Antimicrobial Efficacy of Photodynamic Therapy as an Adjunct to Brix 3000 in Minimally Invasive Management of Carious Lesions in Primary Teeth

<b>Background/Objectives</b>: In the context of minimally invasive dentistry, photodynamic therapy (PDT) is regarded as a biologically oriented method for controlling microbial activity during caries excavation. Brix 3000 is a modern material used in chemo-mechanical removal of carious lesions, enabling selective elimination of infected dentin. The present study compares the antimicrobial effectiveness of Brix 3000 and adjunctive PDT performed with the FotoSan 630 Intro Kit. <b>Methods</b>: This study included 30 children aged 4-7 years with carious lesions on primary molars classified as ICDAS II code 06. The lesions were allocated into two groups: Group 1 (the control group), encompassing 15 lesions excavated using Brix 3000 only, and Group 2 (the experimental group), encompassing 15 lesions excavated with Brix 3000 followed by adjunctive PDT with the FotoSan 630 Intro Kit. A total of 75 microbiological samples were collected: 30 from infected dentin before excavation, 30 from partially infected dentin after Brix 3000, and 15 (experimental group only) after subsequent PDT. <b>Results</b>: The results revealed a wide diversity of cariogenic microorganisms in the infected dentin, with S. mutans being the most frequently isolated and present in the highest quantities. Using Brix 3000 reduced microbial diversity and quantity following excavation of partially infected dentin, although <i>S. mutans</i> persisted at lower levels. <b>Conclusions</b>: After the additional photodynamic disinfection, no microorganisms were isolated from the partially infected dentin. Adjunctive PDT provides localized, non-invasive antimicrobial disinfection and can be integrated into minimally invasive caries management in primary teeth.