From: An in vitro study evaluating the effect of ferrule design on the fracture resistance of endodontically treated mandibular premolars after simulated crown lengthening or forced eruption methods
Groups
Fatigue testing
Fracture strength (kN)a
Root fracture sitesb
At or above cervical 1/3
Below cervical 1/3
F0
0/8
1.01(0.26)
7
1
CL/F1
0.91 (0.29)
6
2
CL/F2
0.73 (0.19)
8
0
OE/F1
0.96 (0.25)
OE/F2
0.76 (0.20)