Influence of airborne-particle abrasion on mechanical properties and bond strength of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts.
BACKGROUND
Controversy exists concerning the use of fiber-reinforced posts to improve bond strength to resin cement because some precementation treatments can compromise the mechanical properties of the posts.


OBJECTIVE
The purpose of this study was to analyze the influence of airborne-particle abrasion on the mechanical properties and microtensile bond strength (MTBS) of carbon/epoxy and glass/bis-GMA fiber-reinforced resin posts.


METHODS
Flexural strength (delta(f)), flexural modulus (E(f)), and stiffness (S) were assessed using a 3-point bending test for glass fiber-reinforced and carbon fiber-reinforced resin posts submitted to airborne-particle abrasion (AB) with 50-microm Al(2)O(3), and for posts without any surface treatment (controls) (n=10). Forty glass fiber (GF) and 40 carbon fiber (CF) posts were submitted to 1 of 4 surface treatments (n=10) prior to MTBS testing: silane (S); silane and adhesive (SA); airborne-particle abrasion with 50-microm Al(2)O(3) and silane (ABS); airborne-particle abrasion, silane, and adhesive (ABSA). Two composite resin restorations (Filtek Z250) with rounded depressions in the lateral face were bilaterally fixed to the post with resin cement (RelyX ARC). Next, the specimen was sectioned with a precision saw running perpendicular to the bonded surface to obtain 10 bonded beam specimens with a cross-sectional area of 1 mm(2). Each beam specimen was tested in a mechanical testing machine (EMIC 2,000 DL), under stress, at a crosshead speed of 0.5 mm/min until failure. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy (SEM).


RESULTS
The 3-point bending test demonstrated significant differences among groups only for the post type factor for flexural strength, flexural modulus, and stiffness. The carbon fiber posts exhibited significantly higher mean flexural strength (P=.001), flexural modulus (P=.003), and stiffness (P=.001) values when compared with glass fiber posts, irrespective of surface treatment. An alteration in the superficial structure of the posts could be observed by SEM after airborne-particle abrasion. MTBS testing showed no significant effect for the surface treatment type; however, significant effects for post system factor and for interaction between the 2 factors were observed. For the carbon fiber post, the ABSA surface treatment resulted in values significantly lower than the S surface treatment. SEM analysis of MTBS-tested specimens demonstrated adhesive and cohesive failures.


CONCLUSIONS
Airborne-particle abrasion did not influence the mechanical properties of the post; however, it produced undesirable surface changes, which could reduce the bond strength to resin cement. For the surface treatments studied, if silane is applied, the adhesive system and airborne-particle abrasion are not necessary.
Biomechanical Group, Dentistry and Dental Materials School of Dentistry, Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil. carlosjsoares@umuarama.ufu.br
Carlos Jose
CJ
Soares
Fernanda Ribeiro
FR
Santana
Janaina Carla
JC
Pereira
Tatiana Santos
TS
Araujo
Murilo Souza
MS
Menezes
D000268:Adhesiveness; D000537:Aluminum Oxide / Q000737:chemistry*; D001696:Biomechanical Phenomena; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D004853:Epoxy Resins / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D018583:Pliability; 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; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
D000077482:Carbon Fiber; D003188:Composite Resins; D003764:Dental Materials; D004853:Epoxy Resins; C444701:Filtek Z250; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; D012821:Silanes; C009753:fiberglass; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D002244:Carbon; D000537:Aluminum Oxide