Objectives: Artificial environments were used to simulate the clinical conditions with thermal cycling and mechanical loading (TCML). The aim of this in-vitro study was to examine the influence of varying instrument settings on the fracture behavior of three-unit all ceramic fixed partial dentures (FPDs).

Materials&Methods: Identical CoCr abutments with a 1mm chamfer finishing line were positioned pair-wise in a PMMA resin (Palapress, Kulzer, G) at a distance of 10 mm to represent a molar gap. 8 three-unit posterior FPDs were made of the all-ceramic Empress2 (Ivoclar-Vivadent, FL) according to manufacturer's instructions and adhesively luted using Variolink II (Ivoclar-Vivadent, FL). TCML was performed with varying force: 50N/150N/50-150N staircase; chewing frequency: 1.6Hz/3.0Hz; mouth opening: 2mm/4mm; antagonist: human molar/ceramic sphere (d=6mm), temperature: 5°C-55°C/25°C. After TCML the FPDs were mechanically loaded until failure (UTM 1446: v=1mm/min, Zwick, G). As a reference all-ceramic FPDs without TCML were investigated (Control: 1832±345N). The FPDs were examined optically to describe the forms of fracture. Median and 25%/75% percentiles were calculated. Statistics: Mann-Whitney-U-test (p=0.05).

Results:

Force [N]	50	150	50	50	50-150	50	50	50	50
Mouth opening [mm]	2.0	2.0	4.0	2.0	2.0	2.0	2.0	2.0	2.0
Frequency [Hz]	1.6	1.6	1.6	3.0	1.6	1.6	1.6	1.6	1.6
Abutment Material	CoCr						human	LCP	CoCr
Antagonist Material	ceramic					human	ceramic
Temperature [°C]	5°C/55°C								25°C
Mean [N]	1300	738	1157	1350	831	1126	410	432	1713
std.	557	243	424	487	324	338	135	41	640

Conclusion: Higher loading force and a temperature gradient lead to decreasing fracture resistance. The abutment material has a significant influence on the fracture force. Fracture force after aging is dependent on the parameters of the artificial aging process.

Back to the Scientific Program Program
Back to the Joint Meeting of the Continental European, Israeli, and Scandinavian (NOF) Divisions of the IADR (August 25 -- 28, 2004)

Top Level Search