Relapse and Retention

RETENTION AND RELAPSE

تقويم \ خامس اسنان
د. الاء م(4)
9\ 5\ 2017

DEFINITION RELAPSE

• “loss of any correction achieved by any orthodontic treatment”

• CAUSES OF RELAPSE

Periodontal ligament traction
Relapse due to growth related changes
Bone adaptation
Muscular factors
Failure to eliminate the original cause
Role of third molars
Role of occlusion


Why is retention needed?
gingival and periodontal tissue require time post-treatment to reorganize
Soft tissue pressures are likely to cause relapse if teeth are placed in an unstable position
growth post-treatment may cause relapse
Timing of Tissue Reorganization
Once teeth are able to move individually from one another during mastication, reorganization of tissues can begin:
PDL: 3-4 months
• Collagenous gingival fibers: 4-6 months
• Elastic supracrestal fibers: 1 year
• In cases of severe initial rotations: supracrestal fibrotomies are recommended at or just before appliance removal to prevent relapse

RETENTION

Retention is the final phase of active orthodontic treatment where teeth are maintained in a healthy,functional, and esthetic position.
The method of retention to be incorporated in the treatment plan for each individual case.

• THEORIES OF RETENTION

Teeth that have been moved tend to return to their former position.
Elimination of the cause of malocclusion will prevent relapse.
Malocclusion should be over corrected as a safety factor.
Proper occlusion is a potent factor in holding teeth in their corrected positions.
Bone and adjacent tissues must be allowed time to reorganize around newly positioned teeth
If the lower incisors are placed upright over basal bone they are more likely to remain in good alignment.
•Corrections carried out during periods of growth are less likely to relapse


• KEYS OF RETENTION

• 1-Incisal edges of the lower incisors should be placed on the A‐P line or 1mm in front of it.
• 2-Lower incisors apices should be spread distally to the crowns
• 3-Apex of lower cuspid should be positioned distal of the crown
• 4-All four lower incisors apices must be in the same labiolingual plane
• 5-Lower cuspid root apex must be positioned slightly buccal to the crown apex

• TYPES OF RETENTION

• •NATURAL RETENTION
• •LIMITED RETENTION
• •PROLONGED RETENTION

• NATURAL OR NO RETENTION

• •Anterior cross bite
• •Serial extraction procedures
• •Blocked out or highly placed canines in Class I extraction cases
• •Posterior cross bite in patients having steep cusps.
• •Corrections achieved by retardation of maxillary growth once the patient has completed growth


LIMITED OR SHORT TERM RETENTION

•Class I non extraction with dental arches showing proclination and spacing

•Deep bites
•Class I,Class II div 1 and 2 cases treated by extraction.
•Early corrections of rotated teeth to their normal position before root completion
•Cases involving ectopic eruption or supernumery teeth

PROLONGED OR PERMANENT RETENTION

•Midline diastema
•Severe rotations
•Arch expansion
•Class II div 2 with deep bite cases
•Patients exhibiting abnormal musculature or tongue habits
•Expanded arches in cleft patients

• RETAINERS

• Definition
• Passive Orthodontic appliances maintaining and stabilizing the position of teeth long enough to permit reorganization of the supporting structures after the active phase of orthodontic therapy.


• CRITERIA
• •Should retain all teeth that have been moved into desired positions
• •Should permit normal functional forces to act freely on the dentition
• •Should be self‐cleansing
• •Should permit oral hygiene maintenance
• •Strong enough to bear the rigors of day‐to‐day usage

• CLASSIFICATION

•REMOVABLE RETAINERS
•FIXED RETAINERS

REMOVABLE RETAINERS

•Hawley’s appliance With
long labial bow
With contoured labial bow
Continuous labial bow soldered to clasps
With elastic replacing labial bow
•Wrap around retainer
•Kesling tooth positioner
•Invisible retainers

FIXED RETAINERS

• •Fixed appliance
•Banded canine to canine retainer
• •Bonded lingual retainers

INDICATIONS

• •Maintenance of lower incisor position during late mandibular growth.
• •Closure of diastema
• •Maintaining bridge space
• •Compromised periodontal conditions with the potential for post‐orthodontic teeth migration
• •Prevention of rotational relapse
• •Prevention of relapse after correction of palatally placed canines
• •Prevention of opening up of closed extraction space, adult patients

ADVANTAGES

• •Reduced need for patient co‐operation
• •When conventional retainers do not provide same degree of stability
• •More esthetic
• •No tissue irritation
• •Reduced recall visits
• •Used as permanent retainers
• •Better tolerated

DISADVANTAGES

• •More difficult to insert
• •Increased chair side time
• •More expensive
• •Banded variety interfere with oral hygiene maintenance
• •More prone to breakage

Adams clasp

“L” clasp
“C” clasp
Long modified Adams clasp
Modified Adams clasps
Ball clasp