Impact of adhesive surface and volume of luting resin on fracture resistance of root filled teeth.
OBJECTIVE
To investigate the correlation between geometric parameters of severely compromised root filled (RCT) pre-molar teeth with irregular root canals and their fracture resistance. The null hypothesis tested was that the fracture resistance of root filled teeth is not influenced by: (i) the adhesive surface of the post-space preparation (A(PS) ), (ii) the coronal tooth surface (A(A) ), (iii) the amount of resin cement (V(C) ) and (iv) the Young's modulus of the specimens.


METHODS
A total of 48 noncarious human pre-molar teeth with irregular root canals were decoronated, root filled and adhesively restored with post-retained direct composite crowns. After thermomechanical loading (1,200,000×, 5-50° C), static load was applied until failure. The geometric parameters of the tooth were evaluated by microcomputed tomography (μCT) using impressions taken after post-space preparation. Linear regression analyses were performed to correlate the geometric parameters of the specimens with their fracture resistance.


RESULTS
The amount of resin cement (V(C) ) comprised up to 88% of the entire post-space (mean 67%) and had no impact on the maximal load (P = 0.88). The latter was significantly influenced by post-space preparation (P = 0.003).


CONCLUSIONS
Amongst the geometric parameters tested, the surface area in the root canal had the greatest impact on fracture resistance of root filled pre-molars restored with posts and composite crowns, whilst the fit of the post was less important.
Department of Periodontology, Endodontology and Cariology, School of Dental Medicine, University of Basel, Basel, Switzerland. gabriel.krastl@unibas.ch
G
G
Krastl
J
J
Gugger
H
H
Deyhle
N U
NU
Zitzmann
R
R
Weiger
B
B
Müller
D001641:Bicuspid; D003442:Crowns; D003738:Dental Cements / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D016014:Linear Models; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation*; D012390:Root Canal Therapy / Q000379:methods*; D013499:Surface Properties; D014082:Tooth Fractures / Q000517:prevention & control*; D055114:X-Ray Microtomography
D003738:Dental Cements