the retention phase. The type of device (Hawley retainer or functional appliance retainer) was not associated with compliance, as shown in the boxplots in Figure 5, A. The remaining parameters clinically, but not statistically, influenced the participants' compliance to a greater or lesser extent. Female patients wore the retainer daily for a median of 7.2 hours; this was 0.8 hour longer than the male participants (6.4 hours) (P 5 0.486) (Table II; Fig 5, B). The wear time of patients between 13 and 15 years of age was 1.4 hours longer than that of older patients (16-20 years) (P 5 0.206) (Table II; Fig 5, C). The wear time of 6.0 hours for patients who were treated at the university hospital was 1.2 hours shorter than that of those from private practices (7.2 hours) (P 5 0.188) (Table II; Fig 5, D). Compliance was most closely associated with the type of health
insurance company. Privately insured participants wore the retention device for a median of 3.4 hours less than patients with statutory health insurance during the first 3 months of the retention phase (P 5 0.066) (Table II; Fig 5, E) DISCUSSION
Here we present for the first time the association between clinical and social parameters and wear time of removable retainers with incorporated microelectronic sensors. Asked directly, most study participants said that the installation of a sensor had positively influenced their compliance. This opinion agrees with the results of a previous study in which the patients who were aware of the ability to measure their compliance wore the retainer longer than those who were unaware of the control and monitoring.20 The high reliability of the TheraMon measurement system is of note. Over the evaluated time period of up to 15 months and when the retainer was worn, compliance was registered daily at 15-minute intervals for all 100 study participants, representing exceptional performance of the device. The overall median wear time of 7.0 hours was close to the recommended wear time of about 8 hours for removable retention devices, was accepted by most patients, and was usually adhered to for several months. Although the patients were told that longer daily wear times were favorable because they would positively influence the retention phase, only a few followed these recommendations. The relatively small percentage of patients (20%) who wore their retainer for only a mean of about 3 hours a day throughout the first 3 months of their retention phase were not usually successfully pointed toward better compliance in later stages of treatment. In these instances, the use of a removable retainer was not promising over the whole
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Fig 5. Association of median monthly wear time (hours) with other parameters: A, device type: functional appliance retainer (n 5 29) or Hawley retainer (n 5 71); B, sex (48 female, 52 male); C, age category (13-15 years, n 5 58, or $16 years, n 5 42); D, place of treatment (university hospital, n 5 26, or private practices, n 5 74); E, health insurance status (statutory, n 5 87, or private, n 5 13).
retention phase. Another study should clarify the wear times if the prescribed wear time is 24 hours. The use of microsensors for monitoring wear was not a source of conflict between orthodontists and patients, but a documented measurable that provided added value for both persons. Most patients maintained their compliance without significant change throughout the retention phase. Constant compliance possibly resulted because all patients in this study were already familiar with active removable devices (eg, functional appliances) before they had their fixed appliances. It was not possible to determine how regularly a patient wore the retainer during the retention phase from the established mean monthly daily wear times. This information could only be obtained by analyzing the measured daily wear times, which documented the variability in behavior of the participants. In a patient
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Fig 5. (continued)
with high compliance fluctuation, it remains unknown whether a mean high but irregular fluctuating daily wear time during the retention phase is as effective as a mean high but regular wear time. The interesting,
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Table II. Median monthly wear times in the first 3 months of the retention period for various parameters Wear time (h) Parameter Sex Female Male Age (y) 13-15 16-20 Retainer type Functional Appliance Hawley Place of treatment University hospital Private practice Health insurance status Statutory Private
n
Median
Minimum
25th percentile
75th percentile
Maximum
P value*
48 52
7.2 6.4
0.2 0.1
4.2 2.8
9.0 9.1
15.4 18.6
0.486
58 42
7.5 6.1
0.2 0.0
4.1 3.2
9.3 8.3
15.2 18.6
0.206
29 71
6.8 7.0
0.2 0.0
3.1 3.5
8.7 9.2
12.9 18.6
26 74
6.0 7.2
0.1 0.2
1.9 3.8
8.6 9.3
15.1 18.6
0.188
87 13
7.1 3.7
0.0 0.5
4.1 2.0
9.3 7.3
18.6 10.0
0.066
0.624
*Mann-Whitney U test; level of significance, P #0.05.
