Remodeling of devitalized bone threatens periosteal margin integrity of endosseous titanium implants with threaded or smooth surfaces: indications for provisional loading and axially directed occlusion.

Microradiographic analysis of endosseous implants in dogs revealed similar patterns of healing and remodeling of the alveolar process adjacent to both types of implants. However, substantial differences were noted in bone morphology both at the periosteal margin and within the cervical half of the interface. The grooves of the threaded implant were filled with relatively immature composite bone. In contrast, the smooth cylindrical implant was bordered by a dense cortex of relatively avascular bone except for a 1 mm at the periosteal margin that was remodeled and vital. For both types of implants, areas of apparently nonvital, hypermineralized bone were remodeling near the interface and in subperiosteal areas of the alveolar process. The integrity of the periosteal margin may be threatened by undermining remodeling of adjacent bone during the late healing period. The cervical (alveolar) crest and particularly the periosteal margin of the interface are high stress bearing areas. If overloaded, these areas are subject to "cervical cratering," a common prelude to implant failure. The results of this study suggest that axially directed occlusion and a progressive loading scheme are indicated.