Physical-mechanical properties of glass ionomer cements indicated for atraumatic restorative treatment.

BACKGROUND: This study evaluated mechanical properties of glass ionomer cements (GICs) used for atraumatic restorative treatment. Wear resistance, Knoop hardness (Kh), flexural (F(s)) and compressive strength (C(s)) were evaluated. The GICs used were Riva Self Cure (RVA), Fuji IX (FIX), Hi Dense (HD), Vitro Molar (VM), Maxxion R (MXR) and Ketac Molar Easymix (KME). METHODS: Wear was evaluated after 1, 4, 63 and 365 days. Two-way ANOVA and Tukey post hoc tests (P = 0.05) analysed differences in wear of the GICs and the time effect. F(s), C(s), and Kh were analysed with one-way ANOVA. RESULTS: The type of cement (p < 0.001) and the time (p < 0.001) had a significant effect on wear. In early-term wear and Kh, KME and FIX presented the best performance. In long-term wear, F(s) and C(s), KME, FIX and HD had the best performance. Strong explanatory power between F(s) and the Kh (r(2) = 0.85), C(s) and the Kh (r(2) = 0.82), long-term wear and F(s) of 24 h (r(2) = 0.79) were observed. CONCLUSIONS: The data suggested that KME and FIX presented the best in vitro performance. HD showed good results except for early-term wear.

[Microleakage in class V cavities restored with esthetic materials, using different restorative techniques]. / Infiltração marginal em cavidades de classe V restauradas com materiais estéticos, utilizando diferentes técnicas restauradoras.

The purpose of this study was to compare the microleakage of class V cavities restored with composite resin (CR), resin-modified glass ionomer cement (RMGIC) and polyacid-modified resin composite (PAMRC), using different clinical procedures. Thirty-six noncarious human molars were used in this study. A class V cavity, measuring approximately 3 mm x 4 mm x 2 mm, was prepared in each tooth in both buccal and lingual aspects, with a diamond bur (number 1,093) at high speed, with coolant water spray. The occlusal margin was located on enamel and the gingival margin was located on dentin. The teeth were divided into 9 groups with 8 specimens each. The cavities were restored according to different techniques. The specimens from groups 1, 2, 4 and 5 did not receive acid etching. The samples were stored in water at 37 degrees C for 24 hours, subjected to occlusal load, thermocycled and immersed in rhodamine B. The restorations were then washed and sectioned in buccolingual direction. The depth of dye penetration was scored from zero (no leakage) to 3 (maximum leakage). The Kruskal-Wallis test revealed statistically significant differences between the materials (p < 0.05). PAMRC used without acid etching showed the greatest score of leakage in both margins. In the gingival margin, CR showed scores of leakage lower than those of PAMRC and RMGIC. Additional retentions and acid etching were able to decrease microleakage in PAMRC restorations in both gingival and occlusal margins.

[Stress in teeth restored with gold and copper-aluminum alloys under distributed force. Finite element method]. / Contribuição para o estudo das tensões que ocorrem em dentes restaurados, utilizando ligas de ouro e de cobre-alumínio, sob ação de força distribuída. Método dos elementos finitos.

The author studied the stress distribution which occurs in casted metalic restoration a gold alloy type II and a copper-aluminum, with cavity preparation of both types: intracoronal or extracoronal cavity using the finite elements method in a first right inferior molar. The conclusion was that the mechanical performance of both are very similar. Stress occurred in a dental structure which alloy cast restoration are smaller than that occurred in a tooth without cavity preparation. The cavity preparation with intracoronal shows a better stress distribution in the dentine than that with extracoronal. In the region near the buccopulpal line angle occurs a stress concentration in despite of the type of the cavity metallic alloy used.

[Neuroanatomical study of the orbitofrontal branch of the anterior cerebral artery in human brains]. / Estudo neuroanatômico do ramo orbitofrontal da artéria cerebral anterior em cérebros humanos.

The neuroanatomic study of the orbitofrontal branch of the anterior cerebral artery was performed by simple and careful dissection in 50 human brains. The observation was carried out with stereoscopic magnifying glass. The results with regard to frequency and origin of the artery were the following: the orbitofrontal artery was present in 90% (45/50) of the cases on the right hemisphere and 92% (46/50) on the left hemisphere; in 26 cases (52%) on the right side and 34 cases (68%) on the opposite side, the artery arose between anterior communicating and frontopolar arteries; in 19 cases (38%) on the right side and 12 cases (24%) on the left side the vessel was not the classical first branch of the postcommunical segment of the anterior cerebral artery, it arose between the Heubner artery and the frontopolar artery. With regard at filogenetic signification of the orbitofrontal artery it has been formulated the hypothesis that the artery is homologous to posterior and anterior orbital branches of the anterior cerebral artery described by Watts in sub-human primates.