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The quality of fixed prosthodontic impressions: An assessment of crown and bridge impressions received at commercial laboratories.
J Am Dent Assoc. 2017 Jun 7. pii: S0002-8177(17)30406-3. doi: 10.1016/j.adaj.2017.04.038. [Epub ahead of print]
authors evaluated and quantified clinically detectable errors commonly
seen in impressions sent to commercial laboratories and determined
possible relationships between finish line errors and other factors
authors visited 3 large and 1 small commercial dental laboratories over
a 12-month period. Three calibrated examiners evaluated the
impressions. The examiners evaluated all impressions for errors by using
×2.5 magnification loupes under ambient room lighting without the aid
of additional illumination.
authors evaluated 1,157 impressions; 86% of the examined impressions
had at least 1 detectable error, and 55% of the noted errors were
critical errors pertaining to the finish line. The largest single error
categories evaluated were tissue over the finish line (49.09%), lack of
unprepared stops in dual-arch impressions (25.63%), pressure of the tray
on the soft tissue (25.06%), and void at the finish line (24.38%). The
factors blood on the impression (odds ratio, 2.31; P < .001) and tray
type (odds ratio, 1.68; P < .001) were associated significantly with
finish line errors.
discrepancies made up the largest category of error noted in
impressions evaluated. The authors noted an increase in errors at the
finish line with dual-arch impression techniques and in the presence of
have ethical, moral, and legal obligations bestowed on them by the
profession and need to evaluate critically the work they send to
laboratories. The authors strongly recommend an improvement in technique
and reviewing of all impressions and working casts.