الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Background: Surfaces of ceramic crowns are modified several
times before being exposed to wear in the oral cavity. Grinding
and different finishing procedures may be associated with teeth
wear due to increased surface roughness. Limited data is
available with regard to the effect of polishing procedures on the
surface roughness and wear behavior of ceramic crowns. This
study was conducted to assess the influence of polished and
polished-ground-repolished surface finish on the roughness and
wear performance of three ceramic crowns. Methods: 36 natural
1st molar teeth were prepared using a CNC milling machine and
classified into three groups (n=12/group): zirconia, E-max and
hybrid ceramic (VITA ENAMIC) crowns. Each group was
classified into two subgroups (n=6/subgroup): polished and
polished-ground-repolished crowns. Natural molar teeth served
as an unrestored control group (n=6). All samples were loaded
into a chewing simulator for 100,000 cycles and subjected to
600 thermo-cycles in temperature changes to simulate changes
in intraoral temperature. Natural maxillary 1st premolar teeth
were collected and only buccal half (cusp) of sectioned tooth
was used as antagonists. A profilometer was used to detect the
roughness before and after masticatory cycles. The occlusal
surface was analysed using a scanning electron microscope
(SEM). Results: The E-max crown group had the highest mean
surface roughness value (0.267μm) followed by VITA
ENAMIC crown group (0.266 μm), while the lowest mean
surface roughness value recorded for zirconia crown (0.257μm).
The difference between these means was not significant. The
polished-ground–repolished group had a higher mean surface
roughness (0.266 μm) compared with the polished group (0.260
μm), which was not significantly different. Conclusions: All
tested ceramic crowns showed surface roughness with values
within acceptable clinical parameters (~0.2 μm). Additionally,
intraoral polishing procedures could be considered a reliable
technique for smoothing of zircona, E.max and VITA ENAMIC
crowns after occlusal adjustment.