Reactions of the dental pulp to microbial provocation of calcium hydroxide treated dentin

The purpose of the present study was to determine whether treatment of dentin with calcium hydroxide reduces pulp irritation caused by microbial products. The experiment was carried out in three young monkeys. Cavities were prepared on the buccal tooth surface deep into dentin of 62 teeth. Calcium hydroxyde mixed with distilled water was placed in one group of cavities. A set of control cavities received treatment with saline soaked filter-paper discs. The calcium hydroxide dressing and the saline discs were separated from the oral cavity for a period of 14 or 60 d by a Teflon disc and a layer of zinc oxide-eugenol cement. At the end of these periods the content of each cavity was removed and substituted by lyophilized material from cultivated plaque bacteria. After 3 d of exposure the monkeys were killed and the teeth subjected to histologic treatment. Assessments made in the light microscope revealed that pulps subjacent to calcium hydroxide-treated dentin in the majority of cases showed no or only slight infiltrates of inflammatory cells. In controls, 13 out of 22 pulps showed severe inflammatory cell infiltrates or total pulp tissue necrosis. It was concluded that treatment of dentin with calcium hydroxide may reduce the possibility for bacterial components to cause pulp tissue damage.