Dental Pulp Stem Cells Bioadhesivity: Evaluation on Mineral-Trioxide-Aggregate

Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. Dental Pulp Mesenchymal Stem Cells (DP-MSCs) are involved in dental repair by activation of growth factors, released after caries and have the ability to regenerate a dentin-pulp-like complex. The molecular/cellular research gives the possibility to grow new tissues and biological structures for clinical applications, providing cells for therapies including cell transplantation and tissue engineering. In this study DP-MSCs were derived from dental pulp of 10 donors. To evaluate material toxicity, after in vitro isolation, the cells were seeded on mineral trioxide aggregate (MTA). Initial light microscopy investigation of cells revealed no signs of cell death due to toxicity or infection, on the contrary the scaffolds supplied an excellent support for cell structures, the cells proliferated and adhered to substrate. Similar observation was seen in scanning electron microscopy, in particular the cells had proliferated and spread, covering a considerable part of the surface of the biomaterials investigated, with an elaborate form of attachment, in fact, the cells formed a continuous layer on the upper surface of the MTA. In conclusion, the aim of this study is to demonstrate that DP-MSCs combined with MTA could be a potential source for regenerative medicine, encouraging further study to evaluate the new dentin formation.

Pulp-Dissolving Ability of Several Endodontic Irrigants: A Spectro-Photometry Evaluation

The aim of this study is to test the dissolving action of different concentrations of NaOCl (0.5%, 2.5% and 5%) and EDTA 17% on bovine pulp tissue, testing solutions at three different times (1, 5, 10 minutes). 100 mg. of dental pulp placed into a becher with 20 ml of solution was evaluated using a spectrophotometer. A solution of NaOCl 5% showed the highest solubility value. Samples treated with 2.5% NaOCl showed solubility values of 0.98 in one minute, 29.1 in five minutes and 57 in ten minutes. Groups treated with NaOCl 0.5% showed small dissolving modifications. 17% EDTA showed the lowest values of solubility. 5% NaOCl solution showed highest pulp dissolving ability, even a 2.5% solution showed high dissolving ability but in longer times.

Endodontic-orthodontic relationships: expression of no synthase in human dental pulp during orthodontic tooth movement

Inflamed human pulp tissue presents an increase in the level of nitric oxide synthase (NOS). The aim of this study is to verify the presence of NOS in human pulp of teeth that are subject to orthodontic force. 20 healthy subjects, wearers of fixed braces on the upper arch, were selected. An open coil-spring in NiTi was applied on the upper premolar test tooth (TT); the controlateral control tooth (CCT) was subjected to orthodontic treatment but not to the further force of the open coil-spring; the antagonist control tooth (ACT) did not undergo any orthodontic treatment. Pulps were taken from test, contralateral control and antagonist control teeth immediately after the extractions which were done at 15 and 30 days from the start of application of the orthodontic force. The pulp tissue was analyzed through immunohistochemical and molecular biology examinations. The results showed tooth pulps subject to orthodontic treatment were very inflamed in the first 15 days with high levels of iNOS and low levels of eNOS; after 30 days a decrease of the inflammation and an increase of the pulp vascularization were observed together with a reduction of iNOS and an increase of eNOS respectively.

The cytotoxic effects of resin-based sealers on dental pulp stem cells

AIM

To evaluate the effect of four current resin-based adhesives on expanded ex vivo human dental pulp mesenchymal stem cells (DP-MSCs).

METHODOLOGY

Dental pulp mesenchymal stem cells were derived from dental pulps of ten donors. After in vitro isolation, dental pulp stem cells were analysed using flow cytometry. The immunophenotype of DP-MSCs disclosed the homogeneous expression of the mesenchymal-related antigens CD29, CD44, CD73, CD90, CD105, CD166. DP-MSCs were exposed to four different commercially available bonding systems (CMF Bond, Prime&Bond NT, Clearfil S(3) Bond, XP Bond), and after 24, 48 and 72 h of incubation the morphological features and the cell growth were analysed. Moreover, the cell viability was evaluated at the same times by MTT assay. Data were statistically analysed using a two-way anova and Holm-Sidak method (alpha set at 0.05).

