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DOI: 10.24412/2707-6180-2022-64-125-129 УДК 616.31-06 МРНТИ 76.29.55
RETENTION AND RELAPSE- THE BANE OF ORTHODONTICS
SUKHPAL KAUR1, SANJEEV SONI1, RIPONJOT SINGH2
'Desh Bhagat dental college and hospital, Punjab, India 2Western University, Ontario, Canada
Sukhpal Kaur - https://orcid.org/0000-0003-1792-1431
Citation/
библиографиялык сттеме/ библиографическая ссылка:
Kaur S, Soni S, Singh R. Retention and relapse- the bane of orthodontics. West Kazakhstan Medical Journal. 2022;64(3):125—129. DOI: 10.24412/27076180-2022-64-125-129
Каур С, Сони С, Сингх Р. Ретенция жэне кайталану - ортодонтиянын к1асiретi. West Kazakhstan Medical Journal. 2022;64(3):125—129. DOI: 10.24412/2707-6180-2022-64-125-129
Каур С, Сони С, Сингх Р. Ретенция и рецидив - бич ортодонтии. West Kazakhstan Medical Journal. 2022;64(3):125—129. DOI: 10.24412/27076180-2022-64-125-129
Retention and relapse- the bane of orthodontics
Sukhpal Kaur1, Sanjeev Soni1, Riponjot Singh2 'Desh Bhagat dental college and hospital, Punjab, India 2Western University, Ontario, Canada
Preserving the treatment corrections is the most difficult task for an orthodontist. The long term outcome of treatment depends on retention phase as there are many contributing factors which drag teeth to their original position after completion of active orthodontic treatment. So retention phase is critical time period following orthodontic treatment and use of suitable retention protocol is necessary to prevent relapse. Relapse is unpredictable, therefore it should be presumed that every patient has potential risk of relapse and need appropriate retention. This article gives overview of retention, causes of relapse and clinical guide for retention protocol. Keywords: Retention, relapse, intercanine width, occlusion, alveolar bone.
Ретенция жэне кайталану - ортодонтиянын каарет
Сукхпал Каур', Санджив Сони', Рипонджот Сингх2
'Стоматологиялык колледж жэне Деш Бхагат ауруханасы, Пенджаб, Индия 2Батыс университета, Онтарио, Канада
Емдж TYзетулердi сактау - ортодонт дэрие^ ушш ец киын мщдет. Емдеудщ уза; мерзiмдi нэтижесi устау фазасына байланысты, eйткенi белсендi ортодонтиялык емдеу аякталганнан кейiн тiстердi бастапкы калпына келтретш кептеген факторлар бар. Осылайша, ретенция фазасы ортодонтиялык емдеуден кейiнгi мацызды уакыт кезещ болып табылады жэне рецидивтщ алдын алу уш1н ттст ретенция протоколын колдану кажет. ^айталануды болжау мумкш емес, сондыктан эр пациенттщ кайталану каут бар жэне тшст сактауды кажет етедi. Бул макалада устауга шолу, кайталану себептер жэне устау хаттамасына клиникалык нускаулык берiлген.
