[Prosthodontic considerations in implant therapy].

Abstract

Numerous factors affect the success or failure of the various intra-osseous implants. In particular, such considerations as the implant materials, properly selected or not, preceded by careful patient screening and thorough analysis of soft and hard tissues, implant insertion conditions, oral hygiene and the overlying prostheses determine the success of the implant therapy. Among these, the final overlying prostheses serve two major purposes of restoring lost masticatory function and esthetic improvement. In addition, due to the intimate relationship with the health and remodeling of the surrounding tissues, the prostheses must be designed with the utmost care. Analyzing this kind of osteointegrated system from the histologic standpoint of the implant/bone relationship, one can roughly classify this system into three types. One is a fibro-osseous integration yielded by enveloping with fibro connective tissue. The other is osseointegration by directly contacting with bone. Lastly, the osteoankylosis form whereby fusion of the implant and bone takes place. Irrespective of the different types and a basic physical principle applied, the function of the final prostheses should be to transmit occlusal force widely to the supporting cortical and basal bones (i.e., jaw bones) via the implant device without creating any undesirable concentrated, rotational or lateral force. Therefore, the final prostheses are not designed independently or after the implant operation. Instead, the prostheses design comes first, followed by careful analysis of the opposing occlusion, proximal dentition and other intraoral structures. Based on the determined existing intraoral environment, the particular type of implant and its form is selected to fit the individual case. Preoperative procedure requires articulator mounted study casts to evaluate the opposing occlusion and implant positioning from which the mesiodistal and buccolingual positioning is determined. Subsequently, the final prosthesis design is prewaxed and the required number of implants and their interspan distances are determined from the wax-up. Next, the Surgical Guide Plate device is employed to help determine radiographically the implant positioning and the anatomical jaw morphology. As mentioned earlier, the purpose of the final prosthesis is to restore the lost masticatory function and esthetic improvement along with presservation of the remaining teeth and harmony with the intraoral soft and hard tissues. Implants serve a critical supportive role of helping the success of the final prosthetic treatment. Intraosseous implants can be used as independent support system or can be combined with remaining natural dentition to support the overlying prosthesis.(ABSTRACT TRUNCATED AT 400 WORDS)