Hydrophobic coating of dental PMMA

Camila Gonçalves Duarte, Marina da Rosa Kaizer, Lisia Lorea Valente, Giana da Silveira Lima, Rafael R. Moraes

Introduction: The purpose of the present study was to prepare and apply antiadherent, hydrophobic coatings on dental poly(methylmethacrylate) (PMMA). Methods: Microwave thermal-polymerized PMMA disc-shaped specimens were prepared (10 mm diameter × 2 mm thickness). Two hydrophobic solutions were used for the coatings: HS1 = 2.5 vol% hexadecyl-triethoxy-silane diluted in ethanol, and HS2 = 2.5 vol% perfluorodecyl-triethoxy-silane diluted in dimethyl sulfoxide. The PMMA discs were assigned into three groups, according to the surface treatment: control (C, no coating), HS1 and HS2 coatings. All groups were also subdivided into sandblasted groups (SB) and non-sandblasted groups (NSB). An additional subgroup was used as reference, in which the sandblasted specimens were coated with a conventional silane solution (2.5 vol% methacryloxypropyl-trimethoxy-silane diluted in dimethyl sulfoxide). Each subgroup (n=5) was subjected to water contact angle ( , in degrees) and surface roughness (Ra, in μm) analyses. Contact angle data were statistically analyzed using two-way Analysis of Variance (ANOVA) and SNK’s test (coating × treatment). Sandblasted groups (control, HS1, HS2, KEYWORDS: Hydrophobic and hydrophilic interactions. Polymethyl methacrylate. Surface properties. DOI: https://doi.org/10.14436/2447-911x.15.2.148-157.oar 1. Universidade Federal de Pelotas, Programa de Pós-graduação em Odontologia (Pelotas/RS, Brazil). 2. New York University, College of Dentistry, Department of Biomaterials (New York/NY, USA). and conventional silane) were subjected to one-way ANOVA and SNK’s test. Roughness data before and after sandblasting were compared using paired t-tests ( = 0.05). Results: Means (standard deviations) for were: C-SB = 88.7 ± 9.3o; C-NSB = 61.1 ± 5.2o; HS1-SB = 114.7 ± 3.3o; HS1-NSB = 95.2 ± 6.8o; HS2-SB = 106.9 ± 2.6o; HS2-NSB = 106.4 ± 4.2o; SS-SB = 89.4 ± 4.3o. Sandblasted specimens presented higher than non-sandblasted specimens (p < 0.001). Roughness analyses showed Ra_before = 0.80 ± 0.04 m and Ra_after = 1.78 ± 0.11 m. The effect of surface treatment (sandblasting or not) was dependent of the coating solution (p < 0.001). Conclusion: The hydrophobic coatings determined increased with water. The surface treatments tested, associating sandblasting and the hydrophobic solutions, had a synergistic effect on the increase of water contact angle, suggesting a surface with poorer wettability.

Keywords: Hydrophobic and hydrophilic interactions. Polymethyl methacrylate. Surface properties.

How to cite: Duarte CG, Kaizer MR, Valente LL, Lima GS, Moraes RR. Hydrophobic coating of dental PMMA. J Clin Dent Res. 2018 May-Aug;15(2):148-57. DOI: https://doi.org/10.14436/2447-911x.15.2.148-157.oar

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