Complete dentures Flashcards
What would you write on a lab prescription for after secondary impression? (3)
- Cast up secondary impressions
- Wax registration blocks for maxillary and mandibular arch
- Light cured acrylic base with occlusal wax rims
How does the Incisive papilla help as a reference marker for position of central incisors? (3)
The correct position of the incisal edges should be at the incisive papilla
The incisive papilla marks the midline of where the central incisors should meet
The main horizonal gauges – teeth placed 8-10 mm from incisive papilla for lip support
What are the clinical steps for a bite registration stage? (11)
- Check prescription has been followed
- Inspect registration rims on and off the cast, check for any rough edges or sharp bits on the denture, including fitting and polished surfaces before inserting in patients mouth
- Try in maxillary, check tray is fitting well, extended properly, sitting on ridge (extension, retention and stability)
- Use Foxes plane to check if occlusal rim of maxillary bite block is parallel with ala tragus line and inter-pupillary line
- Adjust as required by removing or adding wax until parallelism is achieved
- Try in lower, and check extensions, retention and stability
- Assess is the occlusal rim is parallel with maxillary rim
- Adjust as required by removing or assessing wax until parallelism is achieved
- Check for occlusal vertical dimensions (already measured OVD on first visit at rest e.g. 70mm, using Willis gauge, FWS = VDR (vertical dimension and rest) – OVD
- Use Willis gauge to measure, trimming lower and keep checking OVD
- Check lip support, modify rims required
- Check labial fullness, correct thickness of anterior region
- Mark midline, canine line, smile line, tooth show at rest
- Ask patient to go onto RCP, ask them to curl tongue to roof of palate and bite down
- Record by putting notches or grooves on ridges
- Make sure is biting down in RCP
- Bite registration paste Jet Bite– a-silicone, squirt material on lower arch and ask patient to bite down on RCP
- Now that we know the height
- We can do a neutral zone impression
- Know bite registration, need to create a tool to put inside patients mouth to capture neutral zone
- Technician will produce a light cure base, added wires or blocks of material to the bases
- Use viscogel, powder and liquid, sticky at beginning, time to manipulate
- Apply over ridge on areas you have created stops at height you have identified before in bite registration
- Put in pts mouth, ask them to do certain movements, tongue movements, mobilise posterior areas, say Mississippi, wait for material to set
- Very thin impression, capturing neutral zone for setting teeth so patient doesn’t bite on cheeks
- Remove from patients mouth
- Disinfect
- Send to lab for prescription for a try in denture
List 5 favourable features of an impression stock tray (5 marks)
- Be rigid and non-flexible under load when takin the impression
- Extend sufficiently to support the impression material in the region being reproduced
- Fit loosely around the dental arch and not touch the soft tissues
- Have adequate means of retaining the impression material in the tray
- Be able to be adequately decontaminated if not meant to be single use
List two impression materials which are suitable to make the first/primary impressions (2 marks)
- Alginate
- Impression compound
- Silicone putty
Choose one of these materials and list three reason why the material is suited for this purpose (3 marks)
- Adequate dimensional stability
- Adequate reproduction of surface detail
- Compatible with the casting material
- Accepted by the patient
- Easy to use
- Cheap
- Self-supporting (compo and silicone putty only not alginate)
How to make a special tray
- Spacers - material put in places to make room for impression material, specific thickness
- Tissue stop holes 2-4mm diameter – helps position the tray correctly in the mouth and ensures an even layer of impression material (control of setting expansion and less likely to displace)
- Tray material is adapted to the cast and excess trimmed away
- Stub handle made from excess material and added in line with middle of palate, handle 10mm high
- Finger rests – not impinge upon tongue, not extend above occlusal plane, near 2nd premolar/1st molar teeth
- Set - light cure 3-5mins, remove spacer and set inside for 3mins
- Smoothed sharp areas
- Trim areas for frena, 2mm clear of periphergy for bournder moulding
- Tray periphery 2-3mm thick, rest of tray 1-2mm thick
Custom tray for flabby ridge
- Alveolar ridge mobile, resilient
- Anterior part of maxilla
- Fibrosis and inflammation, resorption of underlying bone
- Causes replacement of bone by fibrous tissue, ecessive load of residual ridge, unstable occlusal conditions
- Poor support of dentures
- Removed surgically to provide stability
- Mucostatic impression on these areas
- Selective pressure impression technique
- Impression made with medium bodied
Why do you need to border mould
To obtain peripheral seals, optimum retention, the tight contact between full denture base and the mucosa around the periphery of the full denture boundary to prevent entry of air between the base and the mucosa
Outlines the ideal and optimum peripheral extension of the denture where muscles will be attached and captures functional depth of sulcus
Stop over extended dentures causing dislodgement via cheek muscles during functional movements
Why we need to see denture patients yearly + 5 years remake (8 marks)
Bone resorption
Changes in face shape/weight loss
Check denture is still fitting well and if needing any adjustments
Denture stomaitits??
