Prosthodontics

Question 1

define retention

Answer 1

resistance of the denture to displacement in a vertical direction away from tissues

Question 2

define stability

Answer 2

resistance of the denture to displacement in a horizontal direction away from tissues

Question 3

define support

Answer 3

resistance of the denture to occlusally directed load - vertical load towards the tissues

Question 4

define indirect retention

Answer 4

resistance of denture to rotational displacement

Question 5

what are some displacement forces

Answer 5

gravity
muscles
sticky foods
function

Question 6

what are methods of retention of a denture

Answer 6

mechanical - clasps
physical - adhesion-cohesion, coverage of mucosa
muscular - muscles of lips, cheeks and tongue

Question 7

describe adhesion-cohesion

Answer 7

adhesion is the attraction between dissimilar molecules - saliva and mucosa/denture base
cohesion is the attraction between similar molecules - saliva to saliva

Question 8

what are the primary and secondary support bearing areas of maxillary dentures

Answer 8

primary - hard palate
secondary - alveolar ridge, maxillary tuberosity

primary - buccal shelf
secondary - alveolar ridge, pear shaped pad

Question 9

how can you tell if a denture is over extended

Answer 9

retention will be good until the patient begins to talk and then it will fall down
when muscles manipulated - loose

Question 10

how can you tell if a denture is under extended

Answer 10

retention will be poor when tissues lifted away - too much lip support

Question 11

how can ulcers occur with dentures and how are they managed

Answer 11

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

Question 12

what causes angular chelitis

Answer 12

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

Question 13

what causes denture hyperplasia and how is it manage

Answer 13

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

Question 14

what material should be used for denture in patients with periodontally involved teeth

Answer 14

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

Question 15

if a patient only has lower anterior teeth and a complete upper, why is it important to provide a partial lower denture

Answer 15

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

Question 16

provide examples of when different relines/rebases can be used

Answer 16

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

Question 17

how can dentures be repaired

Answer 17

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

Question 18

what must patients be aware of if an addition is being done to a denture

Answer 18

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)

Question 19

what are advantages of acrylic dentures

Answer 19

cheap
easy to make
easy to alter - reline, rebase, additions
aesthetic

Question 20

what are disadvantages of acrylic

Answer 20

low impact resistance
poor resistance to fracture fatigue
water absorption and candida growth
allergy to residual monomer

Question 21

what instructions should be given to patients for denture hygiene

Answer 21

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

Question 22

what is the function of rests in a partial denture

Answer 22

to provide support - direct occlusal forces down long axis of tooth

Question 23

what is the function of clasps in a partial denture

Answer 23

to provide retention

Question 24

why should a rest not be adjacent to a free end saddle

Answer 24

to prevent distal loading

Question 25

what is recirprocation

Answer 25

prevention of movement of clasped tooth
every action has an equal and opposite reaction

Question 26

what is beading of a connector

Answer 26

ensuring the connector is 3mm away from gingival margin

Question 27

what are index teeth and why are they important

Answer 27

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