title: The effect of custom adaptation and span-diameter ratio on the flexural properties of fiber-reinforced composite posts.
abstract: OBJECTIVE
  To evaluate whether custom modification resulting in an anatomically shaped post and whether the span/diameter ratio (L/D) would affect the mechanical properties of fiber-reinforced composite posts.
  
  
  METHODS
  Preformed glass-fiber posts (Group 1) and modified glass-fiber posts (Group 2) and glass-fiber rods (Groups 3 and 4) (n=20) were loaded to failure in a three-point bending test to determine the maximum load (N), flexural strength (MPa) and flexural modulus (GPa). The span distance tested for Group 3 was 10.0mm, while for Group 4 was 22.0mm. Data were subjected to different statistical analysis with significance levels of P<0.05.
  
  
  RESULTS
  The maximum load recorded for Groups 1 and 2 was 72.5+/-5.9N and 73.4+/-6.4N respectively, while for Groups 3 and 4 was 215.3+/-7N and 156.6+/-3.6N respectively. The flexural strength for Groups 1 and 2 was 914.6+/-53.1MPa and 1069.2+/-115.6MPa, while for Groups 3 and 4 was 685.4+/-22.2MPa and 899.6+/-46.1MPa. The flexural modulus recorded for Groups 1 and 2 was 32.6+/-3.2GPa and 33.4+/-2.2GPa respectively, while for Groups 3 and 4 was 13.7+/-0.3GPa and 34.4+/-0.3GPa respectively.
  
  
  CONCLUSIONS
  The flexural properties of an anatomically custom modified fiber post were not affected by the modification procedure and the span-diameter ratio is an important parameter for the interpretation of flexural strength and flexural modulus values.
authors.affiliation: Department of Endodontics, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Grande
authors.forename: Gianluca
authors.initials: G
authors.lastname: Plotino
authors.forename: Pietro
authors.initials: P
authors.lastname: Ioppolo
authors.forename: Rossella
authors.initials: R
authors.lastname: Bedini
authors.forename: Cornelis H
authors.initials: CH
authors.lastname: Pameijer
authors.forename: Francesco
authors.initials: F
authors.lastname: Somma
mesh_terms: D003188:Composite Resins / Q000737:chemistry; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D005898:Glass; D006801:Humans; D018583:Pliability; D011176:Post and Core Technique
chemical_list: D003188:Composite Resins; C009753:fiberglass