Complete dentures Flashcards
What is a complete denture?
- Removable dental prosthesis that replaces entire dentition and associated structure of maxilla and mandible
What are complete dentures made of?
- PMMA acrylic
- Cobalt/chromium
What are some effects of edentulism?
- Loss of masticatory function
- Appearance
- Self esteem
- Soft tissue changes to lip and chin
- Reduction in face height
- Ridge resorption
When does post-extraction resorption most rapidly occur?
- Occurs rapidly after XLA in 1st 6 months
- Occurs throughout life as well
What are the Cawood and Howell’s classifications of alveolar ridge?
Class I - Dentate
Class II - Immediately post extraction
Class III - Well rounded ridge form, adequate in height and width
Class IV - Knife-edged ridge form, adequate in height, inadequate in width
Class V - Flat ridge form, inadequate in height and width
Class VI - Depressed ridge form
Why do we render patients edentulous and make complete dentures?
- Rampant caries
- Periodontal disease advanced with unrestorable teeth
- Severe and debilitating toothwear
- Occlusal collapse
- Appearance
- Head and neck cancer
Why use a replica denture?
- AKA copy dentures
- Maintains existing aesthetics
- Keeps existing design easier to adapt
- Major mods difficult tho
What is included in denture history?
- Age of dentures
- Matched set
- Most recent worn
- How many
- How often worn
etc
Social history you need to be cautious of for denture?
- Mobility
- Barriers to treatment
- Alcohol/smoking
- Capacity to consent
- Support needed
What do is included in assessment of mouth and facial tissues?
- Tissues healthy
- Do they require management before new denture
- Angular cheilitis
- Denture stomatitis
- Denture hyperplasia
What intra-oral are you looking for?
- Support in edentulous areas upper and lower
- Mouth opening (trismus)
How do you calculate freeway space?
Vertical height - RVD - OVD
What are the key concepts you are examining when denture is in mouth?
- Anterior and posterior occlusal planes
- Freeway space
- Occlusion recorded correctly
- Lip support
- Overextension or underextension
- Retention, stability, adaptation
In upper jaw what are the support areas we look for in impressions?
Primary = Hard palate
Secondary = Ridge crest
Denture border does not contribute
In lower jaw what are the support areas we look for in impressions?
1ry = Buccal shelf and pear shaped pad
2ry = ridge crest and genial tubercles
N/C = labial ridge incline
Relief area = lingual ridge and mylohyoid ridge
What is ICP?
- Intercuspal position
- Complete intercuspation of opposing teeth independent of condylar position
What is RCP?
- Retruded contact position
- Guided occlusal relationship occurring at most retruded position of condylars in joint cavities
- Most reproducible position and use in complete not ICP
What is retention?
- Resistance to displacement of denture away from ridge
What is stability?
- Ability of denture to resist displacement by functional stresses
What is adaptation?
- Degree of fit between prosthesis and supporting structures
What is involved in pre-treatment phase?
- Get tissues healthy prior to prosthesis
- Referral for investigation or further opinion if concerns about mucosa
What are primary impressions used for?
- Construct model casts
- Treatment planning
- Construction of special trays
How can stock trays be modified to fit denture bearing area?
- Reduced with acrylic bur
- Soft red wax
- Greenstick
- Putty
- Composition
Benefits and cons of putty?
- Expensive
- Short setting time
Benefits and cons of soft red wax?
- Cheap
- Can manipulate easily in hands
- Poor dimensional stability
Benefits and cons of red composition?
- Cheap
- Requires boiling water
- Less available in practice
- Very short working time
Benefits and cons of greenstick?
- Cheap
- Rarely used in stock trays
- Requires intense heat
- Tricky to manipulate
- Runny so suited for smaller additions on special trays
What materials are used for denture impressions?
- Alginate
- Red composition (useful if patient retches but have to be quick as rapid working time)
- Silicone elastomers/polysulphides
How many mm should be between tray flange and denture bearing area?
- Approx 4mm
What is the clinical procedure for primary impressions?
- Thin layer adhesive over tray and putty/wax and let dry
- Mix alginate and load tray
- Set into mouth
- Border mould muscles (cheeks and lips whilst supporting tray)
- Once set remove with sharp movement
- Assess
What are you assessing for in an impression?
- Are edentulous areas included
- Are sulci areas included
- Deficiencies due to air inclusion?
- Fit for purpose
Why are master impressions done?
- Record denture bearing area, functional depth and width of sulci
- Use special trays prescribed after primary
What landmarks are we looking for in upper denture bearing area?
- Labial sulcus
- Labial and buccal frenum
- Incisive papilla
- Palatine rugae
- Buccal sulcus
- Hamular notch
- Tuberosity
- Vibrating line and palatine foveae
What landmarks are we looking for in lower denture bearing area?
- Labial, buccal, lingual sulcus
- Labial and lingual frenum
- Buccal shelf
- Retromolar pad
What can special trays be made of?
- VLC resin PMMA (acrylic)
- Self-cure PMMA (acrylic) (hard to roll even layer)
Benefits and cons to VLC resin PMMA as special tray material?
- Easy to mould
- Pre rolled sheets
- Very rigid and can be hard to remove from model
What are some advantages of special trays?
- Accurate peripheral extension
- Uniform thickness of material
- Reduces amount of material so less discomfort for pt
- Records denture bearing area more accurate
What are mould stops used for and with what?
- Greenstick
- Maintain spacing for material to allow consistent placing of tray
- Because extension should be approx 2mm short of sulcus depth to allow border moulding
What are the aims of master impressions?
- Well rounded borders
- Minimal air blows and none in important areas
- All clinically relevant areas included
What should you be careful of with master impressions?
- Underextended tray leads to underextended impression
- Incomplete tray seating
- Sharp border to lingual pouch
- Overextended tray leads to overextended impression
How must alginate impressions be handled?
- Kept moist and cast asap
- V imp for masters
How should elastomer impressions be handled?
- More dimensionally stable so don’t need moist environment
- Cast to avoid damage
Disinfection of impressions?
- Needed to prevent cross contamination of micro-organisms via blood or saliva
- Rinse in running water to remove saliva, blood or debris
- Disinfect for 10mins in disinfectant sol
- Rinse thoroughly with clean gloves
- Damp towel around them
- Label and place in plastic lab bag
- Lab prescription disinfected and take to lab asap for casting
What is an impressions?
- Reverse or negative form of the tissues
- It is converted into positive model/cast using plaster or stone or mixture of both
Where should you stand for impression taking?
- Upper stand behind
- Lower stand infront
- Patient not flat
What are tissue stops used for?
- Used with spaced trays either primary or secondary
- Ensure uniform thickness of impression material
- Help localise tray during impression taking
- Greenstick or incorporated into tray in acrylic
Where are tissue stops placed?
Lower tray = canine region and over retromolar pad
Upper tray = Canine region and post dam area
What are finger rests used for?
- Lower special trays
- Placed in 2nd premolar and 1st molar region
- To support mandible and ensure even distribution of pressure to tissues
- Help stabilise tray in mouth
When are close fitting trays used?
- Spacing up to 1mm
- Resorbed ridges and replicas
- Use light bodied elastomers like ZOE
When are spaced trays used?
- Most common
- 3mm spacing
- Alginate or heavy body elastomers
- Most situations
What is mucocompression?
- Pressure applied to mucosa so shape of tissues under load is recorded
What is mucostasis?
- Minimum pressure applied to tissues to record shape at rest
