The Journal of Adhesive Dentistry, 05/2009

Purpose: The aim of this study was to evaluate the effect of different cavity disinfectants on dentin bond strengths ofcomposite resin applied with two different adhesive systems. Materials and Methods: One hundred mandibular third molars were sectioned parallel to the occlusal surface to expose midcoronal dentin. The dentin surfaces were polished with waterproof-polishing papers. The specimens were randomly divided into 5 groups of 20 each. In group 1, the specimens were not treated with any cavity disinfectants and served as control. From groups 2 to 5, dentin surfaces were treated with the following cavity disinfectants, respectively; 2% chlorhexidine solution, 2.5% NaOCl, 1% chlorhexidine gel, 3% H2O2. The specimens were then randomly divided into 2 subgroups including ten teeth each to evaluate the effect of different bonding systems. Dentin bonding systems were applied to the dentin surfaces and the composite buildups were created. After the specimens were stored in an incubator for 24 h, the shear bond strength was measured at a crosshead speed of 1 mm/min. The bond strength data were analyzed with one way analysis of variance and Tukey-HSD tests. Results: There was no significant difference between chlorhexidine gel and control groups regardless of the type of the bonding agent (p > 0.05). On the other hand, pretreatment with NaOCl, H2O2 or chlorhexidine solutions had a negative effect on the shear bond strength of self-etching bonding systems. Conclusion: The findings of this study suggest that when NaOCl, H2O2 or chlorhexidine solution are used as a cavity disinfectant, an etch-and-rinse bonding system should be preferred. Keywords: bond strength, adhesive, composite resin, cavity disinfection, CHX gel

Purpose: To evaluate the dentin bonding durability of two one-step self-etching adhesive systems with and without the presence of surrounding enamel. Materials and Methods: Tri-S Bond (Kuraray) and G-Bond (GC), commercially available adhesive systems, were used in this study. The occlusal enamel was removed in order to form a flat, midcoronal dentin surface. The adhesives were applied to both the dentin and the surrounding enamel surfaces according to the manufacturers' instructions. Resin composite crowns (Clearfil AP-X, Kuraray) were incrementally built up with each layer being photocured for 40 s. Half the bonded teeth were sectioned perpendicular to the adhesive interface into 0.7-mm-thick slabs, and then trimmed to an hourglass shape with a 1 mm2 cross-sectional area for microtensile bond strength testing, followed by storage in water for 6 months (direct water exposure group, DE). The other half were left untrimmed and stored in water for 6 months (indirect water exposure group, IE). As control groups, additional bonded teeth were prepared for water storage for 24 h. After the designated periods of water storage, the specimens were subjected to bond strength testing at a crosshead speed of 1.0 mm/min. The µTBS data were statistically analyzed using three-way ANOVA and post-hoc tests (t-test and Tukey's HSD comparison tests) (α = 0.05). Results: Indirect water exposure of the resin/dentin interface did not affect the µTBS of either adhesive after 6 months water storage (p 0.05). However, direct exposure to water significantly reduced the µTBS of both adhesives to dentin (p 0.05). In addition, there were no significant differences in µTBS between the two adhesive systems for each experimental storage condition (p > 0.05). Conclusion: The durability of resin-dentin bonds was found to be dependent on the method in which the bonded specimens were aged in water. Significantly lower bond strengths were observed for specimens that were sectioned into an hourglass shape before aging compared to those that were sectioned after water storage. Keywords: surrounding enamel, durability of dentin bond, one-step self-etching adhesives, microtensile bond strength

