Study of the bismuth oxide concentration required to provide Portland cement with adequate radiopacity for endodontic use

Cell viability and physicochemical effects of different concentrations of bismuth trioxide in a mineral trioxide aggregate cement

PURPOSE

To evaluate the effect of three concentrations of bismuth trioxide (Bi₂O₃) on the biological and physicochemical properties of an experimental mineral trioxide aggregate-type (MTA-type) cement at different time points.

METHODS

Three experimental groups with white Portland cement containing 15, 20, or 25 wt% of Bi₂O₃ were assessed. Cellular proliferation in human periodontal ligament fibroblasts was evaluated with an MTT assay. Radiopacity, dimensional stability, pH, and compressive strength were evaluated at different time points.

RESULTS

Bismuth trioxide induced cell proliferation in the Bi15 and Bi25 groups in a time-dependent manner; pH was similar in all groups. Compressive strength was associated with time and bismuth concentration. Bi25 had significantly contracted at day 7 and expanded at day 14 (ANOVA P < 0.05, post hoc Tukey test P < 0.05).

CONCLUSION

A higher Bi₂O₃ concentration had a negative effect on the physical properties of the cement at all time points.

A Short Review on Biomedical Applications of Nanostructured Bismuth Oxide and Related Nanomaterials

In this review, we reported the main achievements reached by using bismuth oxides and related materials for biological applications. We overviewed the complex chemical behavior of bismuth during the transformation of its compounds to oxide and bismuth oxide phase transitions. Afterward, we summarized the more relevant studies regrouped into three categories based on the use of bismuth species: (i) active drugs, (ii) diagnostic and (iii) theragnostic. We hope to provide a complete overview of the great potential of bismuth oxides in biological environments.

Calcium Phosphate Cement with Antimicrobial Properties and Radiopacity as an Endodontic Material

Calcium phosphate cements (CPCs) have several advantages for use as endodontic materials, and such advantages include ease of use, biocompatibility, potential hydroxyapatite-forming ability, and bond creation between the dentin and appropriate filling materials. However, unlike tricalcium silicate (CS)-based materials, CPCs do not have antibacterial properties. The present study doped a nonwashable CPC with 0.25–1.0 wt % hinokitiol and added 0, 5, and 10 wt % CS. The CPCs with 0.25–0.5 wt % hinokitiol showed appreciable antimicrobial properties without alterations in their working or setting times, mechanical properties, or cytocompatibility. Addition of CS slightly retarded the apatite formation of CPC and the working and setting time was obviously reduced. Moreover, addition of CS dramatically increased the compressive strength of CPC. Doping CS with 5 wt % ZnO provided additional antibacterial effects to the present CPC system. CS and hinokitiol exerted a synergic antibacterial effect, and the CPC with 0.25 wt % hinokitiol and 10 wt % CS (doped with 5 wt % ZnO) had higher antibacterial properties than that of pure CS. The addition of 10 wt % bismuth subgallate doubled the CPC radiopacity. The results demonstrate that hinokitiol and CS can improve the antibacterial properties of CPCs, and they can thus be considered for endodontic applications.

Biological evaluation of a new pulp capping material developed from Portland cement

This study evaluates the biological properties of a new pulp capping material developed from Portland cement. This study was conducted on 48 teeth in 4 dogs (12 teeth/dog). The dogs were classified into two equal groups (n=24 teeth) according to the evaluation period including: group A (3 weeks) and group B (3 months). Each group was further subdivided into three equal subgroups (n=8 teeth) according to the capping material including: subgroup 1: mineral trioxide aggregate (MTA), subgroup2: Portland cement+10% calcium hydroxide+20% bismuth oxide (Port Cal) and subgroup 3: Portland cement+bismuth oxide. After general anesthesia, a class V buccal cavity was prepared coronal to the gingival margin. After pulp exposure and hemostasis,the capping materials and glass ionomer filling were placed on the exposure sites. All histopathological findings, inflammatory cell count and dentin bridge formation were recorded. Data were analyzed statistically. After 3 months, the histopathological picture of the pulp in subgroup 1 showed normal pulp, continuous odontoblastic layer and complete dentin bridge formation while subgroup 2 showed partial and complete dentin bridge over a normal and necrotic pulps. Subgroup 3 showed loss of normal architecture, areas of necrosis, complete, or incomplete dentin bridge formation, attached and detached pulp stones and fatty degeneration in group B. For group A, MTA subgroup showed the least number of inflammatory cell infiltrate followed by Port Cal subgroup. While subgroup 3 showed the highest number of inflammatory cell infiltrate. For group B, the mean inflammatory cell count increased with the three tested materials with no statistical difference. Regarding dentin bridge formation at group A, no significant differences was found between subgroups, while at group B, MTA subgroup exhibited significantly higher scores than other subgroups. In conclusion, addition of calcium hydroxide to Portland cement improves the dentin bridge formation qualitatively and quantitatively.

Physical evaluation of a new pulp capping material developed from portland cement

Background

This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material.

Material and Methods

The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide.

Results

The statistical analysis was performed with ANOVA and Duncan’s post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001).

Conclusions

Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material.

Key words:Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength.

