Influence of calcium chloride and chlorhexidine on physical-chemical properties of a Bis-EMA/MTA-based root-end filling material

The incorporation of resinous light-curable compounds to MTA has been proposed to improve the properties and to reduce the setting time. The aim of this study was to evaluate the radiopacity, sorption, solubility and antibacterial activity of a Bis-EMA / MTA based dual-cure retro-filling material (MTA-E) in comparison with mineral trioxide aggregate (MTA) and to evaluate the effect of CaCl2 on these properties. Another aim of the study was to evaluate the influence of 2% chlorhexidine (CHX) on pH, calcium ion release and setting time of an E-MTA compared to white-MTA (W-MTA). For radiopacity analysis specimens of each material (PCC; E-MTA + 5% CaCl2; E-MTA) were prepared with metal rings (6 mm diameter, and 1 mm thickness). The radiopacity values were determined according to the radiographic density (mm Al). To evaluate the sorption and solubility, specimens (n = 10) were prepared for each material with the aid of a matrix according to ISO 4049/2009 specifications. The direct contact test (DCT) was used to assess the antibacterial activity of each material against E. faecalis at 30 minutes and 24 hours after manipulation. A group of E-MTA + 2% CHX was included for the following tests. The calcium ions release and pH were analyzed with a spectrophotometer and pH meter, respectively. The setting time of each material was analyzed with Gilmore needles. Data were analyzed by analysis of variance and Tukey test (P = 0.05). E-MTA showed higher radiopacity than W-MTA (P 0.05). All materials gained mass after 7 days in water immersion, while the addition of 5% CaCl2 increased water sorption of E-MTA. E-MTA + 5% CaCl2 showed the highest solubility and was statistically different (p 0,05). Todos os materiais ganharam massa após 7 dias de imersão em água, enquanto que a adição de 5% de CaCl2 aumentou a absorção de água do MTA-E. O MTA-E + 5% de CaCl2 apresentou a maior solubilidade e foi estatisticamente diferente dos outros materiais (P <0,05). Todos os materiais foram 100% eficazes contra E. faecalis no prazo de 30 minutos após a manipulação (p = 0,005). Após 24 horas foi observada uma redução da atividade antibacteriana do MTA-E. O pH do MTA-E + CLX foi superior ao dos outros dois materiais após 7 dias e inferior após 30 dias (p <0,05). A adição de CLX aumentou a liberação de íons de cálcio do MTA-E para níveis estatisticamente semelhantes ao MTA-B. MTA-E mostrou um menor tempo de presa inicial e final em comparação com MTA-B (P <0,05). A adição de CLX 2% tanto no MTA como no MTA-E impediu a presa dos materiais. A adição de CLX ao MTA-E aumentou o seu pH e a liberação de íons cálcio. Enfim, o monómero Bis-EMA adicionado ao MTA formou um material (MTA-E) com maior radiopacidade e menor atividade antibacteriana do que o MTA-B. A adição de 5% de CaCl2 não alterou a sua radiopacidade enquanto aumentou a sua absorção de água, solubilidade e atividade antibacteriana. A adição de CLX ao MTA-E aumentou o pH e liberação de íons cálcio, mas impediu a presa do material

Influence of 2% chlorhexidine on pH, calcium release and setting time of a resinous MTA-based root-end filling material

The addition of chlorhexidine (CHX) to a resinous experimental Mineral Trioxide Aggregate (E-MTA) based root-end filling material is an alternative to boost its antimicrobial activity. However, the influence of chlorhexidine on the properties of this material is unclear. The aim of this study was to evaluate the influence of 2% chlorhexidine on the pH, calcium ion release and setting time of a Bisphenol A Ethoxylate Dimethacrylate/Mineral Trioxide Aggregate (Bis-EMA/MTA) based dual-cure experimental root-end filling material (E-MTA), in comparison with E-MTA without the addition of CHX and with conventional white MTA (W-MTA). The materials were placed in polyethylene tubes, and immersed in deionized water to determine pH (digital pH meter) and calcium ion release (atomic absorption spectrometry technique). The setting time of each material was analyzed using Gilmore needles. The data were statistically analyzed at a significance level of 5%. E-MTA + CHX showed an alkaline pH in the 3 h period of evaluation, the alkalinity of which decreased but remained as such for 15 days. The pH of E-MTA + CHX was higher than the other two materials after 7 days, and lower after 30 days (p < 0.05). All of the materials were found to release calcium ions throughout the 30 days of the study. The addition of CHX increased the calcium ion release of E-MTA to levels statistically similar to W-MTA. E-MTA showed shorter initial and final setting time, compared with W-MTA (p < 0.05). The addition of 2% CHX to MTA prevented setting of the material. The addition of CHX to E-MTA increased its pH and calcium ion release. However, it also prevented setting of the material