Materials and methods: 5 New Zealand male-rabbits were chosen within a 3-week observation period; the work was done on the four upper and lower incisors of each rabbit. The group consists of 20 rabbit-teeth. MTA was randomly applied to 10 teeth (5 upper incisors, 5 lower incisors), PRF was also randomly assigned to the other 10 teeth (5 upper incisors, 5 lower incisors). A drill were used to prepare a V class preparation on the buccal surface of the incisors until mechanical pulpal exposure has performed, hemostasis were done to the exposure site, and the materials of the study were applied, all the teeth groups were restored with glass ionomer cement (GIC). After three weeks, the animals were stripped; incisors were extracted and embedded in 10% formalin, later histological cross sections were obtained for microscopic study.

Results: no statistically significant differences were obtained between MTA and PRF at 95% confidence level for the inflammatory reaction and formation of the dentinal bridge.

Conclusions: similarity of PRF and MTA as pulp capping materials.