[Effect of calcium hydroxide based desensitizing agent on cast crown retention]

A layer of desensitizing agent for prepared teeth was applied to tooth stump prior to the final cementation of cast crowns in order to alleviate postoperative sensibility. The aim of the study was to establish under in vitro conditions whether the application of the suspension of calcium hydroxide (Kaviner) on prepared teeth decreased the cast crown bonding strength. 40 intact human premolars were extracted for orthodontic reasons and prepared by high capacity machine using water supply cooling. Experimental crowns were made by a standard procedure using NiCrMo alloy and cemented by zinc phosphate or glass ionomer luting cements (20 in each group). Bond strength between prepared teeth and crowns was mechanically tested by using electronic dynamometer, at first without suspension of calcium hydroxide and then after its application. The results obtained pointed to decrease of bonding strength with both used luting cements: decrease of retention force with zinc phosphate cement was equal to 1.9% and with glass ionomer cement - 4.2%. However, the retention forces values obtained after the application of Kaviner for both dental cements observed were still clinically acceptable.