Evaluation of biocompatibility of sodium perborate and 30% hydrogen peroxide using the analysis of the adherence capacity and morphology of macrophages

NE strengthens the immunosuppression induced by AlCl₃ through β₂-AR/cAMP pathway in cultured rat peritoneal macrophages

To investigate the effect of noradrenaline (NE) on the immunosuppression induced by aluminum trichloride (AlCl3), the peritoneal macrophages were cultured with RPMI-1640 medium containing 0.97 mM AlCl3 (1/10 IC50). NE was added to the medium at the final concentrations of 0 (control group, N-C), 0.1 (low-dose group, N-L), 1 (mid-dose group, N-M), and 10 (high-dose group, N-H) nM, respectively. No addition of both AlCl3 and NE serviced as blank group (D-C). Chemotaxis, adhesion, phagocytosis, tumor necrosis factor α (TNF-α) secretion, cyclic adenosine monophosphate (cAMP) content, β2 adrenergic receptors (β2-AR) density, and messenger RNA (mRNA) expression of macrophages were detected. The results showed that AlCl3 reduced the chemotaxis, adhesion, phagocytosis, and TNF-α secretion and increased the cAMP content, β2-AR density, and mRNA expression of peritoneal macrophages. Meanwhile, the chemotaxis, adhesion, phagocytosis, TNF-α secretion, β2-AR density, and mRNA expression were reduced while the cAMP content was increased in NE-treated groups than those in N-C group. The results indicated that NE strengthens the immunosuppression induced by AlCl3 in cultured rat peritoneal macrophages through the β2-AR/cAMP pathway.

Effects of Laser Irradiation on Pulp Cells Exposed to Bleaching Agents

The aim of this study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like cells exposed to a bleaching agent. Mouse dental papilla cell-23 cells were seeded in wells of 24-well plates. Eight groups were established according to the exposure to the bleaching agent and LLLT (0, 4, 10 and 15 J cm(-2) ). Enamel-dentin disks were adapted to artificial pulp chambers, which were individually placed in wells containing Dulbecco's modified Eagle's medium (DMEM). A bleaching agent (35% hydrogen peroxide [BA35%HP]) was applied on enamel (15 min) to obtain the extracts (DMEM + BA35%HP components diffused through enamel/dentin disks). The extracts were applied (1 h) to the cells, and then subjected to LLLT. Cell viability (Methyl tetrazolium assay), alkaline phosphatase (ALP) activity, as well as gene expression of ALP, fibronectin (FN) and type I collagen, were evaluated. The bleaching procedures reduced the cell viability, ALP activity and gene expression of dentin proteins. Laser irradiation did not modulate the cell response; except for FN, as LLLT decreased the gene expression of this protein by the cells exposed to the BA35%HP. It can be concluded that BA35%HP decreased the activities of odontoblasts that were not recovered by the irradiation of the damaged cells with low-level laser parameters tested.

Effect of several bleaching agents on teeth stained with a resin-based sealer

AIM

To evaluate the effect of peroxide-based bleaching agents on teeth stained with AH26 sealer (Dentsply De Trey, Konstanz, Germany), using digital images and computer analysis.

METHODOLOGY

Thirty-five maxillary central incisors were root filled, and the internal walls of the access cavity were coated with AH26 sealer. Internal bleaching commenced 4 months after the root fillings. In three experimental groups (n = 10), the teeth were bleached for 21 days using 45% carbamide peroxide (CP) gel, 45% sodium perborate + carbamide peroxide (SP + CP) or sodium perborate + distilled water (SP + W). No bleaching was undertaken in the control group. Digital images of each specimen were made before treatment, 4 months after endodontic treatment and 2 weeks after bleaching. Colour differences (∆E) were calculated by determining L*a*b* values using digital images and imaging software. Differences between the original colour and sealer-stained teeth, between sealer-stained and bleached teeth and between original colour and bleached teeth were calculated. Data were analysed using one-way anova and Duncan tests (α = 0.05).

RESULTS

Colour differences between baseline and sealer staining were in the range of 8.1-9.9, but differences between the groups were not significant. After bleaching, the degree of lightening was essentially identical for the carbamide peroxide and sodium perborate + carbamide peroxide groups, but was significantly greater (P < 0.05) in these two groups than in the sodium perborate + water group.

