Genotoxicity and cytotoxicity of mineral trioxide aggregate and regular and white Portland cements on Chinese hamster ovary (CHO) cells in vitro

Evaluation of the radiopacity and cytotoxicity of Portland cements containing bismuth oxide

OBJECTIVE

This study aimed at evaluating the radiopacity and cytotoxicity of Portland cements containing bismuth oxide (PcBo) in varying ratios.

STUDY DESIGN

Specimens measuring 10 mm in diameter and 1 mm in thickness were radiographed with an aluminum step wedge using an occlusal film. The radiographs were digitized, and the radiopacity of each material was compared to the different thicknesses of the aluminum step wedge. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells.

RESULTS

The results demonstrated that Portland cement with 20% bismuth oxide presented greater radiopacity (P < .05) compared to the mixtures with less bismuth oxide. The cell viabilities of all PcBo groups were statistically similar (P > .05) throughout the experimental period.

CONCLUSION

These results indicate that Portland cement with 20% bismuth oxide has a greater potential for being used as a root-end filling material compared to Portland cement with less bismuth oxide.

Histological analysis of the effect of accelerated portland cement as a bone graft substitute on experimentally-created three-walled intrabony defects in dogs

BACKGROUND AND AIMS

Recent literature shows that accelerated Portland cement (APC) is a non-toxic material that may have potential to promote bone healing. The objective of this study was to histologically evaluate periodontal healing focusing on new bone regeneration following implantation of APC into intra-bony defects in dogs.

MATERIALS AND METHODS

Three-wall intra-bony periodontal defects were surgically created at the mesial aspect of the first molar in both sides of mandible in six dogs. One side was randomly filled with the material and other received a flap operation only. The animals were euthanized eight weeks post-surgery when block sections of the defect sites were collected and prepared for qualitative histological analysis.

RESULTS

Compared to control group, stimulation of growth of new bone tissue in the cavity con-taining APC was significantly prominent in three of six cases, showing osteoid formation with osteoblastic rimming and new bone trabeculla. New bone formation was observed just close to cavity containing APC. Connective tissue proliferation and downgrowth of epithelium were signif-icantly less than those of control group.

CONCLUSION

Our results are encouraging for the use of APC as a bone substitute, but more comprehensive study are necessary before warranting clinical use.

Comparative SEM study of the marginal adaptation of white and grey MTA and Portland cement

The use of a suitable substance that prevents egress of potential contaminants into the periapical tissues is important in endodontic surgery. The aim of the present study was to compare the marginal adaptation of three root-end filling materials (white mineral trioxide aggregate (MTA), grey MTA and Portland cement), using scanning electron microscopy. Seventy-five single-rooted extracted human teeth were used. The canals were instrumented and filled with gutta-percha. Following root-end resection and cavity preparation, root-end cavities were filled with white MTA, grey MTA or Portland cement. Using a diamond saw, roots were longitudinally sectioned into two halves. Under scanning electron microscopy, the gaps between the material and dentinal wall were measured. The data were analysed using Kruskal-Wallis test. The mean of the gap in grey MTA, white MTA and Portland cement was 211.6, 349 and 326.3 microm, respectively. The results indicate that the gap between grey MTA and the dentinal wall is less than other materials, but there was no significant difference between the materials tested in this study (P > 0.05).

Metrologic Evaluation of the Surface of White MTA After the Use of Two Endodontic Irrigants

This study examined the effects of calcium-depleting endodontic irrigants, ethylenediamine tetra-acetic acid (EDTA) and BioPure MTAD, on the dissolution, surface characteristics, and ultrastructural characteristics of white mineral trioxide aggregate (MTA). The latter was mixed in a 0.35 water-cement ratio, condensed into cylindrical wells created in Plexiglas platforms, and allowed to harden completely before initial treatment with 1.3% NaOCl and final treatments with either 17% EDTA for 5 minutes, or BioPure MTAD for 1, 3, or 5 minutes. Analysis of the mean depths of material removed using three-dimensional profilometry revealed significantly more material removed by BioPure MTAD. Although these minor depth changes (<10 microm) are unlikely to cause clinical concern, the BioPure MTAD-treated MTA surfaces exhibited higher surface roughness and with more calcium extracted when compared with EDTA treatment. Decomposition of particle-binding hydration phases by acid corrosion raises potential concern on the strength and sealing properties of MTA-repaired perforations following final irrigation by BioPure MTAD.

Genotoxicity in primary human peripheral lymphocytes after exposure to regular and white mineral trioxide aggregate

OBJECTIVE

Taking into consideration that DNA damage plays an important role in carcinogenesis, the purpose of this study was to evaluate whether regular and white mineral trioxide aggregate (MTA) are able to induce genetic damage in primary human cells.

STUDY DESIGN

Human peripheral lymphocytes obtained from 10 healthy volunteers were exposed to 2 presentation forms of MTA at final concentrations ranging from 1 to 1000 microg/mL for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (phosphate buffer solution, PBS) for 1 hour at 37 degrees C and the positive control group was treated with hydrogen peroxide (at 100 microM) for 5 minutes on ice. Results were analyzed by the Friedman nonparametric test.

RESULTS

The results pointed out that either regular or white MTA in all concentrations tested did not induce DNA breakage in human peripheral lymphocytes as depicted by the mean tail moment.

CONCLUSION

In summary, our results indicate that exposure to MTA may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single cell gel (comet) assay.