relationship between duration of pulp exposure and success rate of apexogenesis

introduction: apexogenesis is a way to save vitality of open apex damaged teeth with mild or moderate pulp involvement. such teeth are not repaired through normal and usual treatments. this treatment provides usual and physiological conditions for root to develop in normal length. the aim of this study was to determine the success rate of apexogenesis according to the duration of pulp exposure. materials and methods: in this animal study, mineral trioxide aggregate (mta) and calcium hydroxide (ch) were used. the examined teeth were canines of cats with open apices. the treatment was accomplished in three periods of 1, 3, and 6 weeks after pulpal exposure. four months later, the results were evaluated histologically and radiographically. results: the results showed no significant difference between the success rate of mta and ch. besides, after 6 weeks of pulpal exposure the treatment was successful. root development and apical closure was detected in approximately 42% of teeth, while 33% of samples had a healthy hertwigʼs sheath. conclusion: the findings of this study suggested that the conservative treatment in traumatized teeth after 1.5 month of pulpal exposure could be successful.