Análise físico-química do MTA e do cimento Portland associado a quatro diferentes radiopacificadores

INTRODUÇÃO: O Mineral Trióxido Agregado (MTA) é composto por cimento Portland (CP) e um radiopacificador (óxido de bismuto).OBJETIVO: Avaliar tempo de presa, solubilidade, pH, liberação de íons Cálcio e radiopacidade do cimento Portland puro ou associado a quatro radiopacificadores (sulfato de bário, carbonato de bismuto, óxido de bismuto e iodofórmio), comparados ao MTA branco (Angelus, Londrina, Brasil).MATERIAL E MÉTODO: A proporção empregada CP/radiopacificador foi de 4:1 em peso, (80% de cimento Portland e 20% de radiopacificador). A especificação 57 da ADA foi usada para avaliação do tempo de presa. A solubilidade foi analisada segundo a especificação ISO 6876/2001. A avaliação do pH foi realizada com peagâmetro digital e a liberação de íons Ca++foi verificada por meio de espectrofotômetro de absorção atômica. A radiopacidade foi determinada em milímetros de alumínio (mm/Al). Os resultados foram submetidos aos testes de Análise de Variância e Tukey, nível de significância 5%.RESULTADO: O sulfato de bário não alterou o tempo de presa final do CP. Radiopacidade inferior ao mínimo recomendado pelas normas da ADA nº 57 e ISO 6876/2001 foi observada para CP e CP associado com sulfato de bário. O CP associado ao iodofórmio apresentou solubilidade acima dos 3% recomendados pela ISO 6876/2001. Todos os materiais proporcionaram alcalinização do meio e promoveram liberação de íons cálcio.CONCLUSÃO: Carbonato de bismuto ou óxido de bismuto proporcionaram tempo de presa inicial, solubilidade, pH, liberação de íons Cálcio e radiopacidade adequados quando associados ao CP.

Portland cement with additives in the repair of furcation perforations in dogs

PURPOSE: To evaluate the use of Portland cements with additives as furcation perforation repair materials and assess their biocompatibility. METHODS: The four maxillary and mandibular premolars of ten male mongrel dogs (1-1.5 years old, weighing 10-15 kg) received endodontic treatment (n=80 teeth). The furcations were perforated with a round diamond bur (1016 HL). The perforations involved the dentin, cementum, periodontal ligament, and alveolar bone. A calcium sulfate barrier was placed into the perforated bone to prevent extrusion of obturation material into the periradicular space. The obturation materials MTA (control), white, Type II, and Type V Portland cements were randomly allocated to the teeth. Treated teeth were restored with composite resin. After 120 days, the animals were sacrificed and samples containing the teeth were collected and prepared for histological analysis. RESULTS: There were no significant differences in the amount of newly formed bone between teeth treated with the different obturation materials (p=0.879). CONCLUSION: Biomineralization occurred for all obturation materials tested, suggesting that these materials have similar biocompatibility.

Root perforations treatment using mineral trioxide aggregate and Portland cements

PURPOSE: Clinical, radiological and histological evaluation of root perforations treated with mineral trioxide aggregate (MTA) or Portland cements, and calcium sulfate barrier. METHODS: One molar and 11 premolar teeth of a male mongrel dog received endodontic treatment and furcations were perforated with a high-speed round bur and treated with a calcium sulfate barrier. MTA, Portland cement type II (PCII) and type V (PCV), and white Portland cement (WPC) were used as obturation materials. The teeth were restored with composite resin and periapical radiographs were taken. The animal was euthanized 120 days post-surgery for treatment evaluation. RESULTS: Right lower first premolar (MTA), right lower third premolar (PCV), left lower second premolar (MTA), and right lower second premolar (WPC): clinically normal, slightly radio-transparent area on the furcation, little inflammatory infiltrate, and new-bone formation. Left lower third premolar (PCII), right upper first premolar (WPC), right upper third premolar (PCII), and left upper first molar (PCV): clinically normal, radiopaque area on the furcation, and new-bone formation. Right upper second premolar (MTA), left upper second premolar (WPC), left upper third premolar (PCII): presence of furcation lesion, large radiolucent area, and intense inflammatory infiltrate. CONCLUSION: All obturation materials used in this study induced new-bone formation.

Ex vivo assessment of genotoxicity and cytotoxicity in murine fibroblasts exposed to white MTA or white Portland cement with 15% bismuth oxide

AIMS

To evaluate whether white mineral trioxide aggregate (MTA) or white Portland cement with 15% bismuth oxide were able to induce genetic damage and cellular death ex vivo.

METHODOLOGY

Aliquots of 1 × 10(4) murine fibroblasts were incubated at 37 °C for 3 h with MTA (white) or white Portland cement with 15% bismuth oxide, at final concentrations ranging from 10 to 1000 μg mL(-1) individually. Data of three independent repeats from the comet assay and the trypan blue exclusion test were assessed by the one-way anova followed by Tukey's test.

RESULTS

Mineral trioxide aggregate or Portland cement containing bismuth oxide did not produce genotoxic effects with respect to the single-cell gel (comet) assay data for all concentrations evaluated. Furthermore, no cytotoxicity was observed for MTA or Portland cement.

CONCLUSION

White MTA or white Portland cement containing 15% bismuth oxide were not genotoxic and cytotoxic.