Dynamics of osseointegration in various human and animal models - a comparative analysis

Objective: To investigate the sequential events of osseointegration in various model situations. Material and methods: A series of eight recent sequential studies on the early phases of osseointegration performed in various species analyzing new bone apposition and parent bone resorption at the implant surfaces have been studied. One human, six dog and one rabbit studies were analyzed for old and new bone percentages, assessed at least at 4 periods of the early osseointegration. Data on new and old parent bone in contact with the implant surfaces were collected. The interception point of the two proportions of new and old bone was calculated in terms of osseointegration (y; %) and period of the interceptions (x; days). Results: It has been shown that the interception point of old and new bone proportions was strongly influenced by the choice of the model adopted (human, dog, rabbit), by the density of the surrounding bone (cortical, spongy, trabecular) and by the implant geometry. Implant surface configuration, time of implantation and load influenced the interception point to a lesser degree. The fastest rate of osseointegration was observed in the rabbit model followed by the dog model. The slowest osseointegration rate was seen in humans. Osseointegration was documented best in spongiosa bone when compared to cortical bone. The moderately rough surfaces gave rise to faster osseointegration than did the turned implant surfaces. Conclusions: The interception points may provide information on efficacy of early osseointegration. The slope of the line (m) is related to the efficacy of bone appositions.