The Journal of Adhesive Dentistry, 04/2006

Purpose: To investigate the relationship between the degree of conversion of double bonds of all-in-one adhesives and their shear bond strength on ground human enamel. Materials and Methods: Six commercially available systems and one experimental adhesive were tested: Absolute (ABS; Dentsply-Sankin), Clearfil S3 Bond (CSB; Kuraray), G-Bond (GBO; GC), Hybrid Bond (HYB; Sun Medical), iBond (IBO; Heraeus Kulzer), Xeno IV (XEN; Dentsply Caulk), and experimental iBond NG (ING; Heraeus Kulzer). Conventional shear bond strengths (SBS, n = 8) of adhesive-coated enamel specimens bonded to Venus composite (Heraeus Kulzer) and degrees of conversion (DC) (FTIR, n = 5) were determined after 1 and 10 min, 1, 2, and 24 h of storage. Data were statistically analyzed using ANOVA and Duncan's post hoc test (α< 0.05). Results: The adhesives' SBS (MPa) and DC (%) by testing time followed logarithmic regression lines established by the least square method. Mean shear bond strengths after 1 min/24 h were: ABS 9.8/14.9; CSB 14.7/23.4; GBO 14.8/22.0; HYB 9.7/17.0; IBO 11.3/22.3; XEN 9.1/17.3; ING 9.7/25.6. The corresponding mean DC values were: ABS 51.3/66.2; CSB 83.1/90.8; GBO 75.8/87.7; HYB 49.6/67.2; IBO 72.6/93.7; XEN 61.6/74.1; ING 64.9/89.1. Linear regressions for the relationship DC vs SBS were significant with coefficients of determination (r2) between 0.72 and 0.97. Conclusion: Despite similar acidity, the adhesives showed different SBSs on enamel. Based on the relationships between DC and SBS, the cohesive failure patterns observed, and the composition-property relations discussed, it is concluded that the percentage DC is the main parameter influencing an adhesive's bonding efficacy to ground enamel. Keywords: self-etching adhesives, enamel bonding, degree of conversion, FTIR

Purpose: The aim of this in vitro study was to evaluate the shear bond strength of two adhesive systems - Prime & Bond NT (PBNT) and Clearfil SE Bond (CSEB) - to dentin irradiated before or after adhesive application. Materials and Methods: Thirty extracted molars were sectioned mesiodistally with a diamond bur. The inner surface of each tooth's dentin was ground flat with SiC abrasive papers. The roots of the sectioned teeth were mounted in a cylindrical mold using chemically cured acrylic resin. In groups A1 and B1, a radiation dose of 60 Gy (R) was applied to the dentin surfaces at this point. In all groups, adhesives were applied according to the respective manufacturer's instructions. Cylindrical composite resin restorations (CRR; internal diameter 3 mm, height 4 mm) were then placed on the center of the flattened dentin surfaces. At this point, groups A2 and B2 received 60 Gy of radiation, and groups C1 and C2 remained as nonirradiated controls. Thus, the test groups were: A1: R + PBNT (Primed Bond NT) + CRR; A2: PBNT + CRR + R; B1: R + CSEB (Clearfil SE Bond) + CRR; B2: CSEB + CRR + R; C1: PBNT+ CRR; C2: CSEB+ CRR. Specimens were mounted in a universal testing machine and shear load was applied at a crosshead speed of 1 mm/min until failure. Bond strength values were calculated as MPa and the results were evaluated statistically using repeated measures of two-way ANOVA, with significance set at p < 0.05. Results: Irradiation significantly affected adhesion of composite to dentin in groups A1 and A2 (p = 0.002). Group A1 showed statistically lower bond strength than group A2 (p < 0.05). No statistically significant differences were found among the other groups (p = 0.49). Conclusion: The time point of irradiation can have an adverse effect on bond strength, depending on the type of adhesive material. Keywords: bond strength, dentin adhesives, dentin bonding, radiation

Purpose: The aim of this study was to evaluate the influence of resin liners on the marginal adaptation to dentin of resin composite restorations photoactivated by a conventional quartz-tungsten halogen lamp (QTH), light emitting diodes (LED), and a plasma arc light (PAC). Materials and Methods: The buccal surfaces of 120 bovine incisors were ground until a flat dentin area was obtained. A circular cavity (4 mm in diameter x 1.5 mm in depth) was prepared in this area. Scotchbond Multi Purpose was applied in the cavities following the manufacturer's instructions. The specimens were randomly assigned into 4 groups according to the lining technique: (1) control (1 adhesive layer); (2) three adhesive layers; (3) Filtek Flow; (4) Protect Liner F. Each group was further divided into 3 subgroups according to the light-curing method: (A) QTH; (B) LED; (C) PAC. All cavities were then restored with a single increment of Filtek Z250 restorative composite and polished. Caries Detector was applied to each specimen for 5 s. Images of dye-stained gaps were observed under a stereomicroscope and transferred to a computer measurement program. Gap values were obtained by dividing the dyed margin length by the total cavity length, then multiplying by 100. Data were analyzed using ANOVA and Tukey's test (p < 0.05). Results: All the tested lining techniques significantly decreased marginal gap formation when compared with the control group only for the QTH light groups. There was no significant difference among the light-curing methods. Conclusion: The use of resin liners can effectively reduce the gap formation along dentin margins, but only when QTH light is used Keywords: gab formation, light emitting diodes (LED), quartz tungsten halogen (QTH) lamp, plasma arc (PAC), resin liners

