If third molar erupt after the orthodontictreatment . Exert pressure on the teeth. Late anterior crowding . RELAPSE
Defined as maintaining newly moved teeth in position, long enough to aid in stabilizing their correction. (Moyer) Need Of Retention 1. Gingival and periodontal tissue require time post- treatment to reorganize 2. Soft tissue pressures are likely to cause relapse if teeth are placed in an unstable position 3. Growth post-treatment may cause relapse
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
1. The Occlusal School2. The Apical Base School3. The Mandibular Incisor School4. The Musculature School
According to KINGSLEY properocclusion is a key factor indetermining the STABILITY of thenewly moved teeth.
ALEX LUNDSTROM (1920s) suggested that the apical base is an important factor in the correction of malocclusion and maintenance of the stability of treated cases. McCauley added that the inter canine and inter-molar widths should be maintained during orthodontic therapy.
Grieves and Tweed suggested that post treatment stability was increased when mandibular incisors were placed upright or slightly retroclined over the basal bone.
According to Rojers functional muscle balance is necessary in order to ensure post treatment stability.
Theorem 1.“Teeth that have been moved tend to return to their former position”Theorem 2.“Elimination of the cause of malocclusion will prevent relapse”Theorem 3.“Malocclusion should be over corrected as a safety factor”
Theorem 4.“Proper occlusion is a potent factor in holding teeth in their corrected positions”Theorem 5.“Bone adjacent the tissue must be allowed time to reorganize around newly positioned teeth”Theorem 6.“If the lower incisors are based 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 the teeth have been moved , the lesser is the risk of relapse”Theorem 9.“Arch form, particularly in the mandibular arch, cannot be permanently altered by appliance therapy”Theorem 10.“Many treated malocclusions require permanent retaining devices”
Retention can be three types :1. Natural or no retention2. Limited or short term retention3. Prolonged or permanent retention
Conditions that do not require retention are:-1. Anterior crossbite.2. Serial extraction procedures.3. Posterior cross bite in patients having steep cusps.4. Highly placed canines in class 1 extraction cases.
Most cases routinely treated fall in this category. Retention is given to allow bone n PDL tissues to adapt in their new location.1. Class I, class II div 1 and div 2 cases, treated by extractions.2. Deep bites.3. Class 1 non extraction with dental arches showing proclination and spacing.
Cases requiring permanent retention are1. Midline diastema.2. Severe rotations.3. Arch expansion achieved without ensuring good occlusion.4. Certain class II, div 2 deep bite cases.5. Patients with abnormal musculature or tongue habits.6. Expanded arches in cleft palate patients.
Retainers are passive orthodontic appliances that help in maintaining and stabilizing the position of teeth long enough to permit reorganization of supporting structures after the active phase of orthodontic therapy Three types:-1. Removable Retainers2. Fixed Retainers3. Active Retainers
Should retain all teeth that have been moved into desired positions. Should permit normal functional forces to act on the dentition. Should be self cleansing and should permit oral hygiene maintenance. Should be as inconspicuous as possible.
1. Hawley’s appliance2. - Designed in 1920 by Charles Hawley. Most frequently used retainer Consists of claps on molars and a short labial bow extending from canine to canine having adjustment loops
HAWLEY’S Retainer withHAWLEY’S Retainer long labial bows
1. Bow can be soldered to clasps on 1st molars2. Place C-clasps on second molars and allow bow to run around entire arch
Hawley’s Retainer with labial bow soldered with Adams clasp
Consists of a labial wire that extends till the last erupted molar and curves around it to get embedded in acrylic that spans the palate.Advantage : There is no cross over wire that extends between the canine and premolar thereby eliminating the risk of space opening.
Appliance made of wire framework that runs labially over the incisors and then passes between canine and premolar and is recurved to lie over lingual surface. Both the labial as well as lingual segments are embedded in a strip of clear acrylic. Used to bring about correction of rotations Less comfortable than Hawley Not as good in overbite maintenance Indicated in perio cases where splinting is needed
Extended version of spring aligner that covers all the teeth. Consists of wire that passes along the labial as well as lingual surfaces of all erupted teeth which is embedded in a strip of acrylic. Use : In stabilizing a periodontally weak dentition. Not routinely used.
Described by H.D Kesling in 1945 Made of thermoplastic rubber like material that spans the inter – occlusal space and covers the clinical crowns of the U/L portion of teeth and a small portion of the gingiva. Needs no activation at regular intervals and is durable Disadvantages 1. Bulky and difficult to wear full- time. 2. Difficulty in speech and risk of TMJ problems 3. Do not retain incisor position as well as a conventional retainer b/c patients usually wont wear
VACCUM-FORMED (ESSIX) RETAINER Developed in 1993 This is a polypropylene or polyvinylchloride (PVC) material, typically .020" or . 030" thick. 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 retainers
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•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/softliner and elastic silicone.
