Comparison of flexural properties of composite restoratives using the ISO and mini-flexural tests.

UNLABELLED The purpose of this study was to investigate the flexural properties (flexural strength and flexural modulus) of four commercial composite restoratives (Silux Plus, Z100, Ariston and Surefil) using the ISO 4049 flexural test (IFT) and a mini-flexural test (MFT). Both tests involved the use of three-point loading and the same fixture. The difference between the tests was in the length of the composites specimens and the distance between the supports [20 mm (IFT) and 10 mm (MFT)]. Six specimens were made for each material and flexural test. Test specimens [25 x 2 x 2 mm (IFT) and 12 x 2 x 2 mm (MFT)] were fabricated according to manufacturers' recommendations. After light-polymerization, the specimens were stored in distilled water at 37 degrees C for 24 h. The specimens were subsequently blotted dry, measured and subjected to flexural testing using an Instron Universal Testing Machine with a crosshead speed of 0.75 mm min(-1). Data was analysed using anova/Scheffe's, paired samples test (P < 0.05) and Pearson's correlation (P < 0.01). For both IFT and MFT, results of statistical analysis of flexural strength were identical. Silux had significantly lower flexural strength compared with the other composites and the flexural strength of Ariston was significantly lower than Z100 and Surefil. For IFT, the flexural modulus of Z100 was significantly higher than Silux, Ariston and Surefil while for MFT, Silux had significantly lower modulus compared with Z100, Ariston and Surefil. A significant, strong and positive correlation (r = 0.95) was observed for flexural strength between IFT and MFT. Correlation for flexural modulus was also significant and positive but was weaker (r = 0.53). As MFT has the advantage of ease of specimen fabrication and is more clinically realistic, it is suggested for the testing of composite restoratives. CLINICAL RELEVANCE The mini-flexural test may be better than the ISO flexural test for screening of composite restoratives for clinical applications.

[1]  H O Heymann,et al.  Examining tooth flexure effects on cervical restorations: a two-year clinical study. , 1991, Journal of the American Dental Association.

[2]  I. E. Ruyter,et al.  Composites for use in posterior teeth: composition and conversion. , 1987, Journal of biomedical materials research.

[3]  J. Ferracane,et al.  Rate of elution of leachable components from composite. , 1990, Dental materials : official publication of the Academy of Dental Materials.

[4]  P. Lambrechts,et al.  In vitro flexural fatigue limits of dental composites. , 1994, Journal of biomedical materials research.

[5]  E J Swift,et al.  Update on dental composite restorations. , 1994, Journal of the American Dental Association.

[6]  S. Levartovsky,et al.  A comparison of the diametral tensile strength, the flexural strength, and the compressive strength of two new core materials to a silver alloy-reinforced glass-ionomer material. , 1994, The Journal of prosthetic dentistry.

[7]  G Willems,et al.  A classification of dental composites according to their morphological and mechanical characteristics. , 1992, Dental materials : official publication of the Academy of Dental Materials.

[8]  Y. Liu,et al.  Flexure strength of resin-modified glass ionomer cements and their bond strength to dental composites. , 1996, Acta odontologica Scandinavica.

[9]  J R Kelly,et al.  Perspectives on strength. , 1995, Dental materials : official publication of the Academy of Dental Materials.

[10]  J. Ferracane.  Current trends in dental composites. , 1995, Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists.

[11]  G. Pearson,et al.  Long-term flexural strength of three direct aesthetic restorative materials. , 1998, Journal of dentistry.

[12]  M. Tyas,et al.  Clinical evaluation of four composite resins in posterior teeth. Five-year results. , 1991, Australian dental journal.

[13]  D. Pashley,et al.  Shear bond strength of Scotchbond in vivo. , 1991, Dental materials : official publication of the Academy of Dental Materials.

[14]  Cyclic fatigue of composite restorative materials. , 1989, Journal of oral rehabilitation.

[15]  K. Leinfelder,et al.  Evaluating a microfill posterior composite resin. A five-year study. , 1992, Journal of the American Dental Association.