Prosthodontics Flashcards
What are complete dentures usually made of?
PMMA (acrylic)
How long should an acrylic denture last?
5 years
What can be used as an alternative to an acrylic complete denture if a patient is allergic to acrylic?
Nylon
How long does a Nylon denture last?
18 months
What are effects of edentulism?
- loss of masticatory function
- speech
- aesthetics
- self esteem
- quality of life
- general health effects
In more detail what are some of facial changes that occur in edentulous patients?
- no lip support so lips collapse inwards
- reduced facial height
According the Cawood and Howell classification describe the 6 stages of post-extraction ridge resorption?
stage 1 - before extraction stage
stage 2 - after extraction stage
stage 3 - high well rounded ridge
stage 4 - Knife edge shaped ridge
Stage 5 - low well rounded ridge
Stage 6 - depressed bone level
What can effect the rate of resorption of the ridge post - extraction of teeth?
- dependent on pre extraction state of the teeth and alveolar bone
What are some of the causes for rendering a patient edentulous?
- Caries
- Periodontal disease
- failing dentitions
- appearance
- tooth wear
- occlusal collapse (often caused by failing dentitions)
- occlusal collapse
What are Medical factors that can increase caries risk?
Xerostomia
Sjogren’s syndrome
Radiation caries
Developmental disorders
Disability
Dementia
Addiction
What factors can increase the risk of periodontal disease?
Susceptibility
Disability
Dementia
Medical factors
Social history
What can cause tooth wear?
attrition
abrasion
erosion
lack of posterior support
supervised neglect
What can cause failing dentitions?
- overambitious treatment
- cycles of replacement
- human, social and medical factors
What can cause occlusal collapse?
often secondary to other reason eg perio caries and tooth wear
What are the two methods of complete denture construction?
- conventional dentures
- replica dentures
When would you use conventional construction of complete dentures?
- if patient has never had dentures
- previous dentures are poor
- if you want to make major changes
- easier to correct faults
When would you use the replica method when constructing complete dentures?
- if patient happy with current dentures (dentures just worn)
What is the aim of a primary impression?
to accurately record clinical relevant landmarks without excessive tissue distortion
What is lab stage 1 in construction of complete dentures?
- casts poured in dental stone
- special trays made
What is the primary support areas on a complete upper denture?
hard palate
what is the secondary support areas on a complete upper denture?
ridge crest
which part of a complete upper denture is non- contributing to support?
denture border
where does there need to be relief areas on the upper denture?
midline suture and incisive papillae
Where is the primary support areas on lower dentures?
buccal shelf and retromolar pad
where is the secondary support areas on the lower dentures?
ridge crest and genial tubercles
Where on a lower denture might there need to be relief areas?
- prominent genial tubercles
- prominent mental tubercles
- lingual ridge incline and mylohyoid ridge
which part of a lower denture is non-contributing to support?
labial ridge incline
What materials can be used to modify primary impression trays?
- red ribbon wax, greenstick, putty and red composition
- can reduce tray extension with acrylic bur
What areas on a stock tray commonly have to be altered?
- reduction for buccal, labial and lingual frenulum
- reduction for mandibular tori
- palatal reduction (extending to far posteriorly)
What are the limitations of stock trays?
- trays not made to measure
- peripheral extensions often over or under extended
- limited sizes available
When would you maybe uses red composition without alginate when taking an impression?
- for primary impressions in a patient with a bad gag-reflex
- much shorter setting time
ideally what should be the distance between stock tray flange and denture bearing areas?
4mm
Describe the clinical procedure of primary impression taking?
- explain procedure to patient
- select stock trays you think will be most suitable
- asses the tray visually in the mouth by manipulating lips cheeks and tongue
- change tray size if need be or make modifications using acrylic bur or red wax if needed
- once happy apply adhesive to tray and wax
- mix alginate and load tray
-seat loaded tray in mouth - border mould muscle while alginate is setting (cheeks and lips)
- stick tongue out for lowers to get correct sulcus depth
- once set remove tray with sharp sudden movement
What material is used to make special trays?
VLC resin PMMA (acrylic)
What is used as a spacer when making special trays?
modelling wax
How thick a spacer do you need when your using alginate or silicone elastomers/ polysuphides to take master impressions?
3mm
when would you have no spacer when moulding special trays?
if the impression material to be used was going to be silicone elastomers or ZOE paste
What are the advantages of special trays?
- accurate peripheral extensions
- uniform thickness of impression material
-reduce amount of material needed = less discomfort for patient - records denture bearing areas more accurately
What factors make complete denture retention and stability difficult?
- reduced saliva
- CoCr dentures don’t adapt as well as PMMA
- incomplete palate (cleft palate)
- atrophic ridge
- fibrous ridge
- movement of soft tissues
- ## gag reflex (cant extend denture far enough)
What is adhesion?
the physical attraction of dissimilar molecules to each other
- saliva and mucous membrane
- saliva and denture base
What is cohesion?
the physical attraction between similar molecules
- salivary flow
What is a post dam seal?
A groove cut along the posterior palatal margin of the maxillary denture which produces a ridge on the finished denture to create a posterior seal to aid in retention
How would you achieve optimal retention and stability via the fitting (basal) surfaces of the denture?
- good palatal extension
- post dam seal (maxillary)
- good base shape (adaption to mucosa)
- good extension into the retromylohyoid fossa (mandibular)
- labial and bilateral soft tissue undercuts
How would you achieve optimum retention and stability via the occlusal surfaces?
- occlusal plane and level
- tooth position on arch in relation to ridge, tongue and oral musculature
- balanced occlusion
- good tongue control
How would you achieve optimal retention and stability via the polished surfaces of the denture?
- good contour of buccal, lingual and palatal shapes
- can take 7s out in lower to give tongue more space
What two things can be added to the mucosal surface to aid in denture retention and stability?
- denture adhesives
- implants (titanium)
during anterior tooth selection what 3 factors do you need to take into account that will effect the patient?
- appearance
- function
- speech
What dental factors may influence the choice of artificial teeth and gums?
- previous dentures
- ageing
- size of facial skeleton and skeletal class
- physiological pigmentation
- dentists perception
What patient factors may influence the choice of artificial teeth and gums?
- influence of others
- lifestyle, relationships and goals
- smileorexia
- phycological factors
- perception of aging
- self-esteem
What materials can be used for artificial teeth?
- acrylic (always unless allergic)
- porcelain
- composite resin based
- combination
What factors can influence shade selection of artificial teeth?
- colour washout
- illuminant metameric failure
- observer metameric failure
- technical errors
- patient photographs
- family members
- patient preference
What is the Leon Williams classification?
- Classified faces into square, tapering and oval
- Inverted shape of the face corresponded to the shape of the maxillary central incisor
What measurements are given on a teeth mould guide?
- width of the 6 anterior teeth
- width of central incisor
- length of central incisor
once you have selected the mould of your upper anterior teeth what guide tells you what mould you should use for your lower anterior and posterior teeth?
senator articulation table
What additions can you add to your denture during tooth setting which may give your denture a more natural look?
- characterisation
- imbrication
- diastema
- rotation
- straight
- natural
- recession