Permeability of apical barriers

The purpose of this work was to measure the permeability (hydraulic conductance) of root canal apical barriers in vitro. In 30 extracted teeth, the pulp tissue was removed and the apical opening standardized and enlarged using endodontic files. One-millimeter thick barriers of either autogenous dentin chips, calcium hydroxide powder, or durapatite particles were placed just inside the apical opening. The prepared teeth were mounted in a special chamber, fluid pressure applied, and the resultant flow measured. The permeability of dentin chip barriers in 10 additional teeth with nonstandardized apical openings was measured also. The standardized canals with the autogenous dentin chip barriers had a mean permeability of 0.0010 microliter/s/psi at 20 psi applied pressure. Teeth with calcium hydroxide barriers averaged 0.0012 microliter/s/psi. The durapatite particle barriers were much more permeable and averaged 0.0220 microliter/s/psi. It was concluded that this technique is useful in evaluating the effectiveness of apical barrier materials. For the materials tested, autogenous dentin chips and calcium hydroxide barriers have significantly lower permeability than durapatite barriers (p = 0.05).