Негiзгi свздер: ретенция, рецидив, тiсаралъщ ет, окклюзия, альвеолярлы есюн
Ретенция и рецидив - бич ортодонтии
Сукхпал Каур1, Санджив Сони1, Рипонджот Сингх2 ■Стоматологический колледж и больница Деш Бхагат, Пенджаб, Индия 2Западный университет, Онтарио, Канада
Сохранение лечебных коррекций - самая сложная задача для ортодонта. Долгосрочный результат лечения зависит от ретенционной фазы, так как существует множество факторов, которые возвращают зубы в исходное положение после завершения активного ортодонтического лечения. Таким образом, фаза ретенции является критическим периодом времени после ортодонтического лечения, и использование подходящего протокола ретенции необходимо для предотвращения рецидива. Рецидив непредсказуем, поэтому следует исходить из того, что каждый пациент имеет потенциальный риск рецидива и нуждается в соответствующем удержании. В этой статье дается обзор удержания, причины рецидива и клиническое руководство по протоколу удержания. Ключевые слова: ретенция, рецидив, межклыковая ширина, окклюзия, альвеолярный отросток
О
Sukhpal Kaur
e-mail: docs284@gmail.com
Received/
Keain mycmi/ Наступила: 11.18.2122
Accepted/
Басылымга цабыаданды/ Принята к публикации: 16.1..2122
ISSN 2707-6180 (Print) © 2021 The Authors Published by West Kazakhstan Marat Ospanov Medical University
Introduction
Retention is an essential and final stage of orthodontic treatment. Moyers [1] defined retention as «The holding of teeth following orthodontic treatment in the treated position for the period of time necessary for the maintenance of the result.» Retention planning starts with appropriate diagnosis, treatment planning, application of correct biomechanics for tooth movement and bringing the teeth in optimal functional occlusion [2]. Retention is the most difficult and challenging stage of orthodontic treatment [3]. Many reputed professionals expressed their concerns in retention. Kingsley in 1880 recognized the problem of maintaining the tooth position after orthodontic treatment [4]. Vanarsdall and White said that a misunderstanding developed in Orthodontics. Dental professionals and public started to believe that teeth straightened with orthodontic treatment, remains in the same position for a lifetime [5].
After completion of orthodontic treatment, teeth have tendency to return to their original positions due to stretching of periodontal fibres [6]. Reorganization and adaptation of periodontal fibres takes around one year [3]. Kingsley [4] considered that occlusion is most important factor for stability of teeth after orthodontic tooth movement. According to Lundstrom [7], apical base has prime role in stability whereas McCauley [8] gave importance to canine and molar relationship for stability of teeth after orthodontic treatment. Other factors responsible for relapse are: continuous skeletal growth, genetics, soft tissue maturation, presence of third molars and expansion of dental arches [3]. In 1944, Tweed claimed that inclination of incisors also plays a potent role in stability. Good stability can be gained with upright incisors [9].
Retainers are the orthodontic appliances used to prevent relapse that is return of teeth to their original position following orthodontic correction. To date, for long term stability of treatment results and to minimize relapse, various type of retainers have been advocated. Retainers can be either removable or fixed. Removable retainers can be easily removed and placed by patients, that helps in complete cleaning of teeth and patient can wear retainer on part time basis. However, some situations are best addressed with fixed retainers which remain fixed to teeth for 24 hours a day every day [6]. Retention requirements depend on type of original malocclusion and effects of orthodontic treatment mechanics [10].
Why relapse and need of retention
Relapse is loss of any correction achieved by orthodontic treatment. Several factors contribute to relapse. Some important factors are discussed here.
Alteration in Ach form
Various long term studies evaluated arch stability after orthodontic treatment and changes in arch form were reported in most of study groups. It was found that there is reduction in arch length and intercanine width following orthodontic treatment.Intermolar width also returns to its original value if it is expanded during treatment. These
changes in intercanine width and intermolar width found to be greater in mandibular arch as compared to maxillary arch. It has also been reported that greater changes induced during treatment, lead to more tendency for post treatment relapse. Therefore maintenance of pre treatment arch form is recommended [11, 12].
Role of alveolar bone, periodontal and gingival tissue
Bone remodelling occurs in alveolar bone surrounding teeth during orthodontic treatment. Bone resorption on pressure side allows tooth movement through bone on application of orthodontic force. After completion of tooth movement, alveolar bone and periodontal fibres re established. On tension side, new bone formation take place at slower pace and periodontium maintains tension on the bone which can drag the tooth to its original position [13].
Reitan [14] first reported stretching of periodontal fibres during orthodontic rotation corrections. Periodontal fibres in apical third of root were stretched less than fibres in middle and marginal third of root due to difference in circumference of root surface area from apex to marginal area. Apical and middle third fibres had well reorganized after a retention period of 232 days. However, marginal fibres showed partial reorganization. Similarly new bone was well organized at 232 days of retention along apical and middle third fibres but fairly organized along marginal third fibres. Redlich [15] in his study reported that relapse result from elasticity of whole gingival tissue rather than stretching of only gingival fibres.
