Kennedy classification of the case

Not all edentulous spaces in the dental arch need to be included in the prosthetic treatment plan. Restoration should be limited to areas necessary for achieving esthetics, maintaining function, and preserving occlusal integrity.

Short edentulous spans in the posterior region may be restored for the following purposes:

1. To provide esthetics (e.g., cheek support)
2. To enhance the stability of a maxillary complete denture
3. To prevent overeruption of opposing natural teeth into the edentulous space
4. To prevent migration of adjacent natural teeth

The Kennedy classification of the case is determined once the edentulous spaces that need to be restored have been identified.

Tooth-supported, Class III removable partial dentures are supported by abutment teeth located on both sides of the edentulous space, similar to fixed partial dentures. In such cases, occlusal forces are transmitted directly to the abutment teeth via rests on the abutment teeth. Since the tissues beneath the denture base do not participate in support, the resiliency of the mucosa and the quality and morphology of the underlying bone do not influence the support of the prosthesis. Regardless of the length of the edentulous span, if the abutment teeth are healthy enough to withstand the additional loads, adequate support can be achieved through proper planning by utilizing the teeth adjacent to the edentulous space. However, the prosthesis may move upward due to the effect of sticky foods. This stress-inducing movement must be controlled by appropriately designed prosthetic components.

Class I, II, and IV removable partial dentures derive most of their support from the tissues beneath the denture base and only a limited portion from abutment teeth, thus they are subjected to greater stress with functional forces. In Class I and II cases, the part of the denture base located close to the abutment teeth receives considerable support from the teeth, whereas the farther it extends from the abutments, the more tissue support becomes dominant. In distal extension prosthesis, direct retention and support cannot be achieved in the same manner as in tooth-supported denture bases. Since these prostheses include one or more denture bases positioned on the residual ridge distal to the last existing abutment tooth, they do not possess the full advantage of being entirely tooth-supported. They rely not only on the tissues for support but also on the denture bases for retention. Stress must be controlled through maximum tissue coverage, the correct selection and advantageous positioning of direct and indirect retainers, and other prosthetic components.