Prosthodontics Flashcards
define retention
resistance of the denture to displacement in a vertical direction away from tissues
define stability
resistance of the denture to displacement in a horizontal direction away from tissues
define support
resistance of the denture to occlusally directed load - vertical load towards the tissues
define indirect retention
resistance of denture to rotational displacement
what are some displacement forces
gravity
muscles
sticky foods
function
what are methods of retention of a denture
mechanical - clasps
physical - adhesion-cohesion, coverage of mucosa
muscular - muscles of lips, cheeks and tongue
describe adhesion-cohesion
adhesion is the attraction between dissimilar molecules - saliva and mucosa/denture base
cohesion is the attraction between similar molecules - saliva to saliva
what are the primary and secondary support bearing areas of maxillary dentures
primary - hard palate
secondary - alveolar ridge, maxillary tuberosity
primary - buccal shelf
secondary - alveolar ridge, pear shaped pad
how can you tell if a denture is over extended
retention will be good until the patient begins to talk and then it will fall down
when muscles manipulated - loose
how can you tell if a denture is under extended
retention will be poor when tissues lifted away - too much lip support
how can ulcers occur with dentures and how are they managed
trauma from over extended denture. may have fitted well but increased resorption has caused it to be overextended.
management - check with pressure indicating paste and articulating paper. occlusal reduction or trim and polish of denture base, denture hygiene advice - advise to leave out as much as possible to allow ulcer to heal. review to ensure healing - if no healing after 3 weeks despite no trauma - urgent max fac referral
what causes angular chelitis
increased FWS and reduced OVD causing over closure
also check - ferritin, b12, folate, diabetes
xerostomia - polypharmacy
infection at angles of mouth caused by candida albicans and staph aureus
what causes denture hyperplasia and how is it manage
ill fitting denture causing chronic irritation and trauma of denture - hyperplastic response
management - gross reduction to relieve areas - temporary reline with tissue conditioner coecomfort
once tissues healed - new denture
what material should be used for denture in patients with periodontally involved teeth
depends on prognosis of teeth
if likely to loose teeth soon - acrylic - more destructive to periodontium but easier to add to
if trying to preserve teeth - cocr - less destructive but cant add to
if a patient only has lower anterior teeth and a complete upper, why is it important to provide a partial lower denture
helps with denture transition - get used to a partial before requiring a complete
avoid flabby ridge - occlusal force will be on anterior maxillary mucosa - traumatic and increase resorption - will be replaced with fibrous tissue, a lower partial will help to distribute occlusal forces evenly
provide examples of when different relines/rebases can be used
temporary reline - tissue conditioner when ill fitting dentures causing pathology ie hyperplasia, stomatitis
soft reline - denture is painful in some areas, can improve comfort but needs to be replaced every 18 months - knife edge ridge
hard reline/rebase - when denture is underextended but teeth are not worn - remake of denture base to improve extension
how can dentures be repaired
simple repair - pieces all there and easily fit back together - no need for an impression
piece missing - take impression of denture in situ and send to lab
tooth missing - if patient has it - can be readded using self cure acrylic
what must patients be aware of if an addition is being done to a denture
they will be without the denture for a few days whilst waiting on lab
need to take imp of denture in situ and send to lab either immediate (before tooth is removed - deliver denture when take tooth out) or post immediate (2-3 weeks after xla)
what are advantages of acrylic dentures
cheap
easy to make
easy to alter - reline, rebase, additions
aesthetic
what are disadvantages of acrylic
low impact resistance
poor resistance to fracture fatigue
water absorption and candida growth
allergy to residual monomer
what instructions should be given to patients for denture hygiene
should remove after meals and brush with soft brush and soap
should soak once a day with disinfectant - milton or steradent - for 20 minutes (shorter if CoCr)
should remove at night time and store in water
should regularly visit dentist
what is the function of rests in a partial denture
to provide support - direct occlusal forces down long axis of tooth
what is the function of clasps in a partial denture
to provide retention
why should a rest not be adjacent to a free end saddle
to prevent distal loading
what is recirprocation
prevention of movement of clasped tooth
every action has an equal and opposite reaction
what is beading of a connector
ensuring the connector is 3mm away from gingival margin
what are index teeth and why are they important
teeth that are occluding in ICP - contacting facets of teeth
use these to conform to patients original occlusion
when doing record blocks for partials - use these as a guide, replicate original occlusion
