title: The effect of incomplete crown ferrules on fracture resistance and failure modes of endodontically treated maxillary incisors restored with quartz fiber post, composite core, and crowns.
abstract: OBJECTIVE
  To investigate the fracture resistance of restored endodontically treated teeth (RETT) with fiber posts, cores, and crowns with limited ferrules.
  
  
  METHODS
  Sixty maxillary anterior teeth were endodontically treated and decoronated 2 mm above the cemento-enamel junction, and then divided into 6 groups of 10 teeth each; Group circumferential ferrule (2FR), Group ferrule in the labial, mesial, and palatal region (2FR-LaMPa), Group ferrule in the labial, and palatal region (2FR-LaPa), Group 2FR-Pa and 2FR-La respectively, and Group 0FR (no ferrule). All 60 prepared teeth were then restored with quartz fiber posts, resin composite cores, and metal crowns. The specimens were subjected to load until failure occurred. Data were analyzed using one-way analysis of variance and Tukey's tests (α = 0.05). The mode of failure was determined under a stereoscope.
  
  
  RESULTS
  A statistical significant difference was found among groups 2FR-LaMPa, 2FR-Pa, 2FR-LaPa, and 2FR from the group 2FR-La, and from the group 0FR (P < 0.01). The predominant mode of failure was an oblique palatal to labial root fracture for the groups with remaining ferrules.
  
  
  CONCLUSIONS
  For RETT that have incomplete crown ferrules, the location of the ferrules may affect their fracture resistance.
authors.affiliation: Section of Dental Public Health, Kanchanadit Hospital, Kanchanadit, Suratthani, Thailand.
authors.forename: Panorjit
authors.initials: P
authors.lastname: Muangamphan
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Boonrat
authors.initials: B
authors.lastname: Sattapan
authors.affiliation: Department of Conservative Dentistry, Dental Materials Research Unit, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Boonlert
authors.initials: B
authors.lastname: Kukiattrakoon
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand.
authors.forename: Kewalin
authors.initials: K
authors.lastname: Thammasitboon
keywords: Ferrule design; fracture resistance; post-core restorations; quartz fiber post; restoration of endodontically treated teeth