This study evaluated an alternative method for thermal cycling test on the microleakage and bond strength of the polymer-dentin bond. For the microleakage test the cavities were restored with a TEGDMA+UDMA+bis-EMA composite polymer light cured for 20 s. Samples were immersed in 2% methylene blue solution for 2 h and sectioned. Microleakage scores were submitted to Kruskal-Wallis test. For the shear bond strength test the adhesive was applied to dentin, photoactivated for 10 s and the composite polymer incrementally photoactivated. Samples were submitted to shear bond strength test in a machine with a cross-head speed of 0.5 mm/min and data were submitted to ANOVA and Tukey's test. Studied groups were: 1 - without thermocycling; 2 - thermocycled at 5 ºC and 55 ºC with intermediate bath at 37 ºC; 3 - thermocycled at 5 ºC and 37 ºC; 4 - thermocycled at 37 ºC and 55 ºC; 5 - thermocycled at 5 ºC and 55 ºC (traditional test). Cold baths promoted greater microleakage when compared to control and hot bath, whereas control and hot bath were similar. Cold baths presented significant lower shear bond strength than those submitted to hot bath and control. It was concluded that the alternative method for thermal cycling test showed that cold temperatures increased the microleakage and decreased the bond strength of the polymeric adhesive.

The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10º tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.

This study investigated the dimensional stability of denture bases influenced by packing methods, in relation to post-pressing times, in the Clássico acrylic resin which was prepared according to manufacturer recommendations. Forty maxillary wax bases were made and randomly assigned into 2 groups of 20 specimens each according to the conventional and RS system packing methods. In each method, the specimens were subdivided into immediate, 6, 12 and 24 h post-pressing times. The dough of the acrylic resin was packed in metallic flasks and processed in a water bath curing cycle at 74ºC for 9 h. After cooling at room temperature, the bases were removed from the flasks, finished and fixed on stone casts with instantaneous adhesive. The resin base-stone cast sets were transversally sectioned into 3 sections and the base-stone gap measured at 5 points in each section. The data were submitted to ANOVA and Tukey's test, which showed that the RS system had a smaller base distortion compared to conventional packing, with the exception of the 24-h post-pressing time. There was a statistically significant difference between the packing methods only in section C (posterior palatal zone). In the conventional packing method, the immediate and 6 h times demonstrated values with no statistically significant difference between them, as well as between the 12 and 24 h post-pressing times.

The purpose of this study was to investigate the displacement of teeth occurring in dentures following storage in water at a temperature of 37ºC. Ten maxillary dentures were constructed with Classico heat-cured acrylic resin using conventional metal flasks. Metallic reference pins were placed on the incisal border of the central incisors (I), buccal cusp of the first premolars (PM), and mesiobuccal cusp of the second molars (M). The acrylic resin was polymerized twelve hours after final flask closure in a water cycle at 74ºC for 9 hours. The flasks were removed from the thermo-curing unit after water cooling and then bench stored for 3 hours. After deflasking and finishing, the dentures were stored in water at a temperature of 37ºC for periods of 7, 30, and 90 days. Following deflasking and each storage period tested, the I-I (incisor to incisor), PM-PM (premolar to premolar), and M-M (molar to molar) transverse distances, and LI-LM (left incisor to left molar) and RI-RM (right incisor to right molar) anteroposterior distances were measured with a STM Olympus microscope, with accuracy of 0.0005 mm. Colleted data were submitted to ANOVA and Tukey test (5%). No statistically significant difference was observed in the displacement of teeth in the transverse and anteroposterior distances.

The purpose of this study was to investigate the displacement of teeth occurring in dentures following storage in water at a temperature of 37ºC. Ten maxillary dentures were constructed with Classico heat-cured acrylic resin using conventional metal flasks. Metallic reference pins were placed on the incisal border of the central incisors (I), buccal cusp of the first premolars (PM), and mesiobuccal cusp of the second molars (M). The acrylic resin was polymerized twelve hours after final flask closure in a water cycle at 74ºC for 9 hours. The flasks were removed from the thermo-curing unit after water cooling and then bench stored for 3 hours. After deflasking and finishing, the dentures were stored in water at a temperature of 37ºC for periods of 7, 30, and 90 days. Following deflasking and each storage period tested, the I-I (incisor to incisor), PM-PM (premolar to premolar), and M-M (molar to molar) transverse distances, and LI-LM (left incisor to left molar) and RI-RM (right incisor to right molar) anteroposterior distances were measured with a STM Olympus microscope, with accuracy of 0.0005 mm. Colleted data were submitted to ANOVA and Tukey test (5%). No statistically significant difference was observed in the displacement of teeth in the transverse and anteroposterior distances.