RESUMO
BACKGROUND: This study aimed to evaluate the bond strength and the penetration depth of two adhesive systems to a new experimental semi-IPN fiber post versus a commercial post. MATERIAL AND METHODS: Experimental Kevlar fiber (KF) and control everStick®POST (ES) posts (n=20/ group) with a diameter of 1.5 mm were used, 10 posts coated with StickResin (SR) and the other 10 posts coated with Scotch bond multipurpose (SBMP) adhesives. Composite resin buildup was performed over each post, using a cylindrical plastic mold (10 mm × 6 mm). Four discs of 2 mm thickness were prepared from each post/composite buildup and underwent pushout bond strength test at a crosshead speed of 0.5 mm/min accompanied by failure mode analysis. A further three specimens from each subgroup were bonded with adhesives labeled with 0.1 wt% Rhodamine B and embedded in acrylic resin, sectioned and examined under a confocal Laser-scanning microscope (CLSM) to measure the depth of resin penetration. Statistical analysis included ANOVA and Tukey test, the significance level was assumed at a p-value less than 0.05. RESULTS: The push-out bond strength of KF was comparable to that of ES with both SBMP and SR adhesives (P >0.05). Bond strength value for SBMP was higher than SR adhesive in either ES and KF posts with no significant difference (P > 0.05). ES exhibited higher adhesive penetration depth compared with KF (p<0.05). CONCLUSIONS: The bond strength of Kevlar post was comparable with the everStick post and the semi-interpenetrating structure of Kevlar post displayed some adhesive monomers diffusion indicating its usefulness as a new intracanal post. Key words:Kevlar fiber post, Bond strength, Penetration depth, Confocal, Semi-IPN polymer system.
RESUMO
This study evaluates the reinforcement of semi-interpenetrating network composites of 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl] propane (Bis-GMA)/ triethyleneglycol dimethacrylate (TEGDMA)/polymethyl methacrylate (PMMA) and 25% titanium dioxide (TiO2) nanofiller with surface treated Kevlar fibers for potential application as dental posts. The post material was subjected to thermo-cycling and flexural strength determined, characterised by dynamic mechanical analysis, water sorption, radiopacity and cytotoxicity tests. The results were compared with everStick®POST. Kevlar pre-treatment with acetic acid and silane coupling agent demonstrated a clear effect on the flexural strength of the composites with a significant increase compared to composites with fibers without surface treatment. The inclusion of TiO2 into the final formulation provided the desired radiopacity and improved both aesthetics and flexural strength, which exhibits a higher resistance on thermocycling. The ratios of fatigue limit to static flexural strength were about 0.73 for Kevlar and 0.58 for everStick®POST; MTT assay confirmed the absence of any toxic eluents, indicating its feasibility as new intracanal post material.
