title: Expression levels of the receptor activator of NF-κB ligand and osteoprotegerin and the number of gram-negative bacteria in symptomatic and asymptomatic periapical lesions.
abstract: OBJECTIVE
  The study aimed to verify the potential correlation between the detected amount of gram-negative bacteria and the radiographic sizes of the lesions in patients with symptomatic and asymptomatic apical periodontitis. Furthermore, to evaluate whether the expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) and the RANKL/OPG ratio are differentially regulated in both groups.
  
  
  METHODS
  Twenty patients with periapical lesions were divided into two groups: symptomatic (SYM) n=10 and asymptomatic (ASYM) n=10. After periapical surgery, the lesions were collected and processed for histological examination, and immunohistochemistry. The percentage of RANKL- and OPG-immunopositive areas relative to the total area of the microscopic field was calculated. For gram staining, the number of gram-negative cells per microscopic field was assessed. The radiographs of each patient were processed and measured. The Student's t-test and the Pearson correlation coefficient were performed.
  
  
  RESULTS
  The SYM group showed a significantly higher number of gram-negative cells (p=0.007) when compared to the ASYM group. A higher number of gram-negative bacteria occurred more frequently in larger periapical lesions and the SYM group (p=0.03). The expression for RANKL and OPG and the RANKL/OPG ratio were not significantly different between the groups. There was a significant positive correlation between the number of bacteria and OPG levels in the SYM group (p=0.01).
  
  
  CONCLUSIONS
  The number of bacteria seems to influence the symptoms and the radiographic size of a periapical lesion. Gram-negative bacteria may play an important role in OPG activity in the SYM group.
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil. Electronic address: everdan.carneiro@pucpr.br.
authors: E
authors: E
authors: Carneiro
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil.
authors: A B
authors: AB
authors: Parolin
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil.
authors: C
authors: C
authors: Wichnieski
authors: Xenobiotics Research Unit, School of Health and Biosciences, Pontifical Catholic University of Paraná, Brazil.
authors: E A R
authors: EA
authors: Rosa
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil.
authors: U X
authors: UX
authors: Silva Neto
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil.
authors: V P D
authors: VP
authors: Westphalen
authors: Department of Endodontics, Pontifical Catholic University of Paraná, Brazil.
authors: L F
authors: LF
authors: Fariniuk
authors: Department of Stomatology, Pontifical Catholic University of Paraná, Brazil.
authors: A C B R
authors: AC
authors: Johann
mesh_terms: D000328:Adult; D058345:Asymptomatic Infections; D005260:Female; D006090:Gram-Negative Bacteria / Q000302:isolation & purification*; D016905:Gram-Negative Bacterial Infections / Q000000981:diagnostic imaging / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D006801:Humans; D008297:Male; D053244:Osteoprotegerin / Q000096:biosynthesis*; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000382:microbiology* / Q000473:pathology; D053245:RANK Ligand / Q000096:biosynthesis*; D055815:Young Adult
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human
keywords: Apical periodontitis; Gram-negative bacteria; OPG; RANKL; Symptomatic