Microtensile Bond Strength of CAD-CAM Restorative Dental Material Blocks to Resin Cement: An In Vitro Study

Today's dentistry frequently employs bonded partial restorations, which are usually fabricated in ceramic materials. In the last decade, hybrid materials have emerged that attempt to combine the properties of composites and ceramics.

To evaluate in vitro, by means of a microtensile test, the bond strength between CAD-CAM restorative materials and the cement recommended by their manufacturer.

From blocks of CAD-CAM restorative material bonded to composite blocks (Filtek 500^®), beams with a bonding area of approximately 1 mm² were made and divided into four groups: EMAX (IPS e.max CAD^® lithium disilicate), VE (VITA Enamic^® polymer-infiltrated ceramic matrix), LUA (Lava Ultimate^® nano-ceramic resin with sandblasting protocol) and LUS (Lava Ultimate^® nano-ceramic resin with silica coating protocol). In each group, perimeter (external) or central (internal) beams were differentiated according to the position in the block. The samples were tested on the LMT 100^® microtensile machine. Using optical microscopy, the fractures were categorized as adhesive or cohesive (of the restorative material or composite), and the data were analysed with parametric tests (ANOVA).

The LUS group had the highest results (42 ± 20 MPa), followed by the LUA group (38 ± 18 MPa). EMAX had a mean of 34 ± 16 MPa, and VE was the lowest in this study (30 ± 17 MPa). In all groups, the central beams performed better than the perimeter beams. Both EMAX and VE had the most adhesive fractures, while LUA and LUS had a predominance of cohesive fractures.

Lava Ultimate^® nanoceramic resin with the silica coating protocol obtains the best bond strength values.