In considering the form of restorations, there seems to be a problem with the standardized fabrication of what is the ideal restoration.
Up to this time only the outer form of the prosthetic restoration has been considered, pursuing such aspects as overcontour, undercontour, and the form of the lower embrasure spaces. However, there are various forms of periodontal tissues in the oral cavity such as those of normal and periodontally involved tissues. With this in mind, it would seem appropriate that the shape of each individual prosthetic restoration might be different.
Nonetheless, it is probably necessary to try and search out a certain standard. If any general agreement could be obtained today about the outer form of prosthetic restorations, it would probably be the shape of the buccal and lingual surfaces.
Esthetics and comfort of fit are not such a problem in this region. It is adequate to consider only how plaque control can best be carried out. The form of a prosthetic restoration where the tips of the toothbrush bristles can easily get into the gingival sulcus for plaque control is undercontoured, and it is desirable to that the transition from the tooth structure to the margin of the restoration be as smooth as possible.
The form for each lower embrasure space changes depending on the form of the interdental papilla. The outer shape of a form which is in harmony with the periodontal tissues is determined by a trial and error process, making use of temporary restorations and taking into consideration esthetics, comfort of fit, and hygiene. However, even if we complete a prosthetic restoration like this which is in harmony with the periodontal tissues, long term function in the oral cavity cannot be expected if the patient does not practice plaque control. Whether or not this is possible depends on the initial preparation which begins with motivation and how well healthy periodontal tissues are maintained.

View full abstract