Abstract
Background:
There are different types of retention protocols and retainers prescribed by the orthodontists across the globe.
Aim:
The study was conducted with the aim of evaluating the retention practices followed by the orthodontists in India.
Materials and Methods:
A questionnaire link with a set of 29 questions was generated using the Google Forms App. The questions related to the basic demographic details followed by retention procedures in maxilla and mandible as related to the type of retainer, duration of wear, retention check-ups, and adjunctive procedures being followed. The Google forms were mailed to 1147 registered life members of the Indian Orthodontic Society.
Results:
The overall response rate was 20.1%. On receiving of the completed questionnaires, the data were statistically analyzed. Dual mode of retention, fixed retainers with removable thermoplastic resin (TR)/vacuum formed retainers (VFR) (24%) were the common type of retention in maxilla whereas the fixed bonded retainer (44.5%) was more commonly used in mandible. Full time wear of maxillary retainer was recommended by 85.2% of the respondents. The recommended duration of the fixed retainer is for 2–5 years (41.9%).
Conclusion:
A trend towards more dual retention instead of solitary removable or solitary fixed retention, more VFR instead of Hawley-type retainers has been demonstrated in the survey.
KEYWORDS: Bonded retainer, Hawley, orthodontist, retention, thermoplastic, vacuum formed
INTRODUCTION
Orthodontic tooth movement results from cellular reactions and structural changes in the supporting tissues that result from the application of force. Teeth have an inherent proneness to return to their inceptive maloccluded position until they are functionally stabilized in their new position. This tendency to relapse has to be zeroed until the teeth settle in their new position. This period of orthodontic treatment that attempts to hold the teeth till they are functionally stabilized in new setting is the retention phase that can be extremely challenging to the orthodontists.[1] The retention protocols, appliances, and techniques used in orthodontics have witnessed a major change over the last two decades with the incorporation of new biomaterials and adjunctive procedures, along with conventional approaches.[2,3] Several retainer designs have evolved over time to suit different retention practices that reduce the chances of relapse. The relative efficacy of few retention appliances were evaluated in previous.[4,5] There is no prescribed set of retention regimen or guidelines available because of lack of evidence at the highest level.[3] A few National Survey-based studies on orthodontic retention practices that were followed in different countries were carried out over the past two decades[6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29] [Table 1]. The results revealed a variation in retention protocols among orthodontists in different regions and a change in trends over a period of time. Knowledge about the most commonly used retention protocols is required to produce the highest quality of evidence regarding the effectiveness of different retention methods. A review of published literature on this topic reveals that no published data as on date were available on surveys of comprehensive nature being conducted to evaluate the retention methods followed by Indian orthodontists. The Indian orthodontists comprise the second-largest workforce next to the USA.[30,31,32] There are around 4250 registered life members of the Indian Orthodontic Society (IOS).[32] The purpose of this study was to evaluate the retention practices, regimen, and protocols followed among the orthodontists in India. It gives an insight for the clinicians to compare their retention treatment methods are in tandem and contemporary nature compared to their professional colleagues in other parts of the world and may aid in formulating proper standardized clinical guidelines regarding the common retention protocols.
Table 1.
