EFFECT OF ROOT-CANAL FILLING MATERIALS CONTAINING CALCIUM HYDROXIDE ON THE ALKALINITY OF ROOT DENTIN

The effect of root canal filling pastes containing calcium oxide resp. calcium hydroxide on the alkalinity of extracted human teeth was inve stigated using a colour indicator (cresol red). An aqueous suspension of calcium hydroxide (Pulpdent), which is normally used for temporary root canal filling, most consistently produced alkalinity. Removal of the smear layer following instrumentation of the root canal led to inc reased proportion of alkaline-positive spots in dentinal locations dis tant from the canal. A clearly smaller effect was found with a calcium salicylate cement (Sealapex) and an oil-paste (Gangraena Merz), both of which are available for definite root canal fillings. Following rem oval of the smear layer, these hard-setting preparations caused modera te alkalinity in dentin adjacent to the canal but no effect was observ ed in locations more distant from the canal. Neither at locations adja cent to nor distant from the root canal was alkalinity found when anot her calcium salicylate cement (Apexit) was used. Apparently the releas e of hydroxyl ions into root dentin from calcium hydroxide containing root canal filling materials is not solely influenced by the absolute amount of calcium hydroxide, but also depends on other ingredients whi ch variably inhibit the release of these ions.