Retention Flashcards
What are the schools of thought on retention?
The occlusion school (if in class 1 occlusion it is stable and will stay)
The apical base school (if it is within the base of the alvveolar bone itll be fine
The mandibular incisal school (if kept at a 90 degree angle to the mandibular plane angle then good retention)
The musculature school (achieve muscular equilibrium and good tongue cheek lip pressures and good retention would result)
What are the theorems observed about tooth movement developed by Richard Riedel?
Teeth which have been moved in or through bone by orthodontic appliances often have a tendency to return to their former positions.
The elimination of causes of a malocclusion will prevent recurrence
Overcorrection of a malocclusion is a safety factor in retention.
Occlusion is an important factor in retention; therefor an orthodontist should attempt to produce the best possible occlusion of teeth
Bone and adjacent tissues must be allowed to reorganize around the newly positioned teeth for some length of time
Placing lower incisors upright +/- 5 degrees from perpendicular to the mandibular plane will result in more stable correction of malocclusion and they are more likely to remain in good alignment
Corrections carried out during periods when the patients are growing are less likely to relapse
The farther the teeth have been moved the less likelihood of relapse similar to overcorrection
The arch form particularly in the mandibular arch cannot be altered permanently by appliance therapy. Treatment should be directed toward maintaining the arch form presenting by the original malocclusion
What are the most important rules to Richard Riedel?
Teeth tend to move back to their former position
The arch form of the mandibular arch cannot, in the majority of cases be permanently altered by appliance therapy
Bone and adjacent tissues should be allowed time to reorganize around newly positioned teeth
What factors influence the retention of treated malocclusions?
Tooth-size discrepancies
Axial inclinations
Growth
Root paralleling in extraction cases
Equilibrium (overemphaseized effect)
Musculature (cannot accurately predict stable position with respect to equilibrium of muscle)
Duration of retention
What should be done to ensure retention if the maxillary anterior teeth are too large for the mandibular teeth?
Maxillary teeth should be placed in one of several positions:
Deep overbite
Greater overjet
Combination of greater overbite and overjet
Maxillary posterior teeth fitting into a more or less distal relationship to the mandible
What happens if the incisors are too upright?
The overbite becomes really deep.
How does growth influence retention?
Growth is often an aid in correction of orthodontic problems but it is also a cause of relapses.
There is a marked difference between males and females
Which cases require no retention?
Anterior crossbite when adequate overbite has been established
Posterior crossbite after good interdigitation
High cuspid extraction cases
Cases in which maxillary or mandibular molars have been tipped distally or premolars tipped mesially to provide space for eruption of second premolars
Class II cases treated with headgear once growth period has passed
Malocclusions treated by serial extractions only
Which treatments require permanent or semi-permanent retention in one of both arches?
Expansion cases
Class II or III relationship
Severe rotations or severe labiolingual malposition
Spacing
severe overbite in class II Div 2
Cleft palate lateral expansion
Which treatments require varying lengths of retention or greater lengths of retention?
Class II cases extraction or non-extraction
Deep overbite
Class II div 2 cases
Class III corrections with surgery requiring varying length of retention
Cases involving ectopic eruption of teeth or supernumeraries have been present requiring varying lengths of retention period
What are the 3 dogmas of incisor position and stability?
The most stable position for a lower incisor is a cephalometric mean: 90 degrees to the mandibular plane with 5 degrees of standard deviation
Best position for the lower incisors is its original position
There is only one stable position of the lower incisor, in fact, the original malocclusion may be the most stable position
What intrarch factors affect the stability of occlusion?
Reorganization of periodontal fibers
Functional occlusion and stability (Multidirectional chewing had minimal migration of teeth long centric of 0.5 - 1mm from CR is ok)
What is the functional vs anatomical occlusion aim of orthodontic therapy?
To establish a good functional occlusion that is in harmony with the TMJs and mandibular musculature, along with an efficient masticatory apparatus and healthy periodontium.
What are the criteria for an ideal functional occlusion?
Maximum intercuspation
Stress should be directed along the long axis
Posterior teeth should contact equally and evenly
Minimum OJ and OB, but sufficient overbite
Minimal interference
What are the signs and symptoms of occlusal disharmony?
TMD
Occlusal wear and bruxism
Excessive tooth mobility and/or perio disease
Movement or relapse of tooth positions.
What are the 4 types of centric discrepancy?
1) Tooth or inclined plane interference deflects the mandible off the teriminal hinge arc of closure
2) Due to failure to correct the jaw relationship anteroposteriorly
3) Due to insufficient ramus height or short posterior face height/ skeletal open bite pattern
4) Asymmetry of the mandible
What is desired with articulation of teeth and mandibular movement?
Straight protrusive movement
Canine guidance during lateral movements
How should the retention phase be planned?
1) Obtain informed consent (no guarantee it’s gonna work)
2) Original malocclusion and patients growth pattern should be taken into account.
3) Type of treatment performed: Removable (6 months), or fixed
4) Soft and hard tissue adjunctive procedures to enhance stability, fiberotomy, surgical gingivoplasty, frenectomy, and interproximal stripping
5) Type of retention: removable, fixed, passive, or active
6) Duration of retention: No clear indication
What are the advantages and disadvantages of fixed retainers?
Advantages:
Retain corrections of incisor irregularity
Compliance free
Disadvantages:
Less effective with inherently unstable malocclusions
Patients often dismissed
Technique sensitive
What are the advantages and disadvantages of removable retainers?
Advantages:
Cleanness - flossing
Inherently unstable procedures work better
Capability of correcting minor tooth discrepancies
Less time consuming
Patient can be weaned off the appliance
Disadvantages:
Essex retainers - anterior open bite due to posterior teeth overerupting
What are the criteria for ideal removable retainers?
Able to allow for functional occlusion
Sturdy enough to withstand long term use
Flexible enough to allow normal physiological movement of teeth
Convenient for orthodontist to provide and maintain
Patient friendly in both comfort and wear routine
What are the classes of retention based on retention mechanics?
Fixed retention
Removable retention
Functional elastic retainers
