Calcium hypochlorite cytotoxicity mechanism in fibroblasts and effect on osteoblast mineralization.

AIM: To determine the cytotoxicity mechanism of 2.5% calcium hypochlorite [Ca(OCl)2 ] in L929 fibroblasts and the effect of this solution on human osteoblast-like cells (Saos-2) mineralization, compared to that of 2.5% sodium hypochlorite (NaOCl). METHODOLOGY: L929 fibroblasts were exposed to Ca(OCl)2 and NaOCl at different dilutions for 10 min. Cell metabolism was assessed by methyl-thiazole-tetrazolium (MTT); lysosome integrity, by neutral red (NR) assay; type of cell death, by flow cytometry (apoptosis/necrosis); cytoskeleton, by actin and α-tubulin fluorescence and cell ultrastructure, by transmission electron microscopy (TEM). The alkaline phosphatase (ALP) activity and mineralized nodule formation were determined in Saos-2 by thymolphthalein release and alizarin red staining (ARS), respectively. The data were analysed by two-way anova and Bonferroni's post-test (α = .05). RESULTS: Ca(OCl)2 promoted higher cell viability and a lower percentage of apoptosis and necrosis than NaOCl (p < .05). Ca(OCl)2 and NaOCl decreased cell metabolism and lysosome integrity, induced the breakdown of microtubules and actin filaments, promoted alterations of rough endoplasmic reticulum and disruption of mitochondrial cristae. Additionally, Ca(OCl)2 did not induce ALP activity and had no effect on mineralized nodules formation. CONCLUSIONS: Although Ca(OCl)2 and NaOCl promoted the same cytotoxicity mechanism, Ca(OCl)2 was less cytotoxic than NaOCl. As for ALP activity, no differences were observed between NaOCl and Ca(OCl)2 . The production of mineralized nodules induced by Ca(OCl)2 was lower than those induced by NaOCl, but was not different from those induced by the control group.

Physicochemical properties and effect of bioceramic root canal filling for primary teeth on osteoblast biology.

OBJECTIVE: Bio-C Pulpecto (Bio-CP) was recently developed as the first bioceramic root filling material for primary teeth. To evaluate the physicochemical properties of radiopacity, setting time, pH, cytocompatibility and potential of Bio-CP to induce mineralisation, compared with (1) Calen thickened with zinc oxide (Calen-ZO), and (2) zinc oxide and eugenol (ZOE). METHODOLOGY: Physicochemical properties were evaluated according to ISO 6876. Saos-2 (human osteoblast-like cell line) exposed to extracts of the materials were subjected to assays of methyl thiazolyl tetrazolium, neutral red, alkaline phosphatase (ALP) activity and mineralised nodule production. The results were analysed using one-way or two-way ANOVA and Tukey's or Bonferroni's post-tests (α=0.05). RESULTS: All the materials showed radiopacity higher than 3 mm Al. Bio-CP had lower pH than Calen-ZO, but higher pH than ZOE. Calen-ZO and Bio-CP did not set. The setting time for ZOE was 110 min. The cytocompatibility order was Calen-ZO > Bio-CP > ZOE (1:2, 1:4 dilutions) and Calen-ZO > Bio-CP = ZOE (1:12, 1:24 dilutions) and Calen-ZO = Bio-CP > ZOE (1:32 dilution). Bio-CP induced greater ALP activity at 7 days, and greater mineralised nodule production, compared to Calen-ZO (p<0.05). Conclusions Bio-CP showed adequate physicochemical properties, cytocompatibility and potential to induce mineralisation.

Physicochemical properties and effect of bioceramic root canal filling for primary teeth on osteoblast biology

Abstract Bio-C Pulpecto (Bio-CP) was recently developed as the first bioceramic root filling material for primary teeth. Objective To evaluate the physicochemical properties of radiopacity, setting time, pH, cytocompatibility and potential of Bio-CP to induce mineralisation, compared with (1) Calen thickened with zinc oxide (Calen-ZO), and (2) zinc oxide and eugenol (ZOE). Methodology Physicochemical properties were evaluated according to ISO 6876. Saos-2 (human osteoblast-like cell line) exposed to extracts of the materials were subjected to assays of methyl thiazolyl tetrazolium, neutral red, alkaline phosphatase (ALP) activity and mineralised nodule production. The results were analysed using one-way or two-way ANOVA and Tukey's or Bonferroni's post-tests (α=0.05). Results All the materials showed radiopacity higher than 3 mm Al. Bio-CP had lower pH than Calen-ZO, but higher pH than ZOE. Calen-ZO and Bio-CP did not set. The setting time for ZOE was 110 min. The cytocompatibility order was Calen-ZO > Bio-CP > ZOE (1:2, 1:4 dilutions) and Calen-ZO > Bio-CP = ZOE (1:12, 1:24 dilutions) and Calen-ZO = Bio-CP > ZOE (1:32 dilution). Bio-CP induced greater ALP activity at 7 days, and greater mineralised nodule production, compared to Calen-ZO (p<0.05). Conclusions Bio-CP showed adequate physicochemical properties, cytocompatibility and potential to induce mineralisation.

Physicochemical Properties of a Bioceramic Repair Material - BioMTA.

