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Published on: April 29, 2014
Influence of Color and Diameter of Retraction Cords and Teflon Tape on the Accuracy of Tooth Preparations Digitized
Marta Revilla-León1,2,3, Ernesto Pérez-García4, Clara Guinot-Barona5
1Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Washington, USA.
Purpose:
To assess the influence of the color and diameter of retraction cords or Teflon tape and intraoral scanner (IOS) technology/system on the accuracy of crown preparations digitized using three IOSs.
Materials And Methods:
A typodont with a crown preparation with an equigingival finish line was digitized using a laboratory scanner (control). Three groups were created: i700, TRIOS 5, and Aoralscan3. Six subgroups were developed depending on the retraction method: no cord (NC subgroup), purple 00 cord (Knittrax 00; Pascal Dental) (00-K subgroup), yellow-black 00 cord (Ultrapack 00; Ultradent) (00-U subgroup), yellow 02 cord (Knittrax 02) (02-K subgroup), green 02 cord (Ultrapack 02) (02-U subgroup), and Teflon tape (T subgroup) (n = 10). The control scan was used as a reference to measure the root mean square (RMS) error discrepancies with each experimental scan on the preparation and margin areas. Two-way ANOVA and pairwise multiple comparisons tests were used to analyze trueness. Levene and pairwise comparisons tests were used to analyze precision (α = 0.05).
Results:
In the preparation area, trueness differences were found among groups (p < 0.001) and subgroups (p < 0.001), with a significant group×subgroup interaction (p < 0.001). The i700 and Aoralscan3 and the 00-U, 02-U, and T subgroups had the best trueness. In the margin area, trueness discrepancies were found among groups (p < 0.001) and subgroups (p < 0.001). The Aoralscan3 and 02-U and T subgroups demonstrated the best trueness. Finally, precision discrepancies were found only in the preparation area among groups (p < 0.001) and subgroups (p < 0.001). The i700 and Aoralscan 3 groups and 02-U and T subgroups had the best precision.
Conclusions:
The IOS and retraction technique tested influenced the trueness and precision of the single tooth preparation cast.
Clinical Significance:
The color and diameter of the retraction cord or Teflon tape used as the first cord in the double cord technique for digitizing a crown preparation with equigingival finish line did impact the scanning accuracy of the IOSs tested. However, the scanning discrepancies measured are not clinically relevant.
