AN IN-VITRO STUDY OF DENTINAL TUBULE OCCLUSION BY FERRIC OXALATE

THIS STUDY EXAMINED FERRIC OXALATE'S ability to occlude dentinal tubul es both in the presence of a smear layer and after its removal. Radicu lar dentinal chips were prepared with a smear layer created from a hig h speed carbide bur. The dentinal chips were then grouped as follows: 1) those with the smear layer remaining intact; 2) those sonicated for 7 minutes; 3) those treated with 10% tetracycline HCl; 4) those treat ed with 0.5M EDTA; 5) those treated with 20% citric acid; or 6) those treated with saturated citric acid. Six percent ferric oxalate was app lied for 1 minute to the dentinal chips under blinded conditions. The chips were examined under SEM and the number of small and large crysta ls formed were counted. The results indicate that a decrease in the nu mber of small crystals occurs following pretreatment of the smear laye r by chemical means. An increased variability in size and shape of the crystals is also observed when no chemical pretreatment is used. Thus , relative to the number of crystals that form, no chemical pretreatme nt of radicular dentin is indicated prior to application of ferric oxa late in the treatment of root sensitivity.