Antimicrobial Efficacy and Dentin Collagen Damage Caused by Calcium Hypochlorite and Sodium Hypochlorite.

This study aimed to evaluate the antimicrobial activity of calcium hypochlorite (Ca (OCl)2) and sodium hypochlorite (NaOCl) using confocal laser scanning microscopy (CLSM) and dentin organic matrix alteration by picrosirius staining and light microscopy (LM). Samples of human extracted teeth were infected with Enterococcus faecalis by centrifugation of the bacterial suspension and were treated with Ca(OCl)2 or NaOCl at 0.5%, 2.5%, and 6% for 15, 30, and 60 seconds. CLSM and viability staining were used to quantitatively analyze the proportions of dead/live bacteria in the canal lumen and border of the root canal. The data were analyzed by ANOVA and Fisher test. For LM analysis, one hundred bovine teeth were randomly divided into 10 test groups (n=10): G1- Without treatment; G2- 17% EDTA; G3- 6% NaOCl; G4- 6% NaOCl + EDTA; G5- 0.5% Ca(OCl)2; G6- 0.5% Ca(OCl)2 + EDTA; G7- 2.5% Ca(OCl)2; G8- 2.5% Ca(OCl)2 + EDTA; G9- 6% Ca(OCl)2; G10- 6% Ca(OCl)2 + EDTA. The samples were fragmented and stained with Picrosirius. Data were analyzed by Kruskal-Wallis and Dunn (P<0.05). There was a strong correlation between the results of the canal lumen and the border of the root canal (r=0.962). Both hypochlorites at a concentration of 0.5% showed less microbial reduction compared to 2.5% and 6% (P<0.05). There was less antimicrobial activity at 15 seconds compared to 30 and 60 seconds (P<0.05). Ca(OCl)2 and NaOCl showed similar results at the same concentrations (P>0.05). In conclusion, Ca(OCl)2 caused fewer alterations to the dentin organic matrix at concentrations of 0.5% and 2.5%. Ca(OCl)2 presents antimicrobial activity similar to NaOCl, and collagen damage is concentration-dependent.

Antibacterial Efficacy of the Grape Seed Extract as an Irrigant for Root Canal Preparation.

Objective: The purpose of this research was to compare relative effectiveness of sodium hypochlorite 5.25% (NaOCl), 2% chlorhexidine gel (CHX) and 6.5 % grape seed extract (GSE) against Enterococcus faecalis using instrument Reciproc R25 in root canal preparation. Methods: Forty-five mesiobuccal root canals from extracted human maxillary molars were collected and infected with Enterococcus faecalis. The samples were divided into five groups according to the different types of irrigants: saline (positive control) (n=5); in the other groups were used 10 root canals for each group: NaOCl+EDTA; CHX gel+EDTA; GSE solution+EDTA; GSE gel+EDTA. All the groups were prepared with reciprocating instruments Reciproc R25. Bacterial reduction was measured by two-way ANOVA (P<0.001) followed by Tukey HSD post-hoc tests, from the counting of colony forming units (CFUs) from samples collected before instrumentation and after. The significance level established at 5% (P<0.05). Results: The group prepared with the NaOCl resulted in highest antimicrobial capacity among of all (P>0.05), followed by CHX and GSE gel (P<0.05). Control and GSE solution showed similar results (P<0.05) and resulted in the lowest percentage of the reduction of the microorganism into the root canals. Conclusion: NaOCl had the higher elimination capacity of Enterococcus faecalis than GSE and CHX.

Antibacterial Efficacy of Synthetic and Natural-Derived Novel Endodontic Irrigant Solutions.

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.

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.

How does the piston material affect the in vitro mechanical behavior of dental ceramics?

STATEMENT OF PROBLEM: Variables involving the indication, manufacturing, and clinical use of ceramic restorations make the standardization of in vitro studies a challenge and raise questions as to the clinical validity of the resulting data. PURPOSE: The purpose of this in vitro study was to assess the effect of piston material on the fracture behavior of ceramics tested under compressive load. MATERIAL AND METHODS: Two ceramics were evaluated: a lithium disilicate-based glass-ceramic (D) and a feldspathic porcelain (P). Plate-shaped ceramic specimens (1.5-mm thick) were adhesively cemented onto a dentin analog substrate. The specimens from each ceramic were divided into 4 groups according to the piston material (n=20): metal (M) (stainless steel), composite resin (R) (NEMA-G10, fiber-reinforced epoxy resin), ceramic (C) (lithium disilicate-based glass-ceramic), and human tooth (T) (canine). A gradual compressive load (0.5 mm/min) was applied to the center of the specimen with a universal testing machine. The test was performed in 37°C distilled water, and the initial crack was detected by using an acoustic system. The fracture load values (N) were statistically analyzed with the Kruskal-Wallis and Dunn tests (α=.05). A finite element analysis (FEA) was also performed. RESULTS: Piston material had no influence on fracture load and failure mode of ceramic D. Ceramic P showed higher fracture load values when loaded with the composite resin piston. Ceramic P showed more combined failures (cone crack and radial crack) than D. The FEA showed a distinct stress distribution for R piston on P. Pistons C and T resulted in similar stress distribution, fracture load, and failure mode for both ceramics. CONCLUSIONS: The effect of piston material on the ceramic fracture behavior depends on the ceramic being evaluated.

How oral environment simulation affects ceramic failure behavior.

STATEMENT OF PROBLEM: Investigating the mechanical behavior of ceramics in a clinically simulated scenario contributes to the development of new and tougher materials, improving the clinical performance of restorations. The optimal in vitro environment for testing is unclear. PURPOSE: The purpose of this in vitro study was to investigate the failure behavior of a leucite-reinforced glass-ceramic under compression loading and fatigue in different simulated oral environment conditions. MATERIAL AND METHODS: Fifty-three plate-shaped ceramic specimens were produced from computer-aided design and computer-aided manufactured (CAD-CAM) blocks and adhesively cemented onto a dentin analog substrate. For the monotonic test (n=23), a gradual compressive load (0.5 mm/min) was applied to the center of the specimens, immersed in 37ºC water, using a universal testing machine. The initial crack was detected with an acoustic system. The fatigue test was performed in a mechanical cycling machine (37ºC water, 2 Hz) using the boundary technique (n=30). Two lifetimes were evaluated (1×106 and 2×106 cycles). Failure analysis was performed using transillumination. Weibull distribution was used to evaluate compressive load data. A cumulative damage model with an inverse power law (IPL) lifetime-stress relationship was used to fit the fatigue data. RESULTS: A characteristic failure load of 1615 N and a Weibull modulus of 5 were obtained with the monotonic test. The estimated probability of failure (Pf) for 1×106 cycles at 100 N was 31%, at 150 N it was 55%, and at 200 N it was 75%. For 2×106 cycles, the Pf increased approximately 20% in comparison with the values predicted for 1×106 cycles, which was not significant. The most frequent failure mode was a radial crack from the intaglio surface. For fatigue, combined failure modes were also found (radial crack combined with cone crack or chipping). CONCLUSIONS: Fatigue affects the fracture load and failure mode of leucite-reinforced glass-ceramic.