1 Department of Periodontics and Oral Medicine, School of Oral Health Sciences, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa. Electronic address: razia.khammissa@up.ac.za.
2 Department of Periodontology and Oral Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
3 School of Oral Health Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.