clinically relevant, and still unresolved problem of “what is the optimal wear time for a successful treatment result” should form part of the investigations in further studies. The experimental quantification of compliance indirectly corroborated established results in the literature to date.21 Accordingly, female and younger patients were more likely to wear their retainer longer than male and older patients. This study is novel in showing that location of treatment (university hospital or independent private practice) had a greater influence on patient compliance than did age or sex. The clinically relevant better compliance of patients who were treated in a private practice compared with patients treated in a university hospital is probably multifactorial and should be clarified in future studies. Health insurance status, which had the most pronounced influence on patient compliance, was unexpected and has not been described in the literature until now. Although statistical significance was not reached in our study population, possibly because of sample size, this is an interesting and socially relevant variable worthy of further investigation. The precise measurement of levels of patient compliance has previously been extremely difficult. Compliance is multifaceted and difficult to predict.22 The patients' various parameters and personal circumstances, including social lives, activities, personal preferences, and possible dissatisfactions regarding treatment, result in highly individual and dissimilar compliance characteristics, which require individualized retention protocols. Therefore, uniform and mandatory wear protocols for all patients are unlikely to be favorable for success in
the retention phase. By using accurate, objective weartime documentation, orthodontists can initially determine which wear times are acceptable and complement this with longer follow-ups or patient counseling. For instance, based on compliance in the first few months of the retention phase, orthodontists can devise an appropriate retention protocol with both their own and the patient's input. Getting patients involved in treatment decisions and making them aware of their own responsibility for successful retention are important for maintaining high levels of compliance.23 There is no doubt that orthodontists, through both effective communication based on wear-time documentation and clinical skill, hold the key to optimizing and personalizing the treatment. CONCLUSIONS
1.
2.
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Through electronic wear-time documentation, compliance times of orthodontic patients became a comprehensible measurement for the first time. Orthodontists can recall the wear times for the whole retention phase at any time and assess their effect on retention-phase efficiency. The retention protocol can be altered if necessary, the patient can be encouraged, and therapy plans can be adapted in good time. Quantification of compliance showed to what extent the patients contributed to the success of retention and whether possible changes to the retention protocol or treatment plans were necessary.
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3.
4.
5.
The median wear time during the retention period of several months showed that a wear time of about 8 hours for removable retention devices was accepted by most patients and was usually adhered to for several months during the retention phase. The place of treatment and the health insurance status influenced compliance more than did the standard demographics such as age and sex. Unknown compliance, the commonly cited argument against removable retainers, does not apply to removable retainers with built-in wear-time sensors.
REFERENCES 1. Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV. Retention procedures for stabilising tooth position after treatment with orthodontic braces. Cochrane Database Syst Rev 2006;CD002283. 2. Thilander B. Orthodontic relapse versus natural development. Am J Orthod Dentofacial Orthop 2000;117:562-3. 3. Melrose C, Millett DT. Toward a perspective on orthodontic retention? Am J Orthod Dentofacial Orthop 1998;113:507-14. 4. J€aderberg S, Feldmann I, Engstrom C. Removable thermoplastic appliances as orthodontic retainers—a prospective study of different wear regimens. Eur J Orthod 2012;34:475-9. 5. Singh P, Grammati S, Kirschen R. Orthodontic retention patterns in the United Kingdom. J Orthod 2009;36:115-21. 6. Keim RG, Gottlieb EL, Nelson AH, Vogels DS 3rd. 2008 JCO study of orthodontic diagnosis and treatment procedures, part 1: results and trends. J Clin Orthod 2008;42:625-40. 7. Valiathan M, Hughes E. Results of a survey-based study to identify common retention practices in the United States. Am J Orthod Dentofacial Orthop 2010;137:170-7. 8. Cerny R, Lloyd D. Dentists' opinions on orthodontic retention appliances. J Clin Orthod 2008;42:415-9. 9. Renkema AM, Sips ET, Bronkhorst E, Kuijpers-Jagtman AM. A survey on orthodontic retention procedures in The Netherlands. Eur J Orthod 2009;31:432-7.
