1. Chulalongkorn University; Department of Oral Medicine, Faculty of Dentistry; Bangkok Thailand 10330
2. University of Newcastle upon Tyne; Department of Oral Medicine, School of Dental Sciences; Framlington Place Newcastle upon Tyne UK NE2 4BW
3. School of Dentistry, The University of Manchester; Cochrane Oral Health Group; Coupland III Building, Oxford Rd Manchester UK M13 9PL
4. Department of Medicine, Surgery and Dentistry, University of Milan; Unit of Oral Pathology and Oral Medicine; Via Beldiletto 1/3 Milan Italy 20142