Abstract
Objectives: Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration. Study Design: After mixing the cements under aseptic condition and based on the manufacturers` recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three groups (n=10). Specimens were exposed to environments with pH values of 4.4, 7.4, or 10.4 for 3 days. Cement pellets were compressed by using an Instron testing machine. Values were recorded and compared. Data were analyzed by using one-way analysis of variance and a post hoc Tukey’s test. Results: After 3 days, the samples were solid when probed with an explorer before removing them from the molds. The greatest mean compressive strength 133.19±11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA. The values decreased to 111.41±8.26 MPa after exposure to a pH value of 4.4. Increasing of pH had a significant effect on the compressive strength of the groups (p<0.001). The mean compressive strength for the NanoWMTA was statistically higher than for ProRoot WMTA and Bioaggregate (p<0.001). Moreover, increasing of pH values had a significant effect on compressive strength of the experimental groups (p<0.001). Conclusion: The compressive strength of NanoWMTA was significantly higher than WMTA and Bioaggregate; the more acidic the environmental pH, the lower was the compressive strength. Key words:Compressive strength, mineral trioxide aggregate, Nano.
Highlights
Mineral Trioxide Aggregate (MTA) showed better psychochemical properties including bioactivity and setting in the presence of moister in comparison with other similar materials [1]
MTA and BA have same antibacterial behaviour [7], similar ability to prevent leakage [8] and same cell toxicity [6]; the push-out strength in furcal perforations repaired with white MTA (WMTA) was superior than those for BA in acidic condition; both cements are adversely affected by acidic pH [9] but there is no published study reporting the compressive strength of BA. pH changes produce different behaviors of MTA in various conditions; when MTA comes into contact with existing inflamed tissues it may be exposed to a low pH [10], which can affect the sealing and physicochemical properties of MTA producing reduced bond strength to dentin [11]
The means value of compressive strength for experimental groups as following: - WMTA: 63.78, 86.23, and 103.63. - Bioaggregate: 10.88, 25.36, and 29.07. - NanoWMTA: 111.41, 126.81, and 133.19. (Fig 2) The greatest mean compressive strength 133.19±11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA; the values decreased to 111.41±8.26 MPa after exposure to a pH of 4.4
Summary
Mineral Trioxide Aggregate (MTA) showed better psychochemical properties including bioactivity and setting in the presence of moister in comparison with other similar materials [1]. MTA and BA have same antibacterial behaviour [7], similar ability to prevent leakage [8] and same cell toxicity [6]; the push-out strength in furcal perforations repaired with WMTA was superior than those for BA in acidic condition; both cements are adversely affected by acidic pH [9] but there is no published study reporting the compressive strength of BA. PH changes produce different behaviors of MTA in various conditions; when MTA comes into contact with existing inflamed tissues it may be exposed to a low pH (as low as 5) [10] , which can affect the sealing and physicochemical properties of MTA producing reduced bond strength to dentin [11]. Torabinjead et al reported that the compressive strength of MTA increased during 3 weeks after placement in moist environment containing distilled water [22]; other investigators have indicated that the amount of microleakage can be reduced when MTA is in contact with synthetic tissue fluid [13]
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