Commonly followed retention protocols in different countries
| Author/Year/country | Response% | Highlights of the study |
|---|---|---|
| Keim et al.,[6] 2002, USA | 789 out of 8812 (9.0%) | Max and Mand: HR (63.6%), Essix (22.5) |
| Wong and Freer,[7] 2004, Australia and New Zealand | 217 / 370 responded (59%) | Max: HR (44%) |
| Mand: FR/BR (38%) | ||
| Keim et al.,[8] 2008, USA | A total of 808/10,523 of (7.7%) | Fixed: Max: FR/BR (11%) |
| Mand: FR/BR (41%) | ||
| Removable: HR (57%); Essex (37%) | ||
| Renkema et al.,[9] 2009, Netherlands | 254 of 279 responded (91%) | Fixed: Max: FR/BR (62%) |
| Mand: FR/BR (90%) | ||
| Removable: HR (41%); Essex (15%) | ||
| Singh et al.,[10] 2009, United Kingdom | 240/301 (80%). Postal | Variable in NHS, community hospital, and private practice |
| Valiathan and Hughes,[11] 2010, USA | 658 of 2000 received (32.9%) | Max: HR (58.2%) |
| Mand: FR/BR (40.2%) | ||
| Pratt et al.,[12] 2011, USA | 1632 out of 9143 (18%) | Max: HR (47%) |
| Mand: FR/BR (42%) | ||
| Vinicius Schau de Araújo Lima et al.,[13] 2012, Brazil | 91 out of 183 ( 51%). | Max: HR (28%) |
| Mand: FR (67%) | ||
| Vandevska- Radunovic et al.,[14] 2013, Norway | 150 of 193 (77.7%) | Max: FR+RR; FR (50%) |
| Mand: FR (89%) | ||
| Lai et al.,[15] 2014, Switzerland | 145 of 223 (65%). Directly sent questionnaire | Max: HR (37%) |
| Mand: FR/BR (78%) | ||
| Miles,[16] 2013, Australia | 156 of 433 (36%) | Max: HR (37%) |
| Mand:FR/BR (87%) | ||
| Arnold,[17] 2014, Switzerland | 562/768 (73.2 %) | Max: FR Mand: FR |
| Keim,[18] 2014, USA | 209/10,688 sent (2%). Postal | Fixed: Max: FR/BR (23%) |
| Mand: FR/BR (56%) | ||
| Removable: Hawley (57%) | ||
| Meade and Millett,[19] 2013, Ireland | 101/123 (82%). Postal/electronic (e-survey) | Max: VFR (53%) |
| Mand: VFR (34%) | ||
| Al-Jewair et al.,[20] 2016, Saudi Arabia | 167/1200 responses (13.9 %) electronic survey | Max: HR(61.3%) |
| Mand: BR (58.5%) | ||
| Ab Rahman et al.,[21] 2016, Malaysia | 32/97 responses (33%) | Max: VFR (46.9%) |
| Mand: VFR (46.9%) | ||
| Andriekute et al.,[22] 2017, Lithuania | 81/170 questionnaires (75.7%) | Max: HR (90.1%) |
| Mand: FR/BR (80%) | ||
| Padmos et al.,[23] 2018, Holland | 300/306 (98%) Directly sent | Max: RR +BR (54%) |
| Mand: FR/BR (83%) | ||
| Padmos et al.,[24] 2019, New Zealand | 81/92 responses (88%). Directly sent | Max: VFR +FR (37.4%) |
| Mand: FR/BR (62%) | ||
| Meade, and Craig,[25] 2019, Australia | 291/502 (58%). Direct | Max:TR/VFR (40%), Mand: FR (39%) |
| Sandhya et al.,[26] 2019, India | 136 of 250 (54.4%) WhatsApp link |
Max:HR(47%) |
| Mand: FR (67%) | ||
| Attar,[27] 2019. Iran | 156 of 172 questionnaires (90%). e-mailed | Max:VFR (61%) |
| Mand: VFR (60%) | ||
| Popović et al.,[28] 2020, Croatia | 92 /150 responded (61.33%). Individual or by email | Max: VFR (52%), Mand: Dual RR+FR (34%) |
| Mousin et al.,[29] 2020, Iran Kurdistan | 35 to 35 responses (100%). Direct | Max: FR (48.57%) |
| Mand: FR (65.71%) |
‘+” sign=Dual=Combination. ***The total combination may exceed if more than one option was selected by the respondents. Max: Maxilla, Mand: Mandible, RR: Removable retainer, U: Upper, L: Lower, FR: Fixed retainer, BR: Bonded retainer, HR: Removable Hawley/plate, VFR: Vacuum formed retainer, VFX: Removable acetate/clear/Essex/TR/Invisible, TR: Thermoplastic resins
MATERIALS AND METHODS
The Department of Orthodontics and Dentofacial Orthopaedics, Narayana Dental College, Nellore, Andhra Pradesh, India, conducted this descriptive cross-sectional survey for a period of 3 months from July 1, 2019, to September 30, 2019. Clearance from the Institutional Ethical Committee (NDC/IECC/ORT/12-17/3, dated 6/12/2017) was obtained. The study sample was drawn from the population who were registered members of the IOS. All the full time life members with a minimum of 3 years of experience after postgraduation were included. Accordingly, the IOS directory of members, 2017 with full addresses and phone numbers of 3627 registered life members, was utilized for the study.
