Overdentures Flashcards
What is retention and what is it affected by?
Good seal, keeping denture in place by adaptation to underlying tissues, good peripheral seal - sits nicely and needs effort to remove
Affected by soft tissues - cheeks and tongue fall on the polished surface
what is stability?
Wont tip
Instability can cause the denture to become loose
What can cause instability?
Break in the fitting surface - something hard e.g. retained root - difference on the fitting surface that changes the loading and the compressability of the material
May be associated with the opposing arch, fixed teeth working against the denture - uneven occlusion
Why is the alveolar ridge there?
When teeth removed, the alveolous is resorbed - reservior for calcium and phosphorous, used elsewhere
Why have an overdenture? what is it?
Leave the roots behind, bone not resorbed, preserving the alveolar ridge - better support for the denture
What does leaving retained roots cause?
Instability, also the benefit of preserving the alveolar ridge
How does the overdenture adapt to underlying tissues?
Estabilsh good peropheral seal
Convavity
Polished surface
Instability associated with difference on the fitted surface
instability associated with opposing arch, fixed teeth working against opposing denture
what is the definition of an overdenture?
is one which gains its support partly (may be resting no the ridges too) or wholly on roots of retained, decoronated or crown modified teeth
Could put the denture over implant
What are advantages of retaining roots
The retained root preserves the associated alveolar bone
The root face gives extra support to the denture - allows tissues to support greater occlusal loads and protects soft tissues against the effects of mechanical trauma
Extra retention gained via attachment e.g. magnet or CEKA
Psychological benefit
Retained proprioception and tactile discrimination - permits improved function, feedback from the PDL allows better discrimination of particle size and textures
What are the disadvantages of retaining roots?
More expensive - prepare the teeth, do RCT and seal in composite, prmarily in carrying out RCT but also because denture reinforcement and/or extra retention is needed
Failure can occur due to caries - forget to clean, reduced salivary flow under denture
Treatment takes longer - review is less expensive, prep work (RCT) and after care are more prolonged
why is failure of the root a problem
Extracting a carious root is complicated - need MOS
Bisphosphonates - vascularity of bone affected - osteonecrosis
The retained roots are susceptible to caries in the protected area under the denture
What are examples of cases where overdenture is specially indicated
When though alveolar resorption will be significant
When repeated alterations to dentures may be undesirable and extractions are contraindicated - elderly take longer to heal
When increases in face height are produced in cases of tooth wear or hypodontia - lack of teeth and lack of alveolar ridge formation
When it is thought that adaptation might be poor and extra retention is desirable
When is alveolar resorption significant?
Unopposed mandibular anterior teeth can predispose to maxillary atrophy
Retained mandibular teeth - accelerated resorption of the maxilla
Accelerated flabby ridge in the maxilla because of the presence of mandibular incisors
What do you need to consider for tooth selection?
Root
Tooth site
Bone
What do you need to consider when selecting a root?
A simple root canal shape
Adequate tooth size
Sufficient support
