<p>O objetivo deste estudo in vitro foi avaliar a resistência ao cisalhamento de um cimento resinoso à cerâmica feldspática, após a aplicação de diferentes tratamentos de superfície, especialmente a irradiação com laser de Er:YAG. Quarenta e dois discos de cerâmica foram divididos em seis grupos (n = 7): G1- grupo controle: ácido fluorídrico a 10% (HF), G2 - jato abrasivo de Al₂O₃ + HF; G3 - Er:YAG laser com 500 mJ/4Hz (L1); G4- L1 + HF; G5 - Er:YAG laser com 400 mJ/6Hz (L2) e G6 - L2 + HF. Depois disso, todas as amostras foram tratadas com silano e, em seguida, um cilindro de cimento resinoso foi construído sobre a superfície de cerâmica tratada. Depois de 24 h a 37 ^oC, os espécimes foram submetidos ao teste de resistência ao cisalhamento e avaliação estereoscópica para determinar o tipo de fratura. Os valores médios de resistência de união (MPa) obtidos foram: G1 - 17,55, G2 - 18,80, G3 - 21,80, G4 - 12,62, G5 - 15,81 e G6- 11,59. Após análise de variância e teste de Tukey, concluiu-se que o grupo irradiado com laser de Er:YAG laser com 500 mJ/4Hz obteve resultados semelhantes aos grupos que receberam os tratamentos convencionais e foi maior do que os outros grupos irradiados com laser de Er:YAG.</p>

<p>Although several conventional surface treatments have been used on feldspathic ceramic, a few studies investigated the effects of the irradiation with Er: YAG laser using different parameters. The aim of this in vitro study was to evaluate the shear bond strength of a resin cement to feldspathic ceramic, after the application of different surface treatments, especially the irradiation with Er:YAG laser. Forty-two discs made of a feldspathic ceramic were divided into six groups (n = 7): G1: control group - 10% hydrofluoric acid (HF), G2: Air abrasion with Al2O3 + HF; G3: Er: YAG laser with 500 mJ/4Hz, G4: Er: YAG laser with 500 mJ/4Hz: + HF; G5: Er: YAG laser with 400 mJ/6Hz and G6: Er:YAG laser with 400 mJ/6Hz + HF. After this, all the specimens were treated with silane, and then a resin cement cylinder was built on the treated ceramic surface. After 24 h at 37 oC, specimens were submitted to the shear bond strenght test and stereoscopic evaluation to determine the type of failure. The mean bond strength values (MPa) obtained were: G1 - 17.55, G2 - 18.80, G3 - 21.80, G4 - 12.62, G5 - and 15.81 G6- 11.59. After performing the ANOVA and Tukey's test, it was concluded that the group irradiated with Er:YAG laser at 500mJ/4Hz performed similarly to the groups that received the conventional treatments, such as hydrofluoric acid etching and the combination of air abrasion plus hydrofluoric acid, and was higher than the other groups irradiated with Er:YAG laser.</p>

Human, bovine and swine teeth were analyzed by Proton Induced X-ray Emission (PIXE). The aim of this work was to determine the concentration of trace elements in enamel and dentine of different animal species. PIXE analysis was carried out at the Laboratório de Análise de Materiais por Feixes Iônicos da USP (LAMFI) using a 2.4 MeV proton beam to probe the samples. Healthy teeth from São Paulo region were analyzed. Thirteen elements were measured and quantified in the samples: P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Ba. The measured ratio of Ca:P in dentine and enamel teeth is the same expected for hydroxyapatite: 2.13, for all three types. Trace element concentrations were found to be very similar between the three species, except for S, Cl, Fe, Cu and Sr. Ni and Cu concentrations were found to be close to 1 ppm, which is also close to the detection limits of the SP-PIXE system.