1
Nigarish Afreen Hussain
5th year, group 12
Efficacy of removable versus fixed orthodontic retainers.
Systematic Review
Master’s Thesis
Supervisor
Prof. Dr. Kristina Lopatienė
2 LITHUANIAN UNIVERSITY OF HEALTH SCIENCES
MEDICAL ACADEMY FACULTY OF ODONTOLOGY
CLINIC OF ORTHODONTICS
Efficacy of removable versus fixed orthodontic retainers Systematic Review
Master’s Thesis
The thesis was done
by student ……… Supervisor ……….
(signature) (signature)
………. ………
(name surname, year, group) (degree, name, surname)
………20... ……….20…….
(day/month) (day/month)
3
EVALUATION TABLE OF THE MASTER’S THESIS OF THE
TYPE OF SYSTEMATIC REVIEW OF SCIENTIFIC LITERATURE
Evaluation: ... Reviewer: ...
(scientific degree. name and surname)
Reviewing date: ...
No. MT parts MT evaluation aspects
Compliance with MT requirements and evaluation Yes Partially No 1 Summary (0.5 point)
Is summary informative and in compliance with
the thesis content and requirements? 0.3 0.1 0 2 Are keywords in compliance with the thesis
essence? 0.2 0.1 0
3
Introduction, aim and tasks
(1 point)
Are the novelty, relevance and significance of the
work justified in the introduction of the thesis? 0.4 0.2 0 4 Are the problem, hypothesis, aim and tasks formed
clearly and properly? 0.4 0.2 0
5 Are the aim and tasks interrelated? 0.2 0.1 0
6 Selection criteria of the studies, search methods and strategy (3.4 points)
Is the protocol of systemic review present? 0.6 0.3 0 7
Were the eligibility criteria of articles for the selected protocol determined (e.g., year, language, publication condition, etc.)
0.4 0.2 0
8
Are all the information sources (databases with dates of coverage, contact with study authors to identify additional studies) described and is the last search day indicated?
0.2 0.1 0
9
Is the electronic search strategy described in such a way that it could be repeated (year of search, the last search day; keywords and their combinations; number of found and selected articles according to the combinations of keywords)?
0.4 0.1 0
10
Is the selection process of studies (screening, eligibility, included in systemic review or, if applicable, included in the meta-analysis) described?
0.4 0.2 0
11
Is the data extraction method from the articles (types of investigations, participants,
interventions, analysed factors, indexes) described?
0.4 0.2 0
12
Are all the variables (for which data were sought and any assumptions and simplifications made) listed and defined?
4 13
Are the methods, which were used to evaluate the risk of bias of individual studies and how this information is to be used in data synthesis,
described? 0.2 0.1 0
14 Were the principal summary measures (risk ratio,
difference in means) stated? 0.4 0.2 0
15
Systemization and analysis of data (2.2 points)
Is the number of studies screened: included upon assessment for eligibility and excluded upon giving the reasons in each stage of exclusion presented?
0.6 0.3 0
16
Are the characteristics of studies presented in the included articles, according to which the data were extracted (e.g., study size, follow-up period, type of respondents) presented?
0.6 0.3 0
17
Are the evaluations of beneficial or harmful outcomes for each study presented? (a) simple summary data for each intervention group; b) effect estimates and confidence intervals)
0.4 0.2 0
18
Are the extracted and systemized data from studies presented in the tables according to individual tasks?
0.6 0.3 0
19
Discussion (1.4 points)
Are the main findings summarized and is their
relevance indicated? 0.4 0.2 0
20 Are the limitations of the performed systemic
review discussed? 0.4 0.2 0
21 Does author present the interpretation of the
results? 0.4 0.2 0
22
Conclusions (0.5 points)
Do the conclusions reflect the topic, aim and tasks
of the Master’s thesis? 0.2 0.1 0
23 Are the conclusions based on the analysed
material? 0.2 0.1 0
24 Are the conclusions clear and laconic? 0.1 0.1 0
25
References (1 point)
Is the references list formed according to the
requirements? 0.4 0.2 0
26
Are the links of the references to the text correct? Are the literature sources cited correctly and precisely?
