novel nano-ceramic coating on polymethyl methacrylate denture ...
NOVEL NANO-CERAMIC COATING ON POLYMETHYL METHACRYLATE DENTURE MATERIAL 2 3 2 4 1,3
Su Huang1, Randold Binns , Arghya Bishal , Cortino Sukotjo , Christine D. Wu , Christos G. Takoudis , Stephen Campbell2, Bin Yang2 1 Department
of Chemical Engineering, College of Engineering, UIC, Chicago, IL, USA 2 Department of Restorative Dentistry, College of Dentistry, UIC, Chicago, IL, USA 3 Department of BioEngineering, College of Engineering, UIC, Chicago, IL, USA 4 Department of Pediatric Dentistry, College of Dentistry, UIC, Chicago, IL, USA
Abstract Polymethyl-Methacrylate (PMMA) resin has been extensively used as a denture base material due to its aesthetics, processability, and reparability. However, it exhibits insufficient surface hardness, poor wearing resistance and water absorption. Nano-titanium dioxide (TiO2) ceramic coating is proposed to eliminate these drawbacks. Results showed that TiO2 was successfully deposited onto PMMA material by atomic layer deposition (ALD) at low temperature. Compared to uncoated PMMA, TiO2 coated PMMA surface showed super-hydrophilic surface, and less retentive of Candida albicans.
Introduction PMMA resin is widely used as denture base material. However, it deteriorates over time after exposure to water, foods and oral bacteria, resulting in the formation of denture biofilm (denture plaque) that has been associated with denture stomatitis (DS), and systemic disease (e.g., aspiration pneumonia). The objectives of this study are to modify the surface wettability and reduce the retention of microorganisms, while still retaining the other advantages of PMMA by depositing a TiO2 nano-thin film on the PMMA surface.
Materials & Methods PMMA 2 cm x 2 cm x 1mm samples were prepared using commercial poly-methyl methacrylate following the manufacture’s instructions (Lucitone 199, Dentsply International, York, PA). PMMA substrates were pre-cleaned by 5% Sodium hydroxide solution for 15 minutes followed by 1 hour of de-ionized water in an ultrasonic bath at 37℃. The samples were then dried by N2 gas to remove the excess water. Titanium dioxide films were grown from tetrakis(dimethylamido)titanium (TDMAT) and ozone by the ALD method (Fig. 1) at temperatures between 60 and 65℃. Argon was used as purging gas in between successive precursor pulses. One deposition cycle consisted of a 0.5 s TDMAT pulse, 10 s purge, 1 s ozone pulse and 10 s purge. 200 cycles of deposition lead to a thickness of 30 nm TiO2 film. A sessile drop method was used to perform water contact angle measurements in order to monitor the surface wettability. The anti-bacterial property of ceramic-PMMA material was evaluated using the method of plate-counting.
Fig. 1 Three-dimensional representation of the ALD system
aps2016.02100b4 Conclusion
Results b WCA ameasurements were conducted using a Rame’-Hart NRL CA Goniometer (M#100-0, S#2067). A micro-syringe (Hamilton, 802RN) was used to place a 5 μL DI water droplet onto PMMA and TiO2-PMMA surfaces. The results showed that before deposition, the water contact angle was 67°(Fig.2a); however,b after coated with TiO2 a nano-thin film, the WCA value of surface changed into less than 5° (Fig.2b), leading to a superhydrophilic surface. a
a
b
b
Fig. 3 Difference in surface roughness (Ra) between TiO2 coated PMMA (a) and PMMA (b).
b
c
The effect of surface modification on attachment of C. albicans was examined with the adhesion test after 6 hours, and biofilm formation after 12 hours with a prolonged incubation at 37°C. The number of eluted dC.d albicans was then determined by colony forming units (CFU). a
b
Fig. 2 Water contact angles of TiO2 coated PMMA (a), and PMMA (b).
