title: Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems: an in vitro study.
abstract: OBJECTIVE
  This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post-and-core systems after exposure to an artificial mouth.
  
  
  METHODS
  Sixty-four caries-free human maxillary central incisors were selected for standardized size and quality, endodontically treated, and decoronated 2 mm coronal to the cementoenamel junction. Group 1 was restored with titanium posts and composite cores, group 2 received zirconia posts and a composite core, and in group 3 zirconia posts with a heat-pressed ceramic core were used. Teeth restored with cast posts and cores served as controls. All teeth were prepared and restored with complete cast crowns. All samples were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling. In addition, the samples were loaded until fracture in a static testing device.
  
  
  RESULTS
  The survival rates of the different groups were: 94% for titanium/composite, 63% for zirconia/composite, 100% for the all-ceramic post and core, and 94% for the cast post and core. The following mean fracture strengths were obtained: titanium/composite = 425 +/- 155 N, zirconia/composite = 202 +/- 212 N, zirconia/ceramic = 378 +/- 64 N, cast post and core = 426 +/- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant. The use of zirconia posts resulted in fewer oblique root fractures.
  
  
  CONCLUSIONS
  Prefabricated titanium posts with composite cores, zirconia posts with heat-pressed ceramic cores, and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects. Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower, so this combination cannot be recommended for clinical use.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Albert Ludwigs University, Freiburg, Germany. butz@zmk2.ukl.uni-freiburg.de
authors.forename: F
authors.initials: F
authors.lastname: Butz
authors.forename: A M
authors.initials: AM
authors.lastname: Lennon
authors.forename: G
authors.initials: G
authors.lastname: Heydecke
authors.forename: J R
authors.initials: JR
authors.lastname: Strub
mesh_terms: D002484:Cementation; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003442:Crowns; D003722:Dental Alloys / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D007180:Incisor / Q000503:physiopathology*; D008277:Magnesium Oxide / Q000737:chemistry; D008409:Mastication / Q000502:physiology; D008437:Maxilla; D010710:Phosphates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation; D019279:Resin Cements / Q000737:chemistry; D012390:Root Canal Therapy; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D015996:Survival Rate; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000293:injuries; D015034:Zinc Oxide / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D005899:Glass Ionomer Cements; D006047:Gold Alloys; C093719:Panavia TPN-S; D010710:Phosphates; D011076:Polycarboxylate Cement; D019279:Resin Cements; D008277:Magnesium Oxide; C040235:Ketac-cem; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide; D015034:Zinc Oxide