New Concept of Polymethyl Methacrylate (PMMA) and Polyethylene Terephthalate (PET) Surface Coating by Chitosan

Abstract

Abstract:Chitosan is known for its hemostatic and antimicrobial properties and might be useful for temporary coating of removable dentures or intraoral splints to control bleeding after oral surgery or as a supportive treatment in denture stomatitis. This study investigated a new method to adhere chitosan to polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET). There were 70 cylindrical specimens made from PMMA and 70 from PET (13 mm diameter, 6 mm thickness). The materials with ten specimens each were sandblasted at 2.8 or 4.0 bar with aluminum oxide 110 µm or/and aluminum oxide coated with silica. After sandblasting, all specimens were coated with a 2% or 4% acetic chitosan solution with a thickness of 1 mm. Then the specimens were dried for 120 min at 45˝C. The precipitated chitosan was neutralized with 1 mol NaOH. After neutralization, all specimens underwent abrasion tests using the tooth-brushing simulator with soft brushes (load 2N, 2 cycles/s, 32˝C, 3000 and 30,000 cycles). After each run, the specimen surfaces were analyzed for areas of remaining chitosan by digital planimetry under a light microscope. The best chitosan adhesion was found after sandblasting with aluminum oxide coated with silica (U-Test, p < 0.05) in both the PMMA and the PET groups. Hence, with relatively simple technology, a reliable bond of chitosan to PMMA and PET could be achieved.

Chitosan Coating on Silica-Modified Polymethyl Methacrylate for Dental Applications

“…The close molecular proximity may induce other secondary valence forces such as van der Waal forces or hydrogen bonds [23,24]. This hypothesis is supported by the observation that no adhesion occurred when the acetic chitosan solution was neutralized by NaOH prior to drying the process [13]. The amino groups of the chitosan molecules lose their positive charge and do not interact with the hydroxyl groups at the silica surface [25].…”

“…A previous study described in detail the process to achieve adhering chitosan coatings on PMMA surfaces [13]. In the first step, the PMMA surfaces were sandblasted with a 110-micron silicamodified alumina oxide (Rocatec Plus blasting agent, 3M ESPE, Seefeld, Germany) at 2.8 bar (Figure 8a).…”

“…To use PMMA denture bases as a carrier for chitosan requires the adhesion of the hydrophilic chitosan to the hydrophobic PMMA resin surface as well as a predictable thickness of chitosan coatings. A simple technology to achieve the adhesion of chitosan to PMMA has been described in a previous paper [13]. First, the PMMA surfaces are sandblasted at 2.8 bar with 110 μm silica-modified alumina (Rocatec Plus Blasting Agent, 3M ESPE, Seefeld, Germany) [14,15].…”

“…First, the PMMA surfaces are sandblasted at 2.8 bar with 110 μm silica-modified alumina (Rocatec Plus Blasting Agent, 3M ESPE, Seefeld, Germany) [14,15]. Due to the high impact energy, the sandblasting process implants silica-modified alumina particles in the relatively soft PMMA resin surface, creating a hydrophilic silica layer [13]. Then, a 2% acetic chitosan solution is applied to the sandblasted surface and dried in an oven at 45 °C for 120 min.…”

“…This study investigated the application of uniform chitosan coatings on intaglio surfaces of curved dentures bases by modifying the method described above [13]. Variables were the concentration of the acetic chitosan solution (2% and 4%) and the application of one or two consecutively applied layers of acetic chitosan solution, resulting in four different coating procedures.…”