Restorations that are left high tend to cause considerable problems to dentists and patients. Of the countless restorations placed every day, it is unlikely that all will be contoured to hair’s-breadth accuracy. Clearly, some will be left high. While some patients will ignore a high restoration and may eventually adapt to it or wear it down, others will not.

For patients, a high restoration is a matter of discomfort or inconvenience. The patient may well return complaining of pain (usually as tenderness to percussion, but sometimes headaches, muscle soreness, or TMJ pain) or the restoration will break, a cusp will fracture, or there may be tooth mobility and drifting. None of these consequences are good for building up a practice.

Carving or shaping a plastic filling before it is set is relatively straightforward. By contrast, the time spent repeatedly marking, removing, adjusting, and replacing a crown, bridge or onlay can be maddening as the profitability of the exercise evaporates with every turn of the bur. 

Given that accurate materials are being used by skilled dentists and technicians, the restorations coming back from the laboratory should only ever need the minimum of adjustment, but this is not necessarily the case. The key to avoiding a laboratory-made restoration being high is to understand why it happens in the first place. It is invariably human error at one or more of the following stages:

The working impression: This is not a likely source of occlusal error. Accurate materials and strong adhesives are available which do not normally allow the impression to pull away from the tray. The flexibility of the tray can occur with very viscous materials such as putty, but, although this affects the die, the effect on occlusal accuracy is likely to be small.

The opposing impression: The opposing impression has the potential to be the source of considerable occlusal error. Gross distortions of the impression where it pulls away from the tray are common. They result in casts that look fine, but which simply do not articulate properly. 

The occlusal record: Although a wax or silicone record may make the dentist feel secure, there is a significant risk that a wax or silicone record may stop the casts from coming into full contact in ICP. Often it is best not to use an occlusal record at all, or to use one that is trimmed and limited only to the preparations if the ICP is not particularly stable. 

The laboratory handling of casts: Following removal of the impression, dental casts often have little “blebs” of stone on the occlusal surfaces. These are the result of small air bubbles or voids in the impression. Good impression techniques will minimize but not eliminate these. A bleb 1 mm high on the occlusal surface can create a similar space between mounted casts, and 1 mm of excessive occlusal gold takes a lot of grinding. The responsibility for “flicking” off such blebs lies with the laboratory, but it is worth the dentist checking the casts giving feedback, as appropriate, to the laboratory.

The mounting of the casts: This has to be done with great care. It is not uncommon for casts to move slightly during mounting. This stage is mostly about care and attention to detail. Provided the casts are properly mounted, there should not be a problem in constructing the restoration to fit precisely in ICP.

The provisional crown: If the provisional restoration is poorly formed or lost, overeruption and drifting will result. This will cause not only a high crown but also an ill-fitting one with tight proximal contact(s).

None of the steps to avoid these problems is time-consuming or difficult, but attention to important detail can make a fundamental difference.


Applied occlusion; Robert Wassell, Amar Naru, Jimmy Steele, Francis Nohl