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Fractures of denture base polymer material are one of the most frequent reasons for repair of removable dentures. The aim of this study was to determine the influence of depth alignment of glass fiber reinforcements onto denture base polymer flexural obtained with the “short beam” testing method. The study showed higher values of flexural strength when reinforcements were placed 1mm from specimen surface (130,63 to 158,55MPa) compared to 0,5mm distance from specimen surface (117,83 to 153,68MPa). Specimens tested after polymerization had higher flexural strength values than specimens tested after storage in water, while thermocycled specimens unexpectedly revealed the highest values. It could be concluded that fiber reinforcements should be positioned more than 0,5mm (up to 1mm) from the base surface of dental prostheses since lesser distance would diminish the reinforcing effect.

Fractures of polymer material are one of the most frequent reasons for the repair of removable dental prostheses. Therefore, there is a constant endeavor to strengthen them, and polymer materials with high resistance to fracture are being developed. The aim of this study was to determine the flexural strength of polymer materials and their reinforcements and thus give preference to their clinical use. Specimens with dimensions 18 x 10 x 3 mm were tested after polymerization, immersion in water at a temperature 37 degrees C for 28 days, and thermocycling by using the "short-beam" method to determine the flexural strength. Microscopic examination was performed to determine the quality of bonding between the glass fibers and matrix. Common polymer materials (control group) demonstrated the lowest flexural strength, although, when reinforced with fibers they showed higher flexural strength, matching that of the tested high-impact strength resin. Thermocycled specimens had the highest flexural strength, whereas there was no difference (p > 0.05) between specimens tested after polymerization and immersion in water.