Mode of study
The survey instrument consisting of a validated questionnaire with a set of 29 questions slightly modified from the previous study[11] was utilized in the present survey. The questionnaire was divided into three parts with branching logic on certain questions. The first part of the questionnaire (Q1-Q6) was an introductory part regarding the demographic details of the orthodontist. The second part (Q7-Q13) was related to the commonly followed retention procedures in maxilla and mandible. The third part (Q14-Q29) consists of questions related to the suggested duration of wear of retainer, patient's compliance, retention check, and adjunctive procedures followed.
Method of data collection
The method of data collection is by indirect method through an online questionnaire sent through E-mail. A Google form (online questionnaire) was created (retention survey orthodontics @ gmail.com). The first electronic mailing was on July 1, 2019. After 6 weeks of initial mailing, a reminder questionnaire was sent to maximize the response rate without any further reminders. The survey concluded approximately 12 weeks after the initial mailing and when virtually no messages were received over a week time. The information provided by the responders was confidential but not with anonymity and the participation of responders was voluntary.
Sample size determination
About 344 responses were required to attain statistical significance, https://www.checkmarket.com/sample-size-calculator with 95% confidence interval, and a 5% sampling error. With an expected 30% response rate through an E-mail survey, a minimum 1147 orthodontists should be included in the study. Accordingly, 1147 E-mails from the IOS Members Directory 2017 were randomly selected and were sent this questionnaire. Once the completed surveys received, the data were transferred manually to a Microsoft Excel (2007) spreadsheet for analyses.
Data analysis
Using SPSS (Statistical Package for the Social Sciences) 21 version, Statistical Analysis was performed. Descriptive analyses were expressed in frequencies and percentages.
RESULTS
Out of 1147 online survey questionnaires sent through E-mails to the IOS registered orthodontists, 1138 members received the survey questionnaire. About 256 responses were received. About 27 responses were excluded based on the excluder and incompletely filled survey questionnaire. The final study sample analyzed was 229, accounting for a response rate of 20.1%. The size of the invitees, the response rate, and the consistency of answers with previous population studies indicate that the results are prudent and valid [Table 1].
The basic demographic details include method of collection of data, zone of practice, age, gender, number of years of practice, working characteristics, and type of practice of the IOS registered orthodontists [Table 2]. The type of retainer commonly used in the maxilla is dual retention with a combination of clear thermoplastic and fixed retainer (23.4%). The type of retainer commonly used in mandible is fixed bonded (44.5%). The orthodontists who recommend a full-time wear (more than 20 h/day) are about 85.2% [Table 3]. The recommended duration of the fixed retainer is for 2–5 years (41.9%) [Table 4]. The recommended duration of the removable retainer is <2 years (67.7%) [Table 5]. The response to the method fabrication of the retainer is shown in Table 6.
Table 2.
Basic demographic data
| Frequency distribution | n (%) |
|---|---|
| Gender | |
| Males | 180 (78.6) |
| Females | 49 (21.4) |
| Age (years) | |
| <30 | 19 (8.3) |
| 31-40 | 118 (51.5) |
| 41-50 | 76 (33.2) |
| >50 | 16 (7.0) |
| Zone of practice | |
| North | 44 (19.2%) |
| East | 15 (6.6) |
| West | 36 (15.7%) |
| South | 116 (50.7%) |
| Central | 18 (7.9%) |
| Clinical experience in years | |
| 0-5 | 55 (24.0) |
| 6-15 | 116 (50.7) |
| 16-25 | 47 (20.5) |
| >25 years | 11 (4.8) |
| Type of practice | |
| Solely in practice | 80 (34.9) |
| Solely in academics | 25 (10.9) |
| Both | 124 (54.1) |
Table 3.