0.2 0.1 0
27 Is the scientific level of references suitable for
Master’s thesis? 0.2 0.1 0
28
Do the cited sources not older than 10 years old form at least 70% of sources, and the not older than 5 years – at least 40%?
0.2 0.1 0
Additional sections, which may increase the collected number of points
29 Annexes Do the presented annexes help to understand the
analysed topic? +0.2 +0.1 0
30 Practical Are the practical recommendations suggested and
5
Recommen dations
31
Were additional methods of data analysis and their results used and described (sensitivity analyses, meta-regression)?
+1 +0.5 0
32
Was meta-analysis applied? Are the selected statistical methods indicated? Are the results of each meta-analysis presented?
+2 +1 0
General requirements, non-compliance with which reduce the number of points
33
General requirements
Is the thesis volume sufficient (excluding annexes)?
15-20 pages (-2 points)
<15 pages (-5 points) 34 Is the thesis volume increased artificially? -2
points -1 point 35 Does the thesis structure satisfy the
requirements of Master’s thesis? -1 point -2 points 36 Is the thesis written in correct language,
scientifically, logically and laconically? -0.5 point -1 points 37 Are there any grammatical, style or
computer literacy-related mistakes? -2 points -1 points 38 Is text consistent, integral, and are the
volumes of its structural parts balanced? -0.2 point -0.5 points 39 Amount of plagiarism in the thesis. >20% (not evaluated)
40
Is the content (names of sections and sub- sections and enumeration of pages) in compliance with the thesis structure and aims?
-0.2 point -0.5 points
41
Are the names of the thesis parts in compliance with the text? Are the titles of sections and sub-sections distinguished logically and correctly?
-0.2 point -0.5 points
42 Are there explanations of the key terms and
abbreviations (if needed)? -0.2 point -0.5 points 43
Is the quality of the thesis typography (quality of printing, visual aids, binding) good?
-0.2 point -0.5 points
*In total (maximum 10 points):
*Remark: the amount of collected points may exceed 10 points.
Reviewer’s comments:
6
TABLE OF CONTENTS
1. SUMMARY ………...7
2. INTRODUCTION ……….8
3. SELECTION CRITERIA OF THE STUDIES. SEARCH METHODS AND STRATEGY………. 10
3.1 Search strategy………..10
3.2 Search terms………...10
3.3 Electronic database………10
3.4 Inclusion and Exclusion Criteria………...11
3.5 Limitations study design………12
3.6 Risk of Bias………13
4. SYSTEMIZATION AND ANALYSIS OF DATA………...15
5. DISCUSSION OF RESULTS………...….18
6. CONCLUSION………..21
7
SUMMARY
Aim
To evaluate the effects of fixed and removable orthodontic retainers on periodontal health, survival and failure rates of retainers and patient satisfaction.
Methods
A systematic review was carried out to identify relevant studies. The following databases were searched for studies published between 2014 and 2018 (five years); Medline via Ovid, PubMed and google search. The search was limited to the English language. Randomised and non-randomised controlled systematic reviews and case series reporting periodontal health, survival and failure rates of retainers and patient satisfaction were identified.
Results
Thirty studies were identified. Of these only 8 were deemed to be useful for this systematic review. Four randomised controlled trials, one randomised clinical trial, one single-blind randomised trial, one controlled study and one controlled retrospective study was included in this systematic review which had studied and compared the efficacy of fixed and removable retainers in terms of their success and failure rates, impact on periodontal health and patient satisfaction.
There is scarcity of studies on this topic. The incorporated studies in this Systematic Review poorly evidenced the impact of fixed and removable retainers on periodontal health of
participant population. Low quality of evidence is present reporting the success of removable retainers slightly higher than fixed retainers. There is lack of evidence to demonstrate that patient satisfaction is higher with either of the retainers.
Conclusion
The studies included in this systematic review scarcely focused on all the three variables selected as outcome measures. Success of fixed retainers is slightly higher than removable retainers. There is poor evidence of any difference on periodontal health or patient
satisfaction. Further well-designed prospective studies are needed to elucidate the benefits
and potential harms associated with orthodontic retainers.
