Comparison of three luting agents.

Three types of luting cements were compared for acidity, disintegration, and film thickness. The pH during setting of the two types of polycarboxylate cements exceeded 6 after 5 hours; that of the water-settable polycarboxylate cement was the highest, almost reaching neutral. The zinc phosphate cement reached pH 3.4 after 5 hours and 5.5 after 24 hours. All cements tested showed remarkably greater disintegration in the lactic acid solution than in the distilled water. The disintegration of the water-settable zinc polycarboxylate cement in distilled watter was about half that of the other cements. The disintegration in the lactic acid solution was approximately the same for all cements tested. The film thickness was smallest with the water-settable zinc polycarboxylate cement.