This study aimed to assess the physicochemical properties of a repair material in the Brazilian market, BioMTA, in comparison to other two materials currently in use (Biodentine and MTA Angelus). The initial setting time was evaluated using Gillmore needle. The pH was measured with a pH-meter after 24 h, 3, 7, 14 and 21 days. The radiopacity was determined using the equivalence in millimeters of aluminum (mm Al) from digitized occlusal radiographs. Solubility was determined after immersion in water for 7 days. The data were analyzed by one-way ANOVA and Tukey tests (a=0.05). The BioMTA initial setting time (5.2 min) was lower than the other materials (p<0.05). All materials showed an alkaline pH at 21 days. At 24 h, BioMTA was the most alkaline material (p<0.05); and at 3, 7, 14 and 21 days there was no difference between BioMTA and Biodentine (p>0.05), both being more alkaline than MTA Angelus (p<0.05). The radiopacity of BioMTA (4.2 mm Al) was significantly higher compared to Biodentine (p<0.05) and lower than MTA Angelus (p<0.05). The solubility of the materials was -4.2%, -1.6% and 4.1% for BioMTA, MTA Angelus and Biodentine, respectively, with a significant difference between them (p<0.05). Therefore, it can be concluded that BioMTA displayed a shorter setting time, an alkaline pH, a higher radiopacity, and a gain in mass.

Radiopacity of endodontic materials using two models for conversion to millimeters of aluminum.

The aims of the present study were to compare conventional radiography, radiographs digitized with a scanner or photographic camera, and digital radiography, used to evaluate the radiopacity of endodontic materials, and to compare the accuracy of linear and quadratic models used to convert radiopacity values to equivalent millimeters of aluminum (mm Al). Specimens of AH Plus, Endofill, Biodentine and BioMTA materials (n = 8) were radiographed next to an aluminum step-wedge using radiographic films and digital radiography systems (FONA CMOS sensor, Kodak CMOS sensor and photosensitive phosphor plate-PSP). Conventional radiographs were digitized using a scanner or photographic digital camera. Digital images of all the radiographic systems were evaluated using dedicated software. Optical density units (ODU) of the specimens and the aluminum step-wedge were evaluated by a photo-densitometer (PTDM), used in conventional radiographs. The radiopacity in equivalent mm Al of the materials was determined by linear and quadratic models, and the coefficients of determination (R2) values were calculated for each model. Radiopacity of the materials ranged from -9% to 25% for digital systems and digitized radiographs, compared to the PTDM (p < 0.05). The R2 values of the quadratic model were higher than those of the linear model. In conclusion, the FONA CMOS sensor showed the lowest radiopacity variability of the methodologies used, compared with the PTDM, except for the BioMTA group (higher than PTDM). The quadratic model showed higher R2 values than the linear model, thus indicating better accuracy and possible adoption to evaluate the radiopacity of endodontic materials.

Radiopacity of endodontic materials using two models for conversion to millimeters of aluminum

Abstract The aims of the present study were to compare conventional radiography, radiographs digitized with a scanner or photographic camera, and digital radiography, used to evaluate the radiopacity of endodontic materials, and to compare the accuracy of linear and quadratic models used to convert radiopacity values to equivalent millimeters of aluminum (mm Al). Specimens of AH Plus, Endofill, Biodentine and BioMTA materials (n = 8) were radiographed next to an aluminum step-wedge using radiographic films and digital radiography systems (FONA CMOS sensor, Kodak CMOS sensor and photosensitive phosphor plate-PSP). Conventional radiographs were digitized using a scanner or photographic digital camera. Digital images of all the radiographic systems were evaluated using dedicated software. Optical density units (ODU) of the specimens and the aluminum step-wedge were evaluated by a photo-densitometer (PTDM), used in conventional radiographs. The radiopacity in equivalent mm Al of the materials was determined by linear and quadratic models, and the coefficients of determination (R2) values were calculated for each model. Radiopacity of the materials ranged from -9% to 25% for digital systems and digitized radiographs, compared to the PTDM (p < 0.05). The R2 values of the quadratic model were higher than those of the linear model. In conclusion, the FONA CMOS sensor showed the lowest radiopacity variability of the methodologies used, compared with the PTDM, except for the BioMTA group (higher than PTDM). The quadratic model showed higher R2 values than the linear model, thus indicating better accuracy and possible adoption to evaluate the radiopacity of endodontic materials.

Addition of zirconium oxide to Biodentine increases radiopacity and does not alter its physicochemical and biological properties.

OBJECTIVES: To evaluate the radiopacity of Biodentine (BD) and BD associated with 15% calcium tungstate (BDCaWO4) or zirconium oxide (BDZrO2), by using conventional and digital radiography systems, and their physicochemical and biological properties. MATERIALS AND METHODS: Radiopacity was evaluated by taking radiographs of cement specimens (n=8) using occlusal film, photostimulable phosphor plates or digital sensors. Solubility, setting time, pH, cytocompatibility and osteogenic potential were also evaluated. Data were analyzed using one-way ANOVA and Tukey post-test or two-way ANOVA and Bonferroni post-test (α=0.05). RESULTS: BD radiopacity was lower than 3 mm Al, while BD ZrO2 and BD CaWO4 radiopacity was higher than 3 mm Al in all radiography systems. The cements showed low solubility, except for BDCaWO4. All cements showed alkaline pH and setting time lower than 34 minutes. MTT and NR assays revealed that cements had greater or similar cytocompatibility in comparison with control. The ALP activity in all groups was similar or greater than the control. All cements induced greater production of mineralized nodules than control. CONCLUSIONS: Addition of 15% ZrO2 or CaWO4 was sufficient to increase the radiopacity of BD to values higher than 3 mm Al. BD associated with radiopacifiers showed suitable properties of setting time, pH and solubility, except for BDCaWO4, which showed the highest solubility. All cements had cytocompatibility and potential to induce mineralization in Saos-2 cells. The results showed that adding 15% ZrO2 increases the radiopacity of BD, allowing its radiography detection without altering its physicochemical and biological properties.