Flexural Strength and Polymerization Shrinkage Stress of Composite Materials

Objectives: Secondary caries and fracture are the main reasons for restoration failure in the posterior. Thus, shrinkage stress and flexural strength of a composite are two important parameters that can influence the longevity of dental restorations. Objective of the study was to investigate the polymerization shrinkage stress and the flexural strength of various composite materials.
Methods: Composite materials under investigation were Venus Diamond (Kulzer), Venus Pearl (Kulzer), Essentia (GC), Admira Fusion x-tra (VOCO), Filtek Universal (3M), Tetric Prime (Ivoclar), Ceram.x Spectra ST HV (Dentsply Sirona) and Omnichroma (Tokuyama Dental).
Measurement of flexural strength (n=7-11) was conducted according to standard EN ISO 4049:2019. Polymerization shrinkage stress (n=4-5) was investigated after 24 h by photo-elastic measurement following a previously described method from Ernst et al. with the main alteration of 24 h water storage (37°C). Mean and standard deviation (SD) were collected. Results were analysed by ANOVA.
Results: Some significant differences in flexural strength and shrinkage stress between the composite materials were detected (figure 1).
Conclusions: Within the limitations of this study Venus Pearl and Venus Diamond showed the most pronounced combination of high flexural strength and low shrinkage stress.