Abstract: The purpose of this manuscript was to re-discuss apical periodontitis, apical biofilm, and its possible relationship with dendritic cells (DC). DCs are potent regulators of the immune system and their function is divided into three categories that involve the presentation of antigens: the presentation of antigens and activation of T cells; a not well established category suggested that DCs induce and maintain immunological tolerance; and the maintenance of the immune memory in conjunction with B cells. DCs in periapical inflammatory lesions are composed of at least two subpopulations that can be distinguished on the basis of ultrastructure and phenotype. These populations might differ in lineage, state of maturation, differentiation, activation, and/or function. The authors hereby analyzed the root apexes of teeth under SEM, after performing apicoectomy due to the failure of conventional endodontic treatment. Microbial biofilm with multispecies and areas of resorption with the presence of Howship lacunae, and images suggestive of denditric cells could be observed. The presence of DCs in periapical lesion could be an indication of the severity of the lesion, with a constant presence of antigen in the periradicular region.

Aim: To evaluate, by confocal laser scanning microscopy (CLSM), the influence of 17% EDTA final irrigation on the penetration of an endodontic resin-based sealer into dentinal tubules after use of 2% chlorhexidine gel. Methods: Forty extracted bovine incisors were instrumented according to the groups: G1 - root canal preparation with 2% chlorhexidine gel (n=10); G2 - root canal preparation with 2% chlorhexidine gel and final irrigation with 17% EDTA (n=10); G3 - root canal preparation with saline and final irrigation with 17% EDTA (n=10); G4 - root canal preparation with saline (n=10). The samples were filled with gutta-percha using AH Plus sealer with rhodamine B fluorescent dye. After seven days, the teeth were sectioned at the coronal, middle, and apical thirds and viewed under confocal microscope. The most representative area of penetration depth was measured in each group. Statistical significance for the sealer penetration area was determined among groups using one-way ANOVA followed by Tuckey test. For thirds comparison, in each group, data were statistically analyzed using Friedman test (p<0.05). Results: The maximum penetration was provided by G2 - 2% chlorhexidine + EDTA (p=0.000). According to this criterion, no differences were found among the other groups and among thirds within the same group. Conclusions: Based on these results, the use of 17% EDTA should be indicated after root canal preparation with 2% chlorhexidine gel for smear layer removal, enhancing the AH Plus sealer penetration.

OBJETIVO: Diferentes técnicas são propostas para melhorar a remoção da pasta de hidróxido de cálcio. O objetivo do presente estudo in vitro foi comparar a efetividade das técnicas ultrassônica e manual para a remoção do hidróxido de cálcio do canal radicular. METODOLOGIA: Trinta e oito dentes monorradiculares foram divididos em dois grupos de 19 dentes cada. Os dentes foram preparados através da técnica de coroa-ápice até o instrumento memória #50. Após o preparo, os canais foram radiografados e, então, preenchidos com hidróxido de cálcio. A remoção da pasta no grupo I foi feita com o uso do ultrassom enquanto que no grupo II, a pasta foi removida através da técnica manual. Os dentes foram radiografados novamente para avaliar a remoção do hidróxido de cálcio. As radiografias foram digitalizadas e os terços avaliados de acordo com os níveis de cinza para quantificar a remoção do hidróxido de cálcio. Os testes para amostras independentes e o t de Student (α=0.05) foram aplicados para comparar a remoção da pasta entre os grupos e entre os terços do canal. RESULTADOS: Não houve diferença entre as técnicas ultrassônica e manual para a remoção do hidróxido de cálcio do canal radicular. Não houve diferenças estatísticas na comparação ente os terços avaliados. CONCLUSÃO: Nem a técnica manual nem a ultrassônica removeram completamente o hidróxido de cálcio do canal radicular.

PURPOSE: Different techniques have been proposed to improve the removal of calcium hydroxide. The purpose of this in vitro study was to compare the effectiveness of ultrasound and manual techniques in the removal of calcium hydroxide from root canals. METHODS: Thirty-eight single-rooted teeth were divided into two groups of 19 teeth each. The teeth were prepared using the crown-down technique with an apical master file #50. After shaping, the canals were radiographed and dressed with calcium hydroxide. After 14 days, the calcium hydroxide was removed with the ultrasound technique in group I and through manual filing in group II. The teeth were then radiographed again to evaluate the removal of the paste. To assess the calcium hydroxide removal, the radiographs were scanned and analyzed based on the gray levels. The independent samples and Student's t-tests (α=0.05) were used for each group to compare the efficacy of calcium hydroxide removal between the groups and among thirds (cervical, middle and apical). RESULTS: There was no difference between ultrasound and manual techniques in the removal of calcium hydroxide from root canals. There were no statistical differences among the thirds analyzed. CONCLUSION: Neither manual nor ultrasonic techniques completely removed calcium hydroxide from the root canal.