Evaluation of digital colorimetric analysis as an objective indicator representing microbial diversity and biological...

Visual assessment of dental plaque is limited by subjectivity and variability in imaging conditions.

This study aimed to objectively quantify plaque maturation using CIE L*a*b*-based color difference (ΔE*) and evaluate its association with microbial community structure and pathogenicity.

Dental images were obtained from 30 participants after application of a plaque-disclosing agent. Plaque color was quantified as ΔE* relative to unstained tooth surfaces and classified into Low-ΔE* and High-ΔE* groups. Saliva and supragingival plaque samples from Low-ΔE* and High-ΔE* sites were collected, and full-length 16S rRNA gene sequencing was performed using the PacBio Sequel IIe platform.

Saliva showed significantly higher microbial diversity than plaque samples. The Low-ΔE* group was dominated by early colonizers, including Streptococcus sanguinis, whereas the High-ΔE* group showed enrichment of anaerobic and periodontal disease-associated taxa, including Prevotella, Treponema, Selenomonas, Campylobacter, and Porphyromonas endodontalis. The lightness value (L*) was negatively correlated with periodontal pathogens, including Treponema denticola and Tannerella forsythia. PICRUSt2 analysis indicated upregulation of inflammatory pathways, including NOD-like receptor signaling and apoptosis, in the High-ΔE* group.

ΔE*-based colorimetric analysis may serve as an objective indicator of dental plaque maturation and pathogenic potential, supporting personalized oral hygiene feedback.