RETENTION & RELAPSE
By Ahmed Nasef Abdel-Hameed Lecturer of Orthodontics Faculty Dentistry, Mini University M.Sc., PhD in orthodontics Retention
Maintaining newly moved teeth in position, long enough to aid in stabilizing their correction
Using a passive appliance to maintain the post-orthodontic correction of dental and skeletal structures Why is Retention Necessary
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 Types of Retention according to time
No Period of Retention Standard Period of Retention Permanent Period of Retention Some serial extraction cases
Anterior cross bite with adequate bite
Posterior crossbite with adequate cusp height Types of Retention according to time
Standard Period of Retention Most cases routinely treated fall in this category.
Retention is given to allow bone and 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. Types of Retention according to time
Permanent Period of Retention
Midline diastema. Severe rotations. Arch expansion achieved without ensuring good occlusion.
Patients with abnormal musculature or tongue habits. Expanded arches in cleft palate patients. Factors affecting retention period
1- Original mal-occlusion. 2- status of perio-oral muscles.
3- Etiology of malocclusion. 4- Skeletal age of the patient.
5- Cooperation of the patient. 6- Distance of the teeth movement.
7- Length of active period. 8- Status of cranio-facial growth.
9- Post-treatment occlusion. 10- Status of third molars
11- lengths of cusps. 12- Age of the patient RETAINERS
Passive orthodontic appliances that help in maintaining and stabilizing the position of teeth long enough to permit reorganization of supporting structures RETAINERS Types of Retainer
Mechanical Balance appliance occlusion 1. Removable Retainers Last removable appliance 2. Fixed Retainers 3. Active RetainersFunctional appliance after correction Designed in 1920 byHawley Charles retainer Hawley. Most frequently used retainer Consists of claps on molars and a short labial bow extending from canine to canine having adjustment loops RETAINERS
CLIP-ON RETAINER OR SPRING REALIGNER
- Wire framework that runs labially over the incisors and passes between canine and premolar and is recurved to lie over lingual surface. - Clear acrylic. - Correction of rotations - Less comfortable than Hawley - Not as good in overbite maintenance - Indicated in periodontic cases where splinting is needed RETAINERS
BEGG’S RETAINER
- Labial wire extends till the last erupted molar and curves around it to get embedded in acrylic that spans the palate. - There is no cross over wire that extends between the canine and premolar thereby eliminating the risk of space opening. RETAINERS
WRAPAROUND RETAINER
- Wire passes along the labial as well as lingual surfaces of all erupted teeth which is embedded in a strip of acrylic. - Used in stabilizing a periodontally weak dentition. RETAINERS KESLING TOOTH POSITIONER
- 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.
- No need for activation at regular intervals - Bulky and difficult to wear full-time - Difficulty in speech and risk of TMJ problems - 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 RETAINERS
VACCUM-FORMED (ESSIX) RETAINER - Polypropylene or polyvinylchloride (PVC) material, typically .020" or .030" thick. - Plastic removable appliance
- Esthetic - Patient is more likely to wear - Inexpensive - Quick fabrication - Minimal bulk - High strength - No adjustments - Usually does not interfere with speech or function RETAINERS
Mechanical appliance 1. Removable Retainers Utilized2. Fixed in Retainers cases where stability is questionable and 3.prolonged Active Retainers retention is planned
Indications: Maintaining lower incisor position Severely rotated or spaced teeth Diastema maintenance. Implant or pontic space maintenance Retaining closed extraction spaces RETAINERS
2. Fixed Retainers
Maintaining lower incisor position 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 - all teeth (3-3) can be bonded together using a 17.5 mil braided steel wire - allow teeth to move physiologically RETAINERS
2. Fixed Retainers
Diastema maintenance. RETAINERS
2. Fixed Retainers
Implant or pontic space maintenance
To reduces mobility of teeth and often makes it easer to place the fixed bridge
Use a heavy intracoronal wire and bonded it to the adjacent teeth. RETAINERS
ORTHOPEDIC APPLIANCE AS A RETAINER
Chin cup, high-pull for class III till twenties
Chin cup, vertical-pull for open bite till late teen
Face bow with extra-oral pull in skeletal class II maxilla
Functional activator in class II mandible RETAINERS Types of Retainer
Mechanical Balance appliance occlusion
Adequate over bite Anterior cross bite
Inter-incisal angle Anterior deep bite
Antero-posterior intercuspation Dental arch relationship U /L canines, premolars, molars Relapse The loss of any correction achieved by orthodontic treatment after removal of retaining device. 1- Periodontal ligament traction Teeth moved orthodontically
Stretching of periodontal principal fibres and gingival fibres encircling the teeth
Fibres contract
RELAPSE
Relapse
2- Due to growth related changes
Patient with skeletal problems associated with class II and class III
Continued abnormal growth pattern after orthodontic therapy
RELAPSE Relapse
3- Bone adaptation:
Teeth moved recently are surrounded by lightly calcified osteoid bone.
No adequate stabilization of teeth
RELAPSE Relapse
4- MUSCULAR FORCES:
Teeth are encapsulated in all directions by muscles.
If muscular imbalance at the end of orthodontic therapy.
RELAPSE Relapse
5- Persistent etiology:
Cause of malocclusion not eliminated.
RELAPSE Relapse
6- Role of third molars:
If third molar erupt after the orthodontic treatment .
Exert pressure on the teeth.
Late anterior crowding .
RELAPSE Relapse
a- Increase in the reduction of deep bite & over bite
b- Re-opening of closed spaces
c- Re-crowding of de-crowded teeth
d- Re-collapse of expanded arch
e- Re-rotation of de-rotated teeth Sequelae of untreated Malocclusion poor dento-facial esthetics increased caries index predisposition of periodontal diseases substitution of malocclusion with more severe form improper mastication improper swallowing predisposition of respiratory diseases predisposition of speech problems TMJ disorders interfering with normal cranio-facial growth predisposition for accidental fracture of teeth bruxism and clenching GOOD LUCK