Advantages of removable retainer 1. Reestablishes normal tissue when gingival hyperplasia is present. 2. Maintains occlusal relationship and intra-arch position. 3. Unlikely to break. 4. Can be made with jaws rotated down and back to prevent Class III relapse. 5. 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
Utilized in cases where stability is questionable and prolonged retention is planned Four main indications: 1. Maintaining lower incisor position 2. Diastema maintenance. 3. Implant or pontic space maintenance 4. Retaining closed extraction spaces
1. Maintaining lower incisor position during late mandibular growth: Even mild mandibular growth between the ages of 16-20 can cause lower incisor relapse A fixed lingual bar bonded only to canines can prevent distal tipping of lower incisors A heavy wire, 28 or 30 mil, should be used due to long span Studies indicate that placing retention loops on canines will decrease breakage
If teeth were severely rotated or spaced, all teeth (3-3) can be bonded together using a 17.5 mil braided steel wire – as it is not desirable to use too rigid of a wire (must allow physiologic tooth movement) Patients who were evaluated after 20 years of having a lower fixed retainer showed NO signs of periodontal problems If proper flossing is maintained, fixed retainers can remain indefinately
2. Holding diastema closed: Utilize lighter wire (17.5 or 19.5 mil twist) Bond above cingulum – out of occlusion Can prevent bite deepening if lower incisors erupt
3. Implant or pontic space maintance: Reduces mobility of teeth making it easier to place bridge Holds space if prolonged periodontal treatment is required post-ortho, prior to placement of restoration Implants should be placed as soon as ortho is completed so it can be included in initial stages of retention
For posterior teeth, heavy wire is bonded to shallow preparations in adjacent teeth The longer the span, the heavier the wire Placed out of occlusion For anterior teeth, a pontic can be placed on a removable retainer for short term use If the patient must wait an extended period of time prior to completion of vertical growth for placement of final restoration, a bonded bridge is preferred
4. Retaining closed extractions spaces: Placed on facial surfaces of posterior teeth Mainly used in adults, as they tolerate this better than removable retainers More reliable than removable retainer
The Fixed Appliance Banded Canine to Canine Retainer: Bonded Lingual Retainers: Band and Spur Retainers
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 hygeine and are unesthetic.
Retainers bonded on the lingual aspect S.S wire is adapted lingually to follow the anterior curvature. Ends are curved over the canines where its bonded. Various pre fabricated lingual retainers also are available that can be bonded on the teeth Recently use of spiral wire is recommended that can be boneded to each tooth individually.
Used in cases where single tooth has been orthodontically treated for rotation correction or labio lingual displacement.•The tooth that has been moved is banded and spursare soldered on to the bands so as to overlap theadjacent teeth.
Reduced need for patient corporation Can be used when conventional retainers cannot provide same degree of stability. Bonded retainers are more esthetic No tissue irritation unlike what may been seen in tissue bearing areas of Hawley’s retainer Can be used for permanent and semi permanent retention. Do not effect speech.
More cumbersome to insert Increased chair side time More expensive Banded variety may interfere with oral hygiene maintainence More prone to breakages Loss of healthy tooth material Tend to discolor
Relapse in these patients are most likely due to a combination of dental and skeletal changes Dental changes (short-term relapse) : 1-2mm of A-P change tend to occur immediately following treatment, especially when Class II elastics are used Overcorrection is important in preventing relapse Forward movement of lower incisors more than 2mm will require permanent retention, as lip pressure tends to upright these teeth, leading to an increase in crowding, overbite, and overjet
Skeletal changes (long-term relapse): Depends on age, sex, and maturity If original growth pattern continues, treatment that involved growth modification will most likely result in loss of at least some correction Continue headgear at night along with retainer Use a “passive” functional appliance (activator/bionator) to hold position at night and conventional retainers during day (continue for 12-24 months) Patients most likely to require these treatments: 1) The younger the patient at the end of treatment 2) The greater the initial Class II problem Much easier to prevent relapse than to correct later
Bionator/Activator Maintain occlusal relationship Bite registration is taken in CR, so appliance is “passive” Not edge to edge like when used for “active” Class II correction
Relapse occurs mainly from mandibular growth Use of chin cups to restrict mandibular growth has been recommended by some authorsto counter the continued growth tendency of mandible But Chincups and functional appliances: rotate mandible downward causing more vertical growth. Not as effective as maintaining Class II If relapse occurs in normal or excessive face height patients: may need surgical correction after growth In less severe Class III cases: Utilize functional appliances such as reverse activator, FR 3 or class III bionator or positioner. Will maintain occlusal relationship in these cases May position jaws down and back to prevent relapse
Must control overbite during retention period Construct upper removable retainer with a baseplate to prevent lower incisors from over-erupting; posterior occlusion is maintained After stability is achieved, worn at night only Nanda and Nanda found that the pubertal growth spurt in deep bite patients is 1.5-2 years later than that of open bite cases; therefore longer retention period is required for deep bite cases
Patients with habit (thumb or tongue): Relapse occurs due to incisor intrusion. Important to control the habit. Patients without habit: Relapse is due to excessive growth tendencies and continued eruption of posteriors mainly upper molars (extrusion). Important to control eruption of upper molars.
Best retained by high pull headgears to upper molars with use of conventional removable retainers. Appliance with posterior bite blocks (open bite activator or bionator) at night and conventional retainers during the day Use of bite block appliances such as posterior bite plane streches the musculature and produces an intrusive force on the dentition Preferred because: Prevents eruption of upper an lower molars Better patient acceptance