Signs and symptoms were correlated with microorganisms. Endodontic treatment was effective in reducing bacteria and endotoxins but was not capable of completely removing them from the root canal.

Objective:This clinical study sought to evaluate the effectiveness of passive ultrasonic activation (PUA) in eliminating microorganisms in primary endodontic infection (PEI) after instrumentation of root canals using microbiological culture and checkerboard DNA-DNA hybridization.Methodology:Twenty root canals with PEI and apical periodontitis were selected. The root canals were instrumented and then randomly divided into 2 groups, according to the irrigation method: PUA and conventional needle irrigation (CNI). Microbiological samples were collected before instrumentation (S1), after instrumentation (S2) and after irrigation with 17% EDTA (S3). The samples were subjected to anaerobic culture technique and checkerboard DNA-DNA hybridization analysis.Results:A statistically significant difference was found between CNI (23.56%) and PUA (98.37%) regarding the median percentage values for culturable bacteria reduction (p<0.05). In the initial samples, the most frequently detected species was S. constellatus (50%), and after root canal treatment was E. faecalis (50%).Conclusion:Both treatments significantly decreased the number of bacterial species compared with the initial sample. However, no statistical difference in the total microbial load between PUA and CNI groups was detected. The number of cultivable anaerobic bacteria reduced significantly using PUA, and the bacterial composition and number of bacterial species after using either CNI or PUA was similar.

ResumoIntrodução: A formação do Cisto Radicular (CR) está associada à proliferação dos restos epiteliais de Malassez por estímulos inflamatórios, provenientes da proliferação bacteriana do canal radicular de um dente não vital. Quando o dente é removido, esse cisto passa a ser denominado Cisto Residual (CRe). O tratamento de escolha para o CR é endodôntico, com o objetivo de eliminar a inflamação presente no periápice. No entanto, em alguns casos, o cisto pode continuar a crescer, necessitando de tratamento cirúrgico, o que ocorre na maioria dos casos de CRe. Objetivo: Avaliar o metabolismo do epitélio de revestimento de CR e CRe, utilizando a quantificação das AgNORs, e verificar a influência da presença de inflamação sobre o crescimento desses cistos. Material e método: Vinte casos de CR e dez de CRe foram submetidos à técnica de AgNOR. A análise quantitativa das NORs foi realizada utilizando-se o software 'Contando células' . O teste estatístico pós-hock de Newman-keuls foi realizado para a comparação do número médio de AgNORs entre CR e CRe, e entre áreas inflamadas e não inflamadas. Resultado: Diferença estatisticamente significante (p=0,0094) foi observada entre áreas inflamadas (1,86±0,26) e não inflamadas (1,65±0,20). Na comparação entre CR (1,81±0,28) e CRe (1,73±0,16), não houve diferença estatisticamente significante (p=0,37). Conclusão: A inflamação interfere no metabolismo epitelial de CR e CRe, o que reflete a ação de fatores de crescimento na proliferação do epitélio, contribuindo para o crescimento do cisto, independentemente da presença do fator etiológico associado com a origem da lesão.Descritores: Cisto radicular; cisto residual; inflamação; AgNOR. AbstractIntroduction: Radicular Cyst (RC) development is associated with the activation and proliferation of epithelial rests of Malassez. This occurs due to inflammatory stimuli resulting from bacteria proliferation in the root canal of a non-vital tooth. When the tooth is removed, the cyst becomes known as Residual Cyst (ReC). The RC common treatment is the endodontic therapy, with the aim of eliminating the inflammation in the periapical region. Nonetheless, this treatment is not always effective and the cyst may continue to grow, what happens in most cases of ReC. Objective: To evaluate the metabolism of the RC and ReC epithelial lining through the technique of AgNOR quantification and of the influence of the presence of inflammation in the growth of these cysts. Material and method: 20 cases of RC and 10 of ReC, were processed by the AgNOR technique. The AgNOR quantitative analysis was performed using the "Counting cells" software. The statistical post-hock Newman-Keuls test was applied to compare the RC and ReC mean number of AgNORs in inflamed and non-inflamed areas. Result: Statistically significant difference (p=0.0094) was observed between inflamed (1.86±0.26) and non-inflamed (1.65±0.20) areas. No statistically significant difference (p=0.37) was observed in the comparison between RC (1.81±0.28) and ReC (1.73±0.16). Conclusion: Inflammat...