Surface roughness (Ra) of sample surface was tested with white light interferometer (Zygo). The surface of PMMA samples were polished by silicon carbide grinding paper with grit P800 to P2500 before deposition. It can be observed that after deposition, the Ra value is around 0.09 μm (Fig. 3a), when compared with the sample without coating (Fig. 3b), for which Ra=0.13 μm. The decreased surface roughness also help to reduce the water contact angle, leading to a super-hydrophilic surface.
Fig. 4 The adherence (a) and biofilm formation (b) of C. albicans on TiO2-coated PMMA and PMMA.
It was found that TiO2-coated PMMA surfaces reduced the amount of adherent Candida by 63% (Fig. 4a). In addition, the reduction of biofilm formation is 56% after the deposition of TiO2 nano-thin film (Fig. 4b).
Atomic layer deposition is a successful method for titanium coating PMMA resin material at low temperature. The TiO2-coated PMMA resulted in a reduction of Ra (smoother) and a more hydrophilic surface than PMMA alone. The TiO2-coated PMMA showed less C. albicans adherence and biofilm formation than that of PMMA. This is a promising preliminary result that may impact the oral and systemic health of a very large and growing denture population.
References Parahitiyawa NB, Jin LJ, Leung WK, Yam WC, Samaranayake LP. Microbiology of odontogenic bacteremia: beyond endocarditis. Clin Microbiol Rev. 2009; 22(1): 46-64, Gendrau L, Loewy ZG. Epidemiology and etiology of denture stomatitis. J Prosthodont. June 2011; 20(4): 251-60 Selvaraj, Sathees Kannan, and Christos G. Takoudis. Journal of Vacuum Science & Technology A 33.1 (2015): 013201. Su, Wenyue, et al. "Plasma pre-treatment and TiO2 coating of PMMA for the improvement of antibacterial properties." Surface and Coatings Technology205.2 (2010): 465-469.
Funding Source This study is supported by the ACPEF 2014 GSK Innovator Award; College of Dentistry, University of Illinois at Chicago; and the NSF CBET 1067424 and EEC 1062943. The authors thank Dr. W Li for his assistance in microbiology assays.
Su Huang1, Randold Binns , Arghya Bishal , Cortino Sukotjo , Christine D. Wu , Christos G. Takoudis , Stephen Campbell2, Bin Yang2 1 Department
of Chemical Engineering, College of Engineering, UIC, Chicago, IL, USA 2 Department of Restorative Dentistry, College of Dentistry, UIC, Chicago, IL, USA 3 Department of BioEngineering, College of Engineering, UIC, Chicago, IL, USA 4 Department of Pediatric Dentistry, College of Dentistry, UIC, Chicago, IL, USA
Abstract Polymethyl-Methacrylate (PMMA) resin has been extensively used as a denture base material due to its aesthetics, processability, and reparability. However, it exhibits insufficient surface hardness, poor wearing resistance and water absorption. Nano-titanium dioxide (TiO2) ceramic coating is proposed to eliminate these drawbacks. Results showed that TiO2 was successfully deposited onto PMMA material by atomic layer deposition (ALD) at low temperature. Compared to uncoated PMMA, TiO2 coated PMMA surface showed super-hydrophilic surface, and less retentive of Candida albicans.
Introduction PMMA resin is widely used as denture base material. However, it deteriorates over time after exposure to water, foods and oral bacteria, resulting in the formation of denture biofilm (denture plaque) that has been associated with denture stomatitis (DS), and systemic disease (e.g., aspiration pneumonia). The objectives of this study are to modify the surface wettability and reduce the retention of microorganisms, while still retaining the other advantages of PMMA by depositing a TiO2 nano-thin film on the PMMA surface.
