European Journal of Prosthodontics and Restorative Dentistry

In Vitro Effects of 2.5% Titanium Tetrafluoride on Streptococcus Mutans and Lactobacillus Casei in Dentin Followed by Self-Etching Adhesive Systems

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Cover Date

December 2015

Print ISSN

0965-7452

Electronic ISSN

2396-8893

Vol

23

Issue

4

Abstract

Objective: the aim of this study was to compare the marginal and internal fit accuracy
of crowns constructed using three different wax production methods; conventional,
milled, and 3D printed and utilizing three different cement gap thicknesses.
Methods: 15 identical stone dies were made for each method. Wax patterns were produced
and then cast into metal crowns, which were assessed for differences in accuracy
of both marginal and internal fit. Measurement points were 4 points per crown; occlusal,
axial, marginal gap, and marginal discrepancy points. A silicone impression technique
and conventional cementation technique were employed to facilitate the measurements.
Results: there was no significant difference (p> 0.05) in accuracy between the digitally
and manually produced crowns, with the 3D printed crowns being slightly more
accurate. Whereas, statistically significant differences were noticed between the conventional
versus printed groups, in occlusal and marginal gap points (p< 0.05).
Conclusion: The marginal and internal fit of 3D printed wax patterns is more accurate
than the other two production methods. The milling of wax crowns is as accurate as the
conventional hand carved production in terms of internal and marginal fit. The manufacturer
recommended offset/die-spacer of 30μm produced the most accurate internal
and marginal fits.

Keywords
Marginal Gap
Crowns
Internal Fit
CAD-CAM
Cementation