Characterization of sound enamel and natural white spot lesions / Caracterização de esmalte hígido e lesões de mancha branca naturais

Objective: To compare optical, morphological, chemical, and physical aspects of the sound enamel and white spot lesions (WSL) classified as ICDAS 2. Material and Methods: Seventeen human molars with one surface presenting WSL and a sound surface (2 x 2 mm window) were characterized by Quantitative light-induced fluorescence (QLF ®), Optical coherence tomography (OCT), microhardness, and Raman spectroscopy. The ANOVA and Tukey's test were used at 5% significance level. Results: The QLF comparison between distinct substrates yielded decreased ∆Q (integrated fluorescence loss) of -15,37%mm2 and -11,68% ∆F (fluorescence loss) for WSL. The OCT detected mean lesion depth of 174,43 µm. ANOVA could not detect differences in the optical attenuation coefficient between the substrates (p>0.05). Lower microhardness measures were observed in WSL than on sound enamel (p<0.05). The Raman spectra showed four vibrational phosphate bands (v1, v2, v3, v4), where the highest peak was at 960.3 cm-1(v1) for both substrates. However, a 40% decrease in phosphate (v1) was detected in WSL. The peak at 1071 cm-1 was higher for sound enamel, indicating the presence of a phosphate band instead of the B-type carbonate. The spectra showed higher intensity of the organic composition at 1295 cm-1 and 1450 cm -1 for WSL. Conclusion: Non-invasive QLF, OCT and Raman spectroscopy were able to distinguish differences in fluorescence, optical properties, and organic/inorganic components, respectively, between sound enamel and WSL, validated by the destructive microhardness analysis. (AU)

Objetivo: Comparar os aspectos ópticos, morfológicos, químicos e físicos do esmalte sadio e das lesões de mancha branca naturais, classificada como ICDAS 2. Material e métodos: Dezessete molares humanos com uma face apresentando uma lesão de mancha branca natural e outra face o esmalte hígido (2 x 2 mm) foram caracterizados utilizando a Fluorescência quantitativa induzida pela luz (QLF ®), Tomografia de coerência óptica (OCT), Microdureza e Espectroscopia Raman. A ANOVA e o teste de Tukey foram utilizados ao nível de significância de 5%. Resultados: A comparação entre os substratos distintos, utilizando o QLF ® demonstrou uma diminuição no ∆Q (perda de fluorescência integrada) de -15,37%mm2 e -11,68% de ∆F (Perda de fluorescência) para a lesão de mancha branca. O OCT detectou uma profundidade média de lesão de 174,43µm. A ANOVA não detectou diferenças no coeficiente de atenuação óptica entre os substratos (>0,05). Microdureza significantemente menor foi detectada nas lesões de mancha branca do que no esmalte sadio (p<0,05). Os espectros Raman mostraram quatro bandas vibracionais do fosfato (v1,v2,v3,v4), onde o maior pico foi em 960,3cm-1para ambos os substratos. No entanto, uma diminuição de 40% no fosfato (v1) foi detectada na lesão. O pico em 1071cm-1foi maior para o esmalte hígido, demonstrando tratar-se da banda do fosfato, ao invés do carbonato tipo B. Os espectros apresentaram maior intensidade da composição orgânica em 1295cm-1e 1450 cm-1para a lesão de mancha branca. Conclusão:Os métodos não invasivos QLF, OCT e espectroscopia Raman foram capazes dediferenciar a fluorescência, propriedades ópticas e conteúdo orgânico/inorgânico do esmalte sadio comparado com esmalte com lesões de mancha branca, sendo validado pela análise de microdureza. (AU)

Antibacterial efficacy of synthetic and natural-derived novel endodontic irrigant solutions