Purpose: To investigate the influence of different x-ray radiation doses on the bond strength of adhesive restorations to dentin using different bonding strategies. Materials and Methods: Flat dentin surfaces on human molars were obtained and cylinder-shaped specimens for the microshear bond test were built up with a composite (Z250, 3M ESPE), using three adhesive systems: a two-step etch-and-rinse (Single Bond 2 - SB2, 3M ESPE), a two-step self-etching (Clearfil SE Bond - CSE, Kuraray), or a singlestep self-etching (Adper Prompt - ADP, 3M ESPE). The specimens were assigned to 4 groups (n = 10), according to the x-ray dose: 0 (control), 5, 35, or 70 Gy. Radiation was directed to the surface of the resin cylinders. Microshear testing was conducted after 24 h, and the failure modes classified under magnification (200X). Data were submitted to two-way ANOVA and Holm-Sidak's test (p = 0.05). A nonlinear regression analysis was carried out with bond strength as dependent variable. Results: Bond strength results were dose and material dependent. SB2: control > 5 = 35 > 70; CSE: control = 5 > 35 = 70; ADP: control = 5 = 35 = 70. Generally, SB2 > CSE > ADP. The nonlinear regression plots showed that in general, an increase in radiation dose may predict a decrease in bond strength (R2 >= 0.905). Failure modes were dependent on the bonding system, generally with no significant influence of radiation. Conclusion: X-ray radiation might present a dose-dependent detrimental effect on the bond strength of resin composite restorations to dentin. Keywords: adhesive systems, shear bond strength, dentin, radiation, radiotherapy, x-ray

Purpose: To evaluate the effects of Er:YAG laser ablation on the microtensile bond strength and the nanoleakage of Er:YAG-lased dentin bonded to a self-etching adhesive system with and without pulpal pressure. Materials and Methods: Twenty flat dentin surfaces were obtained from extracted molars. Ten specimens were irradiated by Er:YAG laser, other specimens (control group) were ground using #600 SiC paper. Direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cementoenamel junction and parallel to the occlusal surface. The experimental groups were exposed to a simulated pulpal pressure of 15 cm H2O. Each specimen was restored using an adhesive and a photocured composite. The specimens were then sectioned vertically to obtain dentin/adhesive slabs. Ninety-six slabs were prepared for microtensile bond testing. Sixty-four slabs were immersed in ammoniacal silver nitrate tracer solution for 18 h, then rinsed thoroughly, and immersed in photodeveloping solution for 6 h prior to their examination by FE-SEM. Results: The method of dentin preparation and the pulpal pressure storage condition significantly affected the µTBS, while the storage duration did not (p 0.05). The nanoleakage patterns observed in the dentin/bond interface differed depending on whether the dentin was conventionally prepared or ablated by Er:YAG laser. Conclusion: Er:YAG laser ablation to dentin adversely affected the µTBS and the sealing ability of SE Bond bonded to dentin under simulated pulpal condition. Keywords: Er:YAG Laser, simulated pulpal pressure, microtensile bond strength, nanoleakage, resin-dentin interface

Purpose: To investigate the effect of high frequency ultrasonic agitation on the microtensile bond strengths of different self-etching adhesives. Materials and Methods: Thirty-six human molars were wet ground occlusally until dentin was exposed. The one-step self-etching adhesives Clearfil S3 Bond, G-Bond, and Futurabond NR were tested in this study. In the control groups, bonding procedures were performed according to the manufacturers' instructions. In the experimental groups, bonding materials were applied with a 1 MHz therapeutic ultrasonic device on the dentin surfaces. The composite crown was built up incrementally to a height of 5 mm. Each tooth was serially sectioned into rectangular beams, and the specimens were subjected to microtensile testing. Failure modes were observed under a stereomicroscope and classified. Randomly selected specimens from each group were observed with SEM. Results: Two-factor ANOVA indicated that both the adhesive system and the ultrasonic agitation effect influenced bond strength (p 0.05). The bond strength of G-Bond adhesive to dentin was higher after ultrasonic agitation (p 0.05), whereas ultrasonic agitation of Futurabond and S3 Bond did not affect bond strength values (p > 0.05). Failure after the test was commonly due to adhesive failure in the dentin. Conclusion: High-frequency ultrasonic agitation of self-etching adhesives during their application may enhance their bonding performance. Keywords: composite resin, dentin, ultrasonic, dentin bonding agents, self-etching, single-step adhesives

Purpose: To evaluate the interfacial microtensile bond strength between a fiber-reinforced post (Rely X Post) and a core material (Multicore Flow) after placing different bonding agents. Materials and Methods: After post surface treatment, 50 posts were divided into 5 groups. Group 1: Adper Prompt-LPop; group 2: SingleBond2; group 3: ScotchBond Multipurpose Plus; group 4: experimental bonding system (wet ethanol bonding technique); group 5: control group. After core reconstruction, the samples were tested with the microtensile test. Fracture type examination and SEM observation followed. Data were statistically analyzed with Kruskall-Wallis non-parametric ANOVA. Results: Microtensile testing revealed significant differences (p 0.001). There were no differences between groups 1 to 4, but there was a statistically significant difference between groups 1 to 4 and the control. Fracture type observations revealed more adhesive failures than cohesive or mixed ones. Conclusion: The experimental bonding technique did not improve bond strength compared to the different adhesive systems tested. However, placing a bonding agent beween the post and the core seems to significantly increase microtensile bond strength. Keywords: adhesion, fiber post, wet-ethanol bonding, interface

