I have written this article in order to try and answer at least some of the questions you may have.1. The assessment and impression stages.
If you still have questions please e-mail me and I will do my best to answer your queries.
The dentist will discuss with you the reasons for having new dentures, along with your expectations and whether your expectations are achievable. The dentist will examine your mouth to check that all the tissue areas and any remaining teeth are healthy.
After any treatment that may have been required to make your mouth healthy, the dentist will take an impression of your mouth.
This is achieved using a material that is mixed to make a soft dough like material, this is then placed
within a metal or plastic carrier called a stock tray, these are shaped to fit the mouth over either the upper or lower jaw.
The impressions are placed into the mouth one at a time and allowed to set to a stiff rubbery
When removed from your mouth the impression is carefully checked to ensure that all
relevant information is present.
This impression is then sent to the dental laboratory with details of what
Image2 of impressions prior to casting
The impression, which at this time is a negative of your mouth, is cast by the technician to create a plaster cast
model of the inside your mouth.
Trimming The Plaster Cast Model
This is achieved by poring a material made from Plaster of Paris into the impression.
The technicians then use the plaster cast to start to manufacture your dentures.
The next stage, in most cases is that the technician will make a custom made (special) tray to your
individual model, this is so an even more accurate impression to be taken. This is necessary
because with the stock trays used to take the first impressions are only standard sizes, the Custom trays are made to measure. This of course means that at the next appointment at the dentist, some of the
same procedure as the previous one will be repeated. This impression is then returned to the laboratory
and again cast up to produce a model. This will be the model ( Master cast) your dentures are finally
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2. The registering of your jaw positions
Prior to your next visit to the dentist, the 'bite stage'. The technician moulds onto the master model a dental modelling wax to resemble a denture.
(To view my published article page on Dental Wax click here)
The dentist uses this wax mould to register the relationship between your upper and lower jaw.
He/She should also take measurements to determine the correct positions for the individual teeth to be placed.
At this time the tooth colour and size are usually chosen.
The tooth colours are chosen from (shade) guide, with the shape and size often chosen from a mould
These are supplied by the numerous manufacturers of the teeth.
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3. The Try-in stage
The dental laboratory having received all the information from the bite stage will use this information to construct the dentures, using the special wax and the chosen teeth.
To mimic the jaw relationship the Laboratory will hold the models in what we call an Articulator. This will enable the dentures to be made in the correct position in regard to each individuals mouth.
With the models mounted on the articulator, the correct teeth are selected from the information received from you and the dentist.
The wax is then softened using a hot knife, and each tooth is placed onto the wax, until all the teeth have been placed in what the technician believes to be the correct position.
The wax which will become the pink plastic part of your denture, is then shaped to blend in with existing tissues, to try and mimic the natural tissues.
This is then returned to the dentist to be checked with you for correct position of the teeth, correct biting postions, and general appearance.
Full set of Dentures on an Articulator
Dentures on an Articulator diferent view.
Completed dentures constructed in wax and mounted on an articulator ready to be sent to the dentist for the Try-in stage
When both you and the dentist are satisfied that they are correct, they are once again returned to the laboratory.
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4. The Fit Stage
With the wax dentures returned to laboratory, the technicians next stage will be to convert the wax portion of the denture to the finished pink plastic.
This is achieved by creating a plaster mould of the denture in 2 parts.
Dentures in 1 Part of the Plaster Mould
This mould is then immersed in boiling water to soften the wax. The wax when softened enables the 2 parts of the mould are separated, the remaining wax is then boiled away. This leaves the mould with the plastic teeth held in place in the plaster and a space where the wax used to be.
This space is filled with the plastic that is placed into the mould while in a dough like consistency.
(To view my published article page on Denture Plastic click here)
The 2 halves of the mould are then placed together and the excess plastic material is squeezed out under a press.
The mould is then held together under pressure and placed into a curing bath where the process of hardening the plastic takes place, usually over several hours.
When the denture has been processed and has cooled down, the denture is removed from the plaster mould. Any excess material is then trimmed off and the denture is polished.
Polishing the Denture
The finished denture is then returned to your dentist to be fitted at your next visit.
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5. The Final Checking Stage
After your dentures have been fitted the dentist will check that all is as it should be and make any minor adjustments.
After wearing your new dentures for a few hours or days the occasional sore place may develop, this is quite normal, but will require you to return to your dentist for the denture to be trimmed.
These sore spots often occur because the denture is processed onto a rigid plaster cast where as your tissues are soft and slightly pliable.
Your new dentures should now be Ok but just occasionally a further visit to your dentist may be required.
You can expect your new dentures to last you on average between 3-6 years, but we would advise that you have them checked at yearly intervals, as there are many factors that will determine how well they continue to fit and function.