[Obliteration of the mastoid air cell system with porous tricalcium phosphate ceramic. An animal experiment of the bulla tympanica of the pig (author's transl)].

The paper reports on an animal experiment on the obliteration of mastoid cavities with tricalcium phosphate ceramic. The pneumatic air cell system of the bulla tympanica of pigs of 11-12 weeks of age was totally removed in one group of animals and partially removed in the second group. In this second group, apical part of the bulla was left intact. The operation cavity was then obliterated with adjacent layers of porous tricalcium phosphate ceramic. Histological sections wee evaluated for both groups of animals after survival time of 1, 3 and 6 months. Initially, an ingrowth of granulated tissue between the ceramic layers and into the porous surface can be observed. This dissolves the ceramic material, which is substituted by bony tissue. Pneumatic cells in the apical part of the bulla, which were left intact in the second group of animals, do not obliterate after the air supply has been cut off by sealing the basal part. Cystic cavities remain which contain a serous exudate. After 6 months, the mucous membrane of such cells shows signs of "sclerosis". Formation of spongy bony tissue with marrow spaces can be seen in most of the apical areas of the growing bulla. There is no formation of air-containing cells. It appears from our preliminary results obtained from animal experiments that porous tricalcium phosphate ceramic may be a suitable material for the obliteration of mastoid cavities.