Effect of Overlying Material on Mineral Trioxide Aggregate Setting Reaction in Primary Molar Pulpotomies

Purpose: To assess and compare in vitro the effect of overlying materials such as zinc oxide eugenol (ZOE), resin-modified glass ionomer cement (RMGIC), and stainless steel crowns (SSC) on the setting reaction of NeoPUTTY used as a pulpotomy agent in primary molars, restored in a single visit. Methods: Forty-eight extracted primary molars were prepared with standard pulpotomy technique. Approximately 3mm of NeoPUTTY was placed on the pulpal floor of each tooth. The teeth were divided into 4 groups: (1) control group – moist cotton pellet placed over NeoPUTTY, no material applied over MTA, (2) RMGIC applied, (3) ZOE applied, (4) ZOE and SSC applied. Groups 2, 3, 4 were placed in artificially simulated oral cavity conditions. After 24h all teeth were sectioned mesio-distally, polished and microhardness was measured in Knoop Scales (HK) at 1mm, 2mm, 3mm away from NeoPUTTY-overlying material interface following application of a 25gf load force for 30 seconds at each site. One-way ANOVA was used to compare hardness values between groups at each depth (P<.05), and between depths within each group (P<.05). Results: No statistically significant differences in mean HK values were found between groups at each depth, or between depths within each group. Conclusions: The setting reaction of NeoPUTTY, measured as a function of its microhardness, was not affected by presence or absence, or type of overlying material used in a single visit pulpotomy. This in vitro study found no evidence against immediate restoration of NeoPUTTY primary molar pulpotomies.