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CEREC3D / INLAB The New Era of the Digital Dental Solutions. |
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2 PRECISION
2.1 IMAGE PRECISION
The precision of a milled CEREC restoration depends to a large extent
on the quality of the data derived from the digital optical
impression. The intraoral CEREC Bluecam has an innovative optical lens emitting blue light with a short wavelength.
2.1.1 SINGLE TOOTH
The scanning accuracy of CEREC Bluecam is approx. 19 μm.
This high degree
of precision is equivalent to that of the reference
scanner*.
Repeat measurements were in the region of 10 μm and the user
influence
was less than 12 μm. The results were not dependent on
the type of preparation.
2.1.2 QUADRANT
The images with CEREC Bluecam were taken in auto capture mode
and approx. 4–6 exposures were required per quadrant. The software
automatically
triggers the exposure when the camera is positioned
absolutely still above the tooth. CEREC Bluecam demonstrates a
significantly
improved quadrant precision in comparison to the
CEREC 3D camera (34 μm as opposed to 42 μm). The low values
of repeat measurements of approx. 13 μm demonstrate the high
accuracy of the CEREC Bluecam. The user influence on the precision
of the measurement results was extremely low (approx. 15 μm).
CONCLUSION The CEREC Bluecam generates digital optical impressions
with an unprecedented degree of measurement precision.
2.2 MILLING PRECISION
2.2.1 CAMERA/MILLING UNIT
The precision of the CEREC system is determined by the resolution
of the CEREC camera (25 μm) and the reproducibility of the milling
unit (± 30 μm). Excluding user-induced influences (e.g. preparation,
powdering and exposure technique), the precision of CEREC
3D is in the range ± 55 μm.
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2.2.2 MARGINAL FIT OF RESTORATIONS
The marginal accuracy of milled CEREC restorations has continu-ously
improved with each successive software version (from CEREC 1
to current version of CEREC 3D). With regard to the hardware, the
introduction of the step bur (tip diameter: 1 mm) represented a
major improvement. Within the framework of this multi-centre
trial (seven universities) the marginal fit and internal adaptation of
CEREC full crowns were measured and compared with laboratoryfabricated
ceramic crowns. A group of trained CEREC dentists and
a group of non-trained assistants each designed and milled ten
molar crowns on the basis of standard models. The crowns (made
of the VITA Mark II and Ivoclar ProCad materials) were placed with
the aid of Variolink. Empress ceramic crowns sourced from a reputable
dental laboratory were also placed.
The marginal fit of the dentist’s crowns (61.6 ± 27.9 μm) and the
assistants’ crowns (60.8 ± 20.5 μm) did not differ significantly.
The margins of the laboratory-fabricated crowns were slightly
wider (69.1 ± 26.9 μm), which, however, was not statistically
significant. With regard to their axial wall adaptation the CEREC crowns
were clearly better than the laboratory crowns, whereas in terms of
occlusal wall adaptation the laboratory crowns performed better.
CONCLUSION The marginal fit of CEREC crowns tends to be better than that
of laboratory-fabricated ceramic crowns.
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