A bioengineered implant for a predetermined bone cellular response to loading forces. A literature review and case report

The presence of fibrous tissue has long been known to decrease the long-ter m survival of a root-form implant. Excessive loads on an osseointegrated im plant may result in mobility of the supporting device, and excessive loads may also fracture an implant component or body. Although several conditions may cause crestal bone loss, one of these may be prosthetic overload. Exce ssive loads on the bone cause strain conditions to increase. These microstr ains on the bone may affect the bone remodeling rate in a direct relationsh ip. When strain conditions to the interfacial bone are in the mild overload zon e, an increased bone remodeling response occurs, which results in a reactiv e woven bone formation that is less mineralized and weaker. Greater stresse s may cause the interfacial strain to reach the pathologic overload zone an d may cause microfracture of the bone, fibrous tissue formation, and/or bon e resorption. Recent reports suggest that the bone remodeling rate next to an implant may be used to evaluate biomechanical conditions and their influ ence on the implant-to-bone interface. These include a number of factors, s uch as loading conditions, implant body surface conditions, and implant des ign. For a given load condition, the implant design is one of the primary f actors that determine the resultant strain at the interface. A predetermined goal was established to bioengineer a dental implant to loa d the bone at the interface in a predetermined stress strain relationship, in order to maintain lamellar bone at the interface. A case report is prese nted of 2 bioengineered implants loaded for 1 year, which demonstrates that the bone was primarily lamellar in structure, the bone turnover rate was l ess than 5 microns/day, and was the same as the bone away from the interfac e. These findings corroborate those observed in a prior animal study report ed with the same implant design. Although the number of implants evaluated in those 2 reports is few, they support a predetermined histological outcom e.