The development of the alveolar bone by static osteogenesis: microanatomy and clinical implications.

Background: Regeneration of alveolar bone is essential for immediate implant placement after tooth extraction, while the bone formation is still uncertain. To clarify the mechanism of alveolar bone healing we evaluated and compared the bone formation of the jaws during ontogenesis and bone healing after dental extraction. In addition, peri-implant bone remodelling was also evaluated. Materials and Methods: Hamster fetus of 24-days post-conception (n=3), bone cores retrieved during implant placement after three (n=5) and four (n=5) weeks of healing and fractured implants (n=2) retrieved after five years of loading were used in the present study. The investigation was carried out by means of a bright field microscope and a scanning electron microscope (SEM). Results: In Hamster fetus, the alveolar bone formation was related to static osteogenesis (SO) while, the basal bone facing the Meckel’s cartilage was formed by dynamic osteogenesis (DO). In human alveolar sockets, after 3 weeks, the healing appeared to follow the SO mechanism, while after 4 weeks the bone increases by a DO mechanism. Around peri-implant bone the remodelling process was characterized by a DO mechanism. Conclusions: These results demonstrate that the static bone formation (SBF) is a process not only related to skeletal development but it occurs also during the early phase of the bone healing as rapid mechanism of a great ability of space-filling. Later on, the primary bone trabeculae are adapted by dynamic bone formation (DBF). Around dental implant, the remodelling process was governed by a DBF mechanism.