title: Comparative evaluation of the effect of different crown ferrule designs on the fracture resistance of endodontically treated mandibular premolars restored with fiber posts, composite cores, and crowns: An ex-vivo study.
abstract: BACKGROUND
  In cases of severe hard tissue loss, 2 mm circumferential ferrule is difficult to achieve which leads to incorporation of different ferrule designs.
  
  
  OBJECTIVE
  To compare and evaluate the effect of different crown ferrule designs on the fracture resistance of mandibular premolars restored with fiber posts, composite cores, and crowns.
  
  
  METHODS
  Fifty freshly extracted mandibular premolars were endodontically treated and divided into five groups: Group I - 2 mm circumferential ferrule above the cementoenamel junction (CEJ); Group II - 2 mm ferrule on the facial aspect above CEJ; Group III - 2 mm ferrule on the lingual aspect above CEJ; Group IV - 2 mm ferrule on the facial and lingual aspects above CEJ with interproximal concavities, and Group V - no ferrule (control group) and were later restored with fiber posts, composite cores, and crowns. Specimens were mounted on a universal testing machine, and compressive load was applied at a crosshead speed of 1 mm/min until fracture occurred.
  
  
  RESULTS
  The results showed that circumferential ferrule produced the highest mean fracture resistance and the least fracture resistance was found in the control group.
  
  
  CONCLUSIONS
  Circumferential ferrule increases the fracture resistance of endodontically treated teeth restored with bonded post, core, and crown.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: Nikita
authors.initials: N
authors.lastname: Dua
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: Bhupendra
authors.initials: B
authors.lastname: Kumar
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: D
authors.initials: D
authors.lastname: Arunagiri
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Iqbal
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: S
authors.initials: S
authors.lastname: Pushpa
authors.affiliation: Department of Oral Medicine and Radiology, Rama Dental College Hospital and Research Center, Kanpur, Uttar Pradesh, India.
authors.forename: Juhi
authors.initials: J
authors.lastname: Hussain
keywords: Composites cores; ferrule designs; fiber post