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10. Wong P, Freer TJ. Patients' attitudes towards compliance with retainer wear. Aust Orthod J 2005;21:45-53. 11. Shawesh M, Bhatti B, Usmani T, Mandall N. Hawley retainers full- or part-time? A randomized clinical trial. Eur J Orthod 2010;32:165-70. 12. Kacer KA, Valiathan M, Narendran S, Hans MG. Retainer wear and compliance in the first 2 years after active orthodontic treatment. Am J Orthod Dentofacial Orthop 2010;138:592-8. 13. Pratt MC, Kluemper GT, Lindstrom AF. Patient compliance with orthodontic retainers in the postretention phase. Am J Orthod Dentofacial Orthop 2011;140:196-201. 14. Ackerman MB, McRae MS, Longley WH. Microsensor technology to help monitor removable appliance wear. Am J Orthod Dentofacial Orthop 2009;135:549-51. 15. Schott TC, G€ oz G. Applicative characteristics of new microelectronic sensors Smart RetainerÒ and TheraMonÒ for measuring wear time. J Orofac Orthop 2010;71:339-47. 16. Schott TC, G€ oz G. Wearing times of orthodontic devices as measured by the TheraMonÒ microsensor. J Orofac Orthop 2011;72:103-10. 17. Schott TC, Ludwig B, Glasl BA, Lisson JA. A microsensor for monitoring removable-appliance wear. J Clin Orthod 2011;45: 518-20. 18. Busse R. Disease management programs in Germany's statutory health insurance system. Health Aff (Millwood) 2004;23:56-67. 19. Schott TC. Einbau eines mikrosensors in herausnehmbare kieferorthop€adische ger€ate. Quintessenz Zahntech 2011;37:898-904. 20. Ackerman MB, Thornton B. Posttreatment compliance with removable maxillary retention in a teenage population: a short-term randomized clinical trial. Orthodontics (Chic.) 2011; 12:22-7. 21. Pratt MC, Kluemper GT, Hartsfield JK Jr, Fardo D, Nash DA. Evaluation of retention protocols among members of the American Association of Orthodontists in the United States. Am J Orthod Dentofacial Orthop 2011;140:520-6. 22. Fleming PS, Scott P, DiBiase AT. Compliance: getting the most from your orthodontic patients. Dent Update 2007;34:565-6: 569-70, 572. 23. Mollov ND, Lindauer SJ, Best AM, Shroff B, Tufekci E. Patient attitudes toward retention and perceptions of treatment success. Angle Orthod 2010;80:468-73.
American Journal of Orthodontics and Dentofacial Orthopedics
Quantification of patient compliance with Hawley retainers and removable functional appliances during the retention phase Timm Cornelius Schott,a Christoph Schlipf,b Bettina Glasl,c Christian L. Schwarzer,d Joachim Weber,e € rn Ludwigf and Bjo T€ ubingen, Traben-Trarbach, Hameln, Ludwigsburg, and Homburg, Germany
Introduction: The success of retention with removable retainers is highly dependent on efficient patient compliance. The aim of this study was to quantify patient compliance with removable retainers using microelectronic wear-time documentation during the retention phase. Methods: One hundred patients, between 13 and 20 years of age, were retained with removable Hawley retainers and functional appliance retainers after successful multi€bingen, Germany, and in 4 private practices in Germany. Microbracket treatment at the University Hospital of Tu sensors were incorporated into the orthodontic retainers by polymerization, and daily wear time was documented in 15-minute intervals during the retention phase for up to 15 months. Patient compliance was quantified with wear-time documentation. Additionally, the influences of age, sex, place of treatment, device type, and health insurance status on compliance were determined and statistically evaluated. Results: Most study participants complied with the prescribed wear time of 8 hours or more per day. Combined patient data indicated a median wear time of 7.0 hours per day over the evaluation period. Wear-time documentation showed either regular or irregular patterns of compliance. Initial compliance did not usually alter over the retention phase. Compliance was not influenced by device type, but age, sex, place of treatment, and insurance status produced changes in the median wear time of up to 50%. Conclusions: Electronic wear-time documentation of patients' compliance is an easily comprehensible measurement that allows orthodontists to examine the patient's contribution to the success of retention and personalize treatment accordingly. Place of treatment and health insurance status are more closely associated with compliance than are basic patient demographics. (Am J Orthod Dentofacial Orthop 2013;144:533-40)
T
he aim of orthodontic retention is to stabilize the position of the teeth after orthodontic treatment in optimal esthetic and functional positions.1 In the retention phase, the final alignment of the dentition is maintained because the associated soft tissues
