Journal of Dental Research, Vol 73, 1228-1232, Copyright © 1994 by International & American Associations for Dental Research Online Journals
Effects of thermocycling and occlusal force on adhesive composite crowns
I. Krejci, E. Mueller and F. Lutz
Department of Preventive Dentistry, Periodontology and Cariology, Zurich University, Switzerland.
The aim of this in vitro study was to provide first quantitative data on
the marginal adaptation and the required load to fracture of adhesive
composite crowns with and without adhesive composite cores. Eighteen
caries-free extracted human premolars were restored using fine hybrid
composite crowns with margins located entirely in dentin. Six crowns were
adhesively luted to dentin stubs, six to endodontically treated teeth with
adhesive titanium posts and adhesive composite cores, and six to adhesive
composite cores without posts. Another ten unprepared teeth served as a
control. All restored teeth were subjected to long-term occlusal and
thermal stresses. The marginal adaptation was evaluated in the SEM before
and after loading. Load to fracture was recorded at the end of the stress.
Before stressing, 72.2 to 85.0%, and after stressing, 51.9 to 66.2% of
"continuous margin" were recorded at the dentin-luting composite interface.
The best results after stressing were achieved with crowns luted to
adhesive composite cores without titanium posts. At the luting
composite-composite crown interface, 61.6 to 88.7% of "continuous margin"
before and 57.7 to 75.5% after stressing were recorded. The required load
to fracture the restored teeth ranged from 72.0 to 89.2% of the unrestored,
unloaded control. Adhesive composite cores without titanium posts yielded
the best results.
