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The writer of this letter to the editor raises a question about the statistical methods used. The purpose of the study was to analyze whether the use of 1 month Ca(OH)2 followed by MTA would weaken the tooth in comparison with a control tooth (saline control). The fracture strength for the saline control tooth was 310.3 ± 63 MPa (n = 9) in comparison with 327 ± 84 MPa (n = 8) for Ca(OH)2 + MTA. The writer suggests that an anova test should have been used, considering that we also had a Ca(OH)2 group and an MTA included as controls. I agree that anova is the usual way of comparing four patient groups when no a priori knowledge about the interrelations between the groups is known.We did not, however, consider the Ca(OH)2 and the MTA groups as test groups in the study, and we had them included as reference groups. As was mentioned we had shown, in a previous study, that long-term exposure to Ca(OH)2 weakens the tooth. The aim of our study was to determine whether a treatment combination of Ca(OH)2 with subsequent use of MTA would also weaken the tooth in a similar fashion. The emphasis in the study was therefore to compare the Ca(OH)2 + MTA group with the saline group, for which the preferred test is the t-test.The title in Table 2‘Intergroup comparison of difference in fracture strength’ does however not reflect that distinction between test groups and reference groups and could arguably have been performed with an anova test.We agree that the study's conclusions are based on an absolute minimum of samples but it still contributes to important information, namely that the Ca(OH)2 + MTA combination is not as harmful to the structural strength of the tooth as prolonged Ca(OH)2 treatment.

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