Type of retainer prescribed
| Characteristic | Frequency, n (%) | |
|---|---|---|
| Debonded cases per month (cases) | ||
| <10 | 120 (52.4) | |
| 10-20 | 89 (38.9) | |
| 21-50 | 19 (8.3) | |
| >50 | 1 (0.4) | |
| Same type of retainer in upper and lower arch | ||
| Yes | 135 (59.0) | |
| No | 94 (41.0) | |
| Type of retainer if same in maxilla and mandible | ||
| Clear thermoplastic | 20 (16.5) | |
| Hawley | 22 (18.2) | |
| Fixed | 37 (30.6) | |
| Dual combination | 42 (34.7) | |
|
| ||
| Type of retainer preferred in individual arches | Maxilla | Mandible |
|
| ||
| Clear thermoplastic only | 29 (12.6) | 19 (8.6) |
| Hawley only | 51 (22.1) | 41 (18.6) |
| Fixed only | 42 (18.2) | 98 (44.5) |
| Clear thermoplastic and fixed | 54 (23.4) | 38 (17.3) |
| Clear thermoplastic and hawley | 19 ( 8.2) | 4 (2.3) |
| Clear thermoplastic followed by hawley | 12 (5.2) | 5 (1.8) |
| Others | 24 (10.4) | 15 (6.8) |
| Preference of choice of fixed retainer | ||
| Canine to canine | 116 (50.7) | |
| Premolar to premolar | 113 (49.3) | |
Total number’n’>229 and percentage > 100 are higher because of combinations
Table 4.
Duration of wear of retainer
| Characteristic | Frequency (n=229) | |
|---|---|---|
| Fixed retainer removal after certain period | ||
| Yes | 99 (43.2) | |
| No | 130 (56.8) | |
| Full time wear of removable retainer | ||
| Yes | 195 (85.2) | |
| No | 34 (14.8) | |
|
| ||
| Total time period for full time wear of removable retainer | Maxilla | Mandible |
|
| ||
| <3 months | 4 (2.1) | 9 (4.6) |
| 3-9 months | 84 (43.1) | 84 (43.1) |
| 10 months-2 years | 93 (47.7) | 85 (43.6) |
| >2 years | 14 (7.2) | 17 (8.7) |
| Total | 195 (100) | 195 (100) |
|
| ||
| Average number of hours per day -partial time wear of removable retainer (h) | Maxilla | Mandible |
|
| ||
| 0-8 | 11 (32.4) | 8 (23.5) |
| 9-16 | 19 (55.9) | 21 (61.7) |
| 16-19 | 4 (11.7) | 5 (14.8) |
| Total | 34 (100) | 34 (100) |
|
| ||
| Total duration of wear of retainer | Removable retainer | Fixed retainer |
|
| ||
| <2 | 155 (67.7) | 38 (16.6) |
| 2-5 | 50 (21.8) | 96 (41.9) |
| >5 | 9 (3.9) | 35 (15.3) |
| Life time/permanent | 15 (6.6) | 60 (26.2) |
Total number’n’>229 and percentage > 100 are higher because of combinations
Table 5.
Post retention appointments and recall visits
| Characteristic | Frequency (%) |
|---|---|
| Immediate postretention check appointments | |
| <1 month | 84 (36.7) |
| 1-3 months | 109 (47.6) |
| >3 months | 32 (14.0) |
| No retention check | 4 (1.7) |
| Total | 229 (100) |
| Duration of recall for retainer check | |
| Every month | 20 (8.7) |
| Once in 3 months | 129 (56.3) |
| Once in 6 months | 62 (27.1) |
| No definite recall | 18 (7.9) |
| Duration of retainer check | |
| <6 months | 98 (42.8) |
| 1-2 years | 96 (41.9) |
| 2-4 years | 25 (10.9) |
| No appointment | 10 (4.4) |
| Percentage of patients turn up for recall retainer check (%) | |
| <25 | 87 (38.0) |
| 20-50 | 80 (34.9) |
| 50-75 | 42 (18.3) |
| >75 | 20 (8.7) |
Table 6.