Purpose: To determine if bonding incompatibility between a single-step self-etching adhesive and a dual-cured luting cement is prevented by addition of deprotonizing anion exchange resin powder to the amine component of the resin cement. Materials and Methods: iBond adhesive (IBO) (Heraeus Kulzer) and the dual-cured resin cement Twinlook (TWI) (Heraeus Kulzer) were used with base pastes, containing 0, 1, 2, and 4 wt% anion exchange resin (AER) in OH- form. Conventional shear bond strength (SBS) was determined on human dentin. After application of IBO, a cylindrical mold was clamped on the treated surface and bulk filled with TWI. SBS was measured after 24 h in 37°C water at a crosshead speed of 1 mm/min. The following curing protocols were investigated: Group 1: IBO not light cured, TWI redox cured; group 2: IBO light cured, TWI redox-cured; group 3: IBO light cured, TWI dual cured (n = 8). The data were statistically analyzed using ANOVA and Duncan's post-hoc test at α < 0.05. Results: The mean SBSs (MPa) with original TWI in groups 1, 2, and 3 were 12.7aA, 16.4bA, and 24.7cA. The corresponding figures for 1% AER were: 16.6aB, 23.0bB, 22.8bA; for 2% AER: 16.8aB, 22.6abB, 24.6bA; and for 4% AER: 16.2aAB, 22.5bB, 24.7bA. Different small and capital letters denote significant differences by treatment group and by AER content, respectively. Conclusion: Addition of anion exchange resin to the amine component of the dual-cured resin cement enhances the bond strength to dentin upon redox curing by prevention of amine neutralization through functional acid monomers from an all-in-one adhesive, mainly when the adhesive or the luting cement were not light cured. Keywords: self-etching adhesive, resin luting cement, curing mode, compatibility, dentin bond strength

Purpose: The aim of this in vitro study was to evaluate the shear bond strength of two conventional glass-ionomer cements to bovine dentin when using the air-abrasion technique for cavity preparation. Materials and Methods: Forty bovine central incisors were selected, embedded in polyester resin, and ground until the dentin surface was exposed. The teeth were randomly assigned to four groups: I and II - rotating instrument with a carbide bur; III and IV - an air-abrasion system. Groups I and III were restored with Fuji IX and groups II and IV with Ketac Molar. A 3-mm-diameter bonding site was delimited and treated with 10% polyacrylic acid for 10 s in the Fuji IX subgroups and with 25% polyacrylic acid for 10 s in the Ketac Molar subgroups. After surface treatment, a glassionomer cylinder was prepared for each specimen, using a split bisected Teflon matrix. The finished specimens were submitted to the shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed using ANOVA and Scheffé statistical tests. The dentin bonding areas were analyzed under a stereoscopic optical magnifier (40X) to assess the type of failure. Results: The mean (SD) shear bond strengths in MPa were: group I - 3.49 (± 3.77), group II - 7.17 (± 2.93), group III - 7.55 (± 2.99), group IV - 5.67 (± 3.90). Ketac Molar showed higher bond strength values in bur-prepared cavities, while on the air-abraded preparations, Fuji IX showed superior results. Conclusion: It can be concluded that the air-abrasion system used for cavity preparations may influence the bonding performance of conventional glass-ionomer cements to dentin Keywords: air abrasion, cavity preparation, conventional glass-ionomer cement, bovine dentin, shear bond strength

