The effect of antibiotic pastes on microhardness of dentin

The aim of this study was to evaluate the effect of various endodontic regeneration agents on the microhardness of human root dentin after contact for various time intervals.

Thirty-five extracted human maxillary incisors were selected. The canals were enlarged and fixed in acrylic resin blocks. Two sections were obtained from the middle-third of each root (n = 70). The root discs were divided randomly into three groups of 20 and a control group of 10. Baseline microhardness testing was completed using a microhardness tester. The root discs were placed in Petri dishes and then assigned randomly to triple antibiotic paste (TAP), double antibiotic paste (DAP), calcium hydroxide paste (CH) and the control group. The CH and two antibiotic pastes were placed in the Petri dishes, and the discs were covered completely with the mixtures. Microhardness tests were repeated in the same manner after weeks 1, 2 and 3. Data were analysed statistically with a chi-square and Fisher's exact test at the 5% significance level and post hoc analysis was performed.

No significant change in dentin microhardness occurred in the control group (P > 0.05). Overall, the dentin microhardness values decreased after treatment with the CH and antibiotic pastes over all time intervals. The DAP group showed reduced Knoop hardness number (KHN) values compared with the TAP group at the 1 measurements (P < 0.01). Statistically significant differences were found among the control, DAP and TAP groups, but no difference was seen between the control and CH groups at the week 1 measurement. No significant difference was found between the DAP and TAP groups at the week 4 measurement.

Applying DAP and TAP for 4 weeks significantly reduced the microhardness values of dentin discs compared with the baseline values.