Effect of reciprocating instrumentation on chlorhexidine substantivity on human dentin: chemical analysis followed by confocal laser microscopy

The present research analyzed the reciprocating instrumentation associated to chlorhexidine (CHX) substantivity as its correlation with E. faecalis viability in ex vivo root canals. Eighty extracted single-rooted human teeth were used, being 40 to high-performance liquid chromatography (HPLC) and 40 to confocal laser scanning microscopy (CLSM). In both, teeth were decoronated and the cervical third was prepared. In the CLSM analysis, the root canals were inoculated with E. faecalis for 14 days. Samples were divided into 4 groups (n=10) according to instrumentation technique: no instrumentation and irrigation with distilled water (control); manual instrumentation (K-File); rotary instrumentation (ProTaper Next); and reciprocating instrumentation (Reciproc R25). Two percent chlorhexidine was applied as irrigating substance in experimental groups. Longitudinal grooves resulted in 2 halves root and 20 proof bodies in each group. Samples were divided by chance in two groups (n=10) and the outcomes were evaluated after two days and one week. The retained chlorhexidine and live cells after instrumentation techniques in each evaluation time was measured by HPLC and CLSM, respectively. Specific analysis was applied for experimental tests (p≤0.05). Both rotary as well as reciprocating techniques significantly reduced the amount of chlorhexidine on dentin in all observation periods (p<0.05). After evaluation times, all experimental groups presented lower live cells compared to control, but without statistically difference. Intragroup comparisons in times of evaluation showed no differences in instrumentation techniques, in chlorhexidine retention and number of live cells (p>0.05). Reciprocating instrumentation does not interfere on chlorhexidine substantivity.

Association between history of orthodontic treatment and sociodemographic factors in adolescents / Associação entre histórico de tratamento ortodôntico e fatores sociodemográficos em adolescentes

The aim of this study was to assess history of orthodontic treatment and its determinants in adolescents. This was a crosssectional study conducted in the city of Passo Fundo, Brazil, on a representative sample of adolescents aged 15 to 19 years, regularly enrolled in 20 high schools. A structured questionnaire was applied to assess demographic, behavioral and health variables. The association between history of orthodontic treatment and the dependent variables was analyzed by the chisquare test or Fisher's exact test. Additionally, multivariate regression with robust variance was performed. A total 736 students were examined and interviewed, of whom 57.6% had undergone orthodontic treatment, while 42.4% had not. In the multivariable analysis, the following variables were significantly associated with history of orthodontic treatment: female (PR= 1.26; 95% CI: 1.11 ­ 1.43), white (PR= 1.32; 95% CI: 1.11 ­ 1.56), mothers with higher level of education (PR=1.49; 95% CI: 1.28 ­ 1.74), tooth loss (PR=1.21; 95% CI: 1.06 ­ 1.39), and concern about oral health (PR=0.69; 95% CI: 0.61 ­ 0.78). Attending a private school was not significantly associated with history of orthodontic treatment (p>0.05). This study found a high rate for history of orthodontic treatment among adolescents, associated with gender, ethnicity, adolescent's mother with higher education, and tooth loss. Concern about oral health was a protective factor for orthodontic treatment (AU)

Esse estudo objetivou verificar o histórico de tratamento ortodôntico e seus fatores associados. Esse estudo transversal foi conduzido na cidade de Passo Fundo, Brasil, com uma amostra representativa dos adolescentes regularmente matricu lados no ensino médio, com idades entre 15 e 19 anos, de 20 escolas. Um questionário estrutura foi aplicado para acessar variáveis demográficas, comportamentais e de saúde. As associações entre histórico de tratamento ortodôntico e as variáveis independentes foram analisadas pelos testes de quiquadrado ou exato de Fisher. Além disso, regressão multivariada com variância robusta foi realizada. 736 estudantes foram examinados e entrevistados. Tratamento ortodôntico foi reali zado por 57,6% dos adolescentes, enquanto que 42,4% dos participantes não o mencionaram. Na análise multivariada, as seguintes variáveis estiveram significativamente associadas com histórico de tratamento ortodôntico: sexo feminino (PR= 1,26; 95%CI: 1,11 ­ 1,43), branco (PR= 1,32; 95%CI: 1,11 ­ 1,56), mães com alto nível educacional (PR=1,49; 95%CI: 1,28 ­ 1,74), perda dentária (PR=1,21; 95%CI: 1,06 ­ 1,39) e preocupação com a saúde bucal (PR=0,69; 95%CI: 0,61 ­ 0,78). Ir a uma escola privada não esteve significativamente associado com histórico de tratamento ortodôntico (p>0,05). Esse estudo demonstrou que altos níveis de histórico de tratamento ortodôntico são encontrados em adolescentes e isso está associado com sexo, etnia, alta escolaridade da mãe do adolescente e perda dentária. Preocupação com a saúde bucal mostrouse como um fator protetor para o tratamento ortodôntico (AU)