FUNCTIONAL LOADS ON FREESTANDING AND CONNECTED IMPLANTS IN 3-UNIT MANDIBULAR PROSTHESES OPPOSING COMPLETE DENTURES - AN IN-VIVO STUDY

In vivo measurements of vertical forces and bending moments during bit ing and chewing were carried out on 10 three-unit prostheses in the po sterior mandibles of five patients. Each patient had two prostheses, o ne supported by two implants and the other supported by one implant an d one tooth. The results demonstrated no major difference in functiona l load magnitudes related to the support type. The distribution of loa d between the abutments was influenced more by the prosthesis geometry and implant placement than by the difference in load characteristics of tooth and implant. This conclusion, however, is limited to one impl ant connected to a tooth, because multiple implants form a considerabl y stiffer unit than do teeth. An increase in vertical load resulting f rom cantilever extensions on tile prostheses was documented, both at b ite fork measurements and during chewing. No substantial lateral bendi ng was registered, probably because the flat occlusal surfaces and the presence of the opposing complete denture reduced lateral forces.