an invitro evaluation of coronal microleakage in strengthening of weakend teeth with different tooth-coloured material with

introduction: the purpose of this in vitro study was to investigate coronal microlenkage in anterior weakend teeth after root canal therapy, reinforced with different tooth-coloured material and frc post. methods and materials: a total 48 extracted intact central incisor were randomly divided into four experimental groups (n=12). all specimens were endodontically treated using lateral condensation and crowns were totally removed from 2mm of cej and were over flared to simulate weakened teeth . control group (group i) was restored only with gutta percha .in other groups root canal walls were prepared (etching, washing and gentle drying, bonding) and the surface of the posts were cleaned with alcohol and after that covered with bonding agent and then light polymerized for 40 seconds. finally post cementation was done durig reinforcing of weakened root canal walls with packable composite in group ii, self-cure composite in group iii and dual cure composite in group iv. all specimens were thermocycled for 500 cycles between 5ºc and 55ºc0 with a dowel time of 20 seconds before immersion in dye. then all specimens were sealed with sticky wax and coated with two layer of nail polish & then they were placed in 0.5% fuchsine for 24 hours at room temperature and were sectioned longitudinally from the center of post with tooth cutter. dye penetration in both sections of each tooth were evaluated using a stereomicroscope equipped with digital camera at original magnification of 32× and microleakage recorded in m. one-way analysis of variances (anova) and least square difference were used for statistical analysis. result: the control group showed the maximum microleakage and the minimum was related to the third group .there was a significant difference among the average microleakage of all groups. conclusion: combination of frc post and tooth-coloured materials did reinforce structurally compromised root and decreased microleakage and also the microleakage of root/bonding material is more than post/tooth-colored material. microleakge in selfcure group because of its polymerization was the least.