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 Table of Contents  
ORIGINAL RESEARCH
Year : 2022  |  Volume : 14  |  Issue : 4  |  Page : 370-376

Comparative evaluation of patient satisfaction following the use of two different orthodontic removable retainers: A prospective randomized controlled trial


1 Department of Orthodontics, Saveetha Dental College, Saveetha University, Chennai, India
2 Department of Public Health Dentistry, Saveetha Dental College, Saveetha University, Chennai, India

Date of Submission14-Jan-2022
Date of Decision28-Jun-2022
Date of Acceptance29-Jun-2022
Date of Web Publication29-Aug-2022

Correspondence Address:
Dr. Ravindra K Jain
Department of Orthodontics, Saveetha Dental College, Saveetha University, Chennai
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JIOH.JIOH_17_22

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  Abstract 

Aim: To evaluate and compare the patient level of satisfaction with vacuum-formed retainer (VFR) and Clear Bow Hawley’s retainer (CBR). Materials and Methods: This prospective randomized controlled trial included 46 subjects treated with fixed orthodontics who required retainers. The study subjects were randomly segregated into two groups using a table of random numbers. Twenty-three patients received CBRs (group 1) and 23 patients received VFRs (group 2). Following 3 months of usage of retainer, patients were given a pre-validated self-assessment questionnaire consisting of nine items and responses were recorded. Using SPSS software version 23, the data were statistically evaluated. The Shapiro–Wilk normality test followed by non-parametric χ2 test and Mann–Whitney U-test were done. Subject response between gender and age groups was correlated with Pearson’s correlation test. Results: A non-parametric data distribution was obtained (P = 0.05). The Mann–Whitney U-test showed significant differences in median values for difficulty in swallowing fluids (P = 0.039), speech (P = 0.047), appearance of the retainers (P = 0.024), and comfort (P = 0.000), and other parameters such as overall satisfaction (P = 0.544), retainer fit (P = 0.103), and oral hygiene (P = 0.162) did not show any significant differences. In terms of retainer adjustments (P = 0.06) and retainer breakage (P = 0.97), no intergroup difference was noted. Pearson’s correlation test revealed a statistically significant correlation between age and gender for domains of comfort, speech, swallowing, oral hygiene, and overall satisfaction (P < 0.05). Conclusion: This trial concludes a greater comfort and better aesthetics among subjects who used CBRs, and subjects using VFRs had better speech articulation and swallowing of fluids. Between the two retainers, there was no discernible difference in overall satisfaction.

Keywords: Esthetics, Orthodontic Appliance, Relapse, Retainers, Retention


How to cite this article:
Devi S, Jain RK, Balasubramaniam A. Comparative evaluation of patient satisfaction following the use of two different orthodontic removable retainers: A prospective randomized controlled trial. J Int Oral Health 2022;14:370-6

How to cite this URL:
Devi S, Jain RK, Balasubramaniam A. Comparative evaluation of patient satisfaction following the use of two different orthodontic removable retainers: A prospective randomized controlled trial. J Int Oral Health [serial online] 2022 [cited 2022 Oct 5];14:370-6. Available from: https://www.jioh.org/text.asp?2022/14/4/370/355013


  Introduction Top


Retention is the phase of orthodontic treatment following completion of the desired tooth movement, and it is focussed solely on maintaining the finished treatment result and preventing relapse.[1],[2] The available literature suggests that the re-organization of the periodontal ligament occurs over a 3–4-month period. The gingival collagenous fibers re-organize between 4 and 6 months with the supra-crestal fibers taking up to 232 days.[3] Hence, retention appliances are crucial in maintaining the stability of the treatment results.

Retention appliances can be broadly classified into fixed and removable retainers. Bonded retainers do not require patient compliance, but removable appliances demand patient compliance which in turn relies on patient satisfaction levels following the use of the appliance.[4] Clear Bow Hawley’s retainer (CBR) is a removable retainer, and it has a clear bow that replaces Hawley’s metal bow and the Adams clasp but retains the palatal acrylic coverage for retention as Hawley’s appliance. It was first introduced by Needham et al.[5] in a case report.

Appliance acceptance and compliance by patients will be affected if retention appliance is not comfortable to use. Difficulty while swallowing liquids, difficulty in speech, irritation to soft tissues especially the tongue and excessive salivation are most common discomforts encountered by subjects using retainers.[6] Several studies have revealed a universal dislike for orthodontic retainers.[7] Removable retainers pose greater inconvenience than fixed appliances, as described by some patients.[6] It is very important for the orthodontist to provide a retainer with good patient acceptability as it helps in better stability of the results on a long term.