Treatment stability in incisor area depends on thickness of alveolar cortical bone. Rothe [16] et al. observed that patients having thinner mandibular cortical bone showed greater chances of relapse as compared to patients with more thickness of cortical bone.
Mandibular incisor dimensions
Very poor long term mandibular incisor stability after orthodontic treatment was reported. Approximately more than one -quarter of cases showed noticeable crowding [12]. Relationship between mandibular incisor dimensions and crowding has been reported in some studies. Proximal reduction has been advised to promote stability [17, 18]. Boese [19] proposed mandibular incisor proximal stripping to create wider contact points and more arch space availability.
Occlusal factors
A functional and stable occlusion is believed to be potent factor in maintaining treatment results. It was proposed that good interdigitation of teeth with even occlusal contacts and appropriate occlusal loading of dentition provides more stable results. Proper interincisal angle and good interdigitation of posterior teeth along with perfect molar relationship are important for prevention of relapse of cross bite and antero-posterior correction [11, 20, 21].
Soft tissue pressure
The most preferable position of teeth is within neutral zone. Neutral zone is area of balance between tongue on
lingual side of dentition and lips and cheeks on labial aspect of dentition. Movement of teeth away from this zone, results in instability of their position. Weinstein [22] and Mills [23] stated that mandibular incisors lie in a zone of stability and their position should not be changed during orthodontic treatment. Alterations in arch form especially in mandibular inter canine width lead to relapse because of soft tissue pressures. However, there are some conditions in which intercanine width need to be changed. In these cases, orthodontist should plan a suitable retention protocol to minimize relapse chances [20, 24, 25].
Whalen reported that vertical pressure of tongue during swallowing has little influence on vertical positioning of anterior teeth. In his study he also observed that tongue pressure in vertical direction during swallowing in open bite patients is less than patients with normal vertical relationships [26].
Proffitt and Manson in 1975 stated that resting position/posture of tongue and its pressure has much more impact on position of teeth as compared to influence of tongue pressure on dentition during swallowing. It has also been observed that myofunctional therapy along with orthodontic treatment is more successful in preserving open bite correction than does orthodontic treatment alone [27, 28].
Posture of lip particularly lower lip plays a role in causing relapse. Interposed lower lip and lip pressure has significant contribution to relapse of maxillary incisors following orthodontic treatment. Doto and Yamato demonstrated that lip pressure is contributing more to incisor proclination in class II patients than is tongue pressure. Therefore role of both tongue and lips should be considered and teeth should be positioned to create most harmonious relationship between dentition and soft tissue envelope [29, 30].
Physiological relapse
Undesirable tooth movement following treatment can be due to normal age changes, these can occur even in patients who have not undergone orthodontic treatment. The age related changes such as minor alteration in maxilla- mandible relation and soft tissue pressure on teeth, occur throughout the life. The alterations in alignment of teeth results from changes in soft tissue pressure and skeletal structures surrounding the dentition. These soft tissue alterations and continued growth changes are unpredictable and considered as normal ageing process. Therefore retention protocol is needed not only to avoid reversal of orthodontic treatment results but also to avoid undesirable long term age changes [6, 20, 31].
Contribution of orthodontically induced change
Non extraction treatment in cases with mandibular crowding more than 7-8 mm results in increased proclination of incisors, increased arch length and alteration in pretreatment mandibular arch form. Expansion of mandibular intercanine width occurs in non extraction treatment which in most of cases leads to relapse [32-34]. When mandibular arch form is changed, relapse is certainly occurring after discontinuation of retention
protocol. Literature also supports the concept of relapse with increased arch length during orthodontic treatment. Dr. James Boley gave a presentation entitled 'Why try to fit teeth into an ever-shrinking arch? In 1980 to the Colorado Orthodontic society. Increased proclination of mandibular incisors, when molars do not move mesially, results in increased arch length. Several studies concluded that this is unstable after discontinuation of retention [3537].
Habits as contributing factor
Successful correction of open bite may be reversed if patient continues habit of digit sucking. The incidence, duration and intensity of habit are influencing factors [38].
