The Journal of Adhesive Dentistry, 03/2020

Purpose: To compare the clinical performance of a glass hybrid restorative system, EQUIA Forte, with that of a nanohybrid resin composite, Tetric EvoCeram, in two-surface class II cavities. Materials and Methods: This multicenter, randomized controlled clinical study was conducted at four different dental schools. In total, 360 restorations were placed in patients in need of two class-II, two-surface restorations in the molar region of the same jaw. Each patient received one glass hybrid restoration (EQUIA Forte, GC) and one resin composite restoration (Tetric EvoCeram, Ivoclar Vivadent). Two independent evaluators performed a clinical evaluation of each site after 1 week (baseline), 1 year, and 2 years using the criteria of the FDI World Dental Federation (FDI-2). Results: The estimated survival rates at the 2-year recall were 93.6% and 94.5% for EQUIA Forte and Tetric EvoCeram, respectively. There were no significant differences in the survival rates or in any of the evaluated esthetic, functional or biological properties between EQUIA Forte and Tetric EvoCeram restorations (p ˃ 0.05). Conclusion: Both the glass-hybrid restorative system and nanohybrid resin composite showed good clinical performance in moderate to large two-surface class II restorations in a 2-year follow-up. Keywords: clinical trials, resin composite, glass-hybrid system, multicenter, split-mouth

Purpose: The management of complicated crown-root fractures is challenging for endodontic restoration. The present case describes a patient who sustained trauma to the maxillary right central incisor. Materials and Methods: Clinical and radiographic examination showed a complicated crown-root fracture and incomplete root development with periapical radiolucency and inadequate endodontic treatment with overfilling. Orthograde retreatment with MTA apical closure combined with a microsurgical approach to remove of extruded material was performed. Coronal sealing was accomplished with a direct adhesive restoration and marginal relocation. Results: A 5-year follow-up showed complete healing of the periapical lesion and correct preservation of function and esthetic parameters. Conclusion: A modern minimally invasive treatment protocol allows the maximum conservation of residual dental tissues. Keywords: dental trauma, direct composite restoration, marginal relocation, permanent tooth prognosis, surgical microendodontics

Purpose: To evaluate the influence of application protocol on the shear bond strength (SBS) and nanoleakage of simplified adhesives over 18 months. Materials and Methods: 810 dentin slices were obtained from 405 caries-free human molars. They were randomly assigned to 54 experimental groups resulting from the combination of "adhesive" (Adper Scotchbond 1XT [S1XT], Solobond M [SM], Scotchbond Universal Adhesive in etch-and-rinse mode [SUER] and self-etch mode [SUSE], Adper Easy Bond [EB], Clearfil S3 Bond Plus [CS3]), "application protocol" (manufacturer's instructions [MI], two extra layers of adhesive [EL], hydrophobic resin layer [HL]), and "aging time" (24 h [24H], 6 months [6M], and 18 months [18M] in water). SBS tests were carried out using a Watanabe device followed by failure mode analysis. For the nanoleakage study, specimens from 54 additional molars were prepared as previously described, immersed in ammoniacal silver nitrate, and evaluated with SEM. SBS data were analyzed with ANOVA followed by Tukey's post-hoc tests; failure mode data were analyzed using chi-squared tests (α = 0.05). Nanoleakage data were analyzed with the Kruskal-Wallis test followed by LSD tests (α = 0.05). Results: After 18M, S1XT and SUSE achieved the highest mean SBS (p 0.05). Regarding the application protocols, EL and HL provided higher mean SBS than those obtained with MI (p 0.05). HL resulted in the highest mean SBS and the lowest mean nanoleakage after 18M. Conclusion: Simplified adhesives may need an extra hydrophobic resin layer to achieve a stable and durable adhesive interface. The self-etch approach should be recommended for the universal adhesive. Keywords: dental bonding, dentin bonding agents, material testing, self-etch, etch-and-rinse, hydrophobic, water storage, bond strength, nanoleakage

Purpose: To investigate whether dental adhesives modified with polyacrylic acid copper iodide particles could inhibit esterase activity in vitro and the copper release rate from resin matrices, as well as the correlation between the two variables. Materials and Methods: Different concentrations of copper iodide (0.1, 0.5 and 1.0 mg/ml) were incorporated into three commercially available adhesives representative of each type. Disk specimens (n = 3) were fabricated and incubated in cholesterol esterase and pseudo-cholinesterase solutions for 16 days (37°C, pH 7.0). The enzymatic activity and rate of copper release from resin matrices were evaluated at different 4, 8, 12, and 16 days with a UV/visible-light spectrophotometer. Results: Increased copper release and reduced enzymatic activity were observed with higher concentrations of copper iodide (p 0.001). Greater copper release with reduced enzymatic activity was also demonstrated at the earlier time periods with this relationship reversing over time (p 0.001). A moderate negative correlation between the variables was evident (-0.441; p = 0.01). Conclusions: Adhesives containing copper iodide can inhibit esterase activity in a dose- and time-dependent manner. The correlation between the variables suggests that enzymatic activity may depend on the availability of copper. Keywords: adhesives, copper iodide, drug delivery, esterases, resins, saliva

