Dental plaque disclosing gel: An effective detecting agent for guiding debridement of bacterial biofilms in periprosthetic joint infection

Abstract

Objectives

The presence and invisibility of biofilms are critical factors contributing to incomplete debridement in periprosthetic joint infection (PJI), often leading to infection relapse and failure of debridement, antibiotics, and implant retention (DAIR) procedures or subsequent revision surgeries. GC Tri Plaque ID Gel™ (GC gel), a three-tone disclosing gel, is widely used in dentistry to assess plaque presence, maturation and acidity by different colors. However, its potential in PJI remains unvalidated. This study aimed to assess GC gel’s feasibility in visualizing implant surface biofilm, distinguishing maturity and guiding DAIR procedures.

Methods

Murine subcutaneous biofilm infection models with fluorescence-labeled Methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) were used to simulate biofilm formation. Infected implants collected at different time points were observed under fluorescence microscopy, followed by GC gel staining. Staining accuracy, sensitivity, the Dice and the Jaccard scores were calculated by comparing fluorescence and stained images. Bacterial load and inflammatory responses were evaluated via bacterial counting and routine blood tests. A murine PJI model was used to assess the debridement effectiveness of GC gel-guided DAIR through microbiological, hematological, and histological analysis. Clinical PJI prostheses were stained to evaluate GC gel’s clinical applicability.

Results

GC gel demonstrated over 70% accuracy in visualizing MRSA biofilms, and the sensitivity reached 88.67 ± 4.54%. The Dice and the Jaccard scores were 0.81 ± 0.04 and 0.68 ± 0.06, respectively. Infected implants, including clinical PJI prostheses, exhibited distinct red, blue, and purple staining, indicating biofilm maturity and stage. In contrast, sterile implants and non-infected clinical prostheses could not be stained. With prolonged infection, bacterial load and systemic inflammation increased, reflected by changes in staining intensity and area. GC gel-guided DAIR resulted in lower bacterial load and inflammation in the animal model. Staining of clinical prostheses showed biofilm aggregation in static regions of the joint cavity, with low density on the articulating surface.

Conclusions

GC gel can effectively visualize biofilms and assesses biofilm maturity, revealing biofilm distribution patterns on prosthetic surfaces. GC gel-guided DAIR exhibited superior debridement outcome in animal model, supporting its potential in further PJI treatment.