Flexural strength of relined denture base resin after water storage

Objectives: The aim of this study was to evaluate the effect of water storage on the flexural strength of a denture base acrylic resin (Lucitone 550-L) relined with four different hard chairside reline resins (Kooliner-K; New Truliner-NT; Tokuso Rebase Fast-T and Ufi Gel Hard-U). Methods: Eighty specimens of L (64x10x2.0 mm) were relined with 1.3 mm of each reline resin. In addition, twenty intact specimens of L (64x10x3.3mm) were made. Specimens were tested 1) after polymerization and 2) after storage in distilled water for 30 days at 37 ± 1.0ºC. Flexural strength (MPa) was evaluated with a 3-point bending test (0.5 mm/min; span=50 mm). Results: The results were analyzed with 2-way ANOVA and Tukey's tests (alpha=.05). L/U specimens (41.91 MPa) demonstrated an increased (P<.05) flexural strength after water storage (53.69 MPa). After polymerization, L intact specimens showed higher flexural strength (73.27 MPa) than the relined specimens (P<.05), which showed similar results. After water storage, results of L specimens (66.12 MPa) were not statistically different from L/T (57.13 MPa). No significant difference (P>.05) was found between L/T and L/U (53.69 MPa), which produced higher flexural strength than L/K (44.6 MPa) and L/NT (46.21 MPa). Conclusion: Water storage did not detrimentally influence the flexural strengths of materials and improved the flexural strength of L/U. All relined specimens, with the exception of L/T stored in water, showed lower strength than L. Grant FAPESP 02/11637-5