title: Fracture resistance of endodontically treated molars restored with extensive composite resin restorations.
abstract: BACKGROUND
  When cuspal coverage is required, there is no evidence that indirect composite resin restorations are superior to direct restorations in terms of biomechanical behavior.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to compare the fracture resistance of cusp-replacing direct and indirect composite resin restorations in endodontically treated molars.
  
  
  METHODS
  Forty-five human mandibular molars were selected and divided into 3 groups (n=15): DIR specimens, restored with direct composite resin (Estelite Sigma) restorations; IND specimens, restored with indirect composite resin (Estelite Sigma) restorations, and control specimens, which remained intact. Endodontic treatment was performed using NiTi ProTaper rotary instruments, and teeth were filled using lateral condensation of gutta-percha and sealer. Extensive Class II MO cavities were prepared, and the 2 mesial cusps were reduced, allowing a 2-mm layer of composite resin. All teeth were prepared to the same dimensions, considering reasonable human variation. Specimens were loaded to failure and the fracture loads were recorded (N). The mode of fracture was determined using a stereomicroscope and classified as favorable or unfavorable failure. The data were subjected to a Kruskal-Wallis test, multiple-comparison Mann-Whitney test, and a chi-square test (alpha=.05).
  
  
  RESULTS
  Significant differences (P<.001) were observed between the control group and both DIR and IND groups. However, no significant difference was found between the DIR and IND groups. The chi-square test did not show a significant difference in the frequencies of favorable/unfavorable failure modes among the 3 groups (P=.981).
  
  
  CONCLUSIONS
  No significant difference was observed in the fracture resistance of endodontically treated molars restored to original contours with an extensive cusp-replacing direct or indirect composite resin restoration.
authors.affiliation: Department of Endodontics, Catholic University of Sacred Heart, Rome, Italy. gplotino@fastwebnet.it
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.forename: Laura
authors.initials: L
authors.lastname: Buono
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Grande
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Lamorgese
authors.forename: Francesco
authors.initials: F
authors.lastname: Somma
mesh_terms: D001696:Biomechanical Phenomena; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000379:methods; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004853:Epoxy Resins / Q000627:therapeutic use; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D007284:Inlays; D008334:Mandible; D008422:Materials Testing; D008963:Molar / Q000503:physiopathology*; D019279:Resin Cements / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000503:physiopathology / Q000628:therapy*
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D004853:Epoxy Resins; C507124:Estelite sigma; D019279:Resin Cements; D012387:Root Canal Filling Materials; C084018:Scotchbond Multi-Purpose; C115110:Topseal; D006171:Gutta-Percha