In cases where in the mouth teeth are missing, edentulous situations are grouped in 4 categories that were defined by Dr. Edward Kennedy in his classification of partially edentulous arches.
- Class I (bilateral free ended partially edentulous)
- Class II (unilateral free ended partially edentulous)
- Class III (unilateral bounded partially edentulous)
- Class IV (bilateral bounded anterior partially edentulous)
Kennedy Class IThis type is for people who are missing some or all of their teeth on both sides in a single arch and there are no teeth posterior to the edentulous area. Class I RPD´s clasp onto the teeth are more towrds the front of the mouth, while replacing the missing more back of the mouth teeth on both sides with false denture teeth.
Class IIRPD´s are fabricated for people who are missing some or all their posterior teeth on one side in a single arch, and there are no teeth behind the edentulous area. Thus, Class II RPD´s clasp onto teeth that are more towards the mouth, as well as on teeth that are more towards the back of the mouth of the side on which teeth are not missing, while replacing the missing more back of the mouth teeth on one side with false denture teeth.
Class IIIRPD´s are fabricated for people who are missing some teeth such that the edentulous area has teeth remaining both posterior and anterior to it. Unlike Class I and Class II RPD´s which are both tooth and tissue borne, Class III RPD´s are strictly tooth borne, which means they only clasp onto teeth and do not need to rest on the tissue for added support. This makes Class III RPD´s exceedingly more secure as per the three rules of removable prostheses that will be mention later namely: support, stability and retention.
However is the edentulous area described in the previous paragraph crosses the anterior midline, the RPD is classified as a
Class IV RPD. By definition, a Kennedy Class IV RPD design will posses only one edentulous area.
Classes I, II and III RPD´s that have multiple edentulous areas in which replacement teeth are being placed are further classified with modifications states that were defined by Oliver C. Applegate. Kennedy classification is governed by the most posterior edentulous are that is being restored. Thus, if for example, a maxilary arch is missing teeth #1,3, 7-10 and 16, the RPD would be Kennedy Class III model 1. It would not be Class I, because missing third molars are generally not restored in an RPD (although if they were, the classification would indeed be Class I), and it would not be Class IV, because modification spaces are not allowed for Kennedy Class IV.