title: Partial denture metal framework may harbor potentially pathogenic bacteria.
abstract: OBJECTIVE
  The aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time.
  
  
  METHODS
  This descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week (t1) and 4 months (t2) after the RPD was inserted (t0). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity).
  
  
  RESULTS
  A total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 (t1) and 96 (t2) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for t1 and 17 for t2, which were grouped in 5 phyla: Firmicutes (t1=82%; t2=60%), Actinobacteria (t1=5%; t2=10%), Bacteroidetes (t1=2%; t2=6%), Proteobacteria (t1=10%; t2=15%) and Fusobacteria (t1=1%; t2=8%). The libraries also include 3 novel phylotypes for t1 and 11 for t2. Library t2 differs from t1 (P=.004); t1 is a subset of the t2 (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in t2.
  
  
  CONCLUSIONS
  The biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.
authors.affiliation: Department of Conservative Dentistry, Federal University of Rio Grande do Sul, School of Dentistry, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Cristiane Machado
authors.identifier: 0000-0002-1059-8419
authors.initials: CM
authors.lastname: Mengatto
authors.affiliation: Department of Preventive and Community Dentistry, University of Iowa, College of Dentistry, Iowa City, Iowa, USA.
authors.forename: Leonardo
authors.identifier: 0000-0003-1291-6684
authors.initials: L
authors.lastname: Marchini
authors.affiliation: Department of Science and Technology, State University of Santa Cruz, School of Computer Science, Ilheus, Bahia, Brazil.
authors.forename: Luciano Angelo de Souza
authors.initials: LA
authors.lastname: Bernardes
authors.affiliation: Department of Conservative Dentistry, Federal University of Rio Grande do Sul, School of Dentistry, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Sabrina Carvalho
authors.initials: SC
authors.lastname: Gomes
authors.affiliation: Department of Dental Materials and Prosthodontics, State University Julio de Mesquita Filho, School of Dentistry, Sao Jose dos Campos, Sao Paulo, Brazil.
authors.forename: Alecsandro Moura
authors.initials: AM
authors.lastname: Silva
authors.affiliation: Department of Prosthodontics and Periodontology, State University of Campinas, Piracicaba Dental School, Piracicaba, Sao Paulo, Brazil.
authors.forename: Célia Marisa
authors.identifier: 0000-0002-8747-0034
authors.initials: CM
authors.lastname: Rizzatti-Barbosa
keywords: 16S rDNA gene; Denture plaque; Framework; Microorganisms; Removable partial denture
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