CONCLUSION

For bleaching AH26 sealer-stained teeth, carbamide peroxide gel and carbamide peroxide gel mixed with sodium perborate were equally effective and significantly better than sodium perborate mixed with water.

Biocompatibility of various dental materials in contemporary dentistry: a narrative insight

In the past few decades, there has been an increase in demand for safety evaluation and control of dental materials used daily in dentistry; however, this task is difficult and cumbersome. Dental materials that are passive and do not react with the oral environment will be more stable and have superior durability. It is expected that dental materials will be universally accepted and will not cause harm or injury to the surrounding structures in the oral cavity. This is an entirely negative approach to the material tolerance and biocompatibility, and hides the possibility that some positive gains can be achieved. Side-effects of dental materials are believed to be rare, and generally, those that have been reported are mild. There are wide varieties of materials used in dentistry, which include liners, irrigants, intracanal filling materials, intracanal medicaments, prosthetic materials, restorative materials, subgingival implants, and mouth rinses. Therefore, in this study, the biocompatibility of various commonly-used clinical materials used in contemporary dentistry was discussed.

Effects of aluminum exposure on the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages in rats

To investigate the effects of aluminum (Al) exposure on peritoneal macrophages of Wistar rats, four groups of ten rats each were orally exposed to 0, 13, 26, and 52 mg kg(-1) Al(3+) in form of aluminum trichloride (AlCl(3)) in drinking water for 120 days. At the end of the experimental period, the Al concentration in serum, the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages were determined. The results showed that the Al concentration in serum significantly increased in a dose-dependent manner; the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages decreased with the increase of Al dose, and present a dose-effective relationship. Further, they were significantly lower in the high-dose groups (P < 0.01) compared with the control group. It indicates that Al was toxic to peritoneal macrophages of rats, and the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages in rats were significantly suppressed by exposure to 52 mg kg(-1) day Al(3+).

Effects of bleaching on mercury ion release from dental amalgam

The chemical reactions that take place at the amalgam surface when exposed to bleaching agents are not well-understood. It is known, however, that mercury ions are released from dental amalgam when bleached. We hypothesized that increasing concentrations of hydrogen peroxide are more effective than water at increasing mercury ion release from dental amalgam. We prepared dental amalgam discs (n = 65) by packing amalgam into cylindrical plastic molds and divided them into 13 equal groups of 5 discs each. The discs in each group were individually immersed in either 0%, 3.6%, 6%, or 30% (w/v) hydrogen peroxide at exposure periods of 1, 8, 48, and 168 hrs. Samples were taken for mercury ion release determination by inductively coupled plasma mass spectrometry. There were significant increases in mercury release between control and all other hydrogen peroxide concentrations at all exposure times (p < 0.05).

Ex vivo evaluation of the effectiveness of bleaching agents on the shade alteration of blood-stained teeth

AIM

To evaluate ex vivo effectiveness of the three formulations of bleaching materials for intracoronal bleaching of root filled teeth using the walking bleach technique.

METHODOLOGY

Extracted premolar teeth were stained artificially with human blood. After biomechanical preparation, the root canals were filled and a 3-mm thick intermediate base of zinc phosphate cement was placed at the level of the cementoenamel junction. The teeth were divided into four groups (n = 12): C (control, without bleaching material), A1 (sodium perborate + distilled water), A2 (sodium perborate + 10% carbamide peroxide) and A3 (sodium perborate + 35% carbamide peroxide). The bleaching materials were changed at 7 and 14 days. Evaluation of shade was undertaken with aid of the VITA Easyshadetrade mark (DeltaE*ab) and was performed after tooth staining and at 7, 14 and 21 days after bleaching, based on the CIELAB system. Data were analysed by anova for repeated measurements, Tukey and Dunnett tests (alpha = 0.05).

RESULTS

The Tukey test revealed that group A1 (10.58 +/- 4.83 DeltaE*ab) was statistically different from the others (A2, 19.57 +/- 4.72 DeltaE*ab and A3, 17.58 +/- 3.33 DeltaE*ab), which were not different from each other. At 7 days: A1 was significantly different from A2; at 14 and 21 days: A2 and A3 were significantly better than A1; the Dunnett test revealed that the control group was different from A1, A2 and A3 at all periods (P < 0.05).

CONCLUSION

Sodium perborate associated with both 10% and 35% carbamide peroxide was more effective than when associated with distilled water.