a Assistant professor, Department of Orthodontics and Orofacial Orthopedics, Eberhard Karls University, T€ ubingen, Germany. b Postgraduate student, Department of Orthodontics and Orofacial Orthopedics, Eberhard Karls University, T€ ubingen, Germany. c Private practice, Traben-Trarbach, Germany. d Private practice, Hameln, Germany. e Private practice, Ludwigsburg, Germany. f Adjunct professor, Department of Orthodontics, University of Saarland, Homburg, Germany; private practice, Traben-Trarbach, Germany. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Reprint requests to: Timm Cornelius Schott, Department of Orthodontics and Orofacial Orthopedics, University Hospital of Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard Karls University T€ ubingen, Osianderstr 2-8, 72076 T€ ubingen, Germany; e-mail, [email protected]. Submitted, January 2013; revised and accepted, April 2013. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.04.020
remodel at a rate above the baseline,2 and the remodeling process varies among different tissue types.3 Various methods of retention are applied4,5; the main types are the removable Hawley, vacuum-formed, and fixed retainers in the United States.6 In 2010, Hawley retainers were the most commonly used, as reported by active members of the American Association of Orthodontists.7 However, their success is related to patients' compliance. Lack of compliance can destroy the best treatment planning and the most promising treatment strategy. The use of removable retainers means the responsibility for retention lies with the patient. Compliance with removable retainer usage is out of the control of the orthodontist. This can lead to frustration for both practitioners and patients.8 Opinions vary about how many hours the removable retainers should be worn per day.9 It has been reported that more than 50% of patients admitted that they did not wear their retainers as instructed; the most common reasons were discomfort and forgetfulness.10 There are wide variations in the retention regimen used by orthodontists, varying from 533
Schott et al
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immediate night-only wear of retainers to 3 to 6 months of full-time wear followed by night-only wear. Hawley retainers worn only at night were shown to be equally effective at reducing relapse as were the same retainers worn full time for 6 months and only nightly thereafter.11 The results of previously published studies about wear time and compliance were based only on selfreporting of compliance with questionnaires and not objective experimentally determined wear times.12,13 In practice, most orthodontists develop their own retention protocol based on either what they were taught in residency or their clinical experience. With no method of objectively determining whether patients follow the prescribed wear time, orthodontists cannot assess whether unsatisfactory changes in tooth position are caused by poor compliance or by an ineffective retainer. New technologies for the objective measurement of wear time using microsensors incorporated into removable retainers now make experimental quantification of patient compliance possible.14,15 Wear-time measurement and documentation can be performed simply and routinely by staff in an orthodontic office.16,17 The overarching purposes of this study were to quantify removable retainer compliance during the first retention phase and to evaluate the potential association of compliance with several demographic, clinical, and social variables such as age, sex, retainer type, place of treatment, and type of health insurance. A further aim was to determine how much patient compliance can realistically be expected during treatment with removable retainers. MATERIAL AND METHODS
One hundred patients (52 male, 48 female) recruited between January 2011 and June 2012 participated in the study, based on the following inclusion criteria: age between 13 and 20 years, no syndromic illnesses, completed active orthodontic treatment with an indication for use of a removable retainer with a microsensor completely incorporated by polymerization, wear time of 3 or more months after the introduction of the device, and checkup appointments at least every 100 days. The mean patient age at the start of treatment was 15.46 years (range, 13-20 years). Wear-time documentation and follow-up were variable, depending on when the patients were recruited to the study; however, all patients had at least 90 days of wear-time documentation. Representative compliance measured by the wearing times of 15 randomly selected patients with different periods of long-duration therapy are documented in
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Table I. Fifteen randomly selected subjects demonstrate the different monthly wear times during treatment with removable retainers Treatment months 1-3
Patient Subject 47 33 17 75 80 65 25 43 36 11 18 41 7 13 31
Sex F F F M M M M M F M F F F M M
Age (y) 18.1 15.3 18.1 15.7 16.1 15.7 16.7 17.5 14.9 14.5 18.2 15.2 13.2 13.5 13.6
9.0 5.9 7.7 2.6 3.2 2.1 11.2 12.1 4.0 6.7 8.5 9.0 9.0 8.7 8.7
4-6
7-9
10-12
Median wear time (h) 9.2 9.0 6.9 8.1 8.3 9.0 4.4 4.0 2.6 10.8 11.8 7.0 5.8 8.6 7.2 8.2 6.5 9.1 9.8 9.4 10.0 9.7 9.2 10.0 10.1
9.2 9.2
5.1 8.1 6.7 9.1 9.1 8.4
F, Female; M, male.
