Toxicity of Orthodontic Brackets Examined by Single Cell Tracking
Morgan Wishney,
Swarna Mahadevan,
James Anthony Cornwell,
Tom Savage,
Nick Proschogo,
M. Ali Darendeliler,
Hans Zoellner
Affiliations
Morgan Wishney
Discipline of Orthodontics, Sydney Dental School, Faculty of Medicine and Health, University of Sydney, Sydney Dental Hospital, Surry Hills, NSW 2010, Australia
Swarna Mahadevan
The Cellular and Molecular Pathology Research Unit, Oral Pathology and Oral Medicine, Sydney Dental School, Faculty of Medicine and Health, The University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, Westmead, NSW 2145, Australia
James Anthony Cornwell
The Cellular and Molecular Pathology Research Unit, Oral Pathology and Oral Medicine, Sydney Dental School, Faculty of Medicine and Health, The University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, Westmead, NSW 2145, Australia
Tom Savage
School of Geosciences, Faculty of Science, The University of Sydney, Camperdown, NSW 2006, Australia
Nick Proschogo
School of Chemistry, Faculty of Science, The University of Sydney, Camperdown, NSW 2006, Australia
M. Ali Darendeliler
Discipline of Orthodontics, Sydney Dental School, Faculty of Medicine and Health, University of Sydney, Sydney Dental Hospital, Surry Hills, NSW 2010, Australia
Hans Zoellner
The Cellular and Molecular Pathology Research Unit, Oral Pathology and Oral Medicine, Sydney Dental School, Faculty of Medicine and Health, The University of Sydney, Westmead Centre for Oral Health, Westmead Hospital, Westmead, NSW 2145, Australia
Subtle toxic effects may be masked in traditional assays that average or summate the response of thousands of cells. We overcome this by using the recent method of single cell tracking in time-lapse recordings. This follows the fate and behavior of individual cells and their progeny and provides unambiguous results for multiple simultaneous biological responses. Further, single cell tracking permits correlation between progeny relationships and cell behavior that is not otherwise possible, including disruption by toxins and toxicants of similarity between paired sister cells. Notably, single cell tracking seems not to have been previously used to study biomaterials toxicity. The culture medium was pre-conditioned by 79 days incubation with orthodontic brackets from seven separate commercial sources. Metal levels were determined by Inductively Coupled Plasma Mass Spectrometry. Metal levels varied amongst conditioned media, with elevated Cr, Mn, Ni, and Cu and often Mo, Pb, Zn, Pd, and Ag were occasionally found. The effect on human dermal fibroblasts was determined by single cell tracking. All bracket-conditioned media reduced cell division (p p p < 0.05), a seemingly novel measure for toxicity. No clear effect on cell morphology was seen. We conclude that orthodontic brackets have cytotoxic effects, and that single cell tracking is effective for the study of subtle biomaterials cytotoxicity.
