Ante’s Law is a concept given by Irvin Ante in 1926 which helps in determining the amount of support which has to be taken to replace missing teeth which has been given in terms of peri-cemental area of the abutment teeth. This has been adopted and reinforced by other authors – Johnston, Dykema, Shillingburg, and Tylman.
Definition: “The sum of pericemental area of abutment teeth should be equal to or surpass that of teeth being replaced.”
Definition according to GPT: “In fixed partial denture prosthodontics for the observation that the combined pericemental area of all the abutment teeth supporting a fixed partial denture should be equal to or greater in pericemental area than the tooth or teeth being replaced ;as formulated for removable partial prosthodontics the combined pericemental area of the abutment teeth plus the mucosal area of denture base should be equal to or greater than the pericemental area of the missing teeth “
Ratios according to Ante’s law for replacement of missing teeth:
- The optimum crown root ratio for the tooth which can be utilized as an FPD abutment is 2:3.
- Ideal crown root ratio should be 1:2 which is the Root Surface area should be double that of the crown surface area.
- But the ratio can be 1:1 which is the Root can be equal in area to that of the Crown present.
- Tooth support varies depending on length and shape of root and not just the surface area. Here are some of the cases where the shapes of the roots determine the amount of support provided irrespective of the length or surface area it covers.
- Long irregularly shaped and divergent roots offer great support.
- Roots with greater faciolingual dimension will make it a superior abutment to the roots which are circular in cross section.
- Short, conical and blunted roots offer poor support, for example, a molar with divergent roots will provide better support than molar with conical roots with little or no inter-radicular bone.
- Single rooted with elliptical cross section will offer better support than the tooth with a circular cross section. As circular teeth will not give enough resistance to forces exerted on the tooth and in the case of an Elliptical root the forces are dispersed more efficiently thus giving better support.
From the time the law was stated and defined, it has been used extensively and has become a must follow rule for every Fixed prostodontic case where more than two teeth are to be replaced. If the Ante’s law is not followed the resultant Fixed partial denture will be exerting excess forces on the abutment tooth which will lead to bone loss and eventually mobility of the abutment.