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Updated: May 1, 2026
Ratiometric Imaging of Extracellular pH in Dental Biofilms
Published on: March 9, 2016
Mapping dental biofilms: from plaque index through planimetry to volumetric analysis
Katja Povšič1,2, Luka Fijavž3, Haris Munjaković4,3
1Department of Oral Medicine and Periodontology - Dental Clinic, University Medical Centre Ljubljana, Hrvatski trg 6, Ljubljana, 1000, Slovenia. katja.povsic@kclj.si.
Objectives:
Conventional plaque assessment methods, such as clinical indices and planimetry, rely on plaque-disclosing agents and may overemphasize thin biofilm areas due to plaque thickness variations. This study introduces a digital 3D method to quantify and visualize dental plaque volume from consecutive intraoral scans (IOS) and compares it with the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPlI) and planimetry.
Methods:
After professional supragingival debridement at baseline (T0), fifteen participants refrained from oral hygiene for four days (T4). De novo plaque formation was assessed at T4 using TMQHPlI after application of a two-tone (pink/purple) plaque-disclosing agent. IOSs (3Shape TRIOS 4) were obtained at T0 and T4. Plaque accumulation was quantified using color-coded IOS comparisons with the Volumetric Plaque Index (VPI) and Adjusted VPI (AVPI). Machine learning (Trainable Weka Segmentation) was used to calculate the Planimetric Plaque Index (PPI).
Results:
A correlation between plaque surface area and volume was observed only for purple/mature plaque (p = 0.043). Early plaque growth was dominated by expansion of pink-stained, newly formed plaque. Once more than one-third of the surface was covered, further increases resulted mainly from vertical thickening rather than lateral spread.
Conclusions:
3D volumetric analysis offers a comprehensive, objective, and clinician-friendly method for assessing dental biofilms.
Clinical Relevance:
The proposed 3D approach enables accurate monitoring of plaque accumulation and maturation, improving personalized oral hygiene assessment, patient education, and clinical decision-making.
