Statement of problem
The color of dental polymethyl methacrylate (PMMA) is traditionally rendered by organic and inorganic pigments, which are usually not bonded to the polymer network. Functionalized ceramic pigments can be used to color PMMA allowing improved chemical interaction with the resin matrix.
Purpose
The purpose of this in vitro study was to synthesize, functionalize, and characterize pink manganese-doped alumina ceramic pigments. The hypothesis tested was that functionalized ceramic pigments would render pink coloration to a translucent PMMA without jeopardizing its mechanical properties.
Material and methods
Pink alumina powders doped with 1 mol% or 2 mol% of manganese (Al2O3:Mn) were prepared by means of a polymeric precursor method. Pigment particles were functionalized with a silica coating method followed by silanation before preparation of PMMA-based composite resins (5 wt% pigment). The color of composite resins (Pig.1% and Pig.2%) and PMMA controls (Pink and Translucent) was evaluated (CIELAB color coordinates), and their mechanical properties were tested (3-point-bending).
Results
The microstructure of the pigment particles showed approximately 55-nm nanocrystals of manganese-doped α-alumina clustered into irregular porous particles up to 60 μm. The composite resins and Pink PMMA showed similar color parameters (CIE a* Pink=20.1, Pig.1%=14.6, Pig.2%=16.0, Trans=0.19 – P<.001; CIE b* Pink=17.0, Pig.1%=18.6, Pig.2%=19.0, Trans=2.52 – P<.001). No statistical differences were observed in mechanical properties among groups (σf Pink=98.4, Pig.1%=98.1, Pig.2%=98.8, Trans=89.1 – P=.136).
Conclusions
The addition of the functionalized pink ceramic pigments to a translucent PMMA yielded similar coloration to that of the regular pink PMMA used in dentistry and did not jeopardize its mechanical properties.
RESUMO -Dentre os poluentes emergentes, os fármacos, em especial os antibióticos, têm atraído uma maior atenção, pois a entrada destes, no ambiente, é contínua e passível de apresentar toxicidade aos seres vivos e desenvolver bactérias patogênicas resistentes, causando sérios problemas de saúde pública. No presente trabalho, objetivou-se avaliar alguns processos oxidativos avançados (fotólise direta, UV/H2O2, Fenton e foto-Fenton) para o tratamento de efluentes industriais provenientes da formulação de fármacos comerciais, com ênfase nas águas de lavagem de maquinários farmacêuticos contendo amoxicilina (100 mgC.L -1 ). O sistema foto-Fenton apresentou as maiores taxas de remoção de carbono orgânico (TOC), mineralizando 58% da carga orgânica inicial em apenas 30 minutos de reação. A variação da concentração inicial de íons Fe 2+ (0,07 -1 mmol.L -1 ) não afetou o desempenho do processo. O sistema UV/H2O2 apresentou o maior percentual de mineralização (97%) no tempo total de reação (180 min).
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