Retention appliances

details about retention,theories of retention,schools of retention,retention appliances and relapse.

1. JOSNA THANKACHAN FINAL YEAR PART I AL-AZHAR DENTAL COLLEGE RETENTION APPLIANCES

2. INTRODUCTION THEORIES OF RETENTION RALEIGH WILLIAMS KEYS TO ELIMINATE LOWER RETENTION TYPES OF RETENTION RETAINERS CLASSIFICATION REMOVABLE RETAINERS FIXED RETAINERS ACTIVE RETAINERS CONCLUSION REFERENCES CONTENTS

3. What is retention? has been defined by Moyers as “Maintaining newly moved teeth in position long enough to aid in stabilizing their correction”. INTRODUCTION

4. Why is retention necessary? Retention is necessary for 3 main reasons The gingival and periodontal tissues are affected by orthodontic tooth movement and require time for reorganization when the appliances are removed . The teeth may be in an inherently unstable position after the treatment,so that soft tissue pressures constantly produce a relapse tendancy . Changes produced by growth may alter the orthodontic treatment.

5. If teeth are not in an inherently unstable position and if there is no further growth, retention still s vitally important until gingival and periodontal organization is complete. Retention cannot be abandoned until growth is essentially completed.

6. What is relapse? Relapse implies loss of any correction achieved by orthodontic treatment.

7. CAUSES OF RELAPSE L Text book of orthodontics,SRIDHAR PREMKUMAR

8. Schools of thought pertaining to retention/History of retention There are 4 schools of thought pertaining to retention:- Occlusion school of thought( kingsley ) A/C to this,proper occlusion of teeth is a potent factor in maintaining the stability of the teeth. At the end of active orthodontic treatment there should be proper intercuspation and interdigitation . There should be cusp to fossa relationship between maxillary and mandibular teeth.

9. 2. Apical base school of thought(Axel lundstrom ) A/C to this,apical base is one of the most important factors in both correction of malocclusion as well as maintenance of correct occusion . Intercanine and intermolar width should be altered to prevent relapse. Nance advised to increase the arch length only to a minimal extent.

10. 3. Mandibular incisor school of thought(Grieve and Tweed) This theory postulated that the mandibular incisors should be placed upright and over the basal bone. 4. Musculature school of thought(Roger’s) Establishing proper functional muscle balance is a must to achieve stable occlusion. Improper muscle balance leads to relapse.

11. THEOREMS ON RETENTION There are 10 theorems of which 9 are put forward by Riedel and the last one by Moyer. THEOREM 1 “Teeth that have been moved tend to return to their former positions” THEOREM 2 “elimination of the cause of malocclusion will prevent recurrence”

12. THEOREM 3 “Malocclusion should be overcorrected as a safety factor” THEOREM 4 “proper occlusion is a potent factor in holding teeth in their corrected positions” THEOREM 5 “bone and adjacent tissues must be allowed to reorganize around newly positioned teeth”.

13. THEOREM 6 “if the lower incisors are placed upright over basal bone,they are more likely to remain in good alignment” THEOREM 7 “corrections carried out during periods of growth are less likely to relapse” THEOREM 8 “the farther teeth have been moved ,the less likelyhood of relapse.

14. THEOREM 9 “arch form particularly in the mandibular arch,cannot be altered permanently by appliance therapy”. THEOREM 10 “many treated malocclusions require permanent retaining devices”.

15. Principles of Retention Relapse potential may be predicted by evaluation of initial occlusion; teeth usually want to return to their original position; this is due to gingival fibers and unbalanced lip-tongue forces Full-time retention is required for 3-4 months to allow for reorganization of PDL Retention should continue for at least 12 months in non-growing patients or until growth has ceased in growing patients

16. Types of retention natural/no retention Limited or short term retention Medium term/moderate retention prolonged/permanent/semi permanent retention

17. Natural retention --Occlusion is self retentive --an upper incisor is moved over the bite, no retention is required --Conditions that do not require any retention anterior crossbite Serial extraction procedures Blocked out or highly placed canines in class I extraction cases Posterior crossbite in patients having steep cusps

18. Short term retention Limited retention-3-6 months Class I non-extraction with dental arches showing proclination and spacing Deep bite Class I,Class II div 1 and div 2 cases treated by extraction

