Ação da clorexidina e do hipoclorito de sódio sobre a microdureza dentinária / Action of chlorhexidine and sodium hypochlorite over dentin microhardness

Objetivo: Avaliar a microdureza do tecido dentinário bovino após a exposição a soluções irrigantes em Endodontia. Métodos: Amostras de dentina bovina foram divididas aleatoriamente em seis grupos (n=10) e submetidas aos seguintes tratamentos: soro (60 min); NaOCl a 2,5% (hipoclorito de sódio) (60 min); CHX gel a 2% (clorexidina) (60 min); EDTA a 17% (ácido etilenodiaminotetracético) (1 min); NaOCl a 2,5% + EDTA a 17% (60 + 1 min) e CHX gel a 2% + EDTA a 17% (60 + 1 min). A microdureza Knoop foi utilizada para as medidas. Os dados foram avaliados pelo teste ANOVA, seguido pelo método de Duncan, com nível de significância de 5%. Resultados: A solução de NaOCl a 2,5%, seguida ou não de EDTA a 17%, reduziu significativamente a microdureza dentinária (p<0,05). A exposição à clorexidina gel a 2%, seguida ou não de EDTA a 17%, não resultou em alterações na microdureza dentinária (p>0,05). Conclusão: NaOCl a 2,5% reduziu significativamente a microdureza da dentina bovina após 60 minutos de exposição (AU).

Objective: Evaluate the microhardness of bovine den- tin tissue after exposure to endodontic irrigating solu- tions. Methods: Bovine dentin samples were randomly divided into 6 groups (n = 10) and submitted to the following treatments: saline (60 min); 2.5% NaOCl (sodium hypochlorite) (60 min); 2% gel CHX (chlorhexidine) (60 min); 17% EDTA (Ethylenediamine tetraacetic acid) (1 min); 2.5% NaOCl + 17% EDTA (60 + 1 min) and 2% gel CHX + 17% EDTA (60 + 1 min). Knoop microhardness was used for the measurements. Data were evaluated by ANOVA test followed by Duncans Method at 5% signifi- cance level. Results: The 2.5% NaOCl solution, followed or not by 17% EDTA, significative reduced the dentin microhardness (p <0.05). Exposures to 2% gel chlorexidine, followed or not by 17% EDTA, did not result in alterations at dentin tissue microhardness (p>0.05). Conclusion: 2.5% NaOCl significatively reduces the microhardness of bovine dentin after 60 minutes of exposure (AU).

Antimicrobial activity of intracanal dressings composed by natural products associated to chlorhexidine and its influence on dentinal colour change / Avaliação da ação antimicrobiana de medicações intracanais à base de produtos fitoterápicos associados à clorexidina e sua influência na alteração de cor da estrutura dentinária

Purpose: evaluate the antimicrobial activity of intracanal dressings and their influence on dentinal colour changes. Material and methods: eighty single-rooted human extracted teeth were decoronated and divided into eight groups (n=10) according to intracanal dressing protocols inserted into the root canals: G1­distilled water (DW); G2­2% chlorhexidine gel (CHX); G3­calcium hydroxide (Ca[OH]2)+DW; G4­grape seed extract (GSE)+DW; G5­ginger extract (GE)+DW; G6­Ca(OH)2+CHX; G7­GSE+CHX; and G8­GE+CHX. The antimicrobial activity was evaluated by colony-forming units (CFUs) counting and dentinal colour changes was evaluated by digital spectrophotometry. Data were statistically analysed by One-way ANOVA followed by Tukey´s post hoc test (antimicrobial evaluation) and non-parametric Wilcoxon followed by the Mann- Whitney-U test (colour change evaluation) (α=0.05). Results: the highest bacterial reduction was observed in groups 4, 6, 7 and 8, with no significant difference between them (p<0.05). Groups 4 and 7 showed the highest medians of dentinal colour change (p<0.05). Conclusion: the addition of CHX improved the antimicrobial activity of GE-based intracanal dressing, with no effect in GSE-based intracanal dressing; moreover, these protocols induced significant dentinal colour changes. (AU)

Objetivo: avaliar a atividade antimicrobiana de medicações intracanais e sua influência na alteração da cor dentinária. Materiais e métodos: oitenta dentes humanos extraídos unirradiculares foram seccionados e divididos em oito grupos (n = 10), de acordo com os protocolos de medicação intracanal inseridos nos canais radiculares: água destilada G1 (DW); G2-2% de gel de clorexidina (CHX); hidróxido de cálcio G3 ­ (Ca [OH] 2) + DW; extrato de semente de uva G4 (GSE) + DW; extrato de gengibre G5 (GE) + DW; G6- Ca (OH) 2 + CHX; G7 ­ GSE + CHX; e G8-GE + CHX. A atividade antimicrobiana foi avaliada por contagem de unidades formadoras de colônias (UFCs) e as alterações de cor dentinária foram avaliadas por espectrofotometria digital. Os dados foram analisados estatisticamente por ANOVA one-way, seguida pelo teste post hoc de Tukey (avaliação antimicrobiana) e Wilcoxon não paramétrico, seguido pelo teste de Mann- Whitney-U (avaliação da mudança de cor) (α = 0,05). Resultados: a maior redução bacteriana foi observada nos grupos 4, 6, 7 e 8, sem diferença significativa entre eles (p < 0,05). Os grupos 4 e 7 apresentaram as maiores medianas da alteração da cor dentinária (p < 0,05). Conclusão: a adição de CHX melhorou a atividade antimicrobiana da medicação intracanal baseado em GE, sem efeito na medicação intracanal baseado em GSE; além disso, esses protocolos induziram alterações significativas na cor dentinária.(AU)

Effectiveness of final decontamination protocols against Enterococcus faecalis and its influence on bond strength of filling material to root canal dentin.

AIM: The aim of this study was to evaluate the effectiveness of final decontamination protocols against Enterococcus faecalis and their influence on bond strength of filling material to root canal dentin. MATERIAL AND METHODS: Ninety root canals were enlarged with ProTaper system and inoculated with E. faecalis for 15days. Sixty samples were randomly divided into six groups (n=10) and subjected to following protocols: G1-distilled water(control), G2-2% chlorhexidine, G3-QMix, G4-6.5% grape seed extract, G5-photodynamic therapy with optical fiber and G6-photodynamic therapy without optical fiber. The percentage of bacterial reduction was checked by counting of CFUs. The remaining 30 samples were subjected to the same decontamination protocols (n=5) and filled with gutta-percha and AH Plus sealer in order to perform the push-out test. Data from both tests were subjected to one-way ANOVA followed by Tukey's post hoc procedure (α=0.05). RESULTS: The greatest bacterial reduction was observed for 2% chlorhexidine, QMix and 6.5% grape seed extract, with no statistically significant difference between them. Photodynamic therapy, with and without optical fiber, demonstrated a significantly higher reduction than distilled water, with no statistically significant difference between them (p<0.05). For the push-out test, final decontamination protocols showed similar bond strength values (p<0.05), with the highest incidence of cohesive failure in all groups. CONCLUSIONS: The tested final decontamination protocols showed effectiveness against E. faecalis and did not interfere with the bond strength of filling material to root canal dentin.