8
INTRODUCTION
Orthodontics involves the application of force which generates a cellular response resulting in tooth movement. The application of force is provided by means of fixed braces. Once the braces are removed the stretched elastic fibres in the gums try to pull the teeth back to their original position which results in orthodontic relapse. It may take a long time for these fibres to remodel and to stop pulling on the teeth. Orthodontic retention is the maintenance of teeth in the ideal position after orthodontic treatment. It has been established that active retention needs to be life long because regardless of the years of no relapse, there is a tendency for relapse to occur. Continued growth of the jaw can also encourage the teeth to move once treatment has been completed. To help avoid orthodontic relapse orthodontists provide patients with retainers, which hold teeth in their new position until tissue remodelling is complete and stabilised. The use of orthodontic retainers to prevent relapse may be required for many years or even a life time.
Post-treatment orthodontic relapse is one of the most common hazards of any orthodontic intervention. Various measures to reduce risk of orthodontic relapse in addition to the
planning for long-term stability should be part of the initial treatment plan. All risks, benefits and alternatives of various types of orthodontic devices should be discussed with the patient during the process of informed consent. The incidence of orthodontic relapse, malocclusions, mandibular crowding and malalignment of maxillary or mandibular teeth have been reported in several published studies but with variable numbers, intensity and customer satisfaction. [1-9]
Several published studies have shown that the long-term retention is the best way forward to achieve life-long stability. This stability is influenced by several factors such as skeletal and soft tissue growth [10-12]; dental factors [13-5]; treatment mechanics such as changes in arch form, [16] length of the arch, [17] width of the arch, [18] and orthodontic treatment plan [19-25]; final interdigitation of the teeth [26-27]; and functional occlusion or inter-canine spaces, [28] as well as elements of the pre-treatment malocclusion. [29]
Vacuum formed retainer is a removable orthodontic retainer device which is made up of a polypropylene or polyvinylchloride material, more economical and faster to make, typically .020 inch or .030inch thickness. This clear and very transparent orthodontic retainer fits very nicely over the entire arch of the teeth or only from canine to canine (clip-on retainer) and is
9 produced from a mold. It is similar in appearance to Invisalign trays, though the latter are not considered "retainers." The retainer is virtually invisible and clear when worn. Hence, it can provide aesthetics value to the patient. Vacuum formed retainer, if worn for 24 hours continuously, do not allow the upper and lower teeth to coapt because plastic covers the chewing surfaces of the teeth. Some orthodontists feel that it is important for the top and bottom chewing surfaces to meet to allow for "favourable settling" to occur. Vacuum formed retainer are less expensive, less visible, and easier to wear.
An entirely different category of orthodontic retainers is fixed orthodontic retainers. There are many different types of fixed retainers, which include reinforced fibres, fixed canine and canine retainer (only bonded to canine teeth) and multi-strand retainers (bonded to every tooth). Multi-strand stainless steel wire retainers are bound to every tooth in the labial segment, using composite resin or acid-etch composite bonding. Fixed canine and canine retainer are bonded only to the canine teeth; as a result, relapse of the incisors may occur. Reinforced fibre retainers tend to fracture commonly. In order to prevent minor unwanted tooth movement, the fixed retainer must be passive. A fixed retainer typically consists of a passive wire bonded to the lingual-side of the (usually, depending on the patient's bite, only lower) incisors. Unlike the previously mentioned retainer types, fixed retainers cannot be removed by the patient. Some doctors prescribe fixed retainers regularly, especially where active orthodontic treatments have affected great changes in the bite and there is a high risk for reversal of these changes.
Fixed retainers may lead to tartar build-up or gingivitis due to the difficulty of flossing while wearing these retainers. As with dental braces, patients often must use floss threaders to pass dental floss through the small space between the retainer and the teeth. [4]
Aim
The aim of this research is to analyse literature regarding efficacy of removable versus fixed orthodontic retainers. This will include evaluation of success and failure of retainers and level of satisfaction of patients for using retainers.
Tasks
1. To evaluate success and failure rate of fixed and removable orthodontic retainers. 2. To compare effects of removable and fixed orthodontic retainers on periodontal health. 3. To determine the level of patient satisfaction.
