title: A comparative assessment of fracture resistance of endodontically treated and re-treated teeth: An in vitro study.
abstract: OBJECTIVE
  To compare and assess the fracture resistance of endodontically treated teeth with those that have been subjected to endodontic retreatment.
  
  
  METHODS
  30 extracted mandibular premolars were decoronated at cementoenamel junction and randomly divided into 2 groups. In Group I endodontic treatment was performed with ProTaper rotary system till size F2 and obturated. In Group II, cleaning and shaping was done and teeth were subjected to Spiral CT to assess the remaining dentin thickness and obturated. Later retreatment was done using Protaper Universal Retreatment system and final shaping was performed till size F3. Remaining dentin thickness was again assessed using Spiral CT and then obturated. All the specimens were subjected to fracture resistance using universal testing machine. The results were statistically analyzed using Independent Samples t-test for analysis of remaining dentin thickness using SCT within Group II and Paired Samples t-test was used for assessment of fracture resistance between Group I and II (P < 0.05).
  
  
  RESULTS
  In Group II, the intra group comparison of the remaining dentin thickness in the coronal third reveals statistical significance, with a significant difference noted in the apical third. Results of the fracture resistance reveal a statistically significant difference (P < 0.05) between Groups I and II with the mean fracture resistance of Group I being higher than Group II.
  
  
  CONCLUSIONS
  Endodontically retreated teeth have shown significantly decreased resistance to fracture and this has a positive correlation to the increased loss of root dentin during the retreatment procedures.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India.
authors.forename: Arathi
authors.initials: A
authors.lastname: Ganesh
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India.
authors.forename: Nagendrababu
authors.initials: N
authors.lastname: Venkateshbabu
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India.
authors.forename: Aby
authors.initials: A
authors.lastname: John
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India.
authors.forename: Gogulnath
authors.initials: G
authors.lastname: Deenadhayalan
authors.affiliation: Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India.
authors.forename: Deivanayagam
authors.initials: D
authors.lastname: Kandaswamy
keywords: Endodontic treatment; fracture resistance; retreatment; spiral computed tomography