Influence of etching procedures on surface wettability

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Self-adhesive pit and fissure sealant modified with metallic monomers

Physicochemical properties of dental adhesives doped with zinc compounds

E. Piva 1,∗ , A.R. Cocco 1 , C.E.C. Suarez 1 , Wlo Da Rosa 1 , F.S. Rondan 2 , A.F. Silva 1 , M.F. Mesko 2 , R.G. Lund 1

C. Pomacóndor-Hernández 1,∗ , A. Catelan 2 , V.P. Feitosa 3 , S. Consani 4 1

1

School of Dentistry, Federal University of Pelotas, Pelotas, Brazil 2 Center of Chemical, Pharmaceutical and Food Sciences, Federal University of Pelotas, Capão Do Leão, Brazil

2

Purpose/aim: The aim of this study is to evaluate the effect of incorporation of zinc methacrylate and di-nbutyldimethacrylate-tin on an experimental self-adhesive light-curable pit and fissure sealant. Materials and methods: The zinc (Zn) and tin (Sn) containing methacrylates were incorporated at 2.5 or 5 (wt%) in experimental self-adhesive resin-based sealants. The pit and fissure sealants were formulated with the inclusion of acid monomer in a monomer blend with nanometric silica. A composition without the incorporation of metal-based monomers was tested as a control (C). Five groups were tested; Control, Sn 2.5%, Sn 5%, Zn 2.5%, Zn 5%. The degree of conversion, microshear bond strength, translucency parameter, flexural strength, elastic modulus, cytotoxicity assay using Mouse fibroblasts of the L929 immortalized cell line, and Sn leached in water was obtained after 24 h, 7 and 14 days was determined by inductively coupled plasma mass spectrometry (ICP-MS). The statistical analysis was performed using one-Way ANOVA and Tukey’s post hoc method (p < 0.05). Results: The experimental groups showed means for shear bond strength, Translucency parameter, degree of conversion, flexural strength, Young’s modulus and depth of cure were similar to control (10.6 [±2.8] MPa, 70.2 [±4.5], 50.24 [±8.7]%, 1.4 [±0.2] GPa and 5.6 [±0.14] mm respectively). The Sn leached was detected in statistically higher levels after 7 (6.8 ± 3.9 ␮g) and 14 d (9.7 ± 4.9 ␮g) when compared to 24 h (0.36 ± 0.26 ␮g). Conclusions: According to present findings, the experimental formulation of pit and fissure sealant showed suitable immediate bond strength to enamel as a requirement to be used in the self-adhesive technique. Moreover, the incorporation of amounts of 2.5 and 5% of metallic methacrylate (Sn or Zn) in experimental self-adhesive pit and fissure sealant did not impair the mechanical properties of the sealants.

Purpose/aim: To evaluate the influence of addition of different concentrations of zinc chloride (ZnCl2 ) and zinc oxide (ZnO) on the degree of conversion (DC), flexural strength (FS) and modulus of elasticity (ME) of dental adhesives. Materials and methods: Two etch-and-rinse dental adhesives [Adper Single Bond 2 (SB) and Ambar (AM)] were zinc-doped by mixing them with 5, 10, or 20 wt% of ZnO powder, or with 1, 2, or 4 wt% ZnCl2 . The DC of the resulting blends was measured using FT-IR spectroscopy (n = 5), whereas FS and ME were determined by three-point bending test of bar-shaped specimens (n = 10). Data were subjected to one-way ANOVA and Student–Newman–Keuls post hoc test (˛ = 0.05). Results: For both SB-blends and AM-blends, the higher the concentration of ZnCl2 the lower the DC and flexural properties, except for 4% ZnCl2 -doped AM-blend that presented FS similar than AM-control, and ME statistically higher than AMcontrol. Different concentrations of ZnO had no effect or very slight reduction of DC in AM-blends and SB-blends, respectively. When 5% and 10% ZnO were incorporated into SB, it was observed higher FS and ME values than SB-control and 20% ZnO-doped SB-blend. For AM-blends, there was reduction of flexural properties with the addition of 10 and 20% ZnO, whereas 5% ZnO-doped AM-blend presented similar FS and ME than AM-control. Conclusions: Some physicochemical properties were jeopardized when doping simplified dental adhesives with ZnCl2 . Incorporation of 5% ZnO into SB and AM did not negatively affect DC, FS, and ME.

https://doi.org/10.1016/j.dental.2018.08.192

John Paul II Private University, Lima, Peru University of Western Sao Paulo, Presidente Prudente, Brazil 3 Paulo Picanc¸o School of Dentistry, Fortaleza, Brazil 4 University of Campinas, Piracicaba, Brazil

https://doi.org/10.1016/j.dental.2018.08.193 193 Influence of etching procedures on surface wettability of CAD/CAM materials T.S. Porto 1,∗ , F.A.P. Rizzante 1 , I.G.M. Silva 1 , R.C. Roperto 1 , S.T. Porto-Neto 2 , E.A. Campos 2 , F.F. Faddoul 1 , S.T. Teich 1 1 2

Case Western Reserve University, USA Sao Paulo State University, Brazil

Purpose/aim: The aim of this study is to analyze the surface wettability caused by etching procedures on ceramic and polymer-based CAD/CAM materials. Materials and methods: The CAD/CAM ceramic Vitablocs Mark II (VM) (Vita Zahnfabrik) was chosen as control group and

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Table 1 – Contact angle among the conditions tested for each material within this study. Treatment

Material VM

CT HF30 HF90 SB SB30 SB90

LU a

46.60 (±2.94) 36.17 (±1.97)b 36.19 (±4.86)b 43.96 (±4.70)a 36.51 (±2.79)b 37.53 (±4.20)b

