Plaster of Paris: thermal properties and biocompatibility. A study on an alternative implant material for ear surgery.

There is no single technique for reconstruction of the canal wall following radical mastoidectomy. Autograft tissues may be unsuitable because of resorption and limited availability. An ideal foreign implant material should be bone-like in quality, non-ototoxic, readily available and malleable. Plaster of Paris, a degradable ceramic powder of CaSO4, may be regarded as a bone mineral. But a certain amount of heat develops during its solidifying process and may present a risk for injury to the facial nerve and the labyrinth. We studied the temperature rise with respect to added solution, to volume, and to surroundings, and investigated its biocompatibility when implanted in soft tissue in guinea pigs. The investigations suggested no risk of thermal injury and the biocompatibility was excellent. Hence plaster of Paris may constitute an alternative implant material for mastoid obliteration and reconstruction of the canal wall in ear surgery.