Objectives: The effect of acidic pH on Vickers microhardness (HV) of Mineral Trioxide Aggregate (MTA) surface has been already investigated. The present study aimed to evaluate how acidic pH affects MTA microhardness at different depths. Methods: ProRoot MTA (Dentsply Tulsa Dental, USA) was mixed with sterile water and compacted into cylindrical moulds having an internal diameter of 3 mm and height of 6 mm. Specimens were randomly assigned to group 1 (G1, n=12) or 2 (G2, n=12), immediately immersed into buffer solutions at pH values of 7.4 (G1) or 4.4 (G2) and stored for 24h. Thereafter, each specimen was cross-sectioned at a depth of 3 mm. HV analysis was performed on the top, on the intermediate (3 mm) and on the bottom surfaces; three indentations per surface were made. The mean HV values were calculated for each group and subjected to repeated measures analysis of variance, paired and independent samples t-tests (p<0.05). Results: Top surfaces in G2 were found to be crumbling, thus HV reading was unfeasible. HV mean values ±SD were: G1 top 68.60 ±16.48, G1 intermediate 66.51 ±7.66, G1 bottom 62.46 ±5.68; G2 intermediate 56.41 ±4.13, G2 bottom 61.33 ±12,55. No significant differences were found within each group amongst measured surfaces. Similar HV values were found on bottom surfaces in G1 and G2, whilst significantly lower values were recorded in G2 when comparing intermediate surfaces. Conclusions: A pH value of 4.4 affected the HV of MTA on the exposed top surface and at a depth of 3 mm. A similar behavior in clinical conditions can be expected when MTA is used as root-end filling material; further clinical studies are needed.
Microhardness of Mineral Trioxide Aggregate stored in acidic environment
ANGERAME, DANIELE;DE BIASI, MATTEO;
2011-01-01
Abstract
Objectives: The effect of acidic pH on Vickers microhardness (HV) of Mineral Trioxide Aggregate (MTA) surface has been already investigated. The present study aimed to evaluate how acidic pH affects MTA microhardness at different depths. Methods: ProRoot MTA (Dentsply Tulsa Dental, USA) was mixed with sterile water and compacted into cylindrical moulds having an internal diameter of 3 mm and height of 6 mm. Specimens were randomly assigned to group 1 (G1, n=12) or 2 (G2, n=12), immediately immersed into buffer solutions at pH values of 7.4 (G1) or 4.4 (G2) and stored for 24h. Thereafter, each specimen was cross-sectioned at a depth of 3 mm. HV analysis was performed on the top, on the intermediate (3 mm) and on the bottom surfaces; three indentations per surface were made. The mean HV values were calculated for each group and subjected to repeated measures analysis of variance, paired and independent samples t-tests (p<0.05). Results: Top surfaces in G2 were found to be crumbling, thus HV reading was unfeasible. HV mean values ±SD were: G1 top 68.60 ±16.48, G1 intermediate 66.51 ±7.66, G1 bottom 62.46 ±5.68; G2 intermediate 56.41 ±4.13, G2 bottom 61.33 ±12,55. No significant differences were found within each group amongst measured surfaces. Similar HV values were found on bottom surfaces in G1 and G2, whilst significantly lower values were recorded in G2 when comparing intermediate surfaces. Conclusions: A pH value of 4.4 affected the HV of MTA on the exposed top surface and at a depth of 3 mm. A similar behavior in clinical conditions can be expected when MTA is used as root-end filling material; further clinical studies are needed.Pubblicazioni consigliate
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