VE a

59.08 (±4.07) 67.66 (±5.13)b 71.69 (±4.32)b 84.58 (±6.24)c 61.57 (±4.67)a 40.43 (±5.48)d

a

55.88 (±1.93) 38.53 (±3.43)b 33.91 (±1.88)bc 72.32 (±5.33)d 32.89 (±1.88)c 31.37 (±3.17)c

Same letters (columns) no statistically significant difference was found among the conditions (p < 0.05).

compared against two other polymer-based CAD/CAM materials; Lava Ultimate (LU) (3M ESPE) and Vita Enamic (VE) (Vita Zahnfabrik). Forty-eight specimens for each material (n = 8) were prepared with the dimensions of 3 mm × 2.5 mm × 7 mm (width × height × thickness). Each material had 6 different surface treatment as follows: (CT) control – polished surface; (HF30) hydrofluoric acid 9.6% for 30 s; (HF90) hydrofluoric acid 9.6% for 90 s; (SB) sandblaster with aluminum oxide for 10 s (50 ␮m – 2 bar pressure); (SB30) sandblaster aluminum oxide for 10 s followed by hydrofluoric acid 9.6% for 30 s; (SB90) sandblaster aluminum oxide for 10 s followed by hydrofluoric acid 9.6% for 90 s. The contact angle (wettability test) was assessed on the treated surfaces; subsequently scanning electron microscopy (SEM) was utilized to identify the superficial alterations in relation to the data acquired. Results: Means considering materials and conditions tested were below 90◦ (Table 1). VM was the most hydrophilic material followed by VE and LU. The VM CT (46.60 ± 2.94) did not present statistically significant difference from the SB (43.96 ± 4.70) (p < 0.05). Within the conditions where the hydrofluoric acid was applied on the surface of the VM they were not significantly different (p < 0.05). The LU CT (59.08 ± 4.07) was not significantly different from the SB30 (61.57 ± 4.67), likewise LU HF30 (67.66 ± 5.13) was not significantly different from the HF90 (71.69 ± 4.32). The VE CT (55.88 ± 1.93) showed statistically significant difference from all the other treated surfaces. The VE HF30 (38.53 ± 3.43) did not show significant difference from HF90 (33.91 ± 1.88), in addition HF90 was not significantly different from SB30 (32.89 ± 1.88) and SB90 (31.37 ± 3.17). Although morphological surface characterization through SEM showed different etching patterns for each one of the surface treatments applied the CAD/CAM materials showed similarities in the etching pattern within these treated surfaces. Conclusions: All the materials tested presented hydrophilicity to the wettability test. The surface treatments applied to the CAD/CAM materials in this study were sufficient to enhance the surface wettability. However, some of the surface treatments applied will increase the contact angle decreasing the surface wettability when compared to a polish surface. https://doi.org/10.1016/j.dental.2018.08.194

194 Cyclic load-to-failure of hydrofluoric acid etched lithium disilicate restorations C. Prochnow 1,∗ , A.B. Venturini 1 , L.F. Guilardi 1 , M.P. Rippe 1 , C.J. Kleverlaan 2 , M.C. Bottino 3 , G.K.R. Pereira 4 , L.F. Valandro 1 1

Federal University of Santa Maria, Brazil University of Amsterdam and Vu University Amsterdam, Netherlands 3 University of Michigan School of Dentistry, USA 4 Meridional Faculty, Brazil 2

Purpose/aim: To investigate the effect of etching with distinct hydrofluoric acid (HF) concentrations on the cyclic load-to-failure (CLF) of machined and simplified lithium disilicate restorations (e.Max CAD, Ivoclar Vivadent) adhesively cemented to a dentin analogue material. Besides, the present study aimed to compare machined crowns vs. simplified bilayer assemblies. Materials and methods: Pairs of dentin analogue prosthetic preparations and lithium disilicate ceramic crowns with simplified geometry were machined as well as pairs of dentin analogue discs (G10; Ø = 10 mm; thickness = 2.0 mm) and lithium disilicate discs (Ø = 10 mm; thickness = 1.5 mm) were produced. For luting, the dentin analogue preparations/discs were etched (10% HF for 60 s) and received a primer coating. The inner surface of the ceramic crowns/discs was treated as follows: non-etched/control (CTRL), or etched for 20 s with HF acid at 3% (HF3), 5% (HF5), or 10% (HF10). A silane coating was then applied onto the treated ceramic surfaces. Fatigue tests followed the staircase approach (initial load = 720 N; step-size = 70 N; 500,000 cycles per sample; 20 Hz) using a hemispheric stainless-steel piston (Ø = 40 mm) under water. The CLF data were analyzed using the Dixon and Mood method. Topographic and fractographic analyses were also conducted. Results: For the machined crowns, all groups showed similar CLF (in N) (CTRL = 805.00 ± 91.23; HF3 = 781.25 ± 29.87; HF5 = 755.00 ± 154.49; HF10 = 833.75 ± 100.74); meanwhile for the cemented discs HF3 (1355.00 ± 32.00) and HF5 (1335.00 ± 58.80) groups (Table 1) were the highest and statistically similar; HF10 presented an intermediate CLF (1175.00 ± 132.90), while the non-etched/CTRL group had the lowest one (965.00 ± 145.00). The topographical analyses of the machined crowns depicted a quite similar surface for all groups, being preponderant the pattern established by CAD/CAM machining; for the discs, the higher the HF acid concentration, the more pronounced the topographical changes. For all groups, all the failures (radial cracks) started from the inner surface of the cemented assemblies. Conclusions: When considering a simplified assembly on cemented discs without the topography introduced by CAD/CAM milling, the importance of surface treatment for enhanced performance is depictable, and intermediary acid concentrations (3 and 5%) led to the best performance. Although, when considering a complex scenario (machined and cemented crowns) the machined topography proved to be