title: Performance of techniques used for re-attachment of endodontically treated crown fractured teeth.
abstract: OBJECTIVE
  The aim of this study was to compare the fracture strength of three techniques used to re-attach tooth fragments in sound and endodontically treated fractured teeth with or without fiber post placement.
  
  
  METHODS
  Ninety human lower incisors were randomly divided into three groups of 30 teeth each. In group A teeth were not subjected to endodontic treatment; while teeth from groups B and C were endodontically treated and the pulp chamber restored with a composite resin. All teeth were fractured by an axial load applied to the buccal area in order to obtain tooth fragments. Teeth from each group were then divided into three subgroups, according to the re-attachment technique: bonded-only, buccal-chamfer and circumferential chamfer. Before the re-attachment procedures, fiber posts were placed in teeth from group C using dual cure resin luting cement (Duo-Link). All teeth (groups A-C) had the fragments re-attached using a same dual cure resin luting cement. In the bonded-only group, no additional preparation was made. After re-attachment of the fragment, teeth from groups buccal and circumferential chamfer groups had a 1.0 mm depth chamfer placed in the fracture line either on buccal surface or along the buccal and lingual surfaces, respectively. Increments of microhybid composite resin (Tetric Ceram) were used in subgroups buccal chamfer and circumferential chamfer to restore the chamfer. The specimens were loaded until fracture in the same pre-determined area. The force required to detach each fragment was recorded and the data was subjected to a three-way analysis of variance where factors Group and Re-attachment technique are independent measures and Time of fracture is a repeated measure factor (first and second) and Tukey's test (alpha=0.05).
  
  
  RESULTS
  The main factors Re-attachment technique (p=0.04) and Time of fracture (p=0.02) were statistically significant. The buccal and circumferential chamfer techniques were statistically similar (p>0.05) and superior to the bonded-only group (p<0.05). The first time of fracture was statistically superior to second time of fracture (p<0.001).
  
  
  CONCLUSIONS
  The use of fiber post is not necessary for the reinforcement of the tooth structure in re-attachment of endodontically treated teeth. When bonding a fractured fragment, the buccal or circumferential re-attachment techniques should be preferable in comparison with the simple re-attachment without any additional preparation. None of the techniques used for re-attachment restored the fracture strength of the intact teeth.
authors.affiliation: Department of Restorative Dentistry, Universidade Estadual de Ponta Grossa Rua Carlos Covalcanti 4748 Bloco M, Sala 64 A, Vvaranas, Ponta Grossa, 84030-900 PR, Brazil. aloguercio@hotmail.com
authors.forename: Alessandro Dourado
authors.initials: AD
authors.lastname: Loguercio
authors.forename: Gilmara
authors.initials: G
authors.lastname: Leski
authors.forename: Daiana
authors.initials: D
authors.lastname: Sossmeier
authors.forename: Alexander
authors.initials: A
authors.lastname: Kraul
authors.forename: Margereth
authors.initials: M
authors.lastname: Oda
authors.forename: Rafael Tiago
authors.initials: RT
authors.lastname: Patzlaff
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding / Q000379:methods*; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D011176:Post and Core Technique; D019279:Resin Cements; D019228:Tooth Crown / Q000293:injuries*; D014082:Tooth Fractures / Q000628:therapy*; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C121818:Tetric ceram