An investigation of thermal changes of various permanent dental cements.

The aim of this study was to investigate and compare the temperature rises which occurred during the setting reactions of different permanent cements used to lute fixed partial prosthodontics. In this study, four cements were used. They were mixed in three different proportions: according to manufacturers' recommendations, at doubled powder ratio, and at doubled liquid ratio. With a thermocouple, the temperature rises which occurred during the setting reactions were measured. For each proportion, the measurement was repeated five times such that a total of 60 measurements were done for the four different cements. Data were analyzed using analysis of variance (ANOVA). ANOVA results showed that cement type and the interaction between cement type and the powder-liquid ratio were statistically significant factors (p<0.001). Similarly, the powder-liquid ratio was a statistically significant (p<0.01) factor. Among the dental cements tested, zinc phosphate cement showed the highest temperature rise during setting reaction, whereas glass ionomer cement showed the lowest.

Effects of different solutions on the surface hardness of composite resin materials.

In this study, the surface hardness of five light-cured composite resins were evaluated, namely: filled (Estelite), nanofil (AElite), unfilled (Valux Plus), hybrid (Tetric ceram), and Ormocer-based (Admira) composite resins. The microhardness values of composite specimens were measured at the top and bottom surfaces after 24 hours or 30 days of immersion in different solutions (tea, coffee, Turkish coffee, mouthwash, cola, and distilled water). Comparisons were made with univariate analysis of variance and Duncan's multiple range test. It was found that rough specimens of reinforced nano-hybrid composite material immersed in cola for 30 days had the lowest surface hardness (33.20), whereas rough specimens of hybrid composite material immersed in cola for 24 hours had the highest surface hardness (156.00). In both tea and coffee, the top surfaces tended to be harder than the bottom ones. In conclusion, the five different materials exhibited different hardnesses, and that the hardness values of composite materials were statistically different in different immersion solutions.

Radiological evaluation of changes in the gonial angle after teeth extraction and wearing of dentures: a 3-year longitudinal study.

OBJECTIVE: The aim of this study was to evaluate the gonial angle measurements of 20 adult patients made from panoramic radiographs and to assess differences from dentate state to edentate state-with dentures. STUDY DESIGN: A total of 100 panoramic radiographs of 20 patients were evaluated, and gonial angle sizes were measured. Panoramic radiographs were made while the patients were dentulous and in the first month, sixth month, first year, and third year after tooth extraction and wearing dentures after a 2-3-month healing period. All radiographs used in this study were made with the same panoramic machine by the same person. Gonial angles were measured by tracing a line on panoramic radiographs tangential to the most inferior points at the gonial angle and the lower border of the mandibular body and another line tangential to the posterior borders of the ramus and the condyle. RESULTS: Difference in size of the gonial angle was found for both sides between continuous measurements. The gonial angle values tend to increase in both sides after tooth extractions. After the third measurement for both sides, the values start to decrease. CONCLUSION: After wearing denture for 3 years, a statistically significant decrease was found in the gonial angle values according to the edentulous state (P < .05).