Experimental bacterial anachoresis in dog dental pulps capped with calcium hydroxide

The pulps of 36 permanent dog teeth were mechanically exposed and capped with Dycal, calcium hydroxide powder mixed with saline, or Teflon. At 2, 14, and 28 days postoperatively, nine teeth treated with the materials were extracted (treated control teeth): A suspension of streptococci was then injected intravenously. Twenty-four h later the dogs were killed and both the 27 treated teeth (experimental group) and 6 unoperated control teeth were removed in tissue blocks. Tissue sections were examined for the presence of bacteria, hard tissue formation, inflammatory cell response and necrosis. Bacteria were not observed in the unoperated and treated control teeth or in three of four teeth capped with Teflon for 29 days. In all the remaining specimens colonies of gram-positive cocci were found.