This study was carried out to evaluate the pulpal response to polycarboxylate cement with 25% iodoform or with 5% potassium nitrate, MTA and ferric sulfate when used as pulp capping agents in dog’s teeth. Also, to compare them with and without nickel chromium caps. Class I cavities prepared in 120 teeth of 6 dogs. In each interval (4, 8 &12 weeks) there were 20 teeth treated with caps (totally 60) and 20 teeth without caps (totally 60). The results with caps in all groups showed increasing by time of the calcific bridge with greater thickness and better quality. There was no significant difference in the calcific bridge thickness between polycarboxylate with 5 % KNO3 and MTA groups in the specimens treated with caps throughout the study. In the specimens without caps MTA showed greater thickness than other groups. All specimens showed no or mild inflammation in all intervals. In conclusion using of the metal cap in pulp capping improve the quality and quantity of the hard tissue formation when used with different capping materials, especially when combined with ferric sulfate and polycarboxylate with 5% KNO3 as this method fulfill the entire requirement for pulp capping success.