Changes in Bone Metabolisim Around Osseointegrated Implants Under Loading

The use of osseointgrated dental implants to replace missing teeth is a highly predictable procedure. The scientific lierature is replete with reports of high success rates over long periods of time. Since the phenomenon of osseointegration was first introduced by Branemark, this procedure has gained great popularity. One of the measurements for success of an osseointegrated implant is that it be load-bearing and transmit these occlusal forces directly to the adjacent bone. Controlling this load is considered a determinant factor in the long term success of the implant. A related consideration is how this load or mechanical stress influences bone metabolism around the osseointegated implant. Mechanical stress may lead to an alteration in bone quality and architecture and a distinct reaction within the bone cells at the bone-implant interface. However, there is little published data to support this theory. A few studies have suggested that occlusal overload may contribute to bone loss around an implant and/or loss of integration of a successfully integrated implant. (Rangert et al.,1995; Miyata et al., 2000; Piattelli et al., 2003). Isidor reported implant mobility caused by progressive peri-implant bone loss after the implant were expose to mechanical occlusal trauma for 18 month (Isidor, 1997, 1998). Others report that peri-implant bone loss and/or loss of osseointegration is associated with biological complications such as peri-implant infection (Lang at al., 2000). A certain level of mechanical loading is required for normal, healthy bone remodeling (Frost, 1989). Misch observed that the change in bone strength from loading and mineralization after one year alters the stress-strain relationship and reduces the risk of microfracture during following years. Mechanical stress might induce a metabolic turnover of the bone based on the changes in osteocyte responses around the implant, resulting in bone remodeling (Misch, 1999). This chapter is to investigate the dynamic changes in bone metabolism around osseointegrated implants under mechanical loading.