R. LANG*, M. ROSENTRITT, M. BEHR and G. HANDEL
(Department of Prosthetic Dentistry, University of Regensburg, Germany)
During clinical application provisional crown & bridge restorations may fail due to fracture. In this in vitro study the fracture strength of three-unit bridges of eight provisional crown & bridge materials were determined. Identical alloy dies (Biosil F, Degussa, Hanau, G) were fixed in resin at a distance of 10 mm simulating posterior gap (with an artificial polyether periodontium). Twenty bridges of each material were bonded with Procem (Espe). After 14days/ H20 storage and subsequent thermal cycling and mechanical loading (TCML: 50 N, 480000 times; 600 cycles 5°/55° C, 2 min each; automatic failure detection) ten samples of each group were loaded to fracture (Zwick, G; v=1mm/min). Ten samples of each material were stored for 24 hours/H20 as a control group and loaded to fracture. Fracture forms were determined optically. Medians and 25%/75% percentiles were calculated. Statistics: One-Way-Anova (p=0,05).
All samples of Snap showed insufficient stability during TCML. Self-curing Protemp 3 Garant and light-curing Provipont DC showed highest fracture strength after 24hrs storage and after TCML and might be recommended even for long term temporary restorations.