10
SELECTION CRITERIA OF THE ARTICLES. SEARCH METHODS
AND STRATEGY
3.1. Search Strategy
In order to identify appropriate academic papers and for identification of common themes relevant to the objectives of the study, systematic search strategy was applied. Relevant literature was identified by accessing and identifying academic search engines, relevant journals and by searching reference lists. The databases which have been used for the study are presented in table 1 alongside their justification for use. An electronic search was conducted by use of appropriate search terms. In order to locate most relevant papers,
Boolean operators OR and AND were used. The search was validated by confirmation by the researcher if it contained relevant data, initially through abstract screening.
3.2. Search Terms
Carefully selected search terms facilitate searching strategy by maximising the success of a search. Search terms used for this study included ‘retainers’, ‘fixed retainers’, ‘removable retainers’, ‘orthodontic retainers’, ‘periodontal health’, ‘patient satisfaction orthodontic’, and ‘fixed versus removable retainers.’ The search terms were ensured to allow access to only relevant data thereby reducing the chances of integration of irrelevant data. Forward and backward searching was performed by the researcher on the papers which were electronically identified and searched, the strategy which helped author to locate the articles and in order to ensure inclusion of key papers.
3.3. Electronic Databases
Electronic databases which were accessed included Google Scholar, PubMed and Embase, to ensure inclusion of studies documenting data for required research objectives.
Table 1 identified the electronic databases accessed for this systematic review with appropriate justifications.
11
Table 1. Accessed Databases
Database Justification
Google Scholar It is a freely accessible web search engine used by researchers that provides metadata or full text of scholarly literature across wide range of disciplines and an array of publishing formats. PubMed This database was selected as it provides more than 29 million
citations for relevant biomedical literature from online books, MEDLINE and life science journals.
Embase This database was chosen as it contains wide range of life science literature and studies published in Europe.
3.4. Inclusion and Exclusion Criteria
Inclusion and exclusion criteria adjusted for a study aids location and identification of only relevant studies when electronic searches result in yielding high volume of literature. Inclusion and exclusion criteria are developed in association with the directed research questions. Moreover, inclusion and exclusion criteria provide the researcher with a facility of transparent framework through which decision making about inclusion is conducted
efficiently while ensuring and minimizing the associated risks of bias. Table 3 identifies the applied inclusion and exclusion criteria for this systematic review with appropriate
justifications. In order to assess the references for eligibility, titles and abstracts of initially selected articles were evaluated systematically to assess if they meet the inclusion criteria. Of the academic papers for which no abstract was available, the full text article was evaluated and analysed for the applied criteria. Moreover, preferred reporting items for systematic reviews and meta-analyses (PRISMA) flow were also used for screening and identification of articles for the systematic review.
The studies had to concur with the predefined focused research question from which the simplified population, intervention, comparators, outcomes (PICO) analysis was derived. After adjustment of protocol for inclusion of studies, PICO was designed as in following table.
12
Table 2. Description of PICO
Population Patients treated with fixed and removable retainers due to certain malocclusion of teeth.
Intervention Fixed retainers for a specified time period identified in the study. Comparators Removable retainers for a specified time period identified in the study. Outcome Failure and success rate of retainers, effects on periodontal health, patient
satisfaction.
Table 3. Inclusion and Exclusion Criteria
Inclusion Criteria Exclusion Criteria Justification
English language Not English Language Fluency of researcher only in English language.
Published Unpublished Due to validity measures of
published data and due to time restraints restricting the use of unpublished data. Published after 2014 Published before 2019 A five-year limit was
adjusted in order to
incorporate only recent data. Primary data Secondary data to present the findings of
studies conducted by other researchers in accordance with the objectives of this study.
3.5. Limitations of Study Design
13
3.6. Risk of bias
The random sequence generation was adequately performed in 6 studies. The assessor was adequately blinded in 5 studies. Overall 7 studies were judged to be of low risk of bias.