RESULTS

Significant differences were observed between the four groups when comparing DP-MSCs appearance. DP-MSCs survived and proliferated without inhibition in the presence of CMF Bond adhesive. On the contrary, microscopic evaluation of the other three groups revealed extensive cytotoxic effects from the dentine bonding agents. The MTT assay revealed no statistically significant differences in cell viability after 72 h between the control group and CMF Bond group. All the other experimental groups had statistically lower optical density values.

CONCLUSIONS

CMF Bond adhesive allowed human dental pulp stem cells to survive and proliferate. All of the other dentine bonding agents had extensive cytotoxic effects.

Nitric oxide synthase in healthy and inflamed human dental pulp

Nitric oxide synthase (NOS) plays a significant role in the pathogenesis of pulpitis. In this study, we hypothesized the existence of endothelial (eNOS) and inducible (iNOS) enzyme isoforms in human dental pulp. Extracted third molar pulps were divided into groups based on clinical diagnosis: healthy, hyperemic, and irreversible pulpitis. We have localized the eNOS and iNOS by immunohistochemistry and have tested their mRNA expression by RT-PCR and protein levels by Western blots. eNOS is present in the endothelial cells and odontoblasts of the healthy pulp, but an elevation of eNOS mRNA and protein levels with a concomitant dilation of vessels was characteristic under pathological conditions. Healthy pulp tissue failed to exhibit any iNOS; however, acute inflammation enhanced the mRNA and protein levels of iNOS, mainly in the leukocytes. There are differences in localization and expression between eNOS and iNOS in healthy and inflamed dental pulp.

Canal filling in primary teeth. Description of two particular cases

Endopedodontics is that branch of child dentistry that regards pulp treatment in childhood. It involves endodontic treatment of all primary teeth and incisives, and of the first permanent molars with immature apex. The pedodontist has to exactly evaluate the techniques and the material to use in treating his patients. It is important to realize that we are facing a continuously evolving and absolutely unstable dentition. Therefore, the success of our work is the result of a careful evaluation of diagnostic parameters and of the techniques and the material. In the current clinical cases it is obvious how the lack of only one of the parameters listed, could represent the cause of severe damage to the patient's dental health and it could lead to psychological discomfort (if not damage), considering the age of the patient.

[Alpha-hemolytic streptococci and root canal irrigants. An evaluation of the bactericidal efficacy of sodium hypochlorite and chlorhexidine gluconate plus cetrimide]

BACKGROUND AND AIMS

The main bacterial species present in pulpal and periapical microbic flora is alpha-hemolytic streptococci. They are regarded as facultative anaerobes which prefer to grow in anaerobiosis. Canal irrigation plays an important role in the success of endodontic treatment given that, on the one hand, it encourages the gradual elimination of the smear layer, and on the other it neutralises microbic flora in the root canal. The aim of this study was to test the microbiological efficacy of sodium hypochlorite 1% and s new generation irrigant based on chlorhexidine 0.2% and cetrimide 0.2%.

METHODS

The test was performed on the following alpha-hemolytic streptococci bacteria (Dasit, Cornaredo, Italy): Streptococcus mitis ATCC 9811; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; Streptococcus sanguis ATCC 10556. The working concentration (CFU/ml) was defined as 0.5 Mc Farland which corresponds to a concentration of microorganisms of approximately 1.5 x 10(8) bacteria. The following canal irrigants were used: 1) cetrimide 0.2% + chlorhexidine 0.2% (Cetrexidin Vebas, S. Giuliano Milanese, Italy); 2) NaOCl 1% (Ogna, Milan, Italy). Each individual substance remained in contact with the bacterial species used in the test for 10'-20'-30'.

RESULTS

The results obtained show the bactericidal efficacy of both the irrigants used, even after a short period of contact.

CONCLUSIONS

This does not mean that all irrigants are equal and/or promise the same results. This was a microbiological study, but it is nonetheless important to take other variables into account, such as contact time. Moreover, in order to increase the probabilities for the success of endodontic treatment, canal irrigants must also present other characteristics, namely: biocompatibility, scarce toxicity, high proteolytic power.