Porcelain crowns, incorporating a metal alloy foundation, have been used for many years, but lacking the light transmittance of natural teeth, leave the patient with a slightly grey result. These metal crowns can cause a greying of the gums over time, and can also be responsible for allergic reactions. In recent years, newer, healthier and more effective materials have been discovered, giving patients a more satisfactory end result.
Consequently, the tissue-friendly material, zirconium, is now being used in dentistry. Zirconium coatings now offer a similar strength to the previously used metallic alloy used in the past. Zirconium is translucent, does not cause discolouration of the gums, is non-allergic, and is resistant to corrosion, and has since become the first choice for dental restorations.
When are zirconia crowns recommended?
- Zirconia crowns are generally used for aesthetic reasons to create a perfect smile
• To cover or replace teeth with severe discolouration resistant to ‘tooth whitening’ procedures
• As a treatment for genetic tooth discolouration
• To correct for ‘diastema,’ or crooked teeth, as an alternative to orthodontic treatment
• To restore teeth with caries or that have been previously filled
• To restore a deformed tooth
• Can be used as a bridge or veneer for molars
• As a front denture fixed to an implant, or implants
How long will a zirconia crown last?
Providing the patient submits to regular dental controls, zirconia crowns can last for many years. Natural teeth are living tissues, and may become deformed over time due to wear and infections, whereas zirconia crowns are resistant to change over time. However, changes of the mouth structure later in life may cause the zirconia crown to be adapted or replaced where necessary.
Will there be any damage to the underlying natural tooth in the event of the zirconia crown being replaced?
The patient will not feel any discomfort when the crown is removed, and there will be no loss of the natural underlying tooth tissue.
What are the aesthetic benefits of zirconia crowns?
Due to the light transmittance properties of the zirconia material the crown will have the same natural appearance of the patient’s existing natural teeth. Light passes through the enamel of healthy teeth, whereas, the metallic base of conventional porcelain crowns create an opaque, dull and artificial look to the teeth – zirconia crowns eliminate these aesthetic problems.
Can zirconia be used for those who are allergic to metals?
A zirconia crown does not contain any metal material, thus does not cause any allergic reactions.
Do zirconia crowns cause discoloration in future?
The polished and smooth surface of zirconia crowns does not allow for the accumulation of plaque, and neither does it allow for discolouration caused by tea, coffee and smoking.
Will zirconia affect the sense of taste or cause bad breath?
The use of zirconia will not cause any adverse effects to the mouth of the patient.
How is a zirconia crown attached?
The surface of the patient’s natural tooth is reduced very slightly. This may cause some swelling to the surrounding gum. When the swelling has reduced, a dental impression is taken. In our in-house laboratory, a zirconia base is produced matching the colour of the natural teeth. This is then given a fitting trial with the patient. Final adjustments are made, polishing takes place and the final result is permanently cemented into place. The patient can then use the zirconia crown as if it were their natural tooth.
How much tooth loss is required during the process?
As with the preparation for fitting a porcelain crown with a metal alloy base, the surface of the natural tooth is ground down by about 1-2 mm, with loss of material being slightly higher than when fitting a porcelain laminate.
Is the procedure painfull?
The procedure is undertaken with the use of a local anaesthetic. A temporary crown, matching the patient’s own teeth colour, is then attached to prevent sensitivity to cold or hot. A few patients might experience a mild tingling during the procedure, but generally the procedure is usually completed without problems.
Are there any aesthetic problems experienced during treatment?
A temporary zirconia crown will be attached for the front teeth of a similar design to the final permanent zirconia crown. This temporary crown is made of an acrylic material and not overly strong; however the colour match and shape will be very satisfactory.
Is it likely that a zirconia crown can break or be dislodged?
Zirconia crowns may crack or break in the case of excessive or adverse force, however the possibility of breaking or cracking is similar to the possibility of breaking a natural tooth. These problems can be cared for at our clinic. Zirconia crowns may fall out if the natural tooth supporting it beneath decays. In such cases, the tooth is treated where possible, and the crown is again cemented in place.
Can zirconia crowns be offered to people gingival disease?
There is no reason not to attach a zirconia crown after the gingival disease has been adequately treated.