Single implant restorations with cantilever
- Cantilever restorations are used with caution in conventional dentistry.
- Implants with cantilevers should follow specific biomechanical principles.
- Cantilevered restorations require careful planning.
- Cantilevered restorations should only be used in specific clinical presentations.
- Cost of a second implant is not an indication for cantilevering.
The prosthodontic literature has documented the use of cantilever restorations on teeth. The specific guidelines for the use of cantilevers in conventional fixed prosthodontics can be found in traditional prosthodontic text books (Schillenburg, etc). The use of a single cantilevered tooth off of a natural tooth is permitted from a maxillary canine to replace a maxillary lateral incisor. Other cantilevers require either double or triple abutting in order to provide adequate support.
In the realm of implant restorations there may be more flexibility but one should go forward with caution. Some of the considerations are: The arch, the tooth, the length and diameter of the supporting endosseous implant, the opposing occlusion, the edentulous ridge morphology, soft tissue profiles, the esthetic and overall expectations of the patient. In some instances the motivating factor for the cantilever is cost, the patient does not wish to pay for an additional implant. As this may be a consideration the practitioner should counsel the patient against this decision if the clinical demands on the restoration will jeopardize the longevity.
There are indications where a cantilever will serve effectively. Assuming the implant is of sufficient width and length viable cantilever’s can be fabricated as follows. Maxillary lateral incisors from maxillary canines, maxillary central incisors off of each other. Mandibular lateral incisors of off mandibular canines, and mandibular central incisors off of each other. Posterior cantilevers should be avoided at all costs if they are single abutted. The nature of posterior occlusal forces could well exceed the ability of the implant components. This may result in repetitive screw loosening, fracture of implant components, the material the restoration is made of, and potentially a loss of integration.
In the anterior maxilla or mandible the use of cantilevers also requires careful attention to the occlusion. The cantilevered tooth should be kept out of centric occlusion contact and not be utilized in any excursive movements for discussion. Lateral forces on the cantilevered tooth will serve to torque or rotate the supporting implant and result in the complications mentioned above.
In instances where there is insufficient room for a second implant or the patient is not amenable to a three unit fixed partial denture, the cantilevered restoration will provide years of service if the careful attention to the aforementioned criteria are followed.