INTRODUCTION: The purpose of this study was to examine the microhardness and modulus of elasticity (MOE) of White ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK) after setting in moist or dry intracanal conditions. METHODS AND MATERIALS: To simulate root canal system, 14 polyethylen molds with internal diameter of 1 mm and height of 12 mm were used. These molds were filled with 9-mm thick layers of White ProRoot Mineral Trioxide Aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK). The experimental group (n=7) had a damp cotton pellet with 1.5 mm height and a 1.5 mm layer of resin composite placed on it. In control group (n=7) the whole 3 mm above MTA were filled with resin composite. The specimens were kept in 37°C and relative humidity of 80% for 4 days in order to simulate physiological conditions. Specimens were longitudinally sectioned and nanoindentation tests were carried out using Berkovich indenter at loading rate of 2 mN/s at 4×5 matrices of indents which were located in the coronal, middle and apical thirds of the specimen's cross section, to evaluate the microhardness and modulus of elasticity of the specimen to appraise the progression of the setting process. Differences were assessed using nonparametric generalized Friedman rank sum and Wilcoxon Rank-Sum tests. RESULTS: Statistical analysis showed that there was a significant difference in microhardness and MOE between control and experimental groups at coronal (P<0.001), middle (P<0.001) and apical (P<0.001) thirds of the simulated rod from simulated apical foramen. Kruskal-Wallis test showed no significant effect of depth on microhardness of material in experimental or control groups. CONCLUSION: Within limitations of this in vitro study, it seems that moist intracanal environment improves setting of MTA in various depths.

Czech Educational and Dental Research Innovative Group Brno Czech Republic

Department of Anatomy Faculty of Medicine and Dentistry Palacky University Olomouc Czech Republic

Department of Mathematical Analysis and Applications of Mathematics Faculty of Science Palacky University Olomouc Czech Republic

Institute of Dentistry and Oral Sciences Faculty of Medicine and Dentistry Palacky University Olomouc Czech Republic

Joint Laboratory of Optics Palacky University and Institute of Physics Academy of Sciences of the Czech Republic Olomouc Czech Republic

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Torabinejad M, Watson TF, Pitt Ford TR. Sealing ability of a mineral trioxide aggregate when used as a root end filling material. J Endod. 1993;19(12):591–5. PubMed

Torabinejad M, Chivian N. Clinical applications of mineral trioxide aggregate. J Endod. 1999;25(3):197–205. PubMed

Witherspoon DE, Ham K. One-visit apexification: technique for inducing root-end barrier formation in apical closures. Practical procedures & aesthetic dentistry : PPAD. 2001;13(6):455–60. quiz 62. PubMed

Banchs F, Trope M. Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol? J Endod. 2004;30(4):196–200. PubMed

O'Sullivan SM, Hartwell GR. Obturation of a retained primary mandibular second molar using mineral trioxide aggregate: a case report. J Endod. 2001;27(11):703–5. PubMed

Bogen G, Kuttler S. Mineral trioxide aggregate obturation: a review and case series. J Endod. 2009;35(6):777–90. PubMed

Caronna V, Himel V, Yu Q, Zhang JF, Sabey K. Comparison of the surface hardness among 3 materials used in an experimental apexification model under moist and dry environments. J Endod. 2014;40(7):986–9. PubMed

DeAngelis L, Chockalingam R, Hamidi-Ravari A, Hay S, Lum V, Sathorn C, Parashos P. In vitro assessment of mineral trioxide aggregate setting in the presence of interstitial fluid alone. J Endod. 2013;39(3):402–5. PubMed

Witherspoon DE, Small JC, Regan JD, Nunn M. Retrospective analysis of open apex teeth obturated with mineral trioxide aggregate. J Endod. 2008;34(10):1171–6. PubMed

Qu S, Huang Y, Pharr GM, Hwang KC. The indentation size effect in the spherical indentation of iridium: A study via the conventional theory of mechanism-based strain gradient plasticity. Int J Plasticity. 2006;22(7):1265–86.

Budig CG, Eleazer PD. In vitro comparison of the setting of dry ProRoot MTA by moisture absorbed through the root. J Endod. 2008;34(6):712–4. PubMed

Oliver WC, Pharr GM. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J Mater Res. 1992;7:1564–83.

ČŠN EN ISO 14577-1 Kovové materiály - Instrumentovaná vnikací zkouška stanovení tvrdosti a materiálových parametrů - Část 1. Zkušební metoda. 2003

Tabor D. The Hardness of Metals. OUP Oxford; 2000.

Fischer-Cripps AC. Nanoindentation. Springer; 2004.

Ctvrtlik R, Al-Haik M, Kulikovsky V. Mechanical properties of amorphous silicon carbonitride thin films at elevated temperatures. J Mater Sci Mater Med. 2015;50(4):1553–64.

Cheng YT, Cheng CM. Scaling, dimensional analysis, and indentation measurements. Materials Science and Engineering R: Reports. 2004;44(4-5):91–150.

Suresh S. Crystal deformation: Colloid model for atoms. Nat Mater. 2006;5(4):253–4. PubMed

Kulikovsky V, Vorlíček V, Boháč P, Stranyánek M, Čtvrtlík R, Kurdyumov A. Mechanical properties of amorphous and microcrystalline silicon films. Thin Solid Films. 2008;516(16):5368–75.

Shokouhinejad N, Jafargholizadeh L, Khoshkhounejad M, Nekoofar MH, Raoof M. Surface microhardness of three thicknesses of mineral trioxide aggregate in different setting conditions. Restor Dent Endod. 2014;39(4):253–7. PubMed PMC

Lee YL, Lee BS, Lin FH, Yun Lin A, Lan WH, Lin CP. Effects of physiological environments on the hydration behavior of mineral trioxide aggregate. Biomaterials. 2004;25(5):787–93. PubMed

Bolhari B, Nekoofar MH, Sharifian M, Ghabrai S, Meraji N, Dummer PM. Acid and microhardness of mineral trioxide aggregate and mineral trioxide aggregate-like materials. J Endod. 2014;40(3):432–5. PubMed

Namazikhah MS, Nekoofar MH, Sheykhrezae MS, Salariyeh S, Hayes SJ, Bryant ST, Mohammadi MM, Dummer PM. The effect of pH on surface hardness and microstructure of mineral trioxide aggregate. Int Endod J. 2008;41(2):108–16. PubMed

Torabinejad M. Mineral trioxide aggregate. 1. ed. Willey-Blackwell; 2014.

Chedella SC, Berzins DW. A differential scanning calorimetry study of the setting reaction of MTA. Int Endod J. 2010;43(6):509–18. PubMed

Martin RL, Monticelli F, Brackett WW, Loushine RJ, Rockman RA, Ferrari M, Pashley DH, Tay FR. Sealing properties of mineral trioxide aggregate orthograde apical plugs and root fillings in an in vitro apexification model. J Endod. 2007;33(3):272–5. PubMed

Al-Kahtani A, Shostad S, Schifferle R, Bhambhani S. In-vitro evaluation of microleakage of an orthograde apical plug of mineral trioxide aggregate in permanent teeth with simulated immature apices. J Endod. 2005;31(2):117–9. PubMed

Hawley M, Webb TD, Goodell GG. Effect of varying water-to-powder ratios on the setting expansion of white and gray mineral trioxide aggregate. J Endod. 2010;36(8):1377–9. PubMed

Reyes-Carmona JF, Felippe MS, Felippe WT. A phosphate-buffered saline intracanal dressing improves the biomineralization ability of mineral trioxide aggregate apical plugs. J Endod. 2010;36(10):1648–52. PubMed