Determination of pH and calcium ion release provided by pure and calcium hydroxide-containing AHPlus

Aim To compare in vitro the pH and calcium ion release provided by pure and calcium hydroxide-containing AHPlus. Method Pure and modified AHPlus, the latter containing 5 and 10% (w/w) calcium hydroxide added during spatulation, were used. The material was spatulated and stored in 10 tubes that were 1 cm long and 1.5 mm in diameter, and then immersed in 20 mL deionized water before the materials had set. Ten tubes with zinc oxide and eugenol were used as controls. Four millilitres of water was removed from the flasks after 24 and 48 h, and after 7, 14 and 30 days, and pH and calcium release were measured with a pH meter and by atomic absorption spectrophotometry, respectively. The results obtained at each time point were compared statistically. Results A more alkaline pH for AHPlus supplemented with 5 and 10% calcium hydroxide was recorded when compared to pure AHPlus; there were significant differences at 14 and 30 days (P < 0.05). The results of calcium ion release showed no significant difference between pure AHPlus and zinc oxide plus eugenol (P > 0.05). The comparisons between the AHPlus containing 10% calcium hydroxide with AHPlus containing 5% calcium hydroxide, pure AHPlus, zinc oxide plus eugenol demonstrated significant differences (P < 0,05) at all periods. The comparisons between AHPlus containing 5% calcium hydroxide with pure AHPlus and zinc oxide plus eugenol demonstrated significant differences (P < 0,05) at all periods of evaluation. Conclusions The addition of 5 and 10% calcium hydroxide to AHPlus cement favoured a more alkaline pH and greater calcium ion release.