Introduction: Sterilisation using peracetic acid (PAA) has been advocated for orthodontic elastic bands. However, cane-loaded elastomeric ligatures can also become contaminated during processing, packaging, and manipulation before placement in the oral cavity and are therefore susceptible, and possible causes, of cross-contamination. Aim: To test the hypothesis that 0.25% peracetic acid (PAA), following the sterilisation of elastomers, influences the cytotoxicity of elastomeric ligatures on L929 cell lines. Materials and methods: Four hundred and eighty silver elastomeric ligatures were divided into 4 groups of 120 ligatures to produce, Group TP (latex natural, bulk pack, TP Orthodontics), Group M1 (Polyurethane, bulk pack, Morelli), Group M2 (Polyurethane, cane-loaded, Morelli) and Group U (Polyurethane, cane-loaded, Uniden). Of the 120 ligatures in each group, 100 were sterilised in 0.25% PAA at time intervals (N = 20) of 1 hour, 2 hours, 3 hours, 4 hours and 5 hours. The 20 remaining elastomeric ligatures in each group were not sterilised and served as controls. Cytotoxicity was assessed using L929 cell lines and a dye-uptake method. Analysis of variance (ANOVA), followed by the Tukey post hoc test (p < 0.05) determined statistical relevance. Results: There was a significant difference between TP, Morelli and Uniden elastomerics (p < 0.05), but no difference between the two types of Morelli elastomerics at the 1 hour time interval. In addition, there was a significant difference between Group CC and the other groups assessed, except between Groups CC and TP at the 1 hour time interval. The non-sterilised elastomeric ligatures showed similar cell viability to that observed after 1 hour of standard sterilisation. Conclusion: PAA did not significantly influence the cytotoxicity of elastomeric ligatures after a sterilisation time of 1 hour and is therefore recommended for clinical use.

Professor Kazuo Tanne has a degree in Dentistry by the University of Osaka where he also received the title of PhD in Orthodontics. From the 1st of July, 1993 to the 31st of March, 2013 he was the head of the Department of Orthodontics and Craniofacial Development Biology at the University of Hiroshima, in Japan. Professor Tanne has been the head of the Japanese Association of Cleft Lip/Palate, and nowadays is the head of the Asian Orthodontic Society which comprises 18 orthodontic societies in the Asia/Pacific area. He has published more than 700 articles and more than 60 books and/or chapters about many different topics. Professor Tanne has conducted interesting researches that focus on temporomandibular disorders, tooth cryopreservation, cleft lip/palate, molecular/cell biology and genetic engineering for bone repair. I am honored to say that I was advised by Professor Tanne during my Doctorate in Orthodontics between 2006 and 2010. During that period, I had the opportunity to fulfill my expectations towards the excellence of education provided by the University of Hiroshima as well as by Professor Tanne who also proved to be a great human being with a noble heart. We have become great friends and fortunately I had the chance to learn much more than Orthodontics. Tanne Sensei, as he is known in Japan, has a deep admiration for Brazil and the Brazilian culture. He has been in Brazil in three occasions, when he made friends in many different locations.Emanuel Braga Rêgo