title: The relationship between dental caries status and dental plaque urease activity.
abstract: BACKGROUND
  Ammonia production from the metabolism of urea by urease enzymes of oral bacteria moderates plaque acidification and may inhibit dental caries, as suggested by in vitro studies and indirect clinical observations. The objective of this study was to examine the relationship of urease activity with dental caries at the clinical level.
  
  
  METHODS
  Urease activity was measured in dental plaque and saliva samples from 25 caries-free subjects (CF) and in eight subjects with six or more open caries lesions (CA). Plaque and saliva collection was repeated for each subject 1 week later using identical procedures.
  
  
  RESULTS
  Urease-specific activity in the dental plaque of CF subjects was significantly higher compared to that in the subjects with caries. The association of low plaque urease levels with increased caries was further supported by odds ratio analysis using different plaque urease cut-off points. Using a receiver operating characteristic curve it was estimated that there was an approximately 85% probability of correctly classifying the subjects as CA or CF based on the relative ordering of their plaque urease activity levels. No statistically significant differences were observed in salivary urease activity.
  
  
  CONCLUSIONS
  This study suggests that loss of alkali-generating potential of tooth biofilms via the urease pathway has a positive relationship to dental caries.
authors.affiliation: Department of Restorative Dentistry, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shu
authors.forename: E
authors.initials: E
authors.lastname: Morou-Bermudez
authors.forename: E
authors.initials: E
authors.lastname: Suárez-Pérez
authors.forename: C
authors.initials: C
authors.lastname: Rivera-Miranda
authors.forename: C M
authors.initials: CM
authors.lastname: Browngardt
authors.forename: Y-Y M
authors.initials: YY
authors.lastname: Chen
authors.forename: I
authors.initials: I
authors.lastname: Magnusson
authors.forename: R A
authors.initials: RA
authors.lastname: Burne
mesh_terms: D000328:Adult; D000641:Ammonia / Q000378:metabolism; D015169:Colony Count, Microbial; D004245:DMF Index; D003731:Dental Caries / Q000378:metabolism; D003773:Dental Plaque / Q000737:chemistry / Q000201:enzymology* / Q000382:microbiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006868:Hydrolysis; D008297:Male; D011506:Proteins / Q000032:analysis; D012372:ROC Curve; D012463:Saliva / Q000737:chemistry / Q000201:enzymology / Q000382:microbiology; D012471:Salivary Proteins and Peptides / Q000032:analysis; D012680:Sensitivity and Specificity; D014508:Urea / Q000378:metabolism; D014510:Urease / Q000032:analysis*
chemical_list: D011506:Proteins; D012471:Salivary Proteins and Peptides; D000641:Ammonia; D014508:Urea; D014510:Urease