RESUMO
Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths (EFS) on the growth of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 Vâ m(-1). Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli.
Assuntos
Eletricidade , Escherichia coli/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Carga Bacteriana/efeitos da radiação , Técnicas Bacteriológicas , Caseínas , Parede Celular/efeitos da radiação , Meios de Cultura , Citoplasma/efeitos da radiação , Escherichia coli/efeitos da radiação , Géis , Humanos , Viabilidade Microbiana/efeitos da radiação , Microscopia Eletrônica de Transmissão , Hidrolisados de Proteína , Cloreto de Sódio , Staphylococcus aureus/efeitos da radiação , ÁguaRESUMO
OBJECTIVE: In dentistry, metallic alloys are used for dentures, restorative materials, and orthodontic devices. Electric voltages up to 950 mV may occur between different dental alloys in the oral cavity. This study aimed to investigate physiologic reactions of oral leukoplakia cells in vitro to electric fields. STUDY DESIGN: A human leukoplakia cell line (MSK-LEUK1), cultivated in keratinocyte growth medium (KGM-2) supplemented with growth factors in 5% CO(2) humidified air at 37°C, was exposed to electric field strength of 1-20 V/m for 24 hours in a custom-made pulse chamber. The cells were then analyzed for proliferation with the use of BrdU assay and for apoptosis with the use of TUNEL assay. Findings were assessed with the use of fluorescent microscopy. Ultrastructural changes were studied by transmission electron microscopy. RESULTS: Electric field strength of 1-10 V/m led to up-regulation of cell proliferation rate from 10.64% to 44.06% (P = .0001). The apoptotic index increased significantly (P = .0001) from 20.03% at 1 V/m to 46.56% at 10 V/m. Individual cell keratinization was seen in leukoplakia cells treated with 16 V/m. CONCLUSIONS: Oral galvanism induces subcellular changes in oral precancer cells in vitro that closely simulate some of the morphologic features of oral squamous cell carcinoma cells in vivo.