Purpose: The objectives of this study were to compare the bond strength of a stainless steel orthodontic wire vs various fiber-reinforced composites (FRC) used as orthodontic retainers on enamel, analyze the failure types after debonding, and investigate the influence of different application procedures of stainless steel wires on bond strength. Materials and Methods: Caries-free, intact human mandibular incisors (N = 80, n = 10 per group) were selected and randomly distributed into 8 groups. After etching with 37% H3PO4 for 30 s, rinsing and drying, bonding agent (Stick Resin) was applied and light polymerized. Then one of the following FRC materials was applied on the flowable composite (Stick Flow) using standard molds: group 1: Angelus Fibrex Ribbon; group 2: DentaPreg Splint; group 3: ever- Stick Ortho; group 4: Ribbond. In group 5, Quad Cat Wire was applied in the same manner as in FRC groups. In group 6, after applying bonding agent (Stick Resin), Quad Cat Wire was placed directly on the tooth surface and covered with Stick Flow composite. In group 7, after bonding agent (Heliobond) was applied, Quad Cat Wire was placed directly on the tooth surface and covered with Tetric Flow composite. In group 8, after applying bonding agent (Heliobond) and polymerization, Tetric Flow composite was applied, not polymerized, and Quad Cat Wire was placed and covered with Tetric Flow again. Specimens were thermocycled for 6000 cycles between 5°C and 55°C and loaded in a universal testing machine under shear stress (crosshead speed: 1 mm/min) until debonding occurred. The failure sites were examined under an optical light microscope. Data were analyzed using one-way ANOVA and the Tukey-Kramer adjustment test (α = 0.05). Results: Significant differences were found between the groups (p = 0.0011) (ANOVA). Bond strength results did not significantly differ either between the FRC groups (groups 1 to 4) (6.1 ± 2.5 to 8.4 ± 3.7 MPa) (p > 0.05) or the wire groups (groups 5 to 8) (10.6 ± 3.8 to 14 ± 6.7 MPa) (p > 0.05). Failure types varied within the FRC groups, but mainly composite was found left adhered on the enamel surface at varying degrees. In the stainless steel wire groups, when the retainer was applied onto the bonding agent and then covered with flowable resin, partially attached composite on the enamel was often found after debonding. When the wires were embedded in the flowable composite, the Heliobond group (group 8) showed more adhesive failures between the enamel and the composite compared to group 5, where the bonding agent was Stick Resin. Conclusion: Regardless of their application mode, stainless steel orthodontic bonded retainers delivered higher bond strengths than those of fiber retainers. The differences were statistically significant compared to those of Angelus Fibrex Ribbon and DentaPreg Splint. Keywords: bond strength, fiber-reinforced composite, lingual retainer, orthodontics, relapse, stainless steel wire

