Past Newsletter: August 2009

Past Newsletter: August 2009

 

Dentistry terms and procedures are often misunderstood. Crowns and veneers are a case in point – although we have all heard of them, how many of you actually understand what they are and if they are the appropriate treatment?

Our third newsletter demystifies crowns and veneers, and gives you a better understanding of the different types of treatments available and how they can assist to give you a beautiful, healthy smile.

Yours sincerely
Dr Aleksandra Cerny

Crowns or veneers – is there a choice?

There is no such thing as a simple crown and veneer. There are different types of each and they perform different functions. Crowns are recommended when a damaged tooth is beyond repair – i.e., even if it was filled it would be too weak to bite on. The crown then performs the function of the outer structure of the tooth. Veneers, on the other hand, are usually recommended for cosmetic reasons. If whitening cannot be performed on teeth or if minor changes to the shape of the tooth are required, then veneers are considered.

Are there different types of crowns?

Answered simply – yes. If the tooth has a large cavity and filling material cannot sufficiently protect the nerve and remaining part of the tooth and root canals, a crown is indicated. But many of us don’t know that there are two types of crowns that are currently available. The most widely used crowns historically are the metal ceramic crowns that have a base or core of metal covered by three layers of ceramic to deliver the look of a natural tooth. However, these crowns make it difficult to identify underlying problems such as secondary decay or a ‘leaking’ crown as x-rays do not allow one to see through metal. While these crowns remain functional, technology advancements have seen the introduction of a new type of crown.

Zirconia crowns (also known as pure ceramic crowns) feature a core made of zirconia (or zirconium dioxide), a substance that delivers a core just as strong as a metal core for a crown. As with metal crowns, three layers of ceramic cover the zirconia core and the advantage is that the look is more natural – and x-rays can provide a view through the zirconia core, assisting to detect any problems that might occur underneath.

Gold crowns are used to a lesser degree and people find them less aesthetically pleasing. However, because gold crowns are extremely thin they are ideal for patients where there is not much space or vertical dimension, or if the ‘bite’ is close.

Which crown lasts longer?

Generally speaking, a metal or zirconia crown should last between 5 and 10 years. But any crown’s longevity will also depend on your habits, oral hygiene and how you take care of your teeth. Clenching and grinding can damage the crown and as many of us suffer from this, especially at night, a guard or retainer is recommended.

When should I consider veneers?

Veneers are offered purely as an aesthetic treatment such as providing a whiter layer or making minor changes to the shape of the tooth. Veneers will only work on a ‘vital’ tooth where the nerve is still intact. It cannot therefore substitute for a crown. Veneers are becoming increasingly popular with the exposure they have been getting on ‘extreme makeover’ shows but it is important to understand what they are used for, how they are applied and how long they last.

The process of applying a veneer is similar to that of a crown. However, when a crown is cemented to the remaining tooth structure, the margin or part of the crown that fits to the gum it fitted below the gum. With veneers, they touch the margin of the gum and if the gums recede, the edge of the veneer will be visible.

Chair side veneers is another type of veneer that makes use of white ‘filling’ material or resin that is applied as a thin layer over the tooth to build up shape or whiten. This type of veneer is not baked as with ceramic and can therefore discolour – although polishing regularly will prevent this.

Veneers rarely last more than three years and do not have the strength of a crown – they must be treated accordingly. Biting on veneers (veneers are usually applied to the front and side teeth, not back teeth or molars) is not recommended as they can crack or come loose.

With any dental restoration, oral hygiene and care is essential for the treatment to last as long as possible. Wear and tear, such as biting, grinding and clenching, all damage the restoration. It is therefore crucial to be conscious of how your teeth are treated. Be kind to your teeth and they will be kind to you.