19. Medium term/moderate retention Supporting tissue will take longer time to adapt Retention may extend between 1-5 years Class I non extraction cases,with protrusion and spacing of maxillary incisors Corrected deep bites in classI or class II malocclusion Corrected class II div 2 malocclusion

20. prolonged/permanent/semi permanent retention Cases treated by expansion particularly in the mandibular arch Generalized spacing with arch length excess Severe rotatation Midline diastema Cleft palate cases Adult patients with periodontal problems Severe labiolingual malposition

21. RALEIGH WILLIAMS keys to eliminate lower retention. 6 keys:- 1. Incisal edge of the lower incisor should be placed on the A-P line or 1mm infront of it. This position of the lower incisor ensures stability following treatment. It also creates optimum balance of soft tissues in the lower third of the face.

22. 2. The lower incisor apices should bespread distally to the crowns more than is generally considered appropriate and the apices of the lower lateral incisors must be spread more than those of central incisors. In otherwords the lower incisor roots should be diverging.

23. 3. The apex of the lower cuspid should be positioned distal to the crown 4. All 4 lower incisors apices must be in the same labolingual plane 5. The lower cuspid root apex must be positioned slightly buccal to the crown apex. 6. The lower incisors should be slenderised as needed after treatment

24. Retainers Retainers are passive orthodontic appliances that help in maintaining and stabilizing the position of the teeth long enough to permit reorganization of the supporting structures after the active phase of orthodontic therapy

25. Ideal requirements for retainers(Graber) It should restrain each tooth that has been moved in to the desired position It should be easily cleanable It should allow functional forces to be transmitted to the retained teeth if worn It should be self cleansable It should be inconspicuous It should be strong enough to achieve the objectives of retention

26. CLASSIFICATION Hawley retainer and modifictions Wrap around retainers Canine to canine clip on Tooth positioners Essix /invisible retainers Functional appliances Banded canine to canine retainers Bonded canine to canine retainers Diastema maintenance Antirotation band Band and spur Pontic maintenance REMOVABLE FIXED

27. Removable retainers Effective for retention against intra arch stability Effective in growth problems

28. Hawley Retainer Most common removable retainer Developed in 1920s Clasps on molars, palatal coverage, and labial bow with adjustment loops Can incorporate biteplate for deep bite patients

29. MODIFICATIONS Labial bow can be made to extend from 1 st premolar to the opposite 1 st premolar. The design helps in closing spaces distal to canine. Solder the bow to the bridge of the Adam’s clasp.This design avoids the risk of space opening upbetween the canine and premolar due to the crossover wires.

30. Fitted labial bow offers excellent retention Anterior bite planes can be incorporated to retain correct deep bite cases. Advantages Ease of fabrication Minimal patient discomfort Acceptable to most patients.

31. Popularized by P.R.Begg Consists of labial wire that extend till the last erupted molar and curves around it to get embedded in acrylic that spans the palate Advantages:there is no cross over wire between the canine and premolar thereby eliminating the risk of space opening up. Begg’s retainer

32. Clip-on retainer/spring aligner Made of a wire framework that runs labially over the incisors and then passes between the canine and premolar and is recurved to lie over the lingual surface. Both the labial as well as the lingual wire segments are embedded in a strip of clear acrylic. Used for correction of rotations commonly seen in the lower anterior region.

33. Wrap around retainer Extended version of the spring aligner that covers all the teeth. It consists of a wire that passes along the labial as well as lingual surfaces of all erupted teeth which is embedded in a strip of acrylic. APPLICATION Stabilizing a periodontally week dentition.

34. Wraparound Modification: “ 3-3 Clip-on” Used mainly for lower anterior area Can realign incisors and/or maintain lower incisor space closure Used if posterior teeth were well aligned pre-treatment

35. Kesling tooth positioner Described by H.D.Kesling in 1945 It is made of a thermoplastic rubber like material that spans the inter- occlusal space and covers the clinical crowns of the upper and lower teeth and a small portion of the gingiva. Needs no activation at regular intervals and is durable. Drawbacks include difficulty in speech and risk of TMJ problems.

