1. Facultad de Odontologia Etiology and Therapy of Periodontal Diseases (ETEP) Research Group Universidad Complutense de Madrid Madrid Spain
2. Department of Oral Implantology Military Medical Academy Belgrade Serbia
3. Faculty of Organizational Sciences University of Belgrade Belgrade Serbia
4. Institute for Medical Research, Military Medical Academy Belgrade Serbia
5. Department of Periodontics and Oral Medicine University of Michigan Ann Arbor Michigan USA
6. Department of Periodontology Universitat Internacional de Catalunya Barcelona Spain