Abstract The aim of this study was to compare the efficacy of grape seed extract (GSE), calcium hypochlorite [Ca(ClO)2], and sodium hypochlorite (NaOCl) irrigant solutions with rotary or reciprocating instrumentation for disinfection of root canals inoculated with Enterococcus faecalis. The mesiobuccal root canals of mandibular molars were prepared and inoculated with Enterococcus faecalis for 21 days. The roots were then randomly divided into the following eight experimental groups (n=11) according to the instrumentation technique and disinfection protocol: ProTaper Next or Reciproc R25 with sodium chloride (control group), 6% NaOCl, 6% Ca(ClO)2, or 50% GSE used for irrigation during instrumentation. The antimicrobial activity was determined on the basis of a reduction in colony-forming units (CFUs) counted on bacterial samples collected before and after root canal instrumentation and expressed as a percentage of reduction. Data were evaluated by two-way ANOVA followed by Tukey HSD post-hoc tests (p<0.05). No significant differences were observed in bacterial reduction between the ProTaper Next and Reciproc R25 systems (p>0.05), regardless of the irrigant solution used. Furthermore, all active solutions (6% NaOCl, 50% GSE, and 6% Ca(ClO)2) showed similar potential to reduce bacterial counts (p>0.05) and were significantly more effective than sodium chloride (control) (p<0.05). The results suggest that the GSE and Ca(ClO)2 have potential clinical application as irrigant solutions in endodontic therapy since they present bactericidal efficacy against Enterococcus faecalis.

Resumo O objetivo deste estudo foi comparar a eficácia do extrato de semente de uva (ESU), hipoclorito de cálcio [Ca(ClO)2] e hipoclorito de sódio (NaOCl) como soluções irrigadores quando utilizadas com instrumentos reciprocantes e rotatórios para desinfecção de canais radiculares infectados com Enterococcus faecalis. Raízes mesio-vestibulares de molares inferiores foram preparados e inoculados com E. faecalis por 21 dias. As raízes foram aleatoriamente divididas em 8 grupos (n=11) de acordo com a técnica de instrumentação e protocolo de irrigação: ProTaper Next ou Reciproc R25 associados com soro fisiológico (grupo controle), Ca(ClO)2 6%, NaOCl 6% ou ESU 50%. A atividade antimicrobiana foi determinada pela redução do número de Unidades Formadoras de Colonias (UFCs) coletadas antes e após a instrumentação e expressas em porcentagens de redução. Os dados foram analisados estatisticamente pelos testes ANOVA seguido pelo teste complementar de Tukey HSD (p<0,05). Não foi encontrado diferença estatisticamente significante na redução bacteriana entre os sistemas ProTaper Next e Reciproc R25 (p>0.05), independente da solução irrigadora usada. Além disso, todas as soluções ativas (NaOCl, ESU e Ca(ClO)2) mostraram similar potencial em reduzir a quantidade de bactérias (p>0.05) e foram significativamente mais efetivas que o soro fisiológico (p<0.05). Pode-se concluir que o ESU e o Ca(ClO)2 apresentam potencial para aplicação clínica como irrigantes endodônticos uma vez que apresentaram efetividade antimicrobiana contra o E. faecalis.

Effect of chemical and natural irrigant solutions on microhardness of root dentin­ an in vitro study

Aim: Modifications in the mechanical properties of dentin may reduce the fracture resistance of tooth, especially after endodontic treatment. The aim of present study was to evaluate the effect of the irrigation with different root canal irrigants on the microhardness of root dentin. Methods: The coronal portion of 60 single-rooted bovine incisors was sectioned and the pulpal tissue removed using endodontic K-files. The roots were cut transversely to obtain 2 fragments, which were embedded in acrylic resin and randomly distributed into six groups (n=20) according to the irrigation protocol: distilled water (DW) (control); 2% chlorhexidine solution (CHX); 6% sodium hypochlorite (NaOCl); 6% calcium hypochlorite (Ca[OCl]2); QMix; and 6.5% grape seed extract solution (GSE). The solutions were kept in contact with the root dentin specimens for 30 min. After that, irrigation with 5 mL of DW was performed. The Vickers microhardness was determined by performing three indentations in all specimens, using 300-g load and 20-second dwell time. The first indentation was made 1.000 µm from the root canal entrance, and two other indentations were made at a distance of 200 µm from each other. The microhardness value for each specimen was obtained as the average of the results for the three indentations. Data were statistically analyzed using one-way ANOVA with 5% significance level. Results: All the tested irrigant solutions maintained the same microhardness level of the root dentin when compared to the control group, with no statistically significant differences between them (p<0.05) Conclusion: The tested irrigant solutions did not present ability to modify the microhardness of root dentin