Parafunctions and Implant Overloading : How to Avoid Implant Prosthetic Complications

Background and Aim: The aim of this study was to show the destructive effects of abnormal occlusal forces on implant supported prostheses in patients with bruxism, abnormal habits and other parafunctions, and to focus on concepts and the clinical procedures to reduce the potential risk factors for implant failure. Material and Methods: Forty TMD patients were compared to 40 no-TMD patients in which were inserted 430 implants the same features as number, size, position, design. Another experimental group of 50 TMD patients treated by prevention protocol was assessed. Besides, were considered type of restoration, cemented or screwed, malocclusion type, smoking, load timing. The heavy force of compression, clenching and grinding, as in bruxism, simultaneously applied strong pressures to the implants, crestal bone, restorations and temporomandibular joints. This was a potential risk factor for crestal bone loss, loss of integration before and after restoration, abutment screw loosening and fracture, implant fracture, decementation of restorations and fracture of the porcelain. Results: The 5 years follow-up showed a 58% of soft tissues, bone and prosthetic complications in TMD patients versus a 13% in non TMD patients. When TMD patients were undergone to occlusal overload prevention protocol, the complications were diminished to 15% (P< 0.001). The results indicated that increasing the number of implants and reducing cantilevers decreased the stress on each one; using the longest and widest implant possible increases implant/bone surface area and reduces also strain on the restorations. Also implant design, occlusal table size, the direction, duration and magnification of the forces influenced the stress at the crestal bone/implant surface. Using an occlusal splint and performing occlusal adjustment, anterior guidance during excursive movements reduced forces and eliminate all lateral occlusal contact. Frequent occlusal follow-ups were mandatory to eliminate prematurities and interferences Conclusion: Developing treatment plan that control the chronic bruxism through night-guards and an occlusal adjustment protocol to modify the occlusal forces on implants and their restorations, patients with temporomandibular disorders and bruxism can be candidates for implants.