Table I. Twenty-six patients were treated at the Department of Orthodontics at the University Hospital of T€ ubingen, and 74 patients were treated in independent specialist practices in Germany. There were no significant differences in age and sex of the patient groups from the different locations. However, the health insurance status was different among the patients. Statutory health insurance in Germany through sickness funds is compulsory for workers whose gross income does not exceed a certain threshold, for unemployed persons, and for certain other population groups. Employees with incomes above the threshold can opt into a voluntary sickness fund (private health insurance), which is more expensive but offers additional benefits. About 88% of the subjects were covered by the statutory health insurance (74% obligatory, 14% voluntarily).18 No patient was excluded from the study during the treatment period. Written patient consent and that of the parent or legal guardian when necessary was obtained for the incorporation of the wear-time sensor and subsequent data evaluation. The study was approved by the ethics commission of the University of T€ ubingen (project number 339/2012B01). The influences of the following parameters on wear times were evaluated: age, sex, type of retention device (Hawley retainer or functional appliance retainer), place of treatment (university hospital or private orthodontic practice), and health insurance status (statutory health insurance or private health insurance).
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TheraMon software (version 2.1.0.13).14 The actual measured temperature of the oral cavity was transformed by the software to wear times, distinguishing wear times from nonwearing times. The software identified possible temperature manipulations by the patients as abnormal, with conspicuous measurement values highlighted with the built-in detailed analysis. Data processed by the dental staff were displayed as wear-time graphics (Figs 2-4). Statistical analysis
Fig 1. Retention devices with integrated TheraMonsensor: A, Hawley retainer; B, functional appliance retainer.
Hawley retainers in both jaws were used in 71 patients, and functional appliance retainers in 29 patients (Fig 1). The devices were made with Orthocryl (Dentaurum, Ispringen, Germany) according to standard procedures. It was advised that the device should be worn by the patient for a minimum of 8 hours a day. The patients were informed that longer daily wear times were favorable because they could positively influence the outcome of the retention phase. The TheraMon-Sensor (Handelsagentur Gschladt, Hargelsberg, Austria, or Forestadent, Pforzheim, Germany) was used in this study because it offers significant advantages compared with the Smart Retainer, as described by Schott and G€ oz.15 The microsensor was completely embedded in the polymer matrix of the maxillary removable Hawley retainer and the functional appliance retainers without difficulty (Fig 1).19 The nondetachable sensors did not affect the comfort of the retainer. During the entire treatment, the ambient temperature was measured by the sensor every 15 minutes and saved in its integral memory, together with the time and the date. At regular checkup appointments, the recorded data were transmitted outside the oral cavity to a computer within seconds via the TheraMon reading station using radio-frequency identification technology and processed with the proprietary
Statistical analysis of the data was performed with SPSS for Windows (version 20; IBM SPSS, Chicago, Ill). The data distribution was tested for normality using the Shapiro-Wilks t test. Because the mean wear times were mostly not normally distributed, minimum, 25th percentile, median, 75th percentile, and maximum values were used as statistical indexes, and nonparametric tests were used for data analysis. The mean monthly wear times of each group are shown in boxplots (Fig 5), and the summarized mean wear times over a 3month period are presented in Table II. The MannWhitney U test was used to investigate the differences in wear times between the groups. The alpha level was set at 0.05. Thus, P #0.05 was considered significant. RESULTS
The median monthly wear time was only 7.0 hours in all patient groups. Two sets of wear-time documentation presented in Figure 2 show characteristic patterns of wearing behavior. Figure 2, A, shows that a patient wore a Hawley retention device for a mean of 7.7 hours daily over the entire 15-month retention phase, but with mean monthly wear times ranging between 4.9 and 10.4 hours. In contrast to patients with high but fluctuating mean compliance, other patients had high and regular compliance. Figure 2, B, illustrates 12 months of wear times for another patient in this group who wore a Hawley device regularly over the retention period for a mean of 9.0 hours (8.8-9.9) daily. Low monthly wear times usually resulted from the retainer's not being worn for several days or being worn for only a few hours each day, as illustrated in Figure 3. In this example, the sum of the daily hours from which the mean wear time was calculated for the third month was only 4.9 hours (see Fig 2, A). The graphic shows that the retainer was not worn on 11 days, was only worn for less than 3.5 hours on 4 days, and was worn for 9 to 10 hours daily on only 9 days. An evaluation of the wear-time documentation from all study participants over the first 3 months
