Tooth Coloured Crown Procedures ( Porcelain Bonded to Precious Metal Crown)
The following is a short summary outlining the treatment and time-tabling of the commonest type of tooth coloured crown – the porcelain bonded to precious metal crown. There are many types of crowns available today but this is still the most commonly placed crown in my practice. Actual treatment may differ depending upon the clinical situation during your treatment.
Typically a tooth that needs a crown will already be heavily restored, broken or may have been hurting on biting. This is usually due to internal cracks in the teeth flexing or the nerve of the tooth being infected or dying. Indeed the tooth may already be dead and be in need of, or have had root canal therapy. At this surgery we routinely take an X-ray of a tooth to be crowned. This may indicate it’s suitability to be crowned or if a root therapy needs to precede the crown treatment.
( 1/2 hour )
This appointment is to take impressions of your mouth for the fabrication of stone models (study models). An X-ray for the tooth is usually taken at this appointment. These are used to help in the design and treatment planning of your crown. The models are also used to replicate your bite in the laboratory during the manufacture of your crown. Another use of the models is to form a vacuum moulded template to allow a temporary crown to be made for coverage in the time between the 2nd and 3rd appointments.
( 90 minutes – done in the morning)
This is a very long appointment that comprises many procedures. For this reason it is important not to be late as even 10 or 15 minutes can leave the dentist without enough time to complete all the procedures.
Typically the appointment will run as follows. A local anaesthetic will be given following application of topical numbing paste. The shade or shades of your tooth will be determined. All existing restorations and decay will be removed from the tooth. A new core (and possibly posts) will be placed, that is mechanically and chemically attached to the tooth and tooth root. We do not use amalgam in this practice. The material will set in a few minutes so the next stage of preparation can continue during the same appointment. The tooth is cut to size with the design allowing room for the future crown to have resistance to fracture, smooth margins, aesthetic appearance, good contacts and emulation of natural tooth form.
Also done during this appointment is an impression which involves placing 2 small cords around the gums and an accurate mould of your tooth is taken (these cords are only there for a few minutes). These models are then sent to the dental ceramist’s laboratory in Sydney. We don’t send work to be manufactured overseas.
At the end of this appointment we place a temporary crown. This takes place of the crown whilst it is being manufactured and protects the tooth and gums. The temporary looks like a tooth without having the strength or appearance of the finished crown and should be treated with care.
(A one week break is needed for the laboratory to make the crown.)
( 3/4 hour )
The temporary crown is removed. In most instances no anaesthetic is needed for this appointment. The permanent crown is tried in for fit, appearance and bite. In rare instances it may have to be returned to the laboratory for a shade or shape change. The crown is then permanently cemented to the tooth. No eating should be done on the new crown for one hour after the appointment.