title: Evaluation of tooth analogs and type of restoration on the fracture resistance of post and core restored incisors.
abstract: OBJECTIVE
  In in vitro tests, metals and resins are frequently used as substitutes for human teeth. This study aims at determining the suitability of various materials for substituting human incisors in load capability tests.
  
  
  METHODS
  Veneering composite (Adoro; n = 16) and non-precious CoCr-alloy (NPA; n = 16) were used for manufacturing 32 identical specimens based on the model of a maxillary central incisor resin tooth (Morita). Sixteen human incisors served as a control group. After root canal treatment, all specimens were restored with fiber-reinforced composite posts and core build-ups. For each group, eight specimens were chosen randomly and restored either with identical NPA crowns or with all-ceramic crowns. Specimens were exposed to thermal cycling and mechanical loading (TCML) until failure. Statistical analysis was conducted using the Kruskal-Wallis test and the Bonferroni-adjusted Mann Whitney U-test.
  
  
  RESULTS
  In ceramic crowns, the highest median fracture resistance was found in alloy tooth substitutes (430 N) and natural incisors (426 N), which both showed a significantly higher fracture resistance than composite tooth substitutes (162 N). In alloy crowns, alloy tooth substitutes exhibited the highest fracture resistance (348 N), but no statistically significant difference could be detected between natural incisors (158 N) and composite tooth substitutes (117 N). No artificial tooth substitute showed fracture patterns similar to those of natural incisors.
  
  
  CONCLUSIONS
  Mechanical parameters are significantly influenced by the type of restoration and the restorative material used. In in vitro tests, the range of artificial tooth substitutes suitable for the replacement of human incisors is limited by load capability.
authors.affiliation: Department of Prosthetic Dentistry, Regensburg University Medical Center, Regensburg, Germany. martin.rosentritt@klinik.uni-regensburg.de
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
authors.forename: Michael
authors.initials: M
authors.lastname: Naumann
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hahnel
authors.forename: Gerhard
authors.initials: G
authors.lastname: Handel
authors.forename: Margarete
authors.initials: M
authors.lastname: Reill
mesh_terms: D001732:Bite Force; D019245:Compressive Strength; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D011176:Post and Core Technique; D011897:Random Allocation; D012390:Root Canal Therapy; D013314:Stress, Mechanical; D014082:Tooth Fractures
chemical_list: D003764:Dental Materials