The effect of custom adaptation and span-diameter ratio on the flexural properties of fiber-reinforced composite posts

Objectives: 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 10.0 mm, while for Group 4 was 22.0 mm. 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 ± 5.9 N and 73.4 ± 6.4 N respectively, while for Groups 3 and 4 was 215.3 ± 7 N and 156.6 ± 3.6 N respectively. The flexural strength for Groups 1 and 2 was 914.6 ± 53.1 MPa and 1069.2 ± 115.6 MPa, while for Groups 3 and 4 was 685.4 ± 22.2 MPa and 899.6 ± 46.1 MPa. The flexural modulus recorded for Groups 1 and 2 was 32.6 ± 3.2 GPa and 33.4 ± 2.2 GPa respectively, while for Groups 3 and 4 was 13.7 ± 0.3 GPa and 34.4 ± 0.3 GPa 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. © 2009 Elsevier Ltd. All rights reserved.