title: An in vitro investigation into the effects of retained coronal dentine on the strength of a tooth restored with a cemented post and partial core restoration.
abstract: OBJECTIVE
  This study aimed to examine the fracture resistance of teeth restored with cast post and partial cores supported by different heights of coronal tooth structure.
  
  
  METHODS
  Four specimen groups were prepared. Group A was the control and consisted of 10 single-rooted teeth restored with post and cores cemented in dowel channels with no retained coronal dentine.The test groups, B, C and D differed in the amount of retained buccal coronal dentine having 3, 4 and 5 mm, respectively. All groups were tested to failure using an Instron Universal Testing Machine, Model 1195. The mode of failure for representative specimens for each group was recorded photographically.
  
  
  RESULTS
  Specimens in group B where the remaining dentine core was 3 mm in height fractured at a higher force than specimens in the control group (P = 0.0239). There were no statistically significant differences in the forces required to fracture teeth with retained buccal coronal dentine cores of 4 and 5 mm when compared to the control. There was no statistically significant difference between forces required to fracture groups B and C or groups B and D.
  
  
  CONCLUSIONS
  In this in vitro study, 3 mm of retained coronal buccal dentine improved fracture resistance of teeth restored with partial post and cores when compared to teeth without retained coronal dentine.
authors.affiliation: Faculty of Dentistry, Jordan University of Science and Technology, Irbid, Jordan. ahed@just.edu.jo
authors.forename: A
authors.initials: A
authors.lastname: Al-Wahadni
authors.forename: D L
authors.initials: DL
authors.lastname: Gutteridge
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid / Q000503:physiopathology; D002484:Cementation; D003481:Cuspid / Q000503:physiopathology; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000033:anatomy & histology*; D006801:Humans; D007180:Incisor / Q000503:physiopathology; D016555:Matched-Pair Analysis; D011176:Post and Core Technique; D013223:Statistics as Topic; D013314:Stress, Mechanical; D019228:Tooth Crown / Q000033:anatomy & histology*; D014082:Tooth Fractures / Q000503:physiopathology; D019246:Tooth Preparation / Q000379:methods*; D016474:Weight-Bearing