1. Department of Radiation Oncology, University of Witwatersrand, Johannesburg and Charlotte Maxeke Academic Hospital, Johannesburg 2193, South Africa
2. Department of Periodontics and Oral Medicine, School of Oral Health Sciences, Faculty of Health Sciences, University of Pretoria, Pretoria 0084, South Africa
3. Department of Periodontology and Oral Medicine, Sefako Makgatho Health Sciences University, Pretoria 0204, South Africa
4. Retired Professor, Silvela Street, Sandton, Johannesburg 2031, South Africa
5. Retired Professor, Bantry Bay, Cape Town 8005, South Africa