Patient compliance can be assessed using various methods such as one-on-one interview with patients and parents, LIKERT scale-based assessment,[8] questionnaire-based assessment, and charting appliance wear with a device incorporated in the appliance.[9] The results from these methods can be analyzed to improve the compliance of the patients by educating them on the importance of appliance wear. In a previous survey on the satisfaction level of patients after dental implant placement, twin block therapy has been reported.[10],[11] Patient compliance was better with vacuum-formed retainers (VFRs) when compared with Hawley’s retainers as reported by Saleh et al.[12] The rationale for doing the present study was to report on differences in patients’ experience between CBRs and VFRs as only retainers which are esthetic as well as comfortable have better compliance.

The present trial aims to evaluate and compare the subject satisfaction levels using CBRs and VFRs after completion of the fixed orthodontic therapy. Null hypothesis is no difference between the two retainers, and the alternate hypothesis is a significant difference between the two retainers in terms of patients’ acceptance and satisfaction.


  Materials and Methods Top


Trial design

This study was designed and conducted as a prospective randomized controlled trial.

Participants, eligibility criteria, and setting

This trial was approved by the Institutional Scientific Review Board of Saveetha University SRB/SDC/ORTHO-2001/21/006. The patient recruitment for the study was done in March–April 2021 and completed by June–July 2021.

The inclusion criteria were as follows: subjects more than 18 years of age for whom orthodontic treatment was completed with good finishing and settling and no missing teeth, no history of surgical treatment, and lateral arch expansion was not performed. Exclusion criteria for sample selection were subjects who had undergone orthognathic surgery, less than 18 years of age, patients with hypodontia, and patients treated with passive self-ligation mechanotherapy.

Initially, 69 patients were examined for the study and after applying the selection criteria 23 patients were excluded and the rest 46 were included for the study. Out of the excluded patients, five of them had undergone orthognathic surgery, three patients were less than 18 years, seven had hypodontia, and eight underwent lateral arch expansion with passive self-ligation brackets [Figure 1].
Figure 1: Consort flow diagram depicting sample selection

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Participants’ recruitment and flow

A follow-up of 3 months was done in this trial. CONSORT flow diagram explains the patient recruitment, follow-up, and eligibility for data analysis. One patient from group 1 (CBR) did not report as the patient moved to another country. Twenty-two patients from group 1 (CBR) and 23 patients from group 2 (VFR) with a total of 45 patients were included for data analysis.

Sample size calculation

The sample size calculation was done using G*Power 3.1.9.4 software (Germany) with a significance of 5% (0.05) and a power of 90% based on the mean and standard deviation of the satisfaction domain of the two groups (CBR and VFR) from the previous study by Chagas et al.[13] The clinical difference of satisfaction in terms of fit, comfort, appearance, and function was taken into account. A sample size of 40 was obtained after calculation, and with 15% loss to follow-up, the total sample size obtained was 46.

Randomization, allocation concealment, and blinding

Randomization was done using a table of random numbers and each patient was asked to pick one concealed envelope from a black box containing 46 envelopes. The investigator who collected the responses was blinded about the type of intervention received by the participants. Blinding of the study participants and the clinician who delivered the retainers was not possible in this study.

Written informed consent was obtained from all of the study participants after explaining the purpose of the study. Group 1 (intervention) consisted of 23 subjects who received CBRs and group 2 (control) consisted of 23 subjects who received VFRs.

Impressions of the upper and lower arches of these patients were made and sent to the laboratory for fabrication of CBRs and VFRs. The CBRs have a 2.75 mm wide labial bow made of polyethylene terephthalate (PET) extended till the canine or first premolar according to the case (extended till premolar if required) shown in [Figure 2]. All the CBRs and VFRs were made by the same technician at the same laboratory. VFRs were made with PET material of thickness 1 mm and vacuum-formed using a Biostar machine, extended till the last erupted tooth [Figure 3]. Once fabricated, they were delivered to patients by a single clinician and were instructed to wear full time except during meals and brushing. Patients were recalled every 3 months to check the usage and to evaluate oral hygiene.
Figure 2: Clear Bow Hawley’s retainer

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Figure 3: Vacuum-formed retainer

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A questionnaire with demographic details and nine questions pertaining to the evaluation of patient satisfaction and acceptance of retainers was adopted and prepared according to a previous study[13] and was similar to a questionnaire reported for practice of oral hygiene among children.[14] After preparing the questionnaire, it was circulated to 10 practicing orthodontists for face, comprehensive, and content validation. There was a good agreement between the professionals with a Cronbach’s α-value >0.9. Intra-observer reliability was not possible in our study. Modifications in the questionnaire were done as per the suggestion received from the subject experts. The questionnaire consisted of seven questions which assessed the satisfaction levels of retainers on a scale of 1–10.[13] The lower values represent a low level of satisfaction and higher values represent a high level of satisfaction. Two questions with dichotomized responses (yes, no) were framed to assess the acceptance of the retainers [Appendix 1]. The questionnaires were distributed to patients during the 3rd month recall visit and were asked to give their responses. All the procedures have been performed as per the ethical guidelines laid down by the Declaration of Helsinki (2013).