Purpose: This study evaluated the fracture strength and failure types of indirect resin-based composite laminates bonded to teeth with aged Class III composite restorations that were conditioned according to various protocols. Materials and Methods: Maxillary central incisors (N = 60) with window-type preparations received laminates made of a highly-filled resin composite material (Estenia) (10 per group).On the mesial and distal side, Class III cavities (3 x 3 mm) were prepared using ultrasonic burs and filled with resin composite (Quadrant Anterior Shine). The unrestored teeth served as a control group (group 6). All restored teeth (n=50) were thermocycled (5°C to 55°C, 6000X) and subjected to one of the conditioning protocols: (1) air-particle abrasion with alumina particles coated with silica (30-µm SiO2, CoJet)+silanization, (2) air-particle abrasion with alumina particles (50 µm, Al2O3)+silanization, (3) 9.5% hydrofluoric acid (HF) for 90 s (Ultradent)+silanization and (4) protocol of Clearfil Repair Kit, (5) adhesive resin (Quadrant Unibond Sealer). A three-step bonding procedure and dual-polymerizing resin cement (Panavia F 2.0) were employed. The inner surfaces of the laminates were conditioned (CoJet-Sand, 30 µm SiO2) and silanized (ESPE-Sil). All specimens were stored in water at 37°C for one month prior to the fracture test. Results: A significant difference was observed in fracture strength values between the groups (ANOVA, p = 0.0261). The only significant difference was between group 2 (299 ± 103 N) and group 3 (471 ± 126 N) (p = 0.0239) (Tukey's test, α = 0.05). The majority of failures were type C (35/60) (chipping of the laminate with enamel exposure), followed by type B (21/60) (cohesive failure within the composite laminate). Conclusion: The fracture strengths of the laminates tested did not show significant differences, whether they were bonded to existing, aged Class III composite restorations or to intact teeth. The failure types, however, varied between the groups. The lowest strengths were obtained from the air-particle abraded (50 µm, Al2O3) and silanized group. Keywords: indirect composite, fracture strength, laminates, surface conditioning

Purpose: The aim of this prospective study was to evaluate the clinical performance of the restorative material Ceram.X in combination with an experimental one-bottle etch-and-rinse adhesive (K-0127). Materials and Methods: A single operator placed two Class I or II restorations in molars of 43 patients. One molar was restored with Ceram.X/K-0127 (Dentsply DeTrey), the other one with Tetric Ceram/Syntac Classic (Ivoclar Vivadent). At baseline, after one, two, and four years the restorations were evaluated by a second dentist using modified Ryge's criteria. After four years, 27 patients were examined. Results: In one patient, both restorations (Class II) had to be removed for root canal treatment due to pulpitis. Another Class II Ceram.X restoration (3.8%; 4.3% [1 of 23] of Class II restorations) showed score C with regard to wear/anatomical form. Thus, the cumulative failure rate was 7.4% in the Ceram.X group (8.3% of Class II restorations [2 of 24]) and 3.7% in the Tetric Ceram group (4.2% of Class II restorations [1 of 24]). Furthermore, three restorations (11.5%) in each group showed score B for anatomical form and marginal integrity. Slight marginal discoloration (score B) was found at five Ceram.X restorations (19.2%) and four Tetric Ceram restorations (15.4%). Two restorations (7.7%) in each group showed slight changes in color stability (score B). No sensitivity, recurrent caries, or changes in surface texture were recorded after four years. No statistically significant differences were found between the two restorative materials (p > 0.05). Conclusion: After four years of clinical service, 92.6% of Ceram.X/K-0127 and 96.3% of Tetric Ceram/Syntac Classic restorations performed clinically well. Keywords: adhesive, ceramic, clinical trial, posterior restorations, resin composite

Purpose: The aim of this clinical study was to observe the service duration of porcelain laminate veneers (PLVs) and to estimate the influence of the categorical covariates such as location, tooth vitality, preparation depth, incisal, gingival and proximal finishing lines, and peripheral tissue type on the survival rates of event-free and overall service duration. Materials and Methods: A total of forty patients (26 women, 14 men; age range: 16 to 50) who had received 200 PLVs were evaluated in this study. Median follow-up time was 67.25 weeks with a range of 12 to 72 weeks. Fifteen of the restored teeth were nonvital, while the remaining 185 were vital. Categorical covariates related to the restoration design (localization, vitality, preparation depth, incisal, proximal, and gingival finishings, and surrounding tissue type) were recorded in order to estimate their influence on the survival rates. Survival rates of the event-free and overall service duration were calculated with the Kaplan-Meier analysis and Mantel log rank test. Results: Twelve failures were observed. The most frequent failure type (11 units) was debonding of the restoration from the abutment tooth. Nine of them were rebonded and the remaining 2 were remade with a different preparation design. The last failure was observed as a coronal fracture at the cervical level. The overall survival rates were 99.5%, 99%, 97.5%, 94.9%, 94.4% and 93.8% at weeks 8, 9, 11, 15, 16, and 34, respectively, with a mean estimate of 68.45 weeks. Conclusion: PLVs exhibited good clinical results with their conservative specifications and high survival rates. The preparation and design specifications affect the service duration of PLVs. Keywords: porcelain laminate veneers, survival rate, laminate preparation design