Diagnostic performance of a portable autofluorescence imaging system (Qraycam PRO) for the detection of mature supragingival biofilm: a tooth-level diagnostic accuracy study.

BACKGROUND AND OBJECTIVE: Conventional plaque indices are operator-dependent and subject to substantial inter- and intra-examiner variability. Portable autofluorescence imaging-based on red autofluorescence from bacterial porphyrins-has been proposed as a chairside adjunct, but its diagnostic accuracy across different levels of biofilm maturity remains insufficiently characterized. We evaluated the diagnostic performance of the portable Qraycam PRO autofluorescence imaging system for the detection of supragingival dental plaque, using disclosed-plaque scoring as the reference standard.

MATERIALS AND METHODS: In this single-center cross-sectional diagnostic accuracy study, 40 systemically healthy adults underwent autofluorescence imaging of the labial surfaces of the anterior teeth (FDI 13-23 and 33-43). After exclusion of missing or prosthetically restored teeth, 467 tooth surfaces were available for analysis. Fluorescence images were acquired before application of a two-tone plaque disclosing agent to avoid spectral interference; the Silness and Löe Plaque Index (PI) was then recorded for each surface. The presence or absence of red autofluorescence was scored independently from the stored images. To accommodate intra-subject clustering, Generalized Estimating Equations (GEE) with an exchangeable working correlation structure were used to estimate sensitivity, specificity, and adjusted odds ratios (AOR) at two thresholds: any biofilm (PI ≥ 1) and mature biofilm (PI ≥ 2). Reporting follows the STARD 2015 guidelines.

RESULTS: At the PI ≥ 1 threshold the system showed a sensitivity of 19.64% (95% CI 15.41-24.69) and a specificity of 93.58% (95% CI 89.12-96.29) (AOR = 3.65; 95% CI 2.04-6.52; P < 0.001); at PI ≥ 2, sensitivity rose to 33.64% (95% CI 25.49-42.89) and specificity remained high at 91.60% (95% CI 88.26-94.05) (AOR = 4.81; 95% CI 2.63-8.80; P < 0.001). The red-fluorescence detection rate increased monotonically with biofilm maturity (6.42% at PI = 0, 10.59% at PI = 1, 23.29% at PI = 2, and 54.05% at PI = 3).

CONCLUSIONS: The portable Qraycam PRO autofluorescence imaging system demonstrated a maturity-selective diagnostic profile-high specificity (> 90%) combined with limited sensitivity for immature biofilm-consistent with its proposed porphyrin-dependent mechanism. The device is therefore best positioned as a confirmatory chairside adjunct for the identification of clinically significant mature biofilm rather than a stand-alone screening tool, and may contribute to objective plaque-site identification during patient motivation and supportive periodontal therapy.