Effect of relining on fiber post retention to root canal.
One of the clinically relevant problems dentists face when restoring endodontically treated teeth is the mismatch between fiber post and post space diameters, which results in an excessively thick resin cement layer. Fiber post relining appears as a solution for this problem.


OBJECTIVE
The aim of this study was to evaluate the effect of fiber post relining with composite resin on push-out bond strength.


METHODS
Twenty bovine incisors were selected to assess post retention. The crowns were removed below the cementoenamel junction and the root canals were treated endodontically and flared with diamond burs. The roots were allocated into two groups (n=10): G1: fiber posts without relining and G2: fiber posts relined with composite resin. The posts were cemented with a dual-cured resin cement and the specimens were sectioned transversally. Three 1.5-mm thick slabs were obtained per root and identified as cervical, medium and apical thirds. The push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. The failure mode of fractured specimens was analyzed under scanning electron microscopy. Data were analyzed by split-plot ANOVA and post-hoc Tukey's test at a pre-set alpha of 0.05.


RESULTS
Relined fiber posts presented higher retention values than non-relined post in all thirds. No statistically significant differences (p>0.05) were found among thirds for relined posts. All failures occurred at the interface between resin cement and root dentin.


CONCLUSIONS
Relining with composite resin seems to be an effective method to improve the retention of fiber posts to flared root canals.
Faria-e-Silva
André Luís
AL
Department of Dentistry, State University of Montes Claros, MG, Brazil. andrelfsilva@hotmail.com
Pedrosa-Filho
Celso de Freitas
Cde F
Menezes
Murilo de Sousa
Mde S
Silveira
Daniele Machado da
DM
Martins
Luís Roberto Marcondes
LR
D000134:Acid Etching, Dental; D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D003786:Dental Pulp Cavity / Q000473:pathology*; D019232:Dental Restoration Failure; D003804:Dentin / Q000473:pathology; D017220:Dentin-Bonding Agents / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000379:methods; D012821:Silanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D019279:Resin Cements; D012821:Silanes; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate