Avaliação da terapia fotodinâmica antimicrobiana no tratamento endodôntico de dentes decíduos anteriores com necrose pulpar: ensaio clínico randomizado e controlado com análise microbiológica e a avaliação cega dos desfechos clínicos e radiográficos

Abstract

Disinfection of the root canal system remains one of the main challenges in the endodontic treatment of primary teeth with pulp necrosis, and antimicrobial photodynamic therapy (aPDT) has been proposed as an adjunctive strategy for intracanal infection control. This study evaluated the efficacy of aPDT in reducing intracanal microbial load and in the clinical and radiographic progression of anterior primary teeth with pulp necrosis. This randomized controlled clinical trial included 20 anterior primary teeth from seven children aged 2 to 5 years, allocated to two groups: conventional endodontic treatment (G1; n = 10) and antimicrobial photodynamic therapy (G2; n = 10). The experimental unit was the tooth. The initial microbiological sample (S1) was collected after coronal access and before the intervention, whereas the final sample (S2) was obtained after chemomechanical preparation in G1 and after aPDT application in G2, without prior chemomechanical preparation or sodium hypochlorite irrigation. The photodynamic protocol employed 0.005% methylene blue (Chimiolux®), with a pre-irradiation time of 3 minutes, followed by one intracanal application per tooth using a red Therapy XT laser (DMC, São Carlos, SP, Brazil), operating in continuous-wave mode at a wavelength of 660 nm, with a mean radiant power of 100 mW, an irradiation time of 90 seconds, and a radiant energy of 9 J, delivered through an intracanal optical fiber. After the interventions and S2 collection, the root canals were filled with UltraCal® XS calcium hydroxide paste (Ultradent, Indaiatuba, SP, Brazil), a thin gutta-percha base was placed, and the teeth were provisionally sealed with Riva® glass ionomer cement (SDI, Bayswater, Victoria, Australia). After seven days, the teeth were reopened for removal of the intracanal medication, followed by irrigation with 1% sodium hypochlorite solution (Milton solution) and definitive root canal filling with Guedes-Pinto iodoform paste. Restorative treatment was performed in a subsequent session. Microbial load was expressed as log₁₀ CFU/mL and analyzed using a linear mixed-effects model, whereas radiographic outcomes were assessed using Generalized Estimating Equations, with a significance level of 5%. A significant group-by-time interaction was observed (p = 0.008). No difference was found between the groups at the pre-intervention time point (p = 0.634); however, after the intervention, the aPDT group showed a lower intracanal microbial load than the conventional treatment group (p = 0.017), with a greater magnitude of microbial reduction (Δ = −0.716 log₁₀ CFU/mL; p < 0.001) compared with the conventional treatment group (Δ = −0.340 log₁₀ CFU/mL; p = 0.001). Clinical and radiographic outcomes showed favorable progression during follow-up, with no statistically significant differences between the groups regarding the presence of periapical lesions. It was concluded that antimicrobial photodynamic therapy promoted a greater immediate reduction in intracanal microbial load, supporting its potential as an adjunctive strategy for intracanal infection control in anterior primary teeth with pulp necrosis.