The reliability in flexural strength testing of a novel dental composite.
OBJECTIVE
To investigate the reliability of bi-axial flexure and three-point flexure testing of an experimental, low-shrink oxirane-based dental composite, EXL596 compared with two conventional methacrylate based restoratives, Z250 and Z100.


METHODS
Specimens (n=20) of a novel oxirane-based composite and two commercially available methacrylate based composites were fabricated for flexural testing to evaluate mean bi-axial flexure strengths, three-point flexure strengths and the associated Weibull moduli (m) following 24 h immersion in a lightproof waterbath maintained at 37+/-1 degrees C.


RESULTS
Mean bi-axial flexure strengths and the associated m of EXL596, Z250 and Z100 were 168+/-11 MPa (m=16.2+/-4), 140+/-12 MPa (m=11.9+/-3) and 126+/-13 MPa (m=10.2+/-2), respectively. Three-point flexure strengths and the associated m of EXL596, Z250 and Z100 were 113+/-15 MPa (m=9.2+/-2), 92+/-10 MPa (m=8.5+/-2) and 79+/-16 MPa (m=6.3+/-1), respectively.


CONCLUSIONS
The present investigation suggests that bi-axial flexure strength testing of dental resin-based composites provides a more reliable testing method than three-point flexure. The increased reliability was considered in terms of the associated Weibull moduli following bi-axial flexure testing as a result of the elimination of the additional induced variability introduced during the curing regime of three-point flexure specimens.
Palin
William M
WM
Biomaterials Unit, School of Dentistry, University of Birmingham, St Chad's Queensway, Birmingham B4 6NN, UK.
Fleming
Garry J P
GJ
Burke
F J Trevor
FJ
Marquis
Peter M
PM
Randall
Ros C
RC
D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D005027:Ethylene Oxide / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D015203:Reproducibility of Results; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015040:Zirconium
D003188:Composite Resins; D003764:Dental Materials; C479118:EXL596; C444701:Filtek Z250; C083568:Z100 composite resin; D014867:Water; D012822:Silicon Dioxide; D015040:Zirconium; D005027:Ethylene Oxide