14
PRISMA Flow of information through different phases of systematic review:
Studies identified through bibliographic databases
(n=335)
Studies after removing duplicates (n=71)
Full text articles screened for eligibility
(n=30)
Studies excluded (not concurrent with PICO)
(n=41)
Studies included in systematic review
(n=8)
Full text articles excluded with reasons: (n=22) • Due to unavailability in English language. • Unpublished data. • Published before 2014. • Lacked information concerning sample of participants. ID E N T IF IC A T IO N S C R E E N IN G E L IG IB IL IT Y IN C L U D E D
15
SYSTEMIZATION AND ANALYSIS OF DATA
Study Selection
Upon search of literature 335 articles were identified, after removal of duplicates 71 articles were identified and further filtration was performed as depicted in PRISMA flowchart. After full text screening, 41 articles were excluded as the reported data was not concurrent with the applied PICO design. Moreover, 22 articles were excluded on the basis of full text screening of articles due to the reasons given in the PRISMA chart. Upon final consensus and after application of adjusted inclusion and exclusion criteria, 8 studies were included in the systematic review. Four randomised controlled trials, one randomised clinical trial, one single-blind randomised trial, one controlled study and one controlled retrospective study was included in the systematic review which had studied and compared the efficacy of fixed and removable retainers in terms of their success and failure rations, periodontal health and patient satisfaction. Study characteristics of integrated studies have been identified and presented in table 4.
Table 4. Study Characteristics of included Articles
Author/Year Study Design Number of participants
Follow-up period
Mean Age Male/Female Outcome Variables
Edman Tynelius et al., (2015)
Randomised Control Trial
75 patients 2 years 14 30/45 Success and failure of retainers: No significant difference. Effects on periodontal health: Better outcome with removable. O’Rourk N et al., (2016) Prospective Randomised Controlled Clinical Trials 82 patients 18 months
Nr nr Success and failure
of retainers: Fixed retainers significantly better. Rody Jr et al., (2014) Controlled study 31 patients ≥4 years 26.3 nr Effects on periodontal health:
16 No significant difference. Renkema et al., (2014) Controlled retrospective study 221 patients 2.5 years 13.4 years (at the beginning) 16.3 years (at the end of
treatment)
75 girls/146 boys
Success and failure of retainers: No significant difference. Steinnes et al., (2017) Randomised Control trial
67 patients 7 years 24.7 24/43 Success and failure of retainers: Fixed retainers significantly better. Effects on periodontal health: Outcome better with removable. Patient Satisfaction: No significant difference. Torkan S et al., (2014) Randomised clinical Trials
30 Patients 2 year Nr nr Effects on
periodontal health: Outcome better with removable. Sobouti et al., (2016) Single-blind randomised clinical trial 128 patients 6 months 18.0 ± 3.6 years
60/68 Success and failure of retainers:
Success better with fixed retainers. Patient satisfaction: No significant difference. Wiedel & Bondemark (2014) Randomised control trial
64 patients 2 year 9.1±1.2 37 boys/25 girls
Success and failure of retainers:
Success is better with fixed.
17
Methodological Quality
Randomised control trials included in this review reported elaborated work on different patient samples and reported the various follow-up sessions attended by the patient. Most of the RCTs analysed the retention period for the patients and reported the efficacy of applied orthodontic treatment.
18
DISCUSSION OF RESULTS
Failure rate and Success of Retainers
Edman Tynelius et al; [42] conducted the randomised control trial with group of patients subjected to two types of fixed and one removable retainer. According to the findings of the trial, after completion of 2 years, the success rate of all the three retainers were observed to have good capacity to retain the orthodontic treatment, estimated through statistical significance. Rody Jr et al; [40] did not report the failure and success ratio of used retainers in their controlled study. O’Rourk N et al; [31] conducted a randomised controlled trial which included 82 patients. He compared the efficacy of bonded (fixed), and vacuum formed (removable) retainers applied on mandibular arch. The main outcome was to investigate the clinical effectiveness of the two types of retainers in terms of changes in incisor irregularity at 6 months of retention. Bonded (fixed) retainers have a better ability to hold the mandibular incisor alignment in the first 6 months after treatment than do the vacuum formed (removable) retainers.
Steinnes et al; [42] aimed to evaluate the stability measures of orthodontic treatment based on outcome and retention after more than 7 to 8 years in relation to duration of retainer use, type of retainer and post-retention or post-treatment time. Fixed canine-to-canine retainers are reported to be effective to maintain mandibular incisor alignment. However, no success or failure ratio was reported in the randomised controlled trial. Retainer failure in the form of occlusal relapse with either fixed or removable retainer can be expected irrespective of long-term use.