Statistical analysis

The obtained responses were then entered in an Excel spreadsheet and imported to SPSS software version 23.0 for statistical analysis. The handling of the response data was done by an independent statistician not involved in the study. The Shapiro–Wilk numerical test showed a non-normal distribution of data (P < 0.05). The Mann–Whitney U-test was done to find out the intergroup median differences for esthetics, comfort, retainer fit, overall satisfaction, oral hygiene maintenance, swallowing, and speech difficulty. Intergroup differences for retainer adjustment and retainer breakage (dichotomized outcome) were assessed using the non-parametric χ2 test. Pearson’s correlation test was done to find the correlation of age and gender for each domain in the questionnaire. A P-value of less than 0.05 was considered to be significant.


  Results Top


The mean age of subjects in both the groups was 26.74 ± 3.36 and 26.82 ± 2.70 years with no significant difference (P > 0.05). The general characteristics of subjects are mentioned in [Table 1]. Out of the 46 subjects included, one patient in group 1 was lost to follow-up for the 3rd month review. Data from 22 patients of group 1 and 23 patients of group 2 were subjected to statistical analysis. Median values of subject responses to the questionnaire are depicted in [Table 2]. Intergroup differences for retainer adjustment and breakage evaluated with the χ2 test revealed no significance (P > 0.05) [Table 3]. Results of the Mann–Whitney U-test report significant differences for speech, ease of swallowing fluids, comfort, and appearance between the groups (P < 0.05) [Table 4], whereas no significant intergroup differences in fit, overall satisfaction, and oral hygiene (P > 0.05) were noted [Table 4]. Pearson’s correlation of age and gender to question items in each domain reported a significant correlation for comfort, speech difficulty, difficulty in swallowing of fluids, overall satisfaction, and oral hygiene (P < 0.05), and no other domains had any significant correlation [Table 5].
Table 1: General characteristics of study subjects

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Table 2: Median values of subject responses to questionnaire

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Table 3: χ2 test for significance of differences between two retainers in terms of adjustment and breakage (P > 0.05)

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Table 4: Mean rank and Mann–Whitney U-test depicting satisfaction levels among the subjects in both the groups

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Table 5: Pearson’s correlation of age and gender to the included domains

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  Discussion Top


This prospective randomized controlled trial was conducted on a sample of 46 patients who had completed fixed orthodontic treatment to assess and compare patient acceptability of VFRs and CBRs. All study subjects were recalled after 3 months for review to evaluate various parameters of patient satisfaction. Evaluation was done on a scale of 1–10 for seven parameters. Subjects in whom arch lateral expansion was done were not included in this study as VFRs are not indicated in those patients.[12]

In the present study, subjects using CBRs were more comfortable than those using VFRs and this difference was statistically significant. Also subjects using CBRs were more satisfied with their appearance than those using VFRs. Speech articulation and swallowing of fluids were significantly better in subjects using VFRs when compared with those using CBRs. No significant difference in satisfaction levels for fit, overall satisfaction, and oral hygiene was noted between the two groups. More adjustments were required in subjects using CBRs than subjects using VFRs, but the difference was not significant.

There are no previous published studies comparing CBRs with VFRs, whereas there are many studies published comparing VFRs and CBRs with other retainers.[12],[15],[16],[17],[18] Retention stability, occlusal contact changes with VFRs, and other retainers have been reported previously.[19],[20],[21] CBRs are similar to Hawley’s in their design, except for an esthetic labial bow. A previous study by Chagas et al.[13] had compared Hawley’s retainer with VFR and they have pointed out that the overall satisfaction was not different between Hawley’s retainer and VFRs, which is similar to our study. They reported that swallowing of fluids was better with VFRs than Hawley’s retainers, which is similar to our study. Oral hygiene maintenance according to their study was better with Hawley’s appliance; in the present study, even though there was no significant difference between CBRs and VFRs, oral hygiene was comparatively maintained well with CBRs. In Chagas et al.’s study,[13] the study subjects used both Hawley’s and thermoplastic retainers for a period of 1 month alternatively unlike the present study.

Saleh et al.[12] in their study compared VFRs with Hawley’s (HR) and reported more acceptability of VFRs than HRs for comfort during speech and swallowing. When VFRs were compared with bonded retainers, they fared well in terms of swallowing and speech. In the present study also, VFRs were more comfortable during speech and swallowing when compared with CBRs. Swallowing was found to be comparatively easier with VFRs than with CBRs, which could be attributed to the acrylic coverage of the palate in CBRs.[2] A statistically significant correlation was noted between genders, especially women in terms of speech, swallowing difficulty, and comfort (P < 0.05).

