clinical stages Flashcards
What are the stages of making a complete denture
- Primary impressions
- Cast model and create special tray (LAB)
- Secondary impressions
- Cast models and create record rims (LAB)
- Jaw registration
- Mount on articulator and set up teeth (LAB)
- Try in
- Process to fit (LAB)
- Fit
What makes a good impression
An impression should record the entire functional denture bearing area to ensure maximum support, retention + stability for the denture during use
What anatomy should an upper primary impression have
- Hamular notch
- Vibrating line
- Fovea palatinae
- Torus paltaltinus
- Mucogingival line
- Buccal sulcus
- Palatal gingival vestige
- Labial sulcus
- Buccal frenum
- Labia frenum
- Incisive papilla
- Palatal rugae
What anatomy should a lower primary impression have
- Retromolar pad
- Lingual sulcus
- Lingual frenum
- Buccal frenum
- Labial frenum
- Labial sulcus
- Buccal shelf
- Buccal sulcus
9 Pear shaped pad
What is the vibrating line
Junction between the immovable and movable tissue of the soft palate
How can we identify where the vibrating line is
Get the patient to say ahhh
What is the fovea palatinae
The bilateral indentation near the midline of the palate
How is the fovea palatinae formed
Coalescence of several mucous gland ducts
Where is the fovea palatinae found
Posterior to the hard/ soft palate junction (vibrating line)
What is the torus palatines
Harmless bony ingrowth/ exostosis located on the hard palate
What is the palatal gingival vestige
Raided fibrous ridge on the palatal surface of upper residual ridge
What can the palatal gingival vestige be used to do
Distinguish palatal mucosa from vestibular buccal mucosa
can be used a a guide in position maxillary teeth
How should a denture sit
- Sit on firm tissue
- Accommodate for bony undercuts
- Upper should extend to the vibrating lien for a post dam
What criteria must a primary impression fulfil
- Must record tissues without distortion
- Must be completed with minimal discomfort to patient
- must cover max denture bearing area
- Free of significant voids
What makes a bad denture
- Significant voids
- Under extension
- Over extension
- Impression material not adhering to tray
- Not covering full denture bearing area
- Knife edged areas
What is impression compound made up of
- Resin
- Plasticiser
- Filler
How is impression compound used
- Softened in a water bath
- Placed in patients mouth then back in water bath to soften
What is the advantage of impression compound
- Non toxic
- Easy to use
- Can be re softened
- Muco displace
- Corrects gross tray problems
What are the disadvantages of using impression compound
- Poor surface detail
- Poor dimensional stability
What are the advantages of alginate
- Easy to use
- Well tolerated
- Elastic
- Viscosity can be altered
- Good surface detail
- Mucostatic
What are the disadvantages of alginate
- Poor stability after setting
- Cannot be added to
- Increases risk of drying out, shrinkage and syneresis
- Increased risk of swelling and imbibition
- Poor tear resistance
- Requires adhesive to stick to tray
- Unsupported alginate
What is alginate made up fo
Irreversible colloid
What is impression compound made up of
- Resins (paraffin wax, beeswax and shellac)
- Filler (Talc and chalk)
- Plasticiser (stearic acid)
What is silicone putty made up of
Polydimethyl siloxane and platinum catalyst
What are the advantages of silicone putty
- Easy to mix
- Relatively easy to use
- Moderate surface detail
- Well tolerated
- Elastic
- Supports its own weight
- Muco compressive
What are the disadvantages of silicone putty
- Expensive
- Needs tray adhesive
- Long setting time
- Hydrophobic
What do we put in out lab prescription after taking the primary impression
- Draw tray outline approx 2mm short of periphery of impression
- Decide on need for spacing or close fitting design
- Upper handle slightly labially proclined
- Lower vertical handle and finger rests in premolar region
What do we need to add onto special trays to take a secondary impression
Stops
What are the purposes of stops
- Allows for space for material to flow out
- Prevents build up of hydrostatic pressure
- To ensure we get an even layer of material
what are the steps we take for an upper occlusal rim
- Line upper rim with shellac
- Correct lip support
- Adjust incised level by getting the patient to smile
- Ensure occlusal rim is parallel with inter pupillary Line
- Ensure occlusal rim is parallel with Ala tragal plane
What is the ideal naso labial angle
90-100 degrees
How can we alter lip support
By adding or removing wax