The sample will be, at least, 90 primary molars, randomly distributed into three groups: Group 1: IPC; Group 2: SE; Group 3: SCR. Teeth must present deep caries lesions (at least 2/3 of dentin depth), pulp vitality (no clinical or radiographical signs of pulp disease, such as abcesses, fistulae, root resorption, abnormal tooth mobility). This study received approval by the Ethics Committee of Fluminense Federal University (UFF; Brazil) - # CAAE: 58812816.8.0000.5626. The study started in January, 2017; and will finish in December, 2020. Patients will be selected from the public schools in Nova Friburgo. The dental exams and treatment procedures will be done at the clinics from the

School of Dentistry, Health Institute of Nova Friburgo (ISNF). Laboratory proceedings will be done at:

• Clinical and Microbiological Research Laboratory (LAB PECMA - ISNF) - Sample storage, bacterial cultivation and identification.
• University of North Carolina at Chapel Hill
• Rio de Janeiro Federal University

The aims of this Randomized Clinical Trial are:

1. to evaluate the risk of pulpal exposure and tooth vitality maintenance of primary molars with deep caries lesions, treated with conservative techniques, such as Stepwise Excavation (SE) or Selective Caries Removal (SCR), and to compare with those teeth treated with Indirect Pulp Capping (IPC);
2. to verify changes in the cultivable microbiota isolated in the deep carious dentin lesions of deciduous molars, before and after performing the procedures of SE;
3. to clinically evaluate dentin reactions to the SE;
4. to provide longitudinal monitoring of changes in the non-cultivable microbiota (microbiome), found in dentin carious lesions of deciduous and permanent molars, compared to the treatments performed;
5. to determine, in vitro, the microbial metabolome of different strains isolated from dentin samples under conditions of high and low cariogenic challenge;
6. to correlate, in vitro, the microbial metabolites with the clinical classification of the cavitated lesions from which these samples originated.

The sample will be, at least, 90 primary molars, randomly distributed into three groups: Group 1: IPC; Group 2: SE; Group 3: SCR. Teeth must present deep caries lesions (at least 2/3 of dentin depth), pulp vitality (no clinical or radiographical signs of pulp disease, such as abcesses, fistulae, root resorption, abnormal tooth mobility). This study received approval by the Ethics Committee of UFF (Brazil) - # CAAE: 58812816.8.0000.5626. The study started in January, 2017; and will finish in December, 2020. Patients will be selected from the public schools in Nova Friburgo. The dental exams and treatment procedures will be done at the clinics from the

School of Dentistry, Health Institute of Nova Friburgo (ISNF). Laboratory proceedings will be done at:

LAB PECMA - ISNF - Sample storage, bacterial cultivation and identification University of North Carolina at Chapel Hill Rio de Janeiro Federal University

Inclusion Criteria:

1. The child need to be healthy;
2. This should be in the age range of 4 to 6 years of age;
3. The primary molars to be submitted to treatment should have the following characteristics: deep caries lesion (greater than or equal to 2/3 of dentine thickness) without clinical or radiographic aspects of pulp lesion, restoration margins above gingival line, absence of spontaneous pain or mobility, absence of periodontal changes, roots compatible with pulpal maturation stage.

Exclusion Criteria:

1. Children under use of controlled drugs or antibiotics.
2. Children who presented with some neurological or motor disorder that could influence the treatment procedure.
3. Molars with more than three lost walls or margins in subgingival area.
4. Patients with allergies to the medications used.
5. Patients in the pulpal regression stage in which the tooth is likely to be lost within 12 months.