Experimental studies on the osseous restoration and microvascular formation after dental implantation of the pored almina ceramics

Abstract

Sequential changes in the microvasculature and new bone formation, especially in the open pores on the interface of polycrystal ceramic implants were investigated using microcorrosion cast-bone specimens under a scanning electron microscope. The implant materials consisted of a cylinder with a core of single-crystal alumina and an outer pored polycrystal layer (Bioceram Porous Implant 42 POSSS^® and 42 PX10^®). Implantations were performed in extraction sockets of mandibular premolars and molars in adult Japanese monkeys. Five days after implantation, no primary bone trabeculae were observed. However, new sinusoidal capillaries had sprouted from pre-existing blood vessels. At one week, new bone and capillaries had not yet passed through pore openings, but active proliferation of sinusoids and new bone formation were seen. At two weeks, new capillaries began to enter the pores and form glomeruli, while bone trabeculae only invaded large-caliber pores. At three weeks, mature capillaries and tiny needle-like bone trabeculae were observed in the pores. From four to nine weeks, almost all of the pores were filled with woven bone, and a cylindrical alveolus was formed outside the polycrystal interface. These results suggest that more tha nine weeks may be required for the invasion of new bone and capillaries from the outer polycrystal interface into the pores of the implant. The capillaries in the pore labyrinth showed, irregular growth characteristics.