Check for sores, ulcers
Make sure patient is cleaning and looking after them properly
Doesn’t fit as well as it should
Adults with incapacity (1)
The legal presumption (1) an adult can be assumed to have capacity in the absence of evidence that they do not
What legally covers you if later someone shows incapacity? (2 marks)
Adults in Capacity Scotlands Act
Assessment of mandibular lower tray fitting (4)
- Visually asses the height and width of the mandibular residual ridge (1)
- Use the index finger to assess the depth of the distolingual sulcus and the mylohyoid ridge (1)
- Eyeball and select a tray that approximately fits the residual ridge. Manipulate the lips, cheeks and the tongue to check approximate fit of the tray to the residual ridge.
- Ensure that the tray do not overextend into the labial, buccal and lingual sulci.
- Ensure the tray is not underextended such that the impression material will not be supported by the tray along the periphery (1).
- Ensure the tray extends over the retromolar pads (1)
Rigid? (1)
Materials for a primary imp (3)
Alginate (irreversible hydrocolloid), impression compound, lab putty (copy denture)
Full complete dentures, clear MH with no known allergies.
5 desirable features of an edentulous stock tray?
Rigid, correct size for patients mouth, comfortable for patient, handle, perforations, able to decontaminate, retention, non-flexible
Mr Keys is an 80-year-old man who attends your practice complaining about his current complete dentures. He explains that his current set of dentures are approximately 10 years old and they no longer stay in place. He has been edentulous for 40 years and this is his third set of dentures. He suffers from arthritis affecting his wrists, hands and knees. He takes painkillers regularly, mainly ibuprofen and codeine. The images below show the maxillary and mandibular edentulous arches of the patient.
Following intra-oral examination, you notice the patient has a severely resorbed mandibular ridge (Class VI; Cawood and Howell, 1988).
Q) Describe how you would identify the denture bearing area and the position of the residual ridge. (6 marks)
Visualize inspect patient’s mouth
Palpate residual ridge to assess height and width
Take primary impression with stock and border moulding which will allow you to see the
* Extensions
* Undercuts
* Thickness
* Width and depth
* Identify anatomical landmarks – retromolar pad, maxillary tuberosity, hamular notch, pear-shaped pad, genial tubercles and mylohyoid line, vibrating line, soft tissues
Mr Keys is an 80-year-old man who attends your practice complaining about his current complete dentures. He explains that his current set of dentures are approximately 10 years old and they no longer stay in place. He has been edentulous for 40 years and this is his third set of dentures. He suffers from arthritis affecting his wrists, hands and knees. He takes painkillers regularly, mainly ibuprofen and codeine. The images below show the maxillary and mandibular edentulous arches of the patient.
Following intra-oral examination, you notice the patient has a severely resorbed mandibular ridge (Class VI; Cawood and Howell, 1988).
Q) What type of occlusion would you prescribe for this patient, and indicate its characteristics in terms of dynamic relationship? (3 marks)
- Conventional bilateral balanced occlusion - ICP = RCP
- Lingualizes bilateral balanced occlusion - Maxillary lingual cusps contact mandibular occlusal surface, patients with severe ridge resorption, buccal cusps take no part in articulation
- Monoplane occlusion - functional but not aesthetic, flat surfaces on flat surfaces
Mr Keys is an 80-year-old man who attends your practice complaining about his current complete dentures. He explains that his current set of dentures are approximately 10 years old and they no longer stay in place. He has been edentulous for 40 years and this is his third set of dentures. He suffers from arthritis affecting his wrists, hands and knees. He takes painkillers regularly, mainly ibuprofen and codeine. The images below show the maxillary and mandibular edentulous arches of the patient.
Following intra-oral examination, you notice the patient has a severely resorbed mandibular ridge (Class VI; Cawood and Howell, 1988).
Q) The ‘finished’ dentures are returned for fit, they have been processed in acrylic as requested. On inspection, you notice ‘bubbles’ in the thickest parts of the dentures. What is this phenomenon called (appearance of bubbles in the heat-cured acrylic) and how does it occur? (3 marks)
Gaseous porosity because the temperature hasn’t been controlled
Gaseous monomer forms causing gaseous porosity
Final dentures are made from heat-cured acrylic
Raise in temp to initiate polymerisation
Avoided by allowing a controlled rise in temp
Can cause crazing if not controlled – internal cracks
Mr Keys is an 80-year-old man who attends your practice complaining about his current complete dentures. He explains that his current set of dentures are approximately 10 years old and they no longer stay in place. He has been edentulous for 40 years and this is his third set of dentures. He suffers from arthritis affecting his wrists, hands and knees. He takes painkillers regularly, mainly ibuprofen and codeine. The images below show the maxillary and mandibular edentulous arches of the patient.
Following intra-oral examination, you notice the patient has a severely resorbed mandibular ridge (Class VI; Cawood and Howell, 1988).
Q) In the case of mandibular dentures, the physical forces of adhesion, surface tension and capillary action are less effective in stabilising the denture. What other forces or factors contribute in stabilising this mandibular denture? (5 marks)
Cohesion – force of attraction between like molecules, maintains integrity of saliva
Muscular forces – patient skills and design of denture
Physical forces – atmospheric pressure and peripheral seal
Saliva viscosity
Effective border seal
