Effectiveness and dentin bond strengths of two materials for reinforcing thin-walled roots.
OBJECTIVE
To investigate the effectiveness of two restorative materials for reinforcing thin-walled roots and their microtensile bond strengths to root canal dentin.


METHODS
Twenty-one decoronated maxillary central incisor roots were root filled and the canals enlarged to leave approximately 1.0 mm thick dentin walls. The roots were distributed randomly to three equal groups. Group 1 (control): a large tapered cast post-core was fabricated. Group 2 (BIS-CORE): a thick layer of dual-cured composite was placed in the post-hole before fabrication of a small-diameter tapered cast post-core. Group 3 (ChemFil Superior): a thick layer of glass-ionomer was placed, as before. Metal-ceramic crowns were fabricated for all teeth. Microtensile bond strength tests and optical and atomic force microscope observations were employed to examine adhesion between the two restorative materials and the root canal dentin.


RESULTS
Mechanical loading (kN) demonstrated that composite 0.64 (S.D. 0.05), but not glass-ionomer 0.49 (0.05), significantly reinforced the fracture resistance of thin-walled roots, P<0.001. Microtensile bond strengths (MPa) were 21.7 (1.6) for composite and 12.9 (1.7) for glass-ionomer, P=002.


CONCLUSIONS
A thick intermediate layer of resin-bonded composite, sandwiched between the root dentin and a small-diameter cast Ni-Cr post or dowel, increased significantly the fracture resistance of the roots.
Wu
Xin
X
Department of Prosthetic Dentistry, College of Stomatology, Nanjing Medical University, Nanjing, PR China.
Chan
Anna T T
AT
Chen
Ya-Ming
YM
Yip
Kevin H-K
KH
Smales
Roger J
RJ
D000328:Adult; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D006801:Humans; D007180:Incisor; D008297:Male; D018625:Microscopy, Atomic Force; D011176:Post and Core Technique / Q000009:adverse effects; D013718:Tensile Strength; D014082:Tooth Fractures / Q000209:etiology / Q000517:prevention & control*; D014092:Tooth Root / Q000502:physiology
C520518:BIS-Core Resin-bonded Composite; C501420:Chemfil Superior; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements