Angiogenesis in newly augmented bone observed in rabbit calvarium using a titanium cap

In our previous work using a rabbit experimental model, we identified the importance of using a rigid support device for augmenting the development of mineralized bone. In the early stage of healing, newly generated tissue has not filled occlusive spaces, and mineralized bone forms and tends to climb along the inner wall of a device. Even though the blood supply is critical for successful bone augmentation, few studies have been conducted on angiogenesis in augmented bone. The purpose of the present study was to evaluate a method for observing angiogenesis in newly augmented bone.

The right and left sections of the calvarium of six adult male Japanese white rabbits were exposed. The cortical bone was penetrated, and custom-made, standardized, hemispherical titanium caps were fixed to the exposed bone. The caps on the right side of each rabbit were filled with granulated beta-tricalcium phosphate (beta-TCP). After a healing period of 1 month, the animals were injected with MICROFIL into the right and left common carotid arteries to form a three-dimensional cast of the vasculature, and the newly generated blood vessels in the augmented bone were observed.

The newly generated blood vessels were observed entering the space beyond the existing calvarial bone. Furthermore, angiogenesis was seen to have occurred to a similar extent through the inter-granular beta-TCP in the right caps. These areas of angiogenesis were observed in a histological study with cross-sections.

The results of the present study suggest that this observation method allows the examination of angiogenesis in hard tissue before the preparation of histological specimens.