Fabrication of the retainer and choice of retention
| Characteristic | Frequency, n (%) | |
|---|---|---|
| Retainer preparation | ||
| Commercial lab | 135 (59.0) | |
| In office lab | 94 (41.0) | |
|
| ||
| Reason for selection of retention in individual arches | Maxilla, n (%) | Mandible, n (%) |
|
| ||
| Aesthetics | 93 (17.0) | 81 (15.4) |
| Easy fabrication | 62 (11.3) | 64 (12.2) |
| User friendly | 130 (23.7) | 129 (24.6) |
| Personal preference | 66 (12.0) | 72 (13.7) |
| Posttreatment status of occlusion | 155 (28.3) | 147 (28.0) |
| Cost factor | 42 (7.7) | 32 (6.1) |
DISCUSSION
The present study highlights only the most common practices in retention followed among orthodontists in India. The IOS is a strong professional body of orthodontists and is the first dental specialty society in India.[32] All the IOS life members with a minimum of 3 years' experience were included in the present study, and hence IOS members directory 2017 was utilized for the study. The online questionnaires require less time to reach the target population, less expensive, and gain easy access to the target population. A response rate of 20.1% was recorded in the present study, and the present E-mail response rate in the present survey was comparable with that of earlier studies.[12,19,20,21,25,26,27,28] In the present study, the work nature of the major portion of orthodontists seems to be engaged with both academics as well as private practice (54.1%). The majority of orthodontists seems to be mostly males (78.6%) when compared with females (21.4%) and the relative proportion of female orthodontists increased compared to a previous study on the same population group[33] [Table 1]. The predominant age group was found to be 30–40 years (51.5%), reflecting the increase in the younger age groups compared to the previous study where the mean age was 44.2 years.[33] [Table 1].
Majority of the respondents (52.4%) debonded <10 cases per month, whereas 0.4% of the orthodontists debonded more than 50 cases [Table 2]. Most of the orthodontists (59%) were inclined to different type of retainers in the individual arches. The type of retainer commonly used in maxilla was a combination of clear thermoplastic and fixed lingual retainer (23.4%) closely followed by Hawley only (22.1%) and fixed only (18.2%). Around 10.4% of orthodontists prescribed other types of retainers such as Begg wrap-around retainer, Hawley with fixed lingual retainer in maxilla [Table 3]. The observations in the present study regarding the type of retainer commonly used in the maxilla was similar to the previous studies conducted in Norway,[14] Dutch population,[23] and in New Zealand.[24] Dual retention with a combination of Hawley and fixed retainer was preferred by Lithuanian Orthodontists[22] whereas the Croatian orthodontists[28] preferred dual mode only in the mandibular arch. The survey conducted in the United Kingdom,[10] Ireland,[19] Malaysia,[21] Australia,[25] and Iran[27] showed that the vacuum formed retainers are commonly used in both maxilla and mandible. The second preferred choice of the removable retainer in maxilla by Indian orthodontists was Hawley (22.1%) in the present study [Table 3]. Hawley was the preferred retainer according to the studies performed in the USA by Keim,[6,8,18] Valiathan and Hughes,[11] and Pratt et al.,[12] Wong and Freer[7] in Australia and New Zealand, Renkema et al.,[9] in the Netherlands and Lima et al.,[13] Brazil and Al-Jewair et al.[20] in Saudi Arabia. The advantages of Hawley retainer (HR) is it can be adjustable for better fit, durable, easily repaired if broken, and can be used if slight realignment is needed. It also facilitates posterior occlusal settling during retention. There is only a small difference in the opinion among orthodontists regarding the usage between Hawley, clear thermoplastic and fixed lingual retainers in the present study. The survey of Keim[6,8,18] in the United States of America (USA) highlighted the changing trends in the prescription of retainer over a period of three decades. It revealed that the HR was still the most commonly used, although it was being replaced by the invisible retainers. The increase in popularity of a clear thermoplastic retainer was attributed to its cost-effectiveness, easy fabrication, patient comfort, and esthetics. It also retains the alignment of anterior teeth when compared to HR. Removable retainer in addition to bonded retainer provides dual retention. If the bonded retainer fails, the removable retainer can hold the teeth in position until the fixed retainer is rebonded.[2]
The type of retainer commonly used in mandible is fixed (44.5%) [Table 2]. This result in the present study is in tandem with the survey conducted in Australia and New Zealand,[7] the Netherlands,[9] the USA,[11,12] Brazil,[13] Norway,[14] Switzerland,[15,17] Saudi Arabia,[20] and in Holland.[23] Minimal patient compliance may be the reason for the preference given to fixed lingual retainers, besides being esthetic and inconspicuous in nature.
