12. Repairs, additions and Immediate dentures

Question 1

• Explain the reasons for denture fracture (like how do the fractures occur?)

Answer 1

Crack Propagation – small cracks develop into large ones with
sudden catastrophic failure
Stress Concentrations are ‘where the crack starts’

Question 2

Explain the reasons for denture fracture (including examples of when this might happen.)

Answer 2

Scratches
* Mid-line diastema
* Deep fraenal notch
* Inclusions: porosity, plaster, dust, nylon
filaments
* Metal strengtheners – so-called

Question 3

Explain the reasons for denture fracture including why the denture base might already be weakened.

Answer 3

Absence of labial flange
* Incomplete polymerisation
* Denture base too thin
* High occlusal loads
* Previous repair

Question 4

Explain the reasons for denture fracture- fracture of the denture base could happen by…

Answer 4

Trauma – dropped, high occlusal forces
* Alveolar resorption – poor fit
* Inaccurate impression – poor fit
* Inadequate relief – rocks on bony palatal torus
* Warping due to recuring – during repairs, rebase.

Question 5

Decision making…
Describe how dentures may be repaired…

Answer 5

(A lower denture is fractured in the midline…).
When deciding if a denture can be repaired, attempt to locate the pieces of the denture. If this can be positively done by hand and held in position, then repair is possible.
If the pieces cannot be easily located together, must consider conventional replacement of the dentures.

Question 6

*Describe how dentures may be repaired…

Answer 6

A fractured lower denture is assembled together and held in position, with a match stick and some sticky wax. This allows the technician to pour a temporary model into the denture, and grind away the area of the fracture, a key for replacement of repair acrylic.
The technician mix auto polymerising PMMA and apply it into the key and allow it to set. This is often set in a Hydroflask in water under pressure and heat and warm water applied to improve the cure of the auto polymerising material.

Question 7

• describe how additions may be made to dentures…(before and after extractions…)

Answer 7

Take impression with denture in mouth
* Ensure denture is correctly seated in
impression when removed, to maintain the correct relationship of the denture when seated in the mouth with the surrounding teeth.
Need to consider the need for opposing impression for the technician to manage the
occlusion appropriately when placing the new teeth.

Question 8

Immediate additions to lower RPD- clinical stages…
Replacing the missing lower lateral tooth (recently lost) and the remaining incisor and canine teeth

Answer 8

The denture is seated in position
Impression in alginate is taken ensuring we have a good impression of the lower anterior labial sulcus.
Teeth are extracted
Denture returned from laboratory with the additional teeth added to the denture converting the partial to a lower complete denture.

Question 9

Laboratory stages to replace lowers canines for a patient

Answer 9

(The patient is going to be rendered edentulous)
Impression is taken and the model is poured. It is Important that the relationship of the denture to the teeth is exactly the same as it is in the mouth
Model is poured, the teeth to be extracted are removed, the dentures are modified to accept the new tooth and the supporting wax work to hold it in position.
A little plaster index now holds the tooth in the correct relationship having been waxed up because the wax is now boiled away. Chemically cured acrylic will now be run in to replace the wax to hold it in position.

Question 10

What is an immediate denture?

Answer 10

Is a denture constructed before the extraction of the teeth which it replaces
and inserted immediately after the teeth
are extracted

Question 11

*Describe immediate dentures as a treatment modality

Answer 11

What are they and what are their advantages and disadvantages?

Question 12

Advantages of immediate dentures?

Answer 12

. No edentulous period
* Duplicate tooth position closely for good
aesthetic and functional result
* Tongue change prevented
* Sockets protected

Question 13

Disadvantages of immediate dentures?

Answer 13

• Can’t duplicate extreme tooth position or
  malocclusion – stability of dentures
  compromised
• Additional time and expense – lose fit
  quickly, rebase/remake required sooner
• When Multiple extractions not possible –
  ? access / health

Question 14

Clinical stages for producing immediate dentures?

Answer 14

Clinical procedures performed as for partial
dentures then after trial stage plaster teeth
removed from master cast and replaced and processed.