Retention and stability Flashcards
what is retention?
what keeps the denture from coming out
what is stability ?
does the denture stay in place during function
what are the 4 things that help with retention in a complete denture ?
what is the border seal?
- edge of denture
- food/air/ fluid can get underneath if you don’t have a good seal = these things can displace ensure from the tissues
- the gap must be as small as possible whilst allowing movement of the soft tissue
- need good impression to achieve good seal
- and good border moulding helps seal
what is a post dam ?
- raised border at the posterior part of the denture that seals air/ fluid out
- purpose: to provide an air tight seal between denture and palatal mucosa
- it presses slightly into hard palate
- too much post dam = trauma, ulceration
- not enough post dam = get things stuck in it displacing the denture and therefore won’t get good enough seal
how do we create a post dam?
- Clinically use a mucocompressive material along the back
edge of the impression tray - Technically – the technician creates a small groove in the
plaster at the back edge of the intended denture
how do we create an effective border seal?
- Non – perforated tray
- Use green / pink stick to compress the post dam area and record the functional width of the sulcus in the tuberosity
region - Ensure retention on the tray before continuing with impression by pulling down vertically
how does saliva help denture stick ?
- saliva particle stick to each other (cohesion) and the mucosa and denture (adhesion)
what can xerostomia be due to?
what muscles contract to hold denture in place?
buccinator
tongue
why is muscle control important?
hold denture in place
which conditions cause a lack of muscle control?
parkinsons
stroke
motor neurone
examples of accessory retention ?
Springs / suction cups now a historic oddity
Implant retained overdentures – becoming more popular as a treatment option for treatment of the atrophic mandible
Denture fixatives – shouldn’t be relied upon for daily use, but can give added confidence when used sparingly
why do we use implants for dentures?
Implants can be used to maintain bone, give support and
provide positive retention
* Higher degree of patient satisfaction
* Improved bite force
* Improved chewing ability
- only need a few to hold dentures
- implant retained over denture = can remove and clean
what is a fixed bridge ?
- harder to clean
what are fixatives ?
- Act by making the saliva more viscous
- Some dentists dislike fixatives as being an excuse for poorly constructed dentures
- Increased levels of plaque
- Patients who need fixative on a daily basis should seek dental treatment
- Zinc overdoses reported
- Numbness and tingling of arms and legs
- Problems with walking and balance
Positive findings
* Increased feeling of security
* Improved seal
* Improved maximum bite force
* Improved Quality of Life
what are some of the problems with denture instability ?
what are the causes of loss of stability
balanced occlusion
teeth meet evenly on both sides at the same time when the patient closes
balanced articulation
during lateral movements the contacts are
shared across as many teeth as possible
what is denture induced hyperplasia ?
scar tissue due to premature contacts
- use articulating paper to identify any pc
what do we mean by tooth position?
what happens if we have our teeth set too buccally?
- there will be a lot of pain in that area and rubbing
- no support as occlusal forces not on ridge
where should Lower teeth be set?
- slightly below tongue
- we do this so muscles of tongue can hold denture in place
what is the neutral zone?
Muscular forces keep denture in place, teeth must be placed in position where those forces are equal.
we have forces come from cheek and tongue
neutral zone is where these forces equal out
what happens if lower denture not placed over the ridge ?
will get displaced by mentails muscle esp when ridge is flat
- seen with ppl who have overjet
how do we want to set the teeth to allow for balanced articulation ?
- make sure theyre not flat
when we push our jaw forwards (in protrusion) what can we do to prevent dentures from displacing ?
- christen phenonmenon
- we set teeth in curve of spee
what articulator do we use for complete dentures?
average value
what can make dentures difficult to work around ?
