In vitro fracture resistance of glass-fiber and cast metal posts with different lengths.
BACKGROUND
Dental fractures can occur in endodontically treated teeth restored with posts.


OBJECTIVE
The purpose of this study was to evaluate the in vitro fracture resistance of roots with glass-fiber and metal posts of different lengths.


METHODS
Sixty endodontically treated maxillary canines were embedded in acrylic resin, except for 4 mm of the cervical area, after removing the clinical crowns. The post spaces were opened with a cylindrical bur at low speed attached to a surveyor, resulting in preparations with lengths of 6 mm (group 6 mm), 8 mm (group 8 mm), or 10 mm (group 10 mm). Each group was divided into 2 subgroups according to the post material: cast post and core or glass-fiber post (n=30). The posts were luted with dual-polymerizing resin cement (Panavia F). Cast posts and cores of Co-Cr (Resilient Plus) crowns were made and cemented with zinc phosphate. Specimens were subjected to increasing compressive load (N) until fracture. Data were analyzed with 2-way ANOVA and the Tukey-Kramer test (alpha =.05).


RESULTS
The ANOVA analysis indicated significant differences (P<.05) among the groups, and the Tukey test revealed no significant difference among the metal posts of 6-mm length (26.5 N +/-13.4), 8-mm length (25.2 N +/-13.9), and 10-mm length (17.1 N +/-5.2). Also, in the glass-fiber post group, there was no significant difference when posts of 8-mm length (13.4 N +/-11.0) were compared with the 6-mm (6.9 N +/-4.6) and 10-mm (31.7 N +/-13.1) groups. The 10-mm-long post displayed superior fracture resistance, and the 6-mm-long post showed significantly lower mean values (P<.001).


CONCLUSIONS
Within the limitations of this study, it was concluded that the glass-fiber post represents a viable alternative to the cast metal post, increasing the resistance to fracture of endodontically treated canines.
Giovani
Alessandro Rogério
AR
Department of Endodontics, University of Ribeirão Preto (UNAERP), São Paulo, Brazil.
Vansan
Luiz Pascoal
LP
de Sousa Neto
Manoel Damião
MD
Paulino
Silvana Maria
SM
D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003481:Cuspid / Q000293:injuries; D003722:Dental Alloys; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D005898:Glass; D006801:Humans; D008437:Maxilla; D011176:Post and Core Technique / Q000295:instrumentation*; D018709:Statistics, Nonparametric; D014082:Tooth Fractures / Q000517:prevention & control*; D019553:Tooth, Nonvital / Q000503:physiopathology*
D003188:Composite Resins; D003722:Dental Alloys; C009753:fiberglass