Optimization of the marginal gap of all-ceramic restorations and gold crowns by ultrasound activated, suspended Al2O3 powder.
OBJECTIVE
To evaluate if the use of ultrasound activated Al203 powder improved the fit especially of all-ceramic restorations.


METHODS
21 extracted teeth were prepared for 14 all-ceramic IPS Empress2 (IPS Empress2) restorations (four crowns, four partial crowns, two inlays, four veneers) and seven gold crowns (Degudent H). Each restoration was adjusted with a suspension of Al2O3 of 25 microm and 50 microm grit, respectively. The effect of the fitting adjustments was recorded with the silicone disclosing medium technique and measured at 11 points under the microscope in an interval of 0.4 mm.


RESULTS
A significant (P < 0.001) improvement of the tight fit of all restorations by means of ultrasound activated Al2O3 powder was noticed. The approach of the restoration towards the prepared stump by the sonoerosive fitting correction was in the mean 201 +/- 60 microm in Empress2 restorations and 87 +/- 24 microm in gold crowns within a period of 10 minutes. SEM observation of the Empress2 specimens showed no microdamage after ultrasound machining.
Department of Prosthodontics, University of Bonn, Welschnonnenstr. 17, 53111 Bonn, Germany. sabinelinsen@web.de
Sabine S
SS
Linsen
Daniela
D
Wirtz
Carola
C
Fischer
Bernd
B
Koeck
D000537:Aluminum Oxide / Q000737:chemistry*; D003442:Crowns; D018772:Dental Marginal Adaptation / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003793:Dental Restoration, Permanent / Q000379:methods*; D003801:Dental Veneers; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry*; D006801:Humans; D007284:Inlays; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012826:Silicone Elastomers / Q000737:chemistry; D013499:Surface Properties; D019246:Tooth Preparation / Q000379:methods; D014465:Ultrasonics
D003764:Dental Materials; D004129:Dimethylpolysiloxanes; C118557:Empress 2; D006047:Gold Alloys; D018020:Lithium Compounds; C020964:MDX 4-4210; D012826:Silicone Elastomers; D003776:Dental Porcelain; D000537:Aluminum Oxide