Third molars
Contribution of third molars to lower incisor crowding remains still a controversy. Some studies supported relation between third molar presence and lower incisor crowding. But other studies reported no impact of third molars on lower incisor crowding. Multiple factors are responsible for late incisor crowding. The extraction of third molar for prevention of lower incisor crowding is not evidence based [11, 20].
Retention protocol
Both fixed and removable retainers are used globally. Significant geographic difference in relation to use of retention methods is reported. For maxillary arch both fixed and removable retainers and for mandibular arch only fixed retainers are recommended in Norway and Netherlands. Switzerland prescription used combination of two retainers in cases of maxillary extraction and expansion. Maxillary removable and mandibular fixed retainers are prescribed in US, Saudi Arabia and Australia. Most of studies demonstrated that vacuum formed retainers are preferred among removable retainers [39]. Use of fixed retainers in mandibular arch and vacuum formed retainers with or without fixed retainer for maxillary arch, is most popular prescription. In one study, it was observed that wearing of maxillary removable retainer alone or its combination with fixed retention showed no significant difference in Peer Assessment Rating scores after three years retention period [40]. In another study no significant difference was observed in lower incisor alignment at one year follow up when lingual fixed retainers combined with only night time wear Hawley retainer and clear plastic retainers used alone [41]. Same lower incisor alignment stability was reported for fixed and vacuum formed retainers at 18 month follow up period but at 4 year follow up, significantly improved outcome was observed for fixed retainers [42]. Fixed retainers were found to be least cost effective two years post retention [43]. Clear retainers were reported to be more discomfortable for patients as compared to fixed retainers [44].
It was reported that fixed retainers increase plaque and calculus accumulation and also increase number of bacteria which cause periodontal diseases and caries. If proper oral hygiene is maintained, a chance of occurrence of these diseases is not there [10, 45, 46]. Also monitoring
on regular basis is needed as occasionally unwanted tooth movement can occur with these fixed retainers due to some activity in bonded wire [47, 48]. Removable retainers also have their own pros and cons. The main cause of failure of removable retainer is poor patient compliance. Cases with severe enamel damage have also been reported as patients drink cariogenic liquids while wearing clear retainers [49].
The duration recommended for retainers is also variable. Most of clinicians suggest use of removable retainers for a period of two years, and even up to five years or more than that [2]. Retention for indefinite time is recommended by less than 20% of clinicians in Norway, 52% in Saudi Arabia, 80% in Australia, US and UK and by 90% orthodontist in Netherlands [39] latest Cochrane review demonstrated that there is no clear evidence proving superiority of full time over part time wear of retainers [50]. So it is recommended to wear either prolonged fixed retainers or part time removable retainers on a long term basis [39].
Moghrabi et al. concluded in their review that selection of retention protocol should be evidence based, tailored for each individual patient while taking into consideration patient's expectations and patient's personal circumstances. With firm evidence, they suggested that night time wear of removable retainer is equally effective as full time wear over a short time period. One more emerging evidence explained the superiority of fixed retainers over removable retainers at prolonged periods of follow up. In spite of this, commitment of patient for optimal wear of removable retainers enhances long term outcomes [39].
What patient needs to know?
It is prime need to provide information to patient as a part of informed consent process regarding limitations of orthodontic therapy and importance of retention phase. Orthodontist should explain the patient that it is his/her long term responsibility to follow retention protocol and patient must be prepared for this responsibility before start of treatment [6]. Long term outcome of treatment requires the biggest commitment of patient to wear and maintain retainers [49]. Previous studies have reported that for some patients, commitment to follow prescribed retention protocol is more of a burden than the actual active orthodontic therapy [51].
Conclusion
Orthodontic retention and relapse continue to be significant issues for all clinicians and must be managed properly. With thorough knowledge regarding retention, factors contributing to relapse and by following suggested guidelines, one can maintain the treatment outcome after completion of active treatment. It is also responsibility of an orthodontist to select suitable retention protocol for each individual patient and to aware the patient regarding need and importance of retainers. The patient has also responsibility to follow the recommended retention protocol, maintain retainers properly, and arrange regular checkups with their orthodontist that will help in maintenance of treatment outcome.
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