Visualisation of human dental pulp vasculature by immunohistochemical and immunofluorescent detection of CD34: A comparative study

Histological evaluation of a novel phosphorylated pullulan-based pulp capping material: An in vivo study on rat molars

AIM

To evaluate the dental pulp response to a novel mineral trioxide aggregate containing phosphorylated pullulan (MTAPPL) in rats after direct pulp capping.

METHODS

Ninety-six cavities were prepared in the maxillary first molars of 56 male Wistar rats. The dental pulps were intentionally exposed and randomly divided into four groups according to the application of pulp capping materials: MTAPPL; phosphorylated pullulan (PPL); a conventional MTA (Nex-Cem MTA, NCMTA; positive control); and Super-Bond (SB; negative control). All cavities were restored with SB and observed for pulpal responses at 1-, 3-, 7- and 28-day intervals using a histological scoring system. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-test with Bonferroni's correction, and the level of significance was set at 0.05. DMP1 and CD34 antigen were used to evaluate odontoblast differentiation and pulpal vascularization, respectively.

RESULTS

On day 1, mild inflammatory cells were present in MTAPPL and NCMTA groups; fewer inflammatory cells were present in the PPL, whereas SB was associated with a mild-to-moderate inflammatory response. A significant difference was observed between PPL and SB (p < .05). No mineralized tissue deposition was observed. On day 3, moderate-to-severe inflammatory cells were present in PPL and SB, whereas MTAPPL and NCMTA had a mild inflammatory response. Initial mineralized tissue deposition was observed in the NCMTA, MTAPPL and SB. A significant difference was observed between MTAPPL and PPL (p < .05). On day 7, a thin layer of mineralized tissue was observed in all tested groups with no or mild inflammatory response. On day 28, no inflammatory response was observed in MTAPPL, whereas NCMTA, PPL and SB had mild inflammatory responses. A significant difference was observed between MTAPPL and SB (p < .05). Complete mineralized tissue barrier formation was observed in MTAPPL, NCMTA and PPL with no significant difference (p > .05). SB exhibited incomplete mineralized tissue barriers, significantly different from NCMTA, MTAPPL and PPL (p < .05). The staining with CD34 was positive in all the groups on all observation days.

CONCLUSION

The favourable pulpal responses and induction of mineralized tissue formation associated with MTAPPL indicate its potential application as a direct pulp capping material.

Monitoring the Process of Endostar-Induced Tumor Vascular Normalization by Non-contrast Intravoxel Incoherent Motion Diffusion-Weighted MRI

Tumor vascular normalization has been proposed as a new concept in anti-tumor angiogenesis, and the normalization window is considered as an opportunity to increase the effect of chemoradiotherapy. However, there is still a lack of a non-invasive method for monitoring the process of tumor vascular normalization. Intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (IVIM DW-MRI) is an emerging approach which can effectively assess microperfusion in tumors, without the need for exogenous contrast agents. However, its role in monitoring tumor vascular normalization still needs further study. In this study, we established a tumor vascular normalization model of CT26 colon-carcinoma-bearing mice by means of Endostar treatment. We then employed IVIM DW-MRI and immunofluorescence to detect the process of tumor vascular normalization at different times after treatment. We found that the D^* values of the Endostar group were significantly higher than those of the control group on days 4, 6, 8, and 10 after treatment, and the f values of the Endostar group were significantly higher than those of the control group on days 6 and 8. Furthermore, we confirmed through analysis of histologic parameters that Endostar treatment induced the CT26 tumor vascular normalization window starting from day 4 after treatment, and this window lasted for 6 days. Moreover, we found that D^* and f values were well correlated with pericyte coverage (r = 0.469 and 0.504, respectively; P < 0.001, both) and relative perfusion (r = 0.424 and 0.457, respectively; P < 0.001, both). Taken together, our findings suggest that IVIM DW-MRI has the potential to serve as a non-invasive approach for monitoring Endostar-induced tumor vascular normalization.

Prolyl hydroxylase inhibitors increase the production of vascular endothelial growth factor in dental pulp-derived cells

INTRODUCTION

Prolyl hydroxylase (PHD) inhibitors can induce a proangiogenic response that stimulates regeneration in soft and hard tissues. However, the effect of PHD inhibitors on the dental pulp is unclear. The purpose of this study was to evaluate the effects of PHD inhibitors on the proangiogenic capacity of human dental pulp-derived cells.

METHODS

To test the response of dental pulp-derived cells to PHD inhibitors, the cells were exposed to dimethyloxalylglycine, desferrioxamine, L-mimosine, and cobalt chloride. To assess the response of dental pulp cells to a capping material supplemented with PHD inhibitors, the cells were treated with supernatants from calcium hydroxide. Viability, proliferation, and protein synthesis were assessed by formazan formation, (3)[H]thymidine, and (3)[H]leucine incorporation assays. The effect on the proangiogenic capacity was measured by immunoassays for vascular endothelial growth factor (VEGF).

RESULTS

We found that all 4 PHD inhibitors can reduce viability, proliferation, and protein synthesis at high concentrations. At nontoxic concentrations and in the presence of supernatants from calcium hydroxide, PHD inhibitors stimulated the production of VEGF in dental pulp-derived cells. When calcium hydroxide was supplemented with the PHD inhibitors, the supernatants from these preparations did not significantly elevate VEGF levels.

CONCLUSIONS

These results show that PHD inhibitors can stimulate VEGF production of dental pulp-derived cells, suggesting a corresponding increase in their proangiogenic capacity. Further studies will be required to understand the impact that this might have on pulp regeneration.

Pulp vitality in patients with intraoral and oropharyngeal malignant tumors undergoing radiation therapy assessed by pulse oximetry

INTRODUCTION

The aim of this study was to evaluate pulp oxygenation levels (%SpO(2)) in patients with malignant intraoral and oropharyngeal tumors treated by radiotherapy (RT).

METHODS

Pulp oxygenation levels were measured by pulse oximetry. Twenty patients were selected, and two teeth of each participant (n = 40) were analyzed, regardless of the quadrant and the area irradiated, at four different time points: TP1, before RT; TP2, at the beginning of RT with radiation doses between 30 and 35 Gy; TP3, at the end of RT with radiation doses between 60 and 70 Gy; and TP4, 4 to 5 months after the beginning of cancer treatment.

RESULTS

Mean %SpO(2) at the different time points were 93% (TP1), 83% (TP2), 77% (TP3), and 85% (TP4). The Student's t test showed statistically significant differences between TP1 and TP2 (P < .01), TP3 (P < .01), and TP4 (P < .01). TP3 was also statistically significantly different when compared with TP2 (P < .01) and TP4 (P < .01). No statistically significant difference could be observed between TP2 and TP4.

CONCLUSIONS

Because the mean %SpO(2) before RT was greater than during and after therapy and values obtained 4 to 5 months after the beginning of RT were close to the initiation of RT, pulp tissue may be able to regain normal blood flow after RT. If the changes in the microcirculation of the dental pulp were indeed transitory, preventive endodontic treatment or extraction in patients who are currently undergoing or recently received RT and who show negative signs of pulp sensitivity may not be necessary for pulpal reasons.