Purpose: To assess the microtensile bond strengths of a core composite with two different viscosities, MultiCore Flow (F) and Heavy Body (HB) (Ivoclar-Vivadent), on dentin and glass-fiber posts with methacrylate resin matrices, in combination with three dentin adhesives: Syntac Classic (S), Excite DSC (E), and AdheSE (A) (Ivoclar-Vivadent). The omission of an intermediate adhesive coating on silanized posts was also examined to see if this resulted in post-core bond strength reduction. Materials and Methods: Six experimental dentin and 6 experimental post groups were formed with different core material viscosity/adhesive combinations. In two control post groups, no adhesive was applied on the silanized posts. The core material was stratified on deep dentin or on the posts. From the built-up teeth and the post-core units, microtensile sticks were obtained. Results: The bond strengths measured on dentin were (MPa): S-F 12.7 ± 6.4; S-HB 18.3 ± 7.6; E-F 33.1 ± 13.7; E-HB 34.1 ± 10.2; A-F 33.5 ± 14.8; A-HB 35.5 ± 14.4. The post-core strengths were: S-F 9.4 ± 2.5; S-HB 7.1 ± 3.8; E-F 8.6 ± 3.8; E-HB 8.1 ± 4.4; A-F 8.1 ± 2.7; A-HB 8.3 ± 2.4; no adhesive-F 10.4 ± 3.6; no adhesive-HB 6.3 ± 2.7. Significantly higher interfacial strengths were achieved on dentin than on posts (p < 0.05). Adhesive type significantly affected core-dentin adhesion, with Excite DSC and AdheSE outperforming Syntac Classic (p < 0.05). Neither core material viscosity nor adhesive type significantly influenced post-core adhesion (p > 0.05). Omission of an intermediate adhesive layer had no effect on post-core adhesion (p > 0.05). Conclusions: Even after post surface silanization, the bond established by the composite core material with the post remains weaker than that created with coronal dentin. Keywords: composite resin, core, fiber post, dentin, bond strength

Purpose: As polymerization shrinkage is compensated by flow of the composite, several attempts have been performed for relief of the contraction stresses. The aim of this in vitro study was to evaluate the effect of flowable composite or fiber use under composite restorations on microtensile bond strength of composite to dentin in Class I cavities or flat dentin surfaces. Materials and Methods: Twenty-four sound extracted human first or second mandibular molars were randomly assigned to two groups (Class I cavities with a high c-factor or flattened dentin surfaces with a low c-factor). The dentin surfaces were treated with adhesive resin and restored with resin composite using four different techniques (bulk; with flowable composite; with a glass fiber (everStick NET); with a polyethylene fiber [Ribbond]). After 24 h storage at 37°C in water, the specimens were thermocycled 600 times between 5 and 55°C. Microtensile test specimens with a 0.9 x 0.9 (± 0.1) mm2 cross-sectional area were produced, and bond strength tests were carried out at a crosshead speed of 1 mm/min. Mean bond strengths were analyzed using two-way ANOVA and Bonferroni's test at a 95% significance level. Results: Flowable composite decreased dentin bond strength in cavities with a high c-factor (p < 0.05). The group restored with everStick NET showed stable bond strengths regardless of the effect of c-factor. Ribbond THM used under composite restorations increased dentin bond strength in cavities with a high c-factor (p < 0.05). Conclusion: Flowable composite decreased dentin bond strength in cavities with a high c-factor; however, using a glass fiber in combination with flowable resin, stable bond strengths can be achieved in cavities with a high c-factor. Polyethylene fiber in combination with flowable resin increases the microtensile bond strength to the dentin floor in cavities with a high c-factor. Keywords: c-factor, glass fiber, polyethylene fiber, flowable composites, microtensile bond strengths

Purpose: In an intra-individual comparison, a 6-month randomized, controlled prospective study evaluated the clinical performance of a self-etching and an etch-and-rinse adhesive in noncarious cervical lesions applied as recommended and after doubling the number of adhesive coats. Materials and Methods: Twenty-nine patients with at least two pairs of similar sized noncarious cervical lesions participated. One hundred sixteen restorations were placed and divided into the following groups: OS2: phosphoric acid + One Step Plus applied according to manufacturer's recommendation (2 coats of adhesive); OS4: phosphoric acid + One Step Plus (4 coats of adhesive); TY2: Tyrian SPE + One Step Plus applied according to manufacturer's recommendation (2 coats of adhesive); TY4: Tyrian SPE + One Step Plus (4 coats of adhesive). The restorations were evaluated at baseline and after 6 months according to the modified USPHS criteria. Statistical analysis was performed with Friedman repeated measures ANOVA by rank and the Wilcoxon sign-ranked test for pairwise significance (α = 0.05). Results: One hundred eight restorations were evaluated at 6 months. The retention rate of the group TY2 was statistically significantly lower than the other groups. Marginal discoloration occurred in all groups, being significantly worst in the group TY2. Conclusion: Tyrian SPE + One Step Plus applied according to manufacturer's recommendations did not meet the ADA provisional acceptance criteria for enamel-dentin bonded restorative materials. The use of four coats of the One Step Plus in the self-etching approach can improve its clinical performance. Keywords: clinical trial, resin composite, adhesives systems, etch-and-rinse adhesive, self-etching adhesive, adhesive application

Since the first resin-bonded fixed partial denture was described, this adhesive technique for splinting mobile teeth has developed into a conservative method for replacing missing teeth. Heat-pressed all-ceramic materials have been introduced for the fabrication of 3-unit fixed partial dentures in the anterior and premolar region. This clinical report describes the replacement of a conventional partial coverage metal-ceramic resin-bonded fixed partial denture with an all-ceramic resin-bonded fixed partial denture in the anterior maxillary area. Keywords: all-ceramic restorations, resin-bonded fixed partial denture