This can be the case where patients present, often in middle age with a combination of erosion and abrasion of tooth substance, often also in association with teeth irregularities, and some gum recession. Only a total assessment and virtual full mouth reconstruction can address all the problems here, and it may be necessary to restore some vertical height by means of bonded composite first sometimes in order to get the patient’s occlusion back to where it should be before the definitive crowns are provided. In these cases where significant support of the occlusion is required then bonded crowns are usually prescribed.
Porcelain veneers can be successful in treating gaps between teeth if they are not too large, but where they are, or are associated with tilting or twisting of teeth, then crowns may be required to adequately overcome the problems.
Crowns themselves do not always manage to achieve the ideal result that they might in terms of appearance due to a number of factors, and there can be problems with crowns themselves in some cases.
There can be a lot of difference between crowns prescribed by different dentists often due to the differences in their actual fabrication by different laboratory technicians, some of who may not be as skilled as others in providing such lifelike restorations. The ideal ceramist needs to have some artistic talent in addition to the exacting technical skills required for precision work with crowns and bridges.
The ideal porcelain crown should be fairly white, but of a shade that is natural, and of course fits in well with the patient’s own teeth. This may require some gradation of colour through the porcelain, either from top to bottom (i.e. gingival margin to incisal edge), or sometimes from a lighter central area towards a slightly darker mesial and distal. Sometimes a degree of translucence needs to be incorporated into the incisal one third of the crown, especially in the case of a younger person. It is essential to first study the patient’s own teeth in order to be able to replicate a natural appearance and this can require the technician to be allowed to examine the patient’s teeth in different lights as well as the dentist.
The margin of a crown can be a problem on the front aspect of a tooth because a tell-tale line here can spoil the overall appearance and make it obvious that it is a crown and not a natural tooth. It is necessary to have the best possible fit here, usually requiring a shoulder preparation for adequate thickness of crown material, and the margin is often placed just below the gum line to ensure that it is not visible. If the gum tissue is very thin here as it often is, and if the crown has a metal component, it can still sometimes give the impression of a dark line, and for this reason all-porcelain crowns are aesthetically preferable at the front of the mouth. Even with these though, a poor fit will encourage plaque formation and tend to cause gum shrinkage and an exposed margin. This is one area where the tapering fit of a thin porcelain veneer is aesthetically better than many crowns.
The perfect crown is all but indistinguishable from a natural tooth and is a joy to behold, but it requires considerable skill on the part of the dentist and technician to achieve something close to perfection which only dedication and patience can aqccomplish.