Failure of fiber posts after cementation with different adhesives with or without silanization investigated by pullout tests and scanning electron microscopy.
BACKGROUND
The aim of the study was to test retentive forces of different adhesive systems after cementation of glass-fiber posts with or without prior silanization of the post by using a pullout test and scanning electron microscope (SEM) observation to detect the mode of failure.


METHODS
Fifty-six roots were randomly divided into 6 experimental and 2 control groups: ParaCore (PAR), Paracore + silane (PAR-SIL), RelyX Unicem (RXU), RelyX Unicem + silane (RXU-SIL), RelyX ARC (RXA), RelyX ARC + silane (RXA-SIL), negative control (NEG-CON), and positive control (POS-CON). ParaCore posts were placed in the experimental groups (each n = 8) by using an adhesive resin with or without prior silanization. NEG-CON received uncemented posts (n = 4); POS-CON received an active screw post with an adhesive (n = 4). All samples were subjected to a pullout test in a universal mechanical testing machine for pullout tests and SEM to assess the fiber posts and the roots after the tests.


RESULTS
Mean failure load values for each ground were PAR 247.4 ± 59.3 N, PAR-SIL 240.5 ± 68.8 N, RXU 102.3 ± 22.8 N, RXU-SIL 106.4 ± 19.8 N, RXA 119.8 ± 27.3 N, RXA-SIL 125.8 ± 28.3 N, NEG-CON 0 ± 0 N, and POS-CON 412.9 ± 27.4 N. There was a statistically significant difference between the 3 experimental adhesive systems (P < .001) and between each experimental group and NEG-CON and POS-CON (P < .05). PAR was significantly different from RXU and RXA (P < .05). No statistically significant differences existed between RXU and RXA and between the use of silanization or not. Representative samples for SEM showed cohesive failure as the principal fracture mode for PAR and mainly adhesive failure for RXU and RXA.


CONCLUSIONS
The results indicated that silanization of fiber posts does not make a difference to prevent dislocation of a post. Full-etching systems demonstrated significantly higher retentive forces than self-etching systems.
Department of Endodontics, School of Stomatology, 4th Military Medical University, Xian, Shaanxi, China.
Yu
Y
Tian
Yunjing
Y
Mu
Frank C
FC
Setzer
Hong
H
Lu
Tiejun
T
Qu
Qing
Q
Yu
D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002484:Cementation / Q000379:methods*; D003738:Dental Cements / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D017268:Dental Prosthesis Retention; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; C483701:Rely X Unicem; C462240:RelyX ARC; D019279:Resin Cements; D012821:Silanes; C009753:fiberglass; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D017438:Bisphenol A-Glycidyl Methacrylate