Repair strength of hypoallergenic denture base materials

Objectives: This in vitro study compared flexural strength and flexural modulus of repaired hypoallergenic denture base materials, with flexural strength/modulus of a PMMA heat-polymerizing acrylic resin. Methods: The denture base resins Eclipse (E), LUXENE 1180 (L), Microbase (M), Polyan (Po), Puran HC (Pu), Sinomer (S), The.r.mo.Free (T), and Paladon 65 (Pa, control group) were examined. Specimens of each material (intact group, 2 x n=5) were tested for flexural strength and flexural modulus according to ISO 1567. Fractured specimens (except L, Po, T) were repaired with the recommended repair materials (R, n=5), and (except Pa) with Versyo.com (V, n=5). Testing of flexural strength and flexural modulus was repeated. The data were analyzed with 1-way ANOVA and Bonferroni-Dunn's multiple comparisons post hoc analysis (α=.05). Results: Fracture strength of the repaired specimens ranged between 66% and 117%, whereas flexural modulus varied from 82% to 109% of the corresponding intact specimens. Significantly higher flexural strength was obtained from the repaired T/V (62 ± 2 MPa, P=.001) compared to the intact group. The flexural strength of repaired S/V (53 ± 3 MPa, P>.05) did not differ significantly from the intact material. Flexural modulus of repaired T/V and Pu/V (P<.05) was significantly higher than the intact material. Flexural strength and flexural modulus of the other materials repaired with R or V were significantly lower than the intact specimens. Pu and S groups (R, V) exhibited significantly lower flexural strength and modulus (T/V significantly lower flexural modulus) than Pa (71 ± 2; 1815 ± 59 MPa). Except for E/R, which was significantly stronger, no differences were detected for the other materials compared to Pa. Repaired specimens showed similar strength values for R and V (P>.05). Conclusions: Most of the tested materials repaired with R or V exhibited similar flexural strength and flexural modulus as the repaired PMMA-material.