Despite of the decline of dental caries, this disease is still common in polarized groups affecting children. Therefore, the aim of this randomized blind in vivo study was to compare the antimicrobial effect of two antimicrobial therapies in deciduous carious dentin. Thirty two patients aging from 5 to 7 years old had partial caries removal in deep carious dentin lesion in deciduous molar and were divided in three groups: 1. Control - chlorhexidine and resin modified glass ionomer cement (RMGIC); 2. LEDTB - antimicrobial photodynamic therapy (APDT) with LED (light emission diode) associated with toluidine blue orto dye solution and RMGIC; 3. LMB - APDT with laser associated with methylene blue dye solution and RMGIC. The patients were submitted to initial clinical and radiographic examination and demographic features were evaluated by biofilm, gingival, and dmft/dmfs indexes, besides clinical and radiographic follow up at 6 and 12 months after the treatments. The carious dentin was collected before and after each treatment and the number of Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, Fusobacterium nucleatum, Atopobium rimae and total bacteria were established by quantitative PCR.

Inclusion Criteria:

• Inclusion criteria consisted of good general health, without syndromes or chronic systemic diseases. They should also have at least one primary molar with deep carious lesion (2/3 of dentin) without pain symptomatology and compatible with reversible pulpits.

Exclusion Criteria:

• Children whose parents refused to sign the informed consent document, who did not cooperate with the clinical exams, whose teeth had the treatment choice changed (pain or evolution to irreversible pulpits), who did not attend to the appointments for the scheduled treatments, or who needed antibiotics treatment for other medical reasons were excluded from the study without prejudice.