Purpose: To evaluate the effect of surface conditioning methods and aging on the repair bond strength between resin composite and nanoceramic CAD/CAM resin. Materials and Methods: Twenty-four blocks of nanoceramic CAD/CAM resin (NCR) (Lava Ultimate, 3M Oral Care) (10 x 5 x 2 mm3) and resin composite (Filtek Z350, 3M Oral Care) (RC) were made, embedded in acrylic resin, polished (#600, #800, #1200) and randomly divided into 8 groups (n = 12 each) according to surface conditioning methods (air abrasion with 30-μm CoJet [CJ] or air abrasion with 50-μm Al2O3 [AB]) and aging prior to repair (without aging, 24 h in water at 37°C; with aging 6 months in water at 37°C). The blocks were air abraded (20 s, 2.5 bar, 10 mm) using a standardized device. A layer of adhesive resin (Scotchbond Universal) was applied (20 s) and photopolymerized for 20 s. RC cylinders (Ø = 2 mm; h = 2 mm) were then bonded to the NCR substrates using a Teflon matrix and photopolymerized for 40 s. All specimens were thermocycled (10,000 cycles, 5°C-55°C) and submitted to the shear bond test (50 kgf, 0.5 mm/min) to measure repair strength. Data (MPa) were analyzed using 3-way ANOVA and Tukey's test (α = 0.05). Failure analysis was performed using stereomicroscopy (20X). Results: ANOVA revealed a significant effect of only the "material" factor (p = 0.00). The group NCR6mCJ presented bond strengths (29.37 ± 5.41) which were significantly higher than those of the NCR24hCJ (20.88 ± 5.74) and RC groups (p 0.05). The group RC24hCJ (19.71 ± 4.21) presented the lowest shear bond strength (p 0.05). Failure analysis revealed predominantly type B mixed failures (adhesive+cohesive in the substrate material) except for the groups NCR24hCJ and NCR6mAB, where mainly type C failure (adhesive+cohesive at the RC) was observed. Conclusion: Air abrasion with Al2O3 particles or silicatization with CoJet followed by adhesive resin application are effective surface conditioning methods for the repair of nanoceramic CAD/CAM resin with resin composite. Keywords: adhesion, nanoceramic resin, repair, resin composite, shear bond strength, surface conditioning

Purpose: To investigate the long-term effect of 0.05% or 0.1% caffeic acid phenethyl ester (CAPE) on dentin matrix stability and hybrid layer stability, using an etch-and-rinse (Adper Scotchbond Multipurpose/ASB) or a self-etch adhesive (Clearfil SE Bond/CSE). Materials and Methods: Dentin matrix specimens were assigned to five groups: 0.05% or 0.1% CAPE, green tea (GT), and the controls distilled water (DW) and dimethyl sulfoxide (DMSO). Following immersion of specimens for 1 h, modulus of elasticity (ME) and dentin mass change (MG) were determined at 3 post-treatment time points: immediately afterwards and at 3 and 6 months. Collagen solubilization (CS) was estimated by hydroxyproline (HYP) quantification. Resin-dentin interfaces with both adhesives were assessed with in situ zymography tests to evaluate gelatinolytic activity (GA). The dentin pretreatments were actively applied for 60 s. The sealing ability of aged resin-bonded slices was assessed by nanoleakage tests. Results: GT increased immediate ME, which decreased significantly after 3 months (p 0.0001). The CAPE groups did not differ from the control groups. GT provided a significant increase in dentin matrix mass after treatment (p 0.0001). No significant differences regarding MG were observed for CAPE 0.1%, CAPE 0.05%, DW, and DMSO groups after 3 and 6 months. Cumulative HYP release revealed that CAPE groups and GT were statistically similar to DW and DMSO; the GT group exhibited statistically significantly less HYP release than did CAPE groups (p = 0.0073). Treatment with 0.05% or 0.1% CAPE presented lower GA when applied to ASB before acid conditioning (p 0.05), but no differences were detected when the CAPE groups were applied to CSE. CAPE at 0.1% significantly reduced nanoleakage for CSE, and 0.05% CAPE with CSE presented levels of nanoleakage similar to those of the CSE control group. Conclusion: CAPE at 0.05% or 0.01% did not influence ME, MG, or CS, but reduced GA when applied to ASB before acid conditioning. CAPE at 0.1% with CSE promoted adhesive layer integrity. Keywords: adhesive, metalloproteinases, elastic modulus, hydroxyproline, zymography, nanoleakage

