title: Influence of TNF-α-308 G/A gene polymorphism on temporomandibular disorder.
abstract: BACKGROUND
  Tumor necrosis factor alpha (TNF-α) levels are significantly upregulated in the synovial fluid of patients with temporomandibular joint disorder (TMD). The TNF-α influences pain generation and maintenance. Therefore, the aim of this study was to investigate the influence of single nucleotide polymorphism TNFA-308 (rs1800629) on TMD risk and on the pressure pain threshold.
  
  
  METHODS
  The genotypic and allelic frequencies of candidate single nucleotide polymorphisms were compared among 152 TMD patients and 91 sex- and age-matched healthy subjects in the control group using the real-time polymerase chain reaction technique. The pressure pain threshold in the temporomandibular joint, anterior fascicle of the temporal muscle, masseter muscle, and Achilles tendon were recorded with an algometer. After the pressure test, all participants received a complete physical examination, including masticatory muscle evaluation, temporomandibular joint palpation, and assessment of mandibular range of motion.
  
  
  RESULTS
  The TNFA-308 polymorphism is positively associated with TMD. Subjects with TMD had a 2.87 (95% confidence interval, 1.256-6.569) times greater chance of having the GA genotype than did the control group. Rare A-allele homozygotes demonstrated decreased pain sensitivity for the temporomandibular joint and anterior fascicle of the temporal muscle in the pressure pain threshold test compared with ancestral allele homozygotes.
  
  
  CONCLUSIONS
  This study presents an unprecedented association between the TNFA-308 (rs1800629) polymorphism and TMD. Future studies are needed to enlighten the association between TNFA-308 G/A single nucleotide polymorphism and mechanical pain sensitivity.
authors.affiliation: Associate professor, Department of Orthodontics, University of North Paraná, Londrina, Paraná, Brazil. Electronic address: brunofurquim@hotmail.com.
authors.forename: Bruno D'Aurea
authors.initials: BD
authors.lastname: Furquim
authors.affiliation: Private practice, Fortaleza, Ceará, Brazil.
authors.forename: Lívia Maria Sales Pinto
authors.initials: LM
authors.lastname: Flamengui
authors.affiliation: Associate professor, Department of Dentistry, Federal University of Sergipe, Lagarto, Sergipe, Brazil.
authors.forename: Carlos Eduardo Palanch
authors.initials: CE
authors.lastname: Repeke
authors.affiliation: Assistant professor, Conservative Dentistry Department, University of Chile, Santiago, Chile.
authors.forename: Franco
authors.initials: F
authors.lastname: Cavalla
authors.affiliation: Editor-in-chief, Journal of Applied Oral Sciences; associate professor and head, Department of Biological Sciences, School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Gustavo Pompermaier
authors.initials: GP
authors.lastname: Garlet
authors.affiliation: Associate professor, Department of Prosthodontics, School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Paulo César Rodrigues
authors.initials: PC
authors.lastname: Conti
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D020641:Polymorphism, Single Nucleotide; D013705:Temporomandibular Joint Disorders / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
chemical_list: D014409:Tumor Necrosis Factor-alpha