title: New portable system for dental plaque measurement using a digital single-lens reflex camera and image analysis: Study of reliability and validation.
abstract: BACKGROUND
  The quantification of the dental plaque (DP) by indices has limitations: They depend on the subjective operator's evaluation and are measured in an ordinal scale. The purpose of this study was to develop and evaluate a method to measure DP in a proportional scale.
  
  
  METHODS
  A portable photographic positioning device (PPPD) was designed and added to a photographic digital single-lens reflex camera. Seventeen subjects participated in this study, after DP disclosure with the erythrosine, their incisors, and a calibration scale ware photographed by two operators in duplicate, re-positioning the PPPD among each acquisition. A third operator registered the Quigley-Hein modified by Turesky DP index (Q-H/TPI). After tooth brushing, the same operators repeated the photographs and the Q-H/TPI. The image analysis system (IAS) technique allowed the measurement in mm(2) of the vestibular total tooth area and the area with DP.
  
  
  RESULTS
  The reliability was determined with the intra-class correlation coefficient that was 0.9936 (P < 0.05) for the intra-operator repeatability and 0.9931 (P < 0.05) for inter-operator reproducibility. The validity was assessed using the Spearman's correlation coefficient that indicated a strong positive correlation with the Q-H/TPI r s = 0.84 (P < 0.01). The sensitivity of the IAS was evaluated with two sample sizes, only the IAS was able to detect significant differences (P < 0.05) with the sample of smaller size (n = 8).
  
  
  CONCLUSIONS
  Image analysis system showed to be a reliable and valid method to measure the quantity of DP in a proportional scale, allowing a more powerful statistical analysis, thus facilitating trials with a smaller sample size.
authors.affiliation: CORE Dental Clinic, Graduate School Foundation, Resistencia, Chaco, Argentina ; Department of Research, Graduate School Foundation, Resistencia, Chaco, Argentina.
authors.forename: Guillermo Martin
authors.initials: GM
authors.lastname: Rosa
authors.affiliation: CORE Dental Clinic, Graduate School Foundation, Resistencia, Chaco, Argentina ; Department of Pediatric Dentistry, School of Dentistry, National University of the Northeast, Corrientes, Argentina ; Department of Pediatric Dentistry, Graduate School Foundation, Resistencia, Chaco, Argentina.
authors.forename: Maria Lidia
authors.initials: ML
authors.lastname: Elizondo
keywords: Dental plaque; image processing/computer-assisted; methodological study; photography/dental