title: Fracture behavior of human mandibular incisors following endodontic treatment and porcelain veneer restoration.
abstract: OBJECTIVE
  Because of existing controversy, the present study investigated the individual and combined effects of endodontic treatment and porcelain veneer restoration on the fracture behavior of human mandibular incisors.
  
  
  METHODS
  Forty extracted intact human mandibular incisors were assigned to four groups of ten with a similar range of labiolingual widths at the cementoenamel junctions. Group A consisted of intact teeth; group B consisted of endodontically treated teeth; group C teeth were restored with labial porcelain veneers; and those of group D were endodontically treated and had labial porcelain veneers. All teeth were subjected to a slow continuous loading test at 30 degrees to the long axis of the teeth and 1 mm below the incisal edge on the labial side.
  
  
  RESULTS
  Fracture forces were 415 +/- 220 N, 370 +/- 89 N, 420 +/- 128 N, and 448 +/- 156 N for groups A, B, C, and D, respectively. Root fracture was the most common mode of failure. There were no statistically significant differences between the groups in terms of fracture forces and modes of failure.
  
  
  CONCLUSIONS
  Human mandibular incisors with endodontic treatment and/or porcelain veneer restorations were able to withstand the same magnitude of oblique loading as intact teeth. Endodontic treatment and/or porcelain veneer restoration did not affect the mode of failure of mandibular incisors.
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, China.
authors.forename: H H
authors.initials: HH
authors.lastname: Ho
authors.forename: F C
authors.initials: FC
authors.lastname: Chu
authors.forename: A N
authors.initials: AN
authors.lastname: Stokes
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D003188:Composite Resins; D003738:Dental Cements; D003776:Dental Porcelain; D003801:Dental Veneers; D017220:Dentin-Bonding Agents; D006171:Gutta-Percha; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology / Q000503:physiopathology*; D008334:Mandible; D016011:Normal Distribution; D012387:Root Canal Filling Materials; D018915:Root Canal Preparation; D012390:Root Canal Therapy; D012821:Silanes; D013314:Stress, Mechanical; D019237:Tooth Cervix / Q000033:anatomy & histology; D014082:Tooth Fractures / Q000503:physiopathology*; D019246:Tooth Preparation; D014092:Tooth Root / Q000293:injuries / Q000503:physiopathology
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D012387:Root Canal Filling Materials; D012821:Silanes; D003776:Dental Porcelain; D006171:Gutta-Percha