Materials & Methods PMMA 2 cm x 2 cm x 1mm samples were prepared using commercial poly-methyl methacrylate following the manufacture’s instructions (Lucitone 199, Dentsply International, York, PA). PMMA substrates were pre-cleaned by 5% Sodium hydroxide solution for 15 minutes followed by 1 hour of de-ionized water in an ultrasonic bath at 37℃. The samples were then dried by N2 gas to remove the excess water. Titanium dioxide films were grown from tetrakis(dimethylamido)titanium (TDMAT) and ozone by the ALD method (Fig. 1) at temperatures between 60 and 65℃. Argon was used as purging gas in between successive precursor pulses. One deposition cycle consisted of a 0.5 s TDMAT pulse, 10 s purge, 1 s ozone pulse and 10 s purge. 200 cycles of deposition lead to a thickness of 30 nm TiO2 film. A sessile drop method was used to perform water contact angle measurements in order to monitor the surface wettability. The anti-bacterial property of ceramic-PMMA material was evaluated using the method of plate-counting.
Fig. 1 Three-dimensional representation of the ALD system
aps2016.02100b4 Conclusion
Results b WCA ameasurements were conducted using a Rame’-Hart NRL CA Goniometer (M#100-0, S#2067). A micro-syringe (Hamilton, 802RN) was used to place a 5 μL DI water droplet onto PMMA and TiO2-PMMA surfaces. The results showed that before deposition, the water contact angle was 67°(Fig.2a); however,b after coated with TiO2 a nano-thin film, the WCA value of surface changed into less than 5° (Fig.2b), leading to a superhydrophilic surface. a
a
b
b
Fig. 3 Difference in surface roughness (Ra) between TiO2 coated PMMA (a) and PMMA (b).
b
c
The effect of surface modification on attachment of C. albicans was examined with the adhesion test after 6 hours, and biofilm formation after 12 hours with a prolonged incubation at 37°C. The number of eluted dC.d albicans was then determined by colony forming units (CFU). a
b
Fig. 2 Water contact angles of TiO2 coated PMMA (a), and PMMA (b).
Surface roughness (Ra) of sample surface was tested with white light interferometer (Zygo). The surface of PMMA samples were polished by silicon carbide grinding paper with grit P800 to P2500 before deposition. It can be observed that after deposition, the Ra value is around 0.09 μm (Fig. 3a), when compared with the sample without coating (Fig. 3b), for which Ra=0.13 μm. The decreased surface roughness also help to reduce the water contact angle, leading to a super-hydrophilic surface.
Fig. 4 The adherence (a) and biofilm formation (b) of C. albicans on TiO2-coated PMMA and PMMA.
It was found that TiO2-coated PMMA surfaces reduced the amount of adherent Candida by 63% (Fig. 4a). In addition, the reduction of biofilm formation is 56% after the deposition of TiO2 nano-thin film (Fig. 4b).
Atomic layer deposition is a successful method for titanium coating PMMA resin material at low temperature. The TiO2-coated PMMA resulted in a reduction of Ra (smoother) and a more hydrophilic surface than PMMA alone. The TiO2-coated PMMA showed less C. albicans adherence and biofilm formation than that of PMMA. This is a promising preliminary result that may impact the oral and systemic health of a very large and growing denture population.
References Parahitiyawa NB, Jin LJ, Leung WK, Yam WC, Samaranayake LP. Microbiology of odontogenic bacteremia: beyond endocarditis. Clin Microbiol Rev. 2009; 22(1): 46-64, Gendrau L, Loewy ZG. Epidemiology and etiology of denture stomatitis. J Prosthodont. June 2011; 20(4): 251-60 Selvaraj, Sathees Kannan, and Christos G. Takoudis. Journal of Vacuum Science & Technology A 33.1 (2015): 013201. Su, Wenyue, et al. "Plasma pre-treatment and TiO2 coating of PMMA for the improvement of antibacterial properties." Surface and Coatings Technology205.2 (2010): 465-469.
Funding Source This study is supported by the ACPEF 2014 GSK Innovator Award; College of Dentistry, University of Illinois at Chicago; and the NSF CBET 1067424 and EEC 1062943. The authors thank Dr. W Li for his assistance in microbiology assays.
