Microarray analysis of the gene expression profile in triethylene glycol dimethacrylate-treated human dental pulp cells.

OBJECTIVE: Triethylene glycol dimethacrylate (TEGDMA) is an important resin monomer commonly used in the structure of dental restorative materials. Recent studies have shown that unpolymerized resin monomers may be released into the oral environment and cause harmful biological effects. We investigated changes in the gene expression profiles of TEGDMA-treated human dental pulp cells (hDPCs) following short- (1-day) and long-term (7-days) exposure. MATERIALS AND METHODS: HDPCs were exposed to a noncytotoxic concentration of TEGDMA, and gene expression profiles were evaluated by microarray analysis. The results were confirmed by quantitative reverse-transcriptase PCR (qRT PCR). RESULTS: In total, 1282 and 1319 genes (up- or down-regulated) were differentially expressed compared with control group after the 1- and 7-day incubation periods, respectively. Biological ontology-based analyses revealed that metabolic, cellular, and developmental processes constituted the largest groups of biological functional processes. qRT-PCR analysis on bone morphogenetic protein-2 (BMP-2), BMP-4, secreted protein, acidic, cysteine-rich, collagen type I alpha 1, oxidative stress-induced growth inhibitor 1, MMP3, interleukin-6, and heme oxygenase-1 genes confirmed the changes in expression observed in the microarray analysis. CONCLUSIONS: Our results suggest that TEGDMA can change the many functions of hDPCs through large changes in gene expression levels and complex interactions with different signaling pathways.

Effects of iRoot BP and white mineral trioxide aggregate on cell viability and the expression of genes associated with mineralization.

AIM: To evaluate the cytotoxicity and mineralization effects of iRoot BP in human dental pulp cells (hDPCs) and to compare them with those of white mineral trioxide aggregate (WMTA). METHODOLOGY: hDPCs were exposed to prepared dilutions (1 : 1-1 : 10) of the test materials. Cell viability was evaluated using the XTT assay after incubation periods of 24, 48 or 72 h. The expression of mineralization-related genes (bone morphogenic protein, osteonectin, bone sialoprotein, osteopontin, dentine sialophosphoprotein and collagen type 1) and heme oxygenase 1 was measured by quantitative real-time polymerase chain reaction (qRT-PCR) at 24 and 72 h. Statistical differences between test materials were analysed with the Mann-Whitney test. RESULTS: The 1 : 1 and 1 : 2 dilutions of iRoot BP were associated with higher cell viability after 24 h (P < 0.05). Only the 1 : 1 dilution of iRoot BP had higher cell viability after 48 h (P < 0.05), and there was no difference between iRoot BP and WMTA after 72 h (P > 0.05). Although somewhat variable, according to the gene expression results, iRoot BP had a mineralization potential similar to that of WMTA. WMTA revealed a higher heme oxygenase 1 (HO-1) mRNA level than iRoot BP (P < 0.001). CONCLUSIONS: iRoot BP and WMTA were biocompatible and facilitated odontoblastic differentiation of hDPCs.

The vasodilatory effect of a synthetic polymer-based root canal material on thoracic aorta.

AIM: To test the hypothesis that, Epiphany, either in its mixed form or as separate components, can alter the vascular reactivity of isolated rat thoracic aorta. The possible mechanism of its vascular action was also investigated. METHODOLOGY: The relaxant effect of the base, the catalyst and mixed Epiphany on isolated rat aortic rings pre-contracted with phenylephrine (PE) was tested. The aortic rings were then incubated with either nitric oxide synthase (NOS) inhibitor, cyclooxygenase (COX) inhibitor or K(+) channel inhibitors; after pre-contraction with PE, relaxations to the various compounds of Epiphany were examined. In another set of experiments, to investigate the Ca(2+)channel antagonistic effect of the Epiphany, the effect of these compounds in Ca(2+)-free solution on extracellular Ca(2+)(CaCl(2))-induced contraction in high-K(+) pre-challenged rings (in K(+)-depolarized rings) was examined to determine whether the direct inhibition of [Ca(2+)] influx increase accounted for the vasodilatory effects of these compounds. For comparison, L-type Ca(2+)channel blocker nifedipine (1 micromol L(-1)), instead of Epiphany compounds, was assayed in adjacent rat aortic rings in parallel. RESULTS: The catalyst and the mixture of Epiphany induced concentration-dependent relaxations. However, the base of Epiphany did not cause relaxation in rat aorta. The relaxation responses were not significantly altered by incubation of aorta with NOS, COX and potassium channel inhibitors. Whilst nifedipine, the catalyst and the mixture of Epiphany inhibited CaCl(2)-induced contractions (P < 0.05), the base of Epiphany did not inhibit CaCl(2)-induced contractions significantly (P > 0.05). CONCLUSION: Epiphany induced relaxation of rat aorta via a calcium antagonistic effect. Provided that the vasodilatory effect elicited by Epiphany can be reversed by the circulation, its haemorrhagic potential by virtue of permanent vascular dilatation can be ignored.

Brain aluminium accumulation and oxidative stress in the presence of calcium silicate dental cements.

Mineral trioxide aggregate (MTA) is a calcium silicate dental cement used for various applications in dentistry. This study was undertaken to test whether the presence of three commercial brands of calcium silicate dental cements in the dental extraction socket of rats would affect the brain aluminium (Al) levels and oxidative stress parameters. Right upper incisor was extracted and polyethylene tubes filled with MTA Angelus, MTA Fillapex or Theracal LC, or left empty for the control group, were inserted into the extraction socket. Rats were killed 7, 30 or 60 days after operation. Brain tissues were obtained before killing. Al levels were measured by atomic absorption spectrometry. Thiobarbituric acid reactive substances (TBARS) levels, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were determined using spectrophotometry. A transient peak was observed in brain Al level of MTA Angelus group on day 7, while MTA Fillapex and Theracal LC groups reached highest brain Al level on day 60. Brain TBARS level, CAT, SOD and GPx activities transiently increased on day 7 and then returned to almost normal levels. This in vivo study for the first time indicated that initial washout may have occurred in MTA Angelus, while element leaching after the setting is complete may have taken place for MTA Fillapex and Theracal LC. Moreover, oxidative stress was induced and antioxidant enzymes were transiently upregulated. Further studies to search for oxidative neuronal damage should be done to completely understand the possible toxic effects of calcium silicate cements on the brain.