Microleakage evaluation of a hydroxyapatite base in comparison with a resin modified glass ionomer cement in vitro

Many attempts have been done to improvethe quality،properties and composition of dental materials to decrease the microleakage and its consequences. The objective of this invitro study was to compare microleakage of light cure resin modified glass ionomer cement and a hydroxyapatite containing base. In this experimental study 40 intact human premolars were divided into 4 groups. On the buccal surface of each tooth، around cavity was prepared with 3 mm in diameter and at least 1 mmdeep into dentin. Teeth were restored using L. C resin modified glass ionomer lining cement،L. C resin modified glass ionomer restorative cement، Lime-Lite with bonding agent، and Lime – Lite without bonding agent. After thermocycling the specimens were immersed in AgNO3 solution for 2 hours. After sectioning the specimens، dye leakage wad evaluated by a stereomicroscope. Microleakage was graded according to ISO 11 405 in occlusal and gingival cavity margins. Obtaineddata were statisticallyanalysed by Kruskal-Wallis، Wilcoxon and Mann-Whitney tests. Most of the samples in group 3 (lime – lite with bonding agent) demonstrated zeromicroleakage grades in gingival and occlusal cavity margins and in group 4 (Lime – Lite – without bonding agant) the majority of samples showedgrade 3 microleakagein both margins. These findings is both margins were significantly higher than those of other groups (p< 0. 05)، but there were not significant differences among glass ionomer groups in marginal microleakage (p> 0. 05). Hydroxyapatite containing base showed more microleakage compared with glass ionomer cement، but application of a bonding agent prior to its placement was effective in reducing its microleakage.