Regarding oral hygiene maintenance with the retainers, VFRs were given comparatively lesser scores in the present study but no significant difference (P > 0.05) was noted. A significant correlation between the age groups for oral hygiene maintenance was noted (P < 0.05). However, Chagas et al.[13] reported that oral hygiene maintenance was easier with VFRs than with HRs. In the present study, esthetic perception with CBRs was significantly better than VFRs (P < 0.05), although CBRs had wire components incorporated in the design. Better esthetic perception with CBR can be subjective because CBRs were more obscure than VFRs with Adams clasp incorporated for retention in the first molar region. Discoloration of VFRs over a 3-month period was noted in the present investigation, and this could be a possible reason for higher esthetic acceptance of CBRs over VFRs.[22]

Overall satisfaction was found to be better with VFRs than with CBRs, but there was no significant difference between them. Hichens et al.[23],[24] compared VFRs and Hawley’s retainers and concluded that overall satisfaction was greater with VFRs. A significant correlation was noted for gender and overall satisfaction. The overall satisfaction was better with males when compared with females (P < 0.05). Regarding adjustment, two patients from group 1 and one patient from group 2 reported for adjustment within the first 3 months. In group 2, one patient who came for adjustment reported sharp edges and it was rectified by mild trimming of the retainer. In group 1, two patients reported mild loosening of the clear bow and it was rectified by compressing the U-loops of the clear bow. The number of adjustments was found to be greater with CBRs than with VFRs.

Breakage of retainers was reported by two patients from each group, and new retainers were given. A study by Forde et al.[25] in 2018 reported a comparison between VFRs and bonded retainers and concluded that breakage and retainer failure were more in VFRs when compared with bonded retainers. From the responses we received, the CBR offers excellent fit, esthetics, comfort, and oral hygiene. A case report by Needham et al.[5] also concluded that the CBR was a highly esthetic appliance when compared with Hawley’s retainer. In the present study, even though it was not our objective to study the cost and time of fabrication, we experienced that both cost and time for fabrication and also the technical difficulties were more with CBRs than with VFRs. Factors such as etiology, type, and severity of malocclusion and also the mechanics used can influence the retention characteristics of a corrected malocclusion but not patients’ responses.

CBR can be advantageous over conventional Hawley’s retainer in terms of esthetics, thus eliminating the unesthetic show of the metal component, and also advantageous over VFR in terms of occlusal settling, which is one of the drawbacks of VFRs.[26] Thus the results of the study suggest that CBRs were perceived to be more esthetic than VFRs; however, no difference exists between two retainers in terms of overall satisfaction. Null hypothesis of the study is accepted, suggesting that the overall satisfaction from both the retainers is the same.

Limitations of this survey include the following: responses are always subjective as they can vary from one individual to another. Cost of the treatment, socio-economic status, psychosocial factors, fabrication time, techniques of fabrication, and technicians ability could influence the results of the present survey. Thus in selecting a suitable retainer, all these factors should be taken into consideration. Evaluation bias is inherent in this type of trial design as both the clinician and patient cannot be blinded and also the patient’s preference for the type of retainer cannot be considered. Another limitation of the present study is that the loss to follow-up in group 1 can lead to reporting bias. However, in sample size calculation, 10% loss to follow-up was calculated and added to the obtained sample size which is expected to manage the reporting bias.


  Conclusion Top


It can be concluded that within the limitations of this study, there was a similar overall satisfaction with both retainers, and CBRs were perceived to be more esthetic than VFRs. Speech articulation and ease of swallowing were better with VFRs. Hence, CBRs can be a good alternative to both VFRs and conventional Hawley’s retainers.

Acknowledgements

I would like to acknowledge the effort of my co-authors along with my Department Head for encouraging us to get involved in interdisciplinary research topics involving matters of concern for orthodontic purposes.

Financial support and sponsorship

The study was partially funded by SIMATS University.

Conflicts of interest

The authors have no conflicts of interest to declare.

Authors’ contributions

The study design, manuscript correction, and formatting were done by Dr. RKJ; study execution, data collection, data analysis, and manuscript preparation were done by Dr. SD; and data analysis was rechecked by Dr. AB. All authors have made substantial contributions to this study, and all have reviewed the final paper prior to its submission. Finally, all authors have given approval for publication.

Ethical policy and Institutional Review Board statement

All procedures were in accordance with the ethical standards of the Research Ethics Committee of Saveetha University with ethical approval number SRB/SDC/ORTHO-2001/21/006.

Patient declaration of consent

The authors had obtained all appropriate patient consent forms. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. This randomized controlled clinical study was held in Saveetha Dental College, Saveetha University, Chennai, India.

Data availability statement

Data are available on reasonable request.

 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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