Impressions for dentures Flashcards
What do you need to do before taking impressions?
Manage soft tissue inflammation e.g. traumatic ulcers or denture granulomas
Treat any oral infections e.g. candida infection, angular cheilitis
Remove any unwanted structures e.g. fibrous tissue (granuloma or flabby ridge), poor prognosis teeth etc
Tooth related complaints e.g. caries, perio, endo and extractions
How do you manage soft tissue inflammation?
E.G. Traumatic ulcers and denture granulomas
Remove causes:-
-trauma ulcer can be from denture border, fit surface or occlusal trauma
-granuloma - remove cause instead of surgery
How do you manage the two types of denture related oral infections?
Angular cheilitis - antifungal cream on corners of mouth
I/O candida infection (denture stomatitis) - antifungal oral rinse or ointment on denture surface or lozenges with dentures out
Treat the acrylic surface to remove stubborn fungal hyphae - overnight soak in sodium hypochlorite 2 weeks
What unwanted structures may you remove before impressions?
Fibrous tissue - denture granulomas and flabby ridges
Poor prognosis teeth - allow socket to heal
Overdenture/onlay denture AB preparations
Buried roots - may leave in situ if non problematic to preserve bone and avoid surgery
Ridge recontouring - of bone that interferes with denture e.g. torus, unwanted bony undercuts, increase inter-ridge space to make room for teeth
What shape should an impression border be relating to flanges and saliva seal?
Which areas are needed on the impression for upper complete dentures for this?
A denture flange not too thin and so that it fills the width of sulcus for accurate seal
Include post dam and hamular notch areas
What sulcus position should you record on your impression and how is this done?
Moving/functional sulcus rather than passive position
Border moulding or zinc oxide impression
Where and what are the different ways should posterior border for C/- be identified for your postdam?
Border should be non moving but displaceable tissue, junction bw hard and soft palate
Look at colour change bw the palates, identify fovea palati, palpate junction with flat plastic, ask patient to say ‘aah’ and see vibrating line
What is postdam and what needs to be done on impression and when
Lab will cast and cut postdam into cast. Extra ridge of acrylic digs into mucosa to give peripheral seal
Need to mark postdam area/line after disinfection of impression
Advantages of using zinc oxide/eugenol impression paste
Dimensionally stable
Excellent surface detail
Unaffected by saliva
Disadvantages of using zinc oxide eugenol impression paste
Not elastic - needs suitable path of withdrawal if udnercuts present
Contraindicated in dry mouths or if allergy to eugenols
Advantages of silicones impression material
Dimensionally stable
Good surface detail
Elastic
Easy to mix
Disadvantage of silicone impression material
Hydrophobic
What common errors occur when using double layer of impression material?
Rolled borders too thick
Impression extension errors
Surface detail errors
What can be added to stock trays if does not extend enough into sulcus depth and what do you need to avoid when placing this?
Pink wax and avoid too much inside tray - shape wax up the retromolar pad areas
What is ideal sulcus depth
2-3 mm from sulcus
