65. When designing a two implant assisted overlay denture for a patient, where are the two most desirable implant locations? Please explain your answer. (4 points – 1/2 page) The answer is in PP#6 Slides 13-18
When designing a two implant assisted overlay denture, the two most desirable implant locations are the canine positions or between the canine and the 1st premolar. This allows for the bar to be configured parallel to the axis of rotation with little or no anterior cantilever extension. This configuration is far enough anteriorly to minimize the anterior cantilever. The anterior, or incisal, loads are borne by the implants while the posterior occlusal loads are born by the primary denture support areas (retromolar pad and the buccal shelf). They should be 12-20 mm apart. Little benefit is gained by increasing the distance between the implants. If implants are placed too close to one another, there will not be enough room for 2 Hader Bar clips (stability and retention of the denture), Hader bar segment cantilevered anteriorly, occlusal forces are minimal, the bar will serve as the axis of rotation. Placing an additional implant (total of 3) provides no additional benefit.