الفهرس 
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Abstract
Background: CAD/CAM resin matrix ceramics are one of the materials used in dental offices. The
long-term success of the restoration depends on the bond strength of the restoration to the tooth and
other materials; thus, surface treatment of the restoration is necessary to achieve this. But such
treatment may affect the restoration strength. The purpose of this study is to assess the impact of
various surface treatments on the surface roughness (Ra) and the biaxial flexural strength of two
CAD-CAM resin-matrix ceramics.
Methods: Thirty-six-disc-shaped specimens, each measuring 1.2 mm in thickness and 12 mm in
diameter, were machined from two resin-matrix ceramic blocks (Lava Ultimate and Cerasmart) (n =
18). Based on the surface treatments, each material was divided into 3 groups: control (no
treatment), 50-μm Al2O3 sandblasting, or 9% hydrofluoric acid etching (n = 6). The surface
roughness (Ra) was evaluated by the 3D laser scanning microscope. Then, specimens were aged by
thermal cycling (5000 cycles) and tested for biaxial flexural strength using a universal testing
machine at a crosshead speed of 1.0 mm/min.
Results: No significant differences in flexural strength or Ra were found for Lava Ultimate among
the surface treatment groups. For Cerasmart, only the sandblasting group showed significantly
higher Ra values than the control group. Also, the Ra values for the sandblasting group were
significantly higher than those for the acid etching group. The flexural strengths of the sandblasting
and acid etching groups for Cerasmart were statistically similar, and both were significantly lower
than the control group.
Conclusions: Although all of the applied surface conditioning techniques improved Ra, they had a
negative impact on the flexural strength of resin-matrix ceramics. Thus, clinicians should utilize the
appropriate surface treatment techniques, taking into account their effects on the surface roughness
and mechanical properties of resin-matrix ceramics.
Keywords: Resin nano-ceramic, flexible hybrid ceramic, surface roughness, flexural strength.