The properties of denture base and reline resins may be affected by daily changes between room temperature and mouth temperature. The purpose of the study was to evaluate the effect of thermocycling on the flexural strength of the relined denture base polymer with reline resin. Three denture base resins, three hard reline resins and their combinations were tested. Fourteen specimens, 65x10x2.5 mm, were fabricated for each material. Polymer combination specimens were made using 1.5 mm hard reline resin on 1.0 mm cured denture base resins. Half of the specimens were stored for 50+/-2 h in distilled water at 37 degrees C, while the other half were thermocycled for 20 000 cycles between 4 and 60 degrees C. Three point bending tests were conducted on a universal testing machine at a cross-head speed of 0.5 cm/s. The flexural strengths were measured and a statistical analysis was performed on the data using three-way ANOVA (P<0.05). The results showed that the flexural strength of relined denture base polymer was significantly higher than that of hard reline polymer. Thermocycling did not affect the flexural strength of the relined denture base polymers, whereas the denture base polymer and reline polymer alone showed a decrease in strength after thermocycling.

Recently a new generation of laboratory-processed composite resins containing submicron glass fillers was introduced, with claims of high strength. The purpose of this study was to evaluate the effect of thermal cycling in water on the flexural strength and hardness of several laboratory composite systems. The flexural strength of the new laboratory processed composite resins (Artglass [AG], Targis [TR] and Estenia [ES]) was significantly higher than that of conventional resins (Dentacolor [DC] and Cesead II [CS]). Thermocycling caused a reduction of the flexural strength but not a reduction of the hardness for most of materials tested. It was concluded that thermocycling affected the properties of the laboratory-processed hybrid type composite resin, ES, AG and TR. However, the changes of these properties were smaller than those of microfine type composite resin DC. Thus, ES, AG and TR may maintain better properties during service compared with DC.

The purpose of this study was to evaluate the influence of the lining design of a soft denture liner on its cushioning effect, using a free drop test and an accelerometer. The peak instantaneous acceleration value was computed. The materials tested were SuperSoft(R) (SS), Kurepeet-Dough(R) (KD), and Molloplast-B(R) (MB). Soft denture liners 2 mm in thickness were placed in test denture bases using three different configurations. Specimens were tested at 24 h and at 180 days after storage in distilled water at 37 degrees C. A three-way ANOVA was used to analyse the data (P=0.05) and Tukey intervals were computed. It was found that all three materials were effective in reducing the impact force. The lining design that had the soft denture liner extended to the periphery of the denture base demonstrated the greatest shock absorbability of all the tested designs. A silicone denture liner using lining design 1 was the most effective in reducing the shock transmitted to the denture bases.

Various types of occlusal scheme have been developed for a complete denture. Some investiga

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