Sobouti et al; [43] conducted the randomised controlled trial and estimated the efficacy of fixed (twisted wire fixed) and removable (spiral wire and fiber reinforced composite) retainers. Success ratio for both types of retainers was evaluated. According to the findings of the trial, the average duration of success of each retainer was 21 months.
Wiedel and Bondemark [48] compared the efficacy of removable and fixed orthodontic retainers in treatment and correction of anterior cross bite. According to the concluded findings of the study, removable or fixed orthodontic retainers can successfully correct anterior cross bite with functional shift.
19 Thus, conclusion is that fixed retainers have high success rate and better survival rate than removable retainers.
Effects on Periodontal Health
Long term use of retainers is also associated with increased risk of periodontal and hard tissue problems. Therefore, analysis of impact of fixed and removable retainers on
periodontal health is necessary during follow up sessions of the patients. Incorporated studies in this systematic review however poorly evidenced the impact of fixed and removable retainers on periodontal health of participant populations.
Rody Jr et al. [40] assessed the periodontal health impacted by bonded (fixed) retainers and as per their findings, periodontal health of no single subject was impacted. Edman Tynelius et al. [32] reported the negative impacts on periodontal health and on damping properties of periodontal tissues associated with bonded (fixed) retainers.
Moreover, these findings have been supported by Steinnes et al. [44] reporting the
disadvantages of fixed retainers. According to the findings of the study conducted by Mondal et al; [38], oral hygiene of group of patients with removable retainers was observed to be better while oral hygiene of another group with fixed retainers was compromised.
Thus, study concluded that removable retainers are more efficient with respect to periodontal health than fixed retainers.
Patient Satisfaction
Pre-treatment, during and post-treatment, patient satisfaction with the type of retainer used, based on their comfortability, is necessary. Lack of patient satisfaction reflects the poor compliance measures followed during the orthodontic treatment. Steinnes et al. [44] assessed the satisfaction ratio of group of patients included in their randomised control trial. According to the reports of the trial, except 4.5% patients who were dissatisfied, majority of patients were evaluated to be satisfied with the orthodontic treatment with fixed retainers during their follow-up sessions.
Sobouti et al. [46] observed that for the increasing number of adults seeking this treatment, patient satisfaction can be considered a major factor defining the choice of retainers. Westerlund et al. [47] evaluated patient satisfaction level with removable as well as fixed
20 retainers after a follow up session of 5 years and reported majority of patients being satisfied with the treatment and choice of the dental health professional. In orthodontics, retention has been recognised an important aspect which significantly influences the patient satisfaction and the associated long-term outcomes of the treatment. Patient satisfaction level, during and after orthodontic treatment with fixed and reliable retainers, varies and relies on various factors [47]. These include the cost effectiveness of the treatment, quality of retainers, appearance of retainers and long-term effects of the retainers in correcting the malocclusion. Patient satisfaction might be negatively influenced by high cost ratio of good quality
treatment, compromised periodontal health due to emergence of periodontal disease and least or no significant outcomes of the treatment [46]. Dental plaque or calculus appearing after treatment with fixed retainers have also been frequently identified as the major reason dissatisfying majority of patients receiving orthodontic treatment.
Removable retainers have better outcome in terms of patient satisfaction.
Author concludes that there is an urgent need for a high quality randomised controlled trials in this crucial area of orthodontics practice to generate strong evidence.
21
CONCLUSION
The integrated studies in this systematic review scarcely focused on all the three variables selected as outcome measures; success and failure rate, periodontal health and patient satisfaction. Rather they focused on one or two of the variables as outcome measures. Both removable and fixed retainers continue to be used widely.
Success is observed to be higher for fixed retainers. Both types of retainers are vulnerable to breakage, degradation or loss.
In context of periodontal health impacts, removable retainers are preferred and observed to pose least risk of periodontal disease. Moreover, maintenance of oral hygiene with removable retainers is easier and more effective.
22
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33. Edman Tynelius, G., Petrén, S., Bondemark, L. and Lilja-Karlander, E., 2014. Five-year
postretention outcomes of three retention methods—a randomized controlled trial. European journal of orthodontics, 37(4), pp.345-353.
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