Efeitos de lasers de alta potência na superfície de cerâmicas vítreas de dissilicato de lítio e sua resistência de união à dentina humana

• Ano de defesa: 2016
• Autor(a) principal: Feitosa, Fernanda Alves [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Bond strength; Ceramic; Er:YAG Lasers; Nd:YAG Lasers; Silanes; Cerâmica; Lasers de Er-YAG; Lasers de Nd-YAG; Silanos
• Link de acesso: http://hdl.handle.net/11449/139434

The aim of this study was to evaluate the efficiency of irradiation with high-power lasers and the influence of silane application before or after irradiation with lasers on the bond strength between lithium disilicate glass-ceramic, resin cement and human dentin. Fifty truncated-cones ceramic specimens (n=10) were randomly divided into 5 groups: Control- etching with hydrofluoric acid 10% for 1 min and application of silane; 2- Er - Er:YAG laser irradiation (200 mJ and 10 Hz), followed by etching with hydrofluoric acid 10% for 1 min and application of silane; 3- Sil + Er - etching with hydrofluoric acid 10% for 1 min, silane application and irradiation with Er: YAG laser in the same parameters as the previous group; 4- Nd:YAG laser - irradiation with Nd: YAG laser (120 mJ and 10 Hz), followed by etching with hydrofluoric acid 10% for 1 min and application of the silane, 5- Sil + Nd- Etching with hydrofluoric acid 10% for 1 min, silane application and irradiation with Nd: YAG laser on the same parameters as the previous group. After treatment, the ceramic specimens were cemented with dual cure resin cement to the dentin of 50 human molars included in acrylic resin. After storage for 24 h it was submitted to tensile test in a universal testing machine with 10 kgf load cell and constant speed of 1 mm/min. Data were submitted to ANOVA 2-way and Dunnet test (α = 5%). The analysis of fracture patterns were analyzed in stereomicroscope. In addition were made 15 ceramic specimens in cylindrical shape, subjected to the same treatment of the above groups (n = 3) and used for analysis of the contact angle analysis and scanning electron microscope. The Dunnet test showed significant differences between Control group (9.42 ± 2.27 MPa) and Er group (19.25 ± 3.7 MPa) and Sil + Er (14.11 ± 4.11 MPa). ANOVA 2-way (p <5%) for Laser Type (p <0.0001) and Technical of Silanization (p = 0.0002) showed significant differences for both factors, but not for their interaction. Thus, the irradiation with Er:YAG laser (16,68 MPa) was more effective than irradiation with Nd:YAG laser (8,19 MPa). The technique of silanization after laser irradiation was more effective (14,46 MPa) than the previous silanization (10,41 MPa). The analysis of fractures showed a prevalence of adhesive failures on dentin and ceramic for the Control group; Nd, Sil + Nd e Sil + Er had a prevalence of adhesive failures in ceramics, and Er group presented predominance of cohesive failures in cement. The analysis of contact angle was submitted to ANOVA 1-way and Tukey test, with significant differences between the groups (p <0.0001). Groups with silanization previous to laser irradiation (Sil + Er = 45,60b degrees; Sil + Nd = 52,10b degrees) had contact angles greater than the other groups. The Scanning Electron Microscopy images showed the presence of a silane layer on the ceramic surface in Sil + Nd group, and an apparent casting of the ceramic surface in Sil + Er group. For Er and Nd Groups was possible to see changes in the normal pattern of ceramic structure, interspersed with areas similar to conventional standard control group after etching with hydrofluoric acid. It is concluded that treatment with Er:YAG laser associated with etching with hydrofluoric acid at 10% for 1 min gives the highest bond strength results and the lower contact angle, resulting in a recommended treatment. Treatment with silane previously to laser irradiation improved bond strength only when associated with the Er:YAG laser, which probably occurred by the efficiency of Er: YAG laser irradiation, and not due to the silanization technique.