Occlusal Management of Implant-Supported Restorations
Thomas J. Salinas, DDS
Various traditional techniques for the creation of occlusal schemes have been studied and suggested for the natural dentition.1,2 These concepts are still valid for the logical development of mutually protected occlusion and efficient masticatory function. As it is not necessary to restore the opposing arch of teeth, cusp tip-to-fossa contact is extremely versatile. The opposing fossa is adjusted without difficulty while maintaining the centric holding contact by the centric cusp, and accuracy can be achieved to an optimum level against unprepared teeth.3
The use of osseointegrated technology to restore single or multiple missing teeth has become a widely utilized treatment modality. The neuroprotective mechanisms described for natural teeth do not exist adjacent to a root form osseointegrated implant. In fact, the effect that osseointegrated implants have on bite force can dramatically increase shortly following treatment.4 Natural teeth with occlusal trauma from "high" restorations, occlusal interferences, and parafunction may precipitate signs and symptoms that indicate the existence of such problems. Tooth mobility, sensitivity, localized pain, and bone loss are several clinical manifestations of these scenarios.5
In the case of osseointegrated technology, there is some degree of proprioception that occurs, but this is markedly different than that associated with the natural dentition. Without similar proprioceptive neuromuscular feedback mechanisms present around a dental implant, the musculo-occlusal protective reflexes do not inhibit any perceived interference or occlusal disharmony. Careful consideration of this fact places strategic emphasis on the development of centric occlusal contacts lighter than those in centric relation and centric occlusion. In addition, lateral forces create inordinate degrees of stress to the most coronal portion of supporting alveolar bone. This is somewhat true for vertical loads, but especially true for lateral and oblique loads. Posterior occlusal contacts created on osseointegrated implants should be developed in a vertical direction. Anterior contacts may be created that exclude the posterior teeth, but this should be accomplished in conjunction with an additional splinted implant, when possible, to minimize lateral forces.
With respect to single-tooth implant-supported restorations, it is desirable to restore anterior dentition with a form of cementable design. The use of such a design enables the implant's long axis to be directed through the greatest bulk of the restoration in order to avoid unhygienic ridge lapping, cingulum access porcelain fracture, and offset occlusal schemes. For the posterior dentition, the choice of restoring osseointegrated implants may vary between cemented or screw-retained prosthetic designs. It is highly desirable to contain the vector of occlusal load within the long axis of the implant. If a screw-retained restoration is planned, the development of a centralized occlusal contact places this functionally critical area within a "retrievable" zone of restorative material (eg, acrylic or composite resin). In these cases, it may be beneficial to place the contacts in the center of the occlusal table by using a cemented design with some sort of an abutment.6 Replacement of posterior teeth with osseointegrated implants opposing natural teeth may mandate a widened occlusal table. The continued development of larger-diameter implants has rendered these axioms more readily applicable. It is still desirable, however, to place the primary contact over the long axis of the implant whenever possible. Other contemporary occlusal designs dictate that one quality contact per tooth is sufficient.7
As this intriguing and intricate art and science develops, it is within the restorative dentist's perspective to apply the knowledge obtained from the literature to osseointegrated implant rehabilitation.
* Department of Dental Specialties, The Mayo Clinic, MN; Associate Professor of Dentistry, Nebraska Medical Center, Omaha, NE; and private practice, Omaha, NE.
- Mann AW, Pankey LD. Oral rehabilitation utilizing the Pankey-Mann instrument and a functional bite technique. Dent Clin North Am 1959;3:215-230.
- Mann AW, Pankey LD. The Pankey-Mann philosophy of occlusal rehabilitation. Dent Clin North Am 1963;7:621-636.
- Dawson PE. Diagnosis and Treatment of Occlusal Problems. 2nd ed. St. Louis, MO:Mosby; 1989:355-357.
- Carlsson GE, Haraldson T. Funtional Response Tissue Integrated Prostheses. In: Branemark PI, Zarb GA, Albrektsson T, eds. Chicago, IL:Quintessence; 1985.
- Ash MM, Ramfjord S. Occlusion. 4th ed. Philadelphia, PA: WB Saunders Co; 1995.
- Misch CE. Contemporary Implant Dentistry. 2nd ed. St. Louis, MO: Mosby; 1999.
- Wiskott HW, Belser UC. A rationale for a simplified occlusal design in restorative dentistry: Historical review and clinical guidelines. J Prosthet Dent 1995;73(2):169-183.