Abstract
The aim of this study was to assess the influence of surface pretreatments of fiber-reinforced posts on flexural strength (FS), modulus of elasticity (ME) and morphology of these posts, as well as the bond strength (BS) between posts and core material. Fifty-two fiber posts (smooth and serrated) were assigned to 4 groups (n=13): no treatment (control), 10% hydrogen peroxide (HP) for 10 min (HP-10), 24% HP for 1 min (HP-24) and airborne-particle abrasion (Al(2)O(3)). To evaluate FS and ME, a 3-point bending test was performed. Three posts of each group were examined by scanning electron microscopy. Composite resin was used as the core build-up and samples were sectioned to obtain microtensile sticks. Data were analyzed by ANOVA and Tukey's test (α=0.05). For FS, significant differences were observed between posts type and surface pretreatment (p<0.05), with the highest means for the smooth posts. Al2O3 provided higher FS than HP-24. Al(2)O(3) promoted higher ME than HP-24 and control. SEM images revealed partial dissolution of the resin matrix in all treated groups. The smooth posts had higher BS and FS than serrated posts (p<0.05). Mechanical properties of the glass fiber posts and the bond strength between posts and composite material were not altered by the surface treatments, except for airborne-particle abrasion that increased the post elastic modulus.
Highlights
Glass fiber-reinforced posts have been proposed for the restoration of endodontically treated teeth due to the esthetic coloration and favorable biomechanical properties [1,2,3]
Some techniques are proposed for conditioning the fiber post surface, such as hydrogen peroxide (HP) solution [12,13,14] and airborne-particle abrasion (7,1517)
Different treatments have been proposed to modify the surface of fiber posts in order to improve the adhesive capability as well as the clinical performance of these materials [19]
Summary
Glass fiber-reinforced posts have been proposed for the restoration of endodontically treated teeth due to the esthetic coloration and favorable biomechanical properties [1,2,3]. Chemical and mechanical treatments of the post surface as well as changes in the matrix of the posts appear to influence the bond strength between resin materials and fiber posts [4,5,6,7,8,9,10]. The post matrix, consisting of epoxy resin, has no functional group able of reacting with the silane and the effectiveness of the adhesion may be compromised [8,11]. Surface post treatments with subsequent silanization are proposed to allow better interaction with the resin cements and enhance chemical and micromechanical bonding [12]. It is speculated that HP is able to degrade the epoxy resin matrix and expose the glass fibers. Airborne-particle abrasion produces a roughened surface as a result of the high-speed impact of abrasive particles, enabling better interaction with the resin cement, but the roughened surface may produce surface damage which, Braz Dent J 23(6) 2012
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