title: Effects of post-core design and ferrule on fracture resistance of endodontically treated maxillary central incisors.
abstract: BACKGROUND
  Studies concerning the effects of post-core design and ferrule on the fracture resistance of endodontically treated teeth remain controversial.
  
  
  OBJECTIVE
  The purpose of this study was to investigate in vitro the effects of post-core design and ferrule on the fracture resistance of root canal treated human maxillary central incisors restored with metal ceramic crowns.
  
  
  METHODS
  Forty-eight extracted human maxillary central incisors were endodontically treated and divided into 4 groups of 12. The following treatments were evaluated: group A: restored with metal ceramic (porcelain fused to metal [PFM]) crowns as control; group B: 2-mm ferrule/custom cast post-core/PFM crowns; group C: no ferrule/custom cast post-core/PFM crowns; and group D: 2-mm ferrule/prefabricated post and resin core/PFM crowns. Each specimen was subjected to load (N) on the lingual surface at a 135-degree angle to the long axis with a MTS 810 material testing machine until fracture at a crosshead speed of 0.02 cm/min. One-way analysis of variance and nonparametric chi-square test were used to compare the results. A significant analysis of variance result was followed by Newman-Keuls pairwise multiple comparisons (P<.05).
  
  
  RESULTS
  There were significant differences among the 4 groups studied (P<.01). Group B had the highest fracture strength (1793.59 +/- 387.93 N). There was no significant difference among the fracture resistances of the other 3 groups (group A: 958.49 +/- 286.02 N; group C: 992.98 +/- 291.00 N; group D: 994.94 +/- 285.04 N).
  
  
  CONCLUSIONS
  Within the limitations of this study, not all of the post-core structures tested improved the strength of the endodontically treated teeth. Those prepared with a 2-mm dentin ferrule more effectively enhanced the fracture strength of custom cast post-core restored endodontically treated maxillary central incisors.
authors.affiliation: Department of Dentistry, Beijing Hospital, Beijing, People's Republic of China. zhiyuel@263.net
authors.forename: Lu
authors.initials: L
authors.lastname: Zhi-Yue
authors.forename: Zhang
authors.initials: Z
authors.lastname: Yu-Xing
mesh_terms: D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D007180:Incisor / Q000473:pathology*; D016555:Matched-Pair Analysis; D008422:Materials Testing; D008437:Maxilla; D016876:Metal Ceramic Alloys / Q000737:chemistry; D011176:Post and Core Technique; D018915:Root Canal Preparation; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000534:rehabilitation*
chemical_list: D003188:Composite Resins; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain