The in-vitro study of the marginal fit accuracy of computer-milled titanium crowns. II. a histological-morphometric marginal-gap analysis
Schlegel, A.; Besimo, C.; Donath, K.
Schweizer Monatsschrift für Zahnmedizin 101(11): 1409-1414
1991
ISSN/ISBN: 0256-2855 PMID: 1962165 Document Number: 376201
The Digitising Computer System (DCS) can be mechanically programmed to produce computer-milled titanium dentures for veneered ceramic single crowns using three-dimensional computer models. A first analysis by electron scanning microscope of the marginal leakage in titanium framework on 12 extracted teeth showed a marginal accuracy of fit of 68.3 +/- 61.1 microns for the shoulder, and 95.7 +/- 83.2 microns for the chamfered preparation. Owing to limited indicative value of recordings by electron scanning microscopes, the crown edges of the 9 teeth with shoulder preparations were subjected to histological-morphometric measurements. Using this more accurate investigational system, a distinctly higher arithmetic mean of 89.2 +/- 69.1 microns for the marginal accuracy of fit was achieved. It also enabled the marginal leakage of cement (96.5 +/- 85.1 microns), the marginal adaptation (37.4 +/- 93.3 microns) and the shoulder formation (44.4 +/- 58.9 microns) to be judged.