36. Essix /invisible retainers Developed in 1993 Plastic removable appliance Advantages: Esthetic Patient is more likely to wear Inexpensive Quick fabrication Minimal bulk High strength No adjustments Usually does not interfere with speech or function Studies have determined that Essix retainers are as efficient as Hawley-type or bonded wire retainer s Graber, Orthodontics, 2005

37. Positioner Can be made as retainer or used for finishing and then maintained as retainer Disadvantages as a retainer : Bulky and difficult to wear full-time Do not retain incisor position as well as a conventional retainer because patients usually wont wear full-time Overbite increases due to limited patient wear

38. Advantages as a retainer: Reestablishes normal tissue when gingival hyperplasia is present Maintains occlusal relationship and intra-arch position Unlikely to break Can be made with jaws rotated down and back to prevent Class III relapse Can be constructed to prevent relapse in skeletal Class II and open bite cases Growth control is less effective than part-time functional appliance or headgear

39. Damon Splint Basically, upper and lower Essix retainers connected Retentive splint for Class II, Class III, and bilateral crossbite treatment Assists in tongue training Holds teeth and arches in corrected position

40. Designed By Dr. Dwight Damon Can be used by adults or patients in mixed dentition Minimal vertical opening to allow for air slot Esthetic Can be made using:hard pressure formed, dual hardness/soft liner and elastic silicone

41. Fixed Retainers Utilized in cases where stability is questionable and prolonged retention is planned Four main indications: Maintaining lower incisor position Holding diastema closed Implant or pontic space maintenance Retaining closed extraction spaces

42. Bonded canine to canine retainer Commonly used in lower anterior region. Canines are banded and a thick wire is contoured over the lingual aspects and soldered to the canine bands. The bands predispose to poor oral hygiene and are unesthetic.in addition when these retainers are removed band spaces are seen around these bands. These drawbacks of the banded retainers have made them less popular than the bonded retainers.

43. Bonded lingual retainers They are retainers that are bonded on the lingual aspect. Stainless steel/ elgiloy wire is adapted lingually to follow the anterior curvature. The ends are curved over the canine where it is bonded. Disadvantage : anterior teeth can sometimes rotate This is overcome by using bonded retainers that are bonded to each of the anterior teeth from canine to canine.

44. In case extractions have been done as part of the orthodontic treatment it may be advisable to extend the retainer to include the 1 st premolar of both the sides. Alternatives Use of etched or perforated metal cast bars that can be bonded on the lingual side of the teeth. Braided or multistranded wire that can be bonded individually to each tooth in a segment.

45. Advantage All individual teeth are retained with no possibility of rotation of the incisors. Use of lighter braided wires permit physiological movement of the teeth within the periodontal ligament. Disadvantage The bonding of the lingual retainers on the lingual surface of the teeth can be accomplished by direct or indirect bonding.

46. Band and spur retainer Used in cases where a single tooth has been orthodontically treated for rotation,correction or labiolingual displacement. The tooth that has been moved is banded and spurs are soldered on to the bands so as to overlap the adjacent teeth. In case it is used to retain a tooth that has been blocked partially,the spurs are made on the labial aspect so that tooth doesnot onceagain get displaced palataly.In derotation cases ,one spur is placed labially and the other lingually to avoid relapse.

47. Active retainers Spring retainer: realign malpositioned incisors Modified functional appliance: manage relapse potential in Class II or Class III cases

48. Active Retainers Spring retainer : realign malpositioned incisors Will usually need to perform IPR prior to appliance placement to prevent proclining incisors into unstable position IPR flattens contacts increasing stability Can reduce incisors 0.5 mm/side If teeth are severely crowded, retreatment with bonded brackets is recommended; followed by fixed retention

49. Modified functional appliance: manage relapse potential in Class II or Class III cases Activator or Bionator : Upper and lower retainers joined by inter- occlusal bite blocks Maintain teeth within arch while slightly altering occlusal relationship Example: If adolescent slips back 2-3 mm into Class II after early correction, this appliance can be used to recover proper occlusion

50. No value if used in adults (as no vertical growth remains) Moves teeth (no skeletal change) Can only be used if no more than 3mm correction is needed Goal: Hold maxillary posterior segment and allow for eruption of mandibular posterior segment anteriorly (Class II)

51. CONCLUSION Goals of occlusion are predefined prior to start of orthodontic treatment.Procedures should be conducted with extreme care to minimize iatrogenic effects on dental hard tissues and periodontium .

52. REFERENCES CONTEMPORARY OF ORTHODONTICS BY WILLIAM PROFITT,HENRY W FIELD,DAVID M SARVER ORTHODONTICS ART AND SCIENCE BY S.I BHALAJHI