Table 1: Control and experimental groups used in the study.
| Groups | N | Experimental procedures |
| G1 (control) | 5 | Negative control-without periapical lesion. Saline solution administered intraperitoneally (IP) one time a week for 2 weeks. Analysis after the last dose. |
| G2 (PL2) | 5 | Positive control-periapical lesion induction, Saline solution administered IP one time a week for 2 weeks and analysis after 2 days after last dose. |
| G3 (PL4) | 5 | Positive control-periapical lesion induction, Saline solution administered IP one time a week for 2 weeks and analysis after 4 days after last dose. |
| G4 (PL7) | 5 | Positive control-periapical lesion induction, Saline solution administered IP one time a week for 2 weeks and analysis after 7 days after last dose. |
| G5 PL-MTX-2 | 5 | Periapical lesion induction, 12 mg/Kg of methotrexate administered one time a week for 2 weeks and analysis after 2 days after last dose. |
| G6 PL-MTX-4 | 5 | Periapical lesion induction, 12 mg/Kg of methotrexate administered one time a week for 2 weeks and analysis after 4 days after last dose. |
| G7 PL-MTX-7 | 5 | Periapical lesion induction, 12 mg/Kg of methotrexate administered one time a week for 2 weeks and analysis after 7 days after last dose. |