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Fig 2. Characteristic median wear times (hours): A, fluctuating over 15 months; B, regularly over 12 months.
Fig 3. An illustration of the sum of the daily hours from which a mean wear time for the third month with only 4.9 hours median wear time (red dots) was calculated in Figure 2, A. Daily wear time is indicated by the purple line, and prescribed wear time by the horizontal blue bar.
demonstrated that 60% of patients wore the retainer for a mean of less than 8 hours daily, 25% wore it between 8 and 10 hours daily, and 15% wore it for more than 10 hours daily. The 15 patients listed in Table I were chosen
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from the data set using a randomization list to illustrate the characteristic patterns of wear. The patterns show that participants usually maintained the same wear behavior demonstrated during the first 3 months for
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Fig 4. Detailed analysis of 1 day of the wear time in Figure 3, showing the measured temperature over time.
the entire treatment period. The mean monthly wear times altered during the retention phase by up to 1.7 hours. Most patients' compliance improved slightly, and it worsened in only a few. Only a few participants showed mean monthly wear time fluctuations of more than 1.7 hours. These data representations can be used by dental staff for high-resolution insight into patient behavior. For instance, using the wear-time graphic in Figure 3 and the detailed analysis (Fig 4), they could determine that on October 19, 2011, the patient had a documented wear time of 14 of 24 hours, and that the retainer was worn from 18:45 to 5:45 (11 hours) continuously, during the day from 14:15 to 14:45 (0.5 hour), and from 16:15 to 17:45 (1.5 hours), providing an additional 2 hours of daytime wear. To better understand the factors influencing compliance, we evaluated how age, sex, place of treatment, device type, and health insurance status were associated with compliance in 100 study participants during the first 3 months of the retention phase. The type of device (Hawley retainer or functional appliance retainer) was not associated with compliance, as shown in the boxplots in Figure 5, A. The remaining parameters clinically, but not statistically, influenced the participants' compliance to a greater or lesser extent. Female patients wore the retainer daily for a median of 7.2 hours; this was 0.8 hour longer than the male participants (6.4 hours) (P 5 0.486) (Table II; Fig 5, B). The wear time of patients between 13 and 15 years of age was 1.4 hours longer than that of older patients (16-20 years) (P 5 0.206) (Table II; Fig 5, C). The wear time of 6.0 hours for patients who were treated at the university hospital was 1.2 hours shorter than that of those from private practices (7.2 hours) (P 5 0.188) (Table II; Fig 5, D). Compliance was most closely associated with the type of health
insurance company. Privately insured participants wore the retention device for a median of 3.4 hours less than patients with statutory health insurance during the first 3 months of the retention phase (P 5 0.066) (Table II; Fig 5, E) DISCUSSION
Here we present for the first time the association between clinical and social parameters and wear time of removable retainers with incorporated microelectronic sensors. Asked directly, most study participants said that the installation of a sensor had positively influenced their compliance. This opinion agrees with the results of a previous study in which the patients who were aware of the ability to measure their compliance wore the retainer longer than those who were unaware of the control and monitoring.20 The high reliability of the TheraMon measurement system is of note. Over the evaluated time period of up to 15 months and when the retainer was worn, compliance was registered daily at 15-minute intervals for all 100 study participants, representing exceptional performance of the device. The overall median wear time of 7.0 hours was close to the recommended wear time of about 8 hours for removable retention devices, was accepted by most patients, and was usually adhered to for several months. Although the patients were told that longer daily wear times were favorable because they would positively influence the retention phase, only a few followed these recommendations. The relatively small percentage of patients (20%) who wore their retainer for only a mean of about 3 hours a day throughout the first 3 months of their retention phase were not usually successfully pointed toward better compliance in later stages of treatment. In these instances, the use of a removable retainer was not promising over the whole
