RESUMO
OBJECTIVE: The aim of this in vitro study was to evaluate the long-term effect of calcium hydroxide (CH) on the microtensile fracture strength (MTFS) of endodontically treated human teeth. MATERIALS AND METHODS: A total of 105 caries-free extracted human mandibular incisors were used. The teeth were divided into seven experimental groups of 15 teeth each. The root canals of all the teeth were rotary instrumented. The teeth in the control group were immediately obturated and tested for MTFS. The rest of the teeth were vertically compacted with CH and a sterile saline solution mixture and sealed with temporary filling. The teeth were stored in a moist environment for 30, 90, 180, 270, 360, and 540 days. On scheduled dates, the root canals were obturated and then the teeth were tested for MTFS with an Instron testing machine. The Kruscal-Wallis test and a post hoc Dunn's multiple comparison test was utilized. The statistical significance level was established at P < 0.05. RESULTS: The introduction of CH into the root canals seems to decrease the MTFS of teeth statistically significantly through the 180th, 270th, 360th, and 540th days, respectively, compared with the control group. The results clearly indicated that there are statistically significant differences between group 2 and group 7 (P < 0.001) and between group 3 and group 7 (P < 0.05). There were no statistically significant differences between the rest of the groups (P > 0.05). CONCLUSIONS: The results indicate that long-term CH treatments can significantly reduce the strength of the teeth, causing an increase in fracture risk.
