Image Analysis of Overnight Natural Plaque Accumulation: Intraoral Distribution

Objective: A pilot clinical study was conducted to measure the intraoral distribution of overnight plaque accumulation in a general population.  

Method: Institutional review and informed consent were obtained, and healthy adult volunteers were recruited and instructed to discontinue oral hygiene the morning of plaque assessment (overnight plaque).  For measurement, subjects rinsed with fluorescein dye and buffer solutions using standard methods.  High resolution intraoral digital images were collected under standardized lighting using a chin rest for positioning.  Plaque surface area was measured objectively via image analysis as area (%) coverage, using masking to separately quantify outcomes for the maxillary and mandibular arches.  

Result: A total of 58 subjects were enrolled, mean (SD) age was 43 (16) years, and females/males were equally represented.  Overnight plaque levels on the two arches were correlated (r=0.63) with significantly (p=0.0007) higher coverage on the mandibular arch.  The mean (SD) overnight plaque area% coverage was 15.4% on the maxillary arch and 21.4% on the mandibular arch.  43 subjects (74%) had more overnight mandibular plaque with mandibular-maxillary arches differing by 10.9% area coverage, while in contrast, 15 subjects (26%) had less mandibular plaque, differing by –7.9%.  While age in general was not an important factor, the 29 female subjects showed directionally higher plaque coverage on the mandibular arch. Comparing the age effect by gender, older females were more likely to have smaller differences between the two arches (r=–0.165) while older males were more likely to have larger differences (r=0.165).  

Conclusion: This research demonstrates factors associated with intraoral plaque distribution, and supports use of image analysis methods to assess overnight plaque accumulation for response mapping.