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Fig 5. Association of median monthly wear time (hours) with other parameters: A, device type: functional appliance retainer (n 5 29) or Hawley retainer (n 5 71); B, sex (48 female, 52 male); C, age category (13-15 years, n 5 58, or $16 years, n 5 42); D, place of treatment (university hospital, n 5 26, or private practices, n 5 74); E, health insurance status (statutory, n 5 87, or private, n 5 13).
retention phase. Another study should clarify the wear times if the prescribed wear time is 24 hours. The use of microsensors for monitoring wear was not a source of conflict between orthodontists and patients, but a documented measurable that provided added value for both persons. Most patients maintained their compliance without significant change throughout the retention phase. Constant compliance possibly resulted because all patients in this study were already familiar with active removable devices (eg, functional appliances) before they had their fixed appliances. It was not possible to determine how regularly a patient wore the retainer during the retention phase from the established mean monthly daily wear times. This information could only be obtained by analyzing the measured daily wear times, which documented the variability in behavior of the participants. In a patient
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Fig 5. (continued)
with high compliance fluctuation, it remains unknown whether a mean high but irregular fluctuating daily wear time during the retention phase is as effective as a mean high but regular wear time. The interesting,
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Table II. Median monthly wear times in the first 3 months of the retention period for various parameters Wear time (h) Parameter Sex Female Male Age (y) 13-15 16-20 Retainer type Functional Appliance Hawley Place of treatment University hospital Private practice Health insurance status Statutory Private
n
Median
Minimum
25th percentile
75th percentile
Maximum
P value*
48 52
7.2 6.4
0.2 0.1
4.2 2.8
9.0 9.1
15.4 18.6
0.486
58 42
7.5 6.1
0.2 0.0
4.1 3.2
9.3 8.3
15.2 18.6
0.206
29 71
6.8 7.0
0.2 0.0
3.1 3.5
8.7 9.2
12.9 18.6
26 74
6.0 7.2
0.1 0.2
1.9 3.8
8.6 9.3
15.1 18.6
0.188
87 13
7.1 3.7
0.0 0.5
4.1 2.0
9.3 7.3
18.6 10.0
0.066
0.624
*Mann-Whitney U test; level of significance, P #0.05.
clinically relevant, and still unresolved problem of “what is the optimal wear time for a successful treatment result” should form part of the investigations in further studies. The experimental quantification of compliance indirectly corroborated established results in the literature to date.21 Accordingly, female and younger patients were more likely to wear their retainer longer than male and older patients. This study is novel in showing that location of treatment (university hospital or independent private practice) had a greater influence on patient compliance than did age or sex. The clinically relevant better compliance of patients who were treated in a private practice compared with patients treated in a university hospital is probably multifactorial and should be clarified in future studies. Health insurance status, which had the most pronounced influence on patient compliance, was unexpected and has not been described in the literature until now. Although statistical significance was not reached in our study population, possibly because of sample size, this is an interesting and socially relevant variable worthy of further investigation. The precise measurement of levels of patient compliance has previously been extremely difficult. Compliance is multifaceted and difficult to predict.22 The patients' various parameters and personal circumstances, including social lives, activities, personal preferences, and possible dissatisfactions regarding treatment, result in highly individual and dissimilar compliance characteristics, which require individualized retention protocols. Therefore, uniform and mandatory wear protocols for all patients are unlikely to be favorable for success in
the retention phase. By using accurate, objective weartime documentation, orthodontists can initially determine which wear times are acceptable and complement this with longer follow-ups or patient counseling. For instance, based on compliance in the first few months of the retention phase, orthodontists can devise an appropriate retention protocol with both their own and the patient's input. Getting patients involved in treatment decisions and making them aware of their own responsibility for successful retention are important for maintaining high levels of compliance.23 There is no doubt that orthodontists, through both effective communication based on wear-time documentation and clinical skill, hold the key to optimizing and personalizing the treatment. CONCLUSIONS
1.