Purpose: To evaluate the remineralization effects of Bioglass 45S5 (BAG) on dentin composition, adhesive-dentin bond strength, as well as interface and diffusion zone thickness. Materials and Methods: Dentin specimens were assigned to a control group (CG), in which the adhesive was applied following the manufacturer's instructions, and a remineralized group (RG), in which remineralization treatment was carried out by rubbing a remineralization solution (0.015 g of BAG with 1.35 ml of distilled water) on the etched dentin surface for 30 s before applying the adhesive. For bioactive analysis (n = 10), control and remineralized dentin were investigated using micro-Raman spectroscopy (mRS) and scanning electron microscopy (SEM). Stick specimens prepared with a three-step etch-and-rinse adhesive were submitted to a microtensile bond strength (µTBS) test (n = 10) after 24 h (24 h) and eight months (8 m). Micro-RS 3D-maps (n = 10) characterized the adhesive-dentin interface composition and diffusion zone thickness, and SEM images (n = 10) evaluated interface thickness. Data were analyzed using Student's t-test or two-way ANOVA and Tukey-Kramer's post-hoc test (α = 0.05). Results: Remineralization treatment increased the mineral content of dentin. Mean µTBSs were statistically different at 24 h, with RG higher than CG; however, this difference was not significant at 8 m. When the adhesive was applied on remineralized dentin, its penetration was reduced, its physical interaction with phosphate was improved, and its degree of conversion increased. The diffusion zone in the CG did not differ from that of the RG, and interface thickness values of the CG did not differ from that of the RG. Conclusion: Remineralization treatment promoted mineral growth on the dentin surface, improved the interaction of dentin with adhesive monomers, and consequently resulted in higher immediate bond strengths. Keywords: adhesive-dentin interface, bioglass, bond strength, dentin remineralization, etch-and-rinse adhesives, Raman spectroscopy

Purpose: To evaluate the effects of double application of resin cement primers to dentin prepared with different diamond burs on the cement-dentin bond strengths. Materials and Methods: Sixty flat dentin surfaces were prepared and divided into 12 groups (n = 5) according to three experimental factors: 1. resin cements: RelyX Ultimate (RU), Multilink Automix (ML), and Panavia V5 (PV); 2. resin cement primer application: single or double; 3. dentin surface preparation with regular or superfine diamond burs. Cement-dentin sticks (1 mm2) were prepared for and underwent microtensile bond strength testing (µTBS). Statistical analysis was performed using three-way ANOVA and Duncan's test (α = 0.05). Fractured surfaces and cement-dentin interfaces were observed using SEM. Additional teeth were used to observe the demineralization effect of resin cement primers with SEM and transmission electron microscopy (TEM). Results: All tested factors demonstrated significant effects on µTBS (p 0.001). The combination of PV with superfine-grit bur and double application yielded the highest bond strengths. Surfaces prepared with superfine-grit burs demonstrated higher µTBS than did the regular-grit group, but a significant effect was not observed for all groups. The double application of primer significantly increased the bond strength for most combinations, except for PV with superfine-grit bur-prepared dentin. Conclusions: PV showed higher bond strengths than other resin cements. Double application of primer improved the bond strength of all cements to dentin. Bond strengths were higher when dentin was prepared with a superfine-grit bur. Keywords: adhesion to dentin, adhesive cementation, microtensile bond strength, resin cements, smear layer, transmission electron microscopy

Purpose: To investigate the effects of root-canal dentin pretreatment with the crosslinker EDC combined with chitosan nanoparticles (Csnp) on the bonding quality of fiber posts in root canals in terms of bond strength, nanoleakage, quantification of collagen degradation, and degree of conversion (DC) of adhesive. Materials and Methods: Forty-eight single-rooted teeth were prepared endodontically and etched using UNI-ETCH (Bisco) as per the adhesive procedure for fiber posts. They were randomly divided into three groups before adhesive (All-Bond 3) application, according to different pretreatments: a. immersed in 2.5% glutaraldehyde for 24 h; b. treated with Csnp solution under ultrasonic agitation for 60 s and immersed in EDC crosslinker for 24 h; c. without treatment (control). Bond strength, nanoleakage, DC within the interface, and collagen fiber degradation were evaluated. Results: The pretreatments had a significant influence on the bonding stability of fiber posts in root canals, but not on the degree of conversion (p = 0.552). Enzymatic degradation significantly influenced bond strength for all groups (p = 0.001), with the greatest effect found in group c. The amount of amino acids released from the adhesive interface differed significantly between groups after hydrolysis and enzymatic degradation (p = 0.000); group c released the highest amount of amino acids. Conclusions: Csnp binding to dentin in combination with EDC reduced degradation of dentinal collagen and improved the stability of the adhesive interface without jeopardizing adhesive polymerization. Keywords: fiber post, root canal, adhesive, bond strength