Introduction: Streptococcus mutans and S. sobrinus are the main causative agents of human dental caries. Objective: To analyze the literature on different genera of Streptococcus such as S. mutans, S. gordonii, S. sanguis, S. sobrinus and S. salivarius in relation to orthodontics.Methodology: Articles on the subject published through the PubMed, SCOPUS and Google Academic databases were analyzed, with an emphasis on the last 5 years. It was carried out with the words "Streptococcus mutans", "S. gordonii", "S. sanguis", "S. sobrinus ", "S. salivarius". Results: S. mutans: produces dental caries and demineralization of the enamel. It can be controlled with proper brushing techniques and oral hygiene. S. gordonii: predominates in the oral microflora and triggers cariogenic biofilms, is present in the formation of white spots around brackets and its development can be inhibited with fluoride-containing rinses. S. sanguis: present in orthodontic appliances, they have adverse effects that help the formation of dental plaque, mouthwash with nanio TiO2 and a good mechanical and chemical cleaning help to eliminate them. S. sobrinus: forms white spots, demineralizes enamel and causes dental caries. S. salivarius: its acid-base physiology plays an important role, the use of orthodontic appliances can produce an increase in bacteria which is associated with metal alloys. Conclusion: Streptococcus species are a problem in orthodontics, they can be eliminated by using Enlight composite resin, 0.02% chlorhexidine rinses, mouthwash with nanioTiO2 and a good mechanical and chemical brushing technique.

Introduction: Root therapy in primary teeth aims to remove the necrotic pulp, to prevent premature tooth loss, and to maintain the primary teeth until exfoliation. Rotary systems allow for more effective root canal treatments. Objective: To analyze the literature for the characteristics of the rotary systems such as root canal preparation, obturation time, post-operative pain and clinical success. Methodology: A exhaustive research was performed in PUBMED, to find relevant studies about the use of rotary systems in pediatric dentistry. Results: Rotary files provide a greater root canal preparation, show more conservation of tooth structure with less mistakes in comparison with other techniques. This technique simplifies the procedure, shows less post operative pain, and is reflected in the cooperation of the pediatric patient. Rotary files exhibit a significant cleaning efficacy and a greater bacterial removal that led to a significant clinical success. Conclusion: due to the complexity of the primary roots and how precise the root canal treatment must be. The use of rotary techniques can improve root canal treatment of primary teeth.

Introduction: Apical periodontitis is a sequela of endodontic infection, which manifests as a host defense response to the microbial challenge emanating from the root canals. To achieve an optimal outcome, microorganisms must be eliminated or reduced to levels that allow healing of the periradicular tissue. Objective: To analyze the literature on microorganisms, such as Enterococcus faecalis, Fusobacterium nucleatum, Candida albicans, Epstein-Barr, which are important in persistent apical periodontitis. Methodology: Articles on the subject published through PubMed, SCOPUS and Google Scholar databases were analyzed, with emphasis on the last 5 years. It was performed with the words "Enterococcus faecalis", "Fusobacterium nucleatum", "Candida albicans", "Epstein-Barr", "Herpesviridae", "Root canals", "Persistent apical periodontitis". Results: E. faecalis involved in persistent apical periodontitis because of its adaptability to extreme environments, growing in alkaline pH and using periodontal ligament fluids as nutrients. Lysed Fusobacterium nucleatum cells could potentially increase the severity of persistent apical periodontitis. Candida albicans is one of the dominant pathogens in persistent apical periodontitis because of its membrane protein Msb2. Epistein-Barr virus may be implicated in the pathogenesis of apical periodontitis by direct cytopathic action on infected cells, however, its replication in persistent apical periodontitis is still unclear. Conclusions: The microbiota of teeth with persistent apical periodontitis, presents a mixed and complex profile, it is important to know the role of these microorganisms, because microbial persistence, seems to be the most important factor in root canal treatment failure.