1. a Department of Periodontology and Oral Medicine, Faculty of Dentistry and the Medunsa Oral Health Center , Medical University of South Africa , Pretoria , South Africa
2. c Department of Chemistry , Technion‐Israel Institute of Technology , Haifa , 32000 , Israel
3. b Department of Oral Pathology, Faculty of Dentistry and the Medunsa Oral Health Center , Medical University of South Africa , Pretoria , South Africa