2.
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Through electronic wear-time documentation, compliance times of orthodontic patients became a comprehensible measurement for the first time. Orthodontists can recall the wear times for the whole retention phase at any time and assess their effect on retention-phase efficiency. The retention protocol can be altered if necessary, the patient can be encouraged, and therapy plans can be adapted in good time. Quantification of compliance showed to what extent the patients contributed to the success of retention and whether possible changes to the retention protocol or treatment plans were necessary.
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3.
4.
5.
The median wear time during the retention period of several months showed that a wear time of about 8 hours for removable retention devices was accepted by most patients and was usually adhered to for several months during the retention phase. The place of treatment and the health insurance status influenced compliance more than did the standard demographics such as age and sex. Unknown compliance, the commonly cited argument against removable retainers, does not apply to removable retainers with built-in wear-time sensors.
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10. Wong P, Freer TJ. Patients' attitudes towards compliance with retainer wear. Aust Orthod J 2005;21:45-53. 11. Shawesh M, Bhatti B, Usmani T, Mandall N. Hawley retainers full- or part-time? A randomized clinical trial. Eur J Orthod 2010;32:165-70. 12. Kacer KA, Valiathan M, Narendran S, Hans MG. Retainer wear and compliance in the first 2 years after active orthodontic treatment. Am J Orthod Dentofacial Orthop 2010;138:592-8. 13. Pratt MC, Kluemper GT, Lindstrom AF. Patient compliance with orthodontic retainers in the postretention phase. Am J Orthod Dentofacial Orthop 2011;140:196-201. 14. Ackerman MB, McRae MS, Longley WH. Microsensor technology to help monitor removable appliance wear. Am J Orthod Dentofacial Orthop 2009;135:549-51. 15. Schott TC, G€ oz G. Applicative characteristics of new microelectronic sensors Smart RetainerÒ and TheraMonÒ for measuring wear time. J Orofac Orthop 2010;71:339-47. 16. Schott TC, G€ oz G. Wearing times of orthodontic devices as measured by the TheraMonÒ microsensor. J Orofac Orthop 2011;72:103-10. 17. Schott TC, Ludwig B, Glasl BA, Lisson JA. A microsensor for monitoring removable-appliance wear. J Clin Orthod 2011;45: 518-20. 18. Busse R. Disease management programs in Germany's statutory health insurance system. Health Aff (Millwood) 2004;23:56-67. 19. Schott TC. Einbau eines mikrosensors in herausnehmbare kieferorthop€adische ger€ate. Quintessenz Zahntech 2011;37:898-904. 20. Ackerman MB, Thornton B. Posttreatment compliance with removable maxillary retention in a teenage population: a short-term randomized clinical trial. Orthodontics (Chic.) 2011; 12:22-7. 21. Pratt MC, Kluemper GT, Hartsfield JK Jr, Fardo D, Nash DA. Evaluation of retention protocols among members of the American Association of Orthodontists in the United States. Am J Orthod Dentofacial Orthop 2011;140:520-6. 22. Fleming PS, Scott P, DiBiase AT. Compliance: getting the most from your orthodontic patients. Dent Update 2007;34:565-6: 569-70, 572. 23. Mollov ND, Lindauer SJ, Best AM, Shroff B, Tufekci E. Patient attitudes toward retention and perceptions of treatment success. Angle Orthod 2010;80:468-73.
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