Browsing by Subject "Surface treatment"

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    Effect of surface conditioning methods on repair bond strength of microhybrid resin matrix composite
    (2010) Rajitrangson, Phitakphong, 1982-; Cochran, Michael A. (Michael Alan), 1944-; Cho, Sopanis D.; Gonzalez-Cabezas, Carlos, 1966-; Matis, Bruce A.; Platt, Jeffrey A., 1958-
    Repair is an alternative treatment option in many cases to replacement of resin matrix composite restoration. However, aged resin matrix composites have a limited number of carbon-carbon double bonds to adhere to a new layer of rein. Therefore, surface treatments of the aged resin matrix composite surface prior to repairing could improve the repair bond strength. The objectives of this study were to: 1) To evaluate various surface treatments on shear bond strength of repair between aged and new microhybrid resin matrix composite, and 2) To assess the influence of applying a silane coupling agent after surface treatments. Eighty disk-shaped resin matrix composite specimens were fabricated and thermocycled 5000 times prior to surface treatment. Specimens were randomly assigned to one of the three surface treatments (n = 20): 1) Airborne abrasion with 50 μm aluminum oxide, 2) Tribochemical silica coating (CoJet), or 3) Er,Cr:YSGG laser and control group (n = 20). Specimens were cleaned with 35-percent phosphoric acid, rinsed, and dried. Each group was assigned into two subgroups (n =10): a) no silanization, and b) with silanization. Adhesive agent was applied and new resin matrix composite was bonded to each conditioned surface. Bond strength was evaluated by shear test. Data were analyzed with a two-way ANOVA model. The interaction between conditioning and silanization was significant(p = 0.0163), indicating that comparisons of silanization must be evaluated for each conditioning method, and that comparisons of conditioning methods must be evaluated separately with and without silanization. Airborne particle abrasion showed significantly higher repair bond strength than Er,Cr:YSGG laser without silanization (p < 0.0001) and with silanization(p = 0.0002), and higher repair bond strength than the control without silanization (p < 0.00001) and with silanization (p < 0.00001). Airborne particle abrasion did not have significantly different in repair bond strength than Tribosilica coating without silanization (p = 0.70) or with silanization (p = 0.33). Tribosilica coating had significantly higher repair bond strength than Er,CR:YSGG laser without silanization (p < 0.0001) and with silanization (p < 0.0001), and significantly higher repair bond strength than control without silanization (p < 0.0001), but not with silanization (p =0.16). Er,CR:YSGG laser and control did not have significantly different repair bond strength without silanization (p = 1.00) or with silanization (p = 0.11). There was no effect of silanization on repair bond strength overall (p = 0.34) for any of the surface conditioning methods (p = 0.76 for airborne particle abrasion; p = 0.39 for tribosilica coating; p = 1.00 for Er,Cr:YSGG laser, or p = 0.39 for control). Airborne particle abrasion with 50-μm aluminum oxide particle and tribochemical silica coating followed by the application of bonding agent provided the highest shear bond strength values, suggesting that they might be adequate methods to improve the quality of the repairs of resin-matrix composites.
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    Influence of ceramic (feldspathic) surface treatments on the micro-shear bond strength of composite resin
    (E.H Angle Education and Research Foundation, 2010-07-01) Yadav, Sumit; Upadhyay, Madhur; Borges, Gilberto Antonio; Roberts, W. Eugene; Orthodontics and Oral Facial Genetics, School of Dentistry
    Objective: To test the null hypothesis that surface treatment has no influence on the micro-shear bond strength between orthodontic composite resin cement and ceramics (feldspathic porcelain). Materials and Methods: Circular specimens of feldspathic porcelain were fabricated and randomly divided into six groups: (1) no treatment; (2) treatment with a mixture of acidic primer and silane agent for 20 seconds; (3) etching with 9.5% hydrofluoric acid; (4) etching with 9.5% hydrofluoric acid and coating with a mixture of acidic primer and silane agent for 20 seconds; (5) airborne-particle abrasion with 50-μm aluminum oxide; and (6) airborne-particle abrasion and coating with a mixture of acidic primer and silane agent for 20 seconds. The porcelain disks were then bonded to resin cylinders with composite resin cement. A micro-shear bond test was carried out to measure the bond strength. Moreover, each ceramic surface was observed morphologically by scanning electron microscopy. One-way analysis of covariance was used to compare the groups for differences in micro-shear bond strength. Results: The mean micro-shear bond strength varied as a function of surface treatment. It ranged from 3.7 to 20.8 MPa. The highest values for micro-shear bond strength were found when the surface was acid-etched with hydrofluoric acid and coated with silane. On the other hand, the control group (no treatment) had significantly lower micro-shear bond strength than all the other groups. Conclusion: The null hypothesis that the surface treatment has no influence on the micro-shear bond strength of orthodontic composite resin was rejected. The bond strength between ceramics and orthodontic resin cement is affected by the ceramic surface treatment. The bond failure was of the adhesive type, except with the hydrofluoric acid + silane group, where it was a cohesive bond failure.
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    Influence of surface treatment on veneering porcelain shear bond strength to zirconia after cyclic loading
    (2013) Nishigori, Atsushi; Platt, Jeffrey A., 1958-; Brown, David T.; Ando, Masatoshi; Bottino, Marco C.; Levon, John A.
    Statement of problem: Yttria-partially stabilized tetragonal zirconia polycrystal (Y-TZP) all-ceramic restorations have been reported to suffer from chipping or cracking of the veneering porcelain (VP) as the most common complication. There is little information in the literature regarding the influence of surface treatment on VP shear bond strength to Y-TZP after cyclic loading. Purpose of this study: The goals of this study were (1) to investigate the influence of zirconia surface treatments on veneering porcelain shear bond strength and (2) to investigate the influence of cyclic loading on the shear bond strength between VP and Y-TZP. Materials and Methods: 48 cylinder–shaped specimens (6mm in diameter and 4mm in height) were divided into 4 groups containing 12 specimens each according to the surface treatment. As a control group (C), no further treatment was applied to the specimens after grinding. Group H was heat-treated as a pretreatment according to the manufacturer’s recommendations. Group S was airborne-particle abraded with 50 µm alumina (Al2O3) particles under a pressure of 0.4 MPa for 10 seconds. In the group SH, the heat-treatment was performed after the airborne-particle abrasion. A VP cylinder (2.4 mm in diameter and 2 mm in height) was applied and fired on the prepared Y-TZP specimens. The shear bond strength was tested using a universal testing machine. Six specimens from each group were subjected to fatigue (10,000cycles, 1.5Hz, 10N load) before testing. Results: The 3-way ANOVA showed no statistically significant effect of surface treatment and cyclic loading on shear bond strength. The highest mean shear bond strength was recorded for the air-particle abrasion group without cyclic loading (34.1 + 10 MPa). The lowest mean shear bond strength was the air-particle abrasion group with cyclic loading (10.7 ± 15.4 MPa). Sidak multiple comparisons procedure demonstrated cyclic loading specimens had significantly lower shear bond strength than non-cyclic loading specimens after air-particle abrasion without heat treatment (p=0.0126) Conclusion: Within the limitations of this study, (1) Shear bond strength between Y-TZP and VP is not affected statistically by surface treatment using heat treatment, airborne-particle abrasion, and heat treatment after airborne-particle abrasion. (2) There is significant difference in shear bond strength with air-particle abrasion between with and without cyclic loading groups. This difference suggested that air-particle abrasion should be avoided in clinical situations as a surface treatment without heat treatment.