Aim: To evaluate and compare the role of macrogol–propylene glycol (MP), aloe vera gel (Aloe barbadensis miller) and distilled water as a vehicle (mixing medium) for triple antibiotic drugs in the success of lesion sterilization and tissue repair (LSTR).

Materials and methods: Fifty-four primary mandibular second molars with irreversible pulpitis and poor prognosis in children aged 3–8 years were included in the study and were randomly divided into three groups (18 per group), in which LSTR was performed. Samples were grouped based on the vehicle used for mixing triple antibiotic drugs as macrogol–propylene glycol (Group A), aloe vera (Group B) and distilled water (Group C). Clinical evaluations were done at 3, 6, 9 and 12 months and radiographic evaluations at 6, 9 and 12 months.

Result: At the end of 12 months, 100% clinical and radiographic success was observed in Group B, while clinical and radiographic success rate in Group A was 82.35% and 88.24% respectively and both clinical, as well as radiographic success rate in Group C, was 81.25%. No statistically significant difference was seen in clinical as well as radiographic success rates (p = 0.156 and 0.176 respectively) among the three groups.

Conclusion: Clinical and radiographic outcomes suggested that all of the three mixing media used in the study could be regarded as a suitable vehicle for 3 Mix in LSTR. However, better results were found when aloe vera was used as a mixing medium.