Abutment Teeth Case Study

Abutment teeth: Structures used for support, stabilization, reciprocation and retention of a REMOVABLE PARTIAL DENTURE. Most of RPD cases requires the alteration of the tooth form to serve as the indicated abutment, in very rare conditions modifications are not considered as a necessity. During the fabrication of any RPD a consideration that is a must to be taken is the possibility to lose the abutment prepared and the need to replace that loss by slight modification to the original design of that denture, although it’s advisable to restore any further missing anterior by means of fixed restorations. The abutments are classified into 3 categories:

 Abutments requiring minor modifications at their coronal parts

 Abutments with restorations

The most favorable crown preparation used in RPD is the complete coverage crown, why? Cause it can be prepared and finished to meet all the requirements of support, stability and retention without the risk of affecting the cosmetic result and that can’t be achieved even by 3-quarter crown.

Guiding planes are to be extended from the marginal ridge to the junction of the middle and gingival thirds of the tooth, the guiding planes shouldn’t extend to the gingival margin.

Occlusal rest seats are to be carved in the wax pattern after accomplishing guiding planes and any other contouring

Regardless of the crown type used, preparations must provide the appropriate depth for the occlusal rest seat and that’s achieved by changing the axial contours of the tooth before conducting the depression at the occlusal surface.

This approach also provides an important feature that can’t be received by using the natural teeth abutment and that would be the CROWN LEDGE or as also called SHOULDER, using this feature will allow us to have an effective stabilization and reciprocation. “Reciprocal arm may provide horizontal stabilization if it is located on axial surfaces parallel to the path of

When the tooth that’s planned to be used as abutment is too weak for one reason or the other splinting to the adjacent tooth or teeth is to be used in order to improve the abutment support.

When any tooth is in a questionable state periodontally then it’s a must to leave it and go for the next tooth to be used as abutment.

The most common application of splinting is to be upon the premolars or the first premolar and canine.

Anterior teeth are also applicable in some cases in which all of anteriors are splinted together to avoid orthodontic movement of any individual tooth, as for when splinting is not a choice to be considered the individual lingual rests on cast restoration are to be slightly inclined apically to avoid possible tooth displacement.

For molars there are some rare cases that depends on splinting technique because molars are multirooted and thus already have their support.

Isolated teeth as Abutments

Any abutment tooth used is subjected to some degree of tipping, rotation, torqueing or even horizontal movement, but it’s always a priority to limit these actions to the minimal by achieving the best design and using the soft tissue support in the most successful way