Introduccion: el disilicato de litio como material ceramico restaurador ofrece resistencia superior a las ceramicas, unas excelentes caracteristicas opticas y la posibilidad de ser adherido al sustrato dentario por medio del grabado con acido fluorhidrico. El proposito de este estudio fue evaluar in vitro el efecto del acido fluorhidrico al 9,5 % y al 4,6 % en tiempos de 20, 40 y 60 s sobre la superficie del disilicato de litio en los procesos de adhesion a un sustrato resinoso. Metodos: se confeccionaron 6 cubos de porcelana IPS e-max® Press y 6 cubos de resina Filtek® Z250. Los cubos ceramicos fueron sometidos a un tratamiento de superficie obteniendo 6 grupos: El grupo control y los grupos 2 y 3 utilizaron acido fluorhidrico al 4,6%, durante 20, 40 y 60 s respectivamente, los grupos 4, 5 y 6 usaron acido fluorhidrico al 9,5%, en tiempos de 20, 40 y 60 s respectivamente. Se cementaron los cubos de porcelana con los de resina con cemento resinoso autoadhesivo y se generaron barras de 1 x 1 x 18 mm, obteniendose 20 muestras en cada grupo y se midio su fuerza de adhesion. Resultados: los valores de resistencia adhesiva en MPa (SD) fueron G1 = 26,69 (± 7,99), G2 = 23,93 (± 7,99), G3 = 20,90 (± 7,91), G4 = 17,56 (± 6,61), G5 = 16,30 (± 11,68), G6 = 18,78 (± 10,22), con diferencias significativas entre el grupo 1 y los grupos 4-5. Conclusiones: las concentraciones de acido fluorhidrico al 4,6%, presentaron mejores promedios de adhesion en comparacion con los grabados al 9,6%. El grupo con concentracion al 4,6% por 20 s presento los mejores resultados. ABSTRACT. Introduction: as a ceramic restorative material, lithium disilicate provides higher resistance to ceramic materials, excellent optical characteristics, and the ability to be bonded to tooth substrate by hydrofluoric acid etching. The purpose of this study was to perform in vitro assessment of the effect of 4.6 and 9.5% hydrofluoric acid at 20, 40 and 60 s on the surface of lithium disilicate during the processes of adherence to a resinous substrate. Methods: 6 IPS e-max® Press porcelain cubes and 6 Filtek Z250® resin cubes were made. The ceramic cubes were subjected to surface treatment obtaining 6 groups: control group and groups 2 and 3 were treated with 4.6% hydrofluoric acid during 20, 40 and 60 seconds respectively, and groups 4, 5 and 6 were treated with 9.5% hydrofluoric acid at 20, 40 and 60 s respectively. Porcelain cubes were cemented with the resin ones with self-adhesive resin cement and bars of 1 x 1 x 18 mm were produced, obtaining 20 samples in each group. Adhesive strength was measured. Results: adhesive strength values expressed in MPa (SD) were as follows: G1 = 26.69 (± 7.99), G2 = 23.93 (± 7.99), G3 = 20.90 (± 7.91), G4 = 17.56 (± 6.61), G5 = 16.30 (± 11.68), G6 = 18.78 (± 10.22), with significant differences between group 1 and groups 4-5. Conclusions: 4.6% hydrofluoric acid produced better adhesive averages compared with the 9.6% concentrations. The group with 4.6% concentration during 20 s offered the best results. Normal 0 21 false false false ES-CO X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;}