ORIGINAL ARTICLE Periodontal and microbiologic evaluation of 2 methods of archwire ligation: Ligature wires and elastomeric rings Ricardo Alves de Souza, a Maria Beatriz Borges de Araújo Magnani, b Darcy Flávio Nouer, c Clevérson Oliveira da Silva, d Marlise Inêz Klein, e Enilson Antonio Sallum, f and Reginaldo Bruno Gonçalves g Piracicaba, São Paulo, and Bahia, Brazil Introduction: Prophylactic programs to prevent dental biofilm accumulation must be implemented to minimize the risk for periodontal diseases in orthodontic patients. Therefore, we assessed the possible periodontal and microbiologic changes resulting from the use of 2 methods of orthodontic archwire ligation: elastomeric rings and steel ligatures. Methods: The following parameters were measured: plaque index, gingival bleeding index, probing depth, and biofilm samples from the maxillary second premolars and the mandibular lateral incisors were evaluated in 14 subjects without clinical signs of gingival inflammation before orthodontic appliance placement and after 6 months of treatment. Each orthodontic arch was fixed with elastomeric rings on 1 side of the midline, and steel ligatures were used on the opposite side. Polymerase chain reaction analysis was used to detect Porphyromonas gingivalis, Tannerella forsythia, Actinobacillus actinomycetemcomitans, Prevotella intermedia, and P nigrescens. Results: The elastomeric rings were associated with a higher score for plaque index and bleeding than steel ligatures, as well as many positive sites of T forsythia and P nigrescens (P 0.05). Conclusions: Elastomeric rings favored these 2 periodon- topathogens and harmed gingival conditions. (Am J Orthod Dentofacial Orthop 2008;134:506-12) T he increased accumulation of biofilm indicates a high risk for adverse effects on the periodon- tium. 1-3 Many researchers have reported that the most important etiologic factor in periodontal dis- ease is the presence of biofilm at the gingival mar- gin. 2,4-6 The combination of orthodontic therapy and poor oral hygiene can cause serious damage to the periodontium. 7-9 The components of fixed orthodontic appliances create new retention areas that are suitable for bacterial colonization and lead to an increase in the number of microorganisms. 10,11 Several studies have used clinical parameters as a reference—plaque index, gingival index, probing depth, and bone loss involving periodontal tissues—around orthodontic appliances. 2,12-17 However, little information is available on the clinical and micro- biologic comparisons with the different methods of ligation used to fix the orthodontic arch. 10,11,18 More microorganisms were found in patients with elasto- meric rings than in those with steel wires; therefore, the orthodontic ligation technique was considered an addi- tional factor for biofilm accumulation. 10 Fixed orthodontic appliances significantly increase the colonization of Streptococcus mutans and Lactoba- cilli, as shown in several studies. 10,11,19-21 Periodontal pathogens such as Actinobacillus actinomycetemcomi- tans 7,22,23 and Tannerella forsythia 22 have also been significantly associated with gingival inflammation during orthodontic therapy. 9,22,23 Among the various species that have preferentially been found in subjects with periodontal disease are Porphyromonas gingivalis, Prevotella intermedia, P nigrescens, Bacteroides forsythus, A actinomycetem- comitans, Fusobacterium nucleatum, and Treponema denticola. 24-27 The chemical and physical characteris- tics of these bacteria have made them the most impor- tant members of peridontopathogenic microbiota. 28 But not all patients with periodontal disease harbor all of the supposedly periodontal pathogen species. 29-34 From Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil. a Postgraduate student, Department of Orthodontics; associate professor, South- west Bahia University, Bahia, Brazil. b Associate professor, Department of Orthodontics. c Chairman and professor, Department of Orthodontics. d Postgraduate student, Division of Periodontics, Department of Periodontics and Prosthodontics. e Postgraduate student, Division of Microbiology and Immunology, Department of Oral Diagnosis. f Professor, Division of Periodontics, Department of Periodontics and Prosth- odontics. g Associate professor, Division of Microbiology and Immunology, Department of Oral Diagnosis. Reprint requests to: Ricardo Alves de Souza, Piracicaba Dental School, University of Campinas, Department of Orthodontics, Av. Limeira, 901, Areão, CEP: 3414-903, Piracicaba, São Paulo, Brazil; e-mail, ricardoalves@fop.unicamp.br. Submitted, July 2006; revised and accepted, September 2006. 0889-5406/$34.00 Copyright © 2008 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2006.09.067 506