Regarding the fixed retainers, 50.7% of orthodontists prescribed canine-to-canine bonded retainers, and 49.3% of orthodontists prescribed premolar-to-premolar bonded retainers when a fixed retainer was prescribed [Table 4]. Interestingly, about 56.8% of orthodontists did not recommend the removal of fixed retainers after a certain period. Another notable observation was that about 85.2% of orthodontists recommended full-time wear (more than 20 h per day) of the removable retainer. The full-time wear protocol prescribed to patients was 10 months–2 years by 47.7% of orthodontists in the maxilla. In the mandible, the prescribed period for full-time wear of the removable retainer is also 10 months–2 years (43.6%).
Concerning the total duration of the wear of removable retainer, most of the orthodontists (67.7%) were of the view that <2 years is suffice. The duration of more than 5 years was prescribed in Norway.[14] The duration of the fixed retainer wear preferred by most of the orthodontists (41.9%) is 2–5 years, followed by lifetime retention (26.2%). Permanent retention for fixed retainers was prescribed in Switzerland,[15,17] and Dutch.[23] A trend toward combination modes of retention by dual methods of retention instead of separate individual removable or solitary fixed retention, more thermoplastic retainers/vacuum-formed retainers instead of Hawley-type retainers and more permanent type of retention instead for a fixed period of time has been demonstrated in New Zealand.[24]
The immediate first post retention check appointment scheduled by most of the orthodontists (47.6%) was within 1–3 months [Table 5]. The duration of recall appointment for retention check scheduled by most of the orthodontists (56.3%) was once in 3 months. The percentage of patients who regularly turned up for retention check appointments is <25% (38%). However, the relapse potential between these visits was not assessed.
Most of the orthodontists fabricated the retainer in the commercial laboratory (59%) and in-office laboratory by 41% of orthodontists. The chief reason for the selection of choice of retention in maxilla and mandible is posttreatment status of malocclusion [Table 6]. Adjunctive procedures for retention were recommended by 61.6% of the respondents. The most commonly used adjunctive procedure is supracrestal fiberotomy (CSF) (28.8%) [Table 7].
Table 7.
Adjunctive procedures for retention (n=229)
| Characteristic | Frequency (%) |
|---|---|
| Commonly used adjunctive procedure | |
| IPR | 27 (61.6) |
| Over-correction of the malocclusion | 55 |
| CSF | 69 |
| No adjunctive procedure | 88 (36.8) |
CSF: Supracrestal fibrotomy, IPR: Interproximal enamel reduction
In the present survey, though the results showed certain similarities and disagreements with the other countries, the retention protocols followed in India are akin to the protocols followed by contemporary orthodontists in different parts of the world [Table 1]. The information gathered in the present study can serve as a source for framing the guidelines regarding the retention procedures in their clinical setting. Considering the cost and prolonged time required for orthodontic treatment, retreatment of cases is not feasible. Hence, further research into the long-term effects of individual retention protocol is needed. This survey provides a source of data for randomized controlled trials that can test the validity of the current retention protocols resulting in high-quality evidence-based information. In this survey, the mode of distribution of the questionnaire is through E-mails only. Mixed-mode surveys can be conducted to increase the response rate.
CONCLUSION
The most commonly used type of retainer in maxilla is clear thermoplastic and fixed lingual retainer, and fixed in mandible
Most of the orthodontists prescribed full-time wear (more than 20 h/day) of removable retainer for 10 months–2 years
The duration of the fixed retainer wear preferred by most of the orthodontists is 2–5 years. Canine to canine bonded retainers are mostly preferred
The duration of the removable retainer wear preferred by most of the orthodontists is <2 years.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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