title: Relationship between Duration of Pulp Exposure and Success Rate of Apexogenesis.
abstract: BACKGROUND
  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.
  
  
  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 Hertwig's sheath.
  
  
  CONCLUSIONS
  The findings of this study suggested that the conservative treatment in traumatized teeth after 1.5 month of pulpal exposure could be successful.
authors.affiliation: Department of Endodontics, Dental Research Center, Dental School, Mashad University of Medical Sciences, Mashad, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Moradi
authors.affiliation: Department of Endodontics, Dental School, Mashad University of Medical Sciences, Mashad, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Naghavi
authors.affiliation: Department of Restorative Dentistry, Dental School, Mashad University of Medical Sciences, Mashad, Iran.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Roohani
authors.affiliation: Department of Oral Pathology, Dental School, Mashad University of Medical Sciences, Mashad, Iran.
authors.forename: Nooshin
authors.initials: N
authors.lastname: Mohtasham
keywords: Apexogenesis; Calcium Hydroxide; MTA