title: Stress pattern generated by different post and core material combinations: a photoelastic study.
abstract: OBJECTIVE
  To analyze the effect of different combinations of post and core materials on stress distribution in dentin of an endodontically treated tooth.
  
  
  METHODS
  This was an experimental stress analysis study. Models were made in photoelastic material, i.e., epoxy resin. Different combinations of post and core materials used were: Glass fiber post with composite core, stainless steel post with composite core, and cast metal post and core. Stresses generated were frozen, models were sliced and viewed under circular polariscope, and photographs were taken. Stress was calculated by counting the number of fringes.
  
  
  RESULTS
  For the combination of glass fiber post with composite core, the shear stresses calculated were 1.196, 1.196, and 2.898 MPa in the apical, mid-root, and cervical region, respectively. For the combination of stainless steel post with composite core, the apical, mid-root and cervical stresses were 1.534, 0.511, and 2.557 MPa, respectively. For cast metal post and core, the apical, mid-root, and cervical stresses were 0.852, 0.511, and 1.534 MPa, respectively.
  
  
  CONCLUSIONS
  The cervical region of the teeth is subjected to the highest stresses irrespective of the material used. The stainless steel post with the composite core generated the highest stress concentration in different regions. A glass fiber post generated a uniform stress distribution. A cast metal post and core combination generated lesser stress than the other combinations. The vast difference in the elastic modulus of the restorative materials can lead to nonuniform stress distribution and concentration of stresses in different areas which can have deleterious effect on the survival of already compromised teeth and restoration. Such combinations should be avoided and the material which has an elastic modulus close to that of dentin should be preferred.
authors.affiliation: Department of Prosthodontics, Dr. ZA Dental College, AMU, Aligarh, India.
authors.forename: Shaista
authors.initials: S
authors.lastname: Afroz
authors.forename: Arvind
authors.initials: A
authors.lastname: Tripathi
authors.forename: Pooran
authors.initials: P
authors.lastname: Chand
authors.forename: Rama
authors.initials: R
authors.lastname: Shanker
mesh_terms: D001696:Biomechanical Phenomena; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000503:physiopathology; D003804:Dentin / Q000503:physiopathology*; D055119:Elastic Modulus; D004853:Epoxy Resins / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006801:Humans; D010781:Photography; D010796:Phthalic Anhydrides / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D012833:Siloxanes / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D019227:Tooth Apex / Q000503:physiopathology; D019237:Tooth Cervix / Q000503:physiopathology; D019553:Tooth, Nonvital / Q000503:physiopathology
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D004853:Epoxy Resins; D010796:Phthalic Anhydrides; D011145:Polyvinyls; D012833:Siloxanes; C480691:aquasil; C009753:fiberglass; D013193:Stainless Steel; C005752:araldite