As a general rule we adopt a conservative approach when restoring lost tooth structure, using a minimal tooth preparation technique so as to retain the maximum amount of tooth structure.
Tooth-coloured composite restorations using a direct bonding technique are ideal materials for such an approach, but there are however many clinical situations in which this is just not possible or recommended. In such instances we use ceramic, thus metal-free, materials for strength and aesthetics.
These restorations – crowns, bridges and veneers – are called indirect restorations, as they are not placed directly into or over the tooth at the time of preparation, but require that a putty type impression be taken of the tooth, which is then sent to a dental technician. The technician fabricates the restoration, and at a subsequent appointment the restoration is cemented or bonded onto the tooth.
What we require from a restoration is excellent life-like aesthetics, proper anatomy and biological contouring, decent contact areas between adjacent teeth, meticulous detail to fit of the restoration and proper shading, staining and surface glazing. To obtain all of these details takes time and expertise – this is why we use the services of an experienced dental technician.
In order to achieve a natural aesthetic result we practice metal-free dentistry, as opposed to the older type porcelain-fused-to-metal crowns (PFM crowns), which either have a dull appearance or a horribly obvious grey tell-tale margin from the underlying metal base. Our ceramic restorations are made of an extremely tough ceramic called Zirconia (zirconium oxide) which forms the high-strength substructure, with another ceramic, emax (nano-fluorapatite glass ceramic) layered over this for a pleasing aesthetic final result. Very tough, yet very natural.
A full crown restoration is a more clinically aggressive technique, but there are numerous indications for this option:
- when there has been substantial loss of tooth structure
- conservative restoration material is not strong enough to withstand constant chewing forces
- a conservative restoration is repeatedly failing, either by fracturing, coming loose, leaking around the margins, or leaving open contacts between adjacent teeth
- the remaining tooth structure is too weak, thin or undermined, and thus structurally unsound. There is a real potential of losing the tooth completely if not adequately restored or supported
- the tooth has had endodontic treatment (root canal therapy) – the removal of the tooth’s pulp results in the loss of its blood supply, and thus loss of fluid, so the tooth will dry out and become brittle and be extremely prone to fracturing
- very deep carious lesions in between teeth make it very difficult to create proper anatomy, decent contacts and a watertight seal with composite restorations
- for aesthetic considerations
- to replace lost biting surface structure in patients who brux or grind excessively
Ceramic bridges are placed to replace missing teeth, as an alternative treatment to either removable dentures or implants. They are a good alternative option when the abutment teeth onto which the bridge will be placed are also good candidates for full crowns themselves – thus achieving two results with one procedure.
Ceramic veneers are used mainly for aesthetic reasons – gaps, severe discolouration which teeth whitening cannot remedy, chipping of biting edges. They are less aggressive in terms of the amount of tooth reduction needed as compared to full crowns. They are indicated when there is sufficient and sound tooth structure to work with, and aesthetics is the main concern. They are especially good for closing up spacing between front teeth, or for building up underdeveloped teeth, as with what is known as peg laterals.