Camillo D'Arcangelo

An evaluation of the action of different root canal irrigants on facultative aerobic-anaerobic, obligate anaerobic, and microaerophilic bacteria.

The aim of this study was to test the effect of different concentrations of sodium hypochlorite, chlorhexidine, and cetrimide on the following bacterial strains: Facultative aerobes-anaerobes: Candida albicans ATCC 10231; Enterococcus faecalis ATCC 29212; Escherichia coli ATCC 25,922; Pseudomonas aeruginosa ATCC 27,853; Streptococcus mitis ATCC 9811; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; and Streptococcus sanguis ATCC 10556. Microaerophiles: Actinobacillus actinomycetemcomitans ATCC 29522. Obligate anaerobes: Actinomyces odontolyticus ATCC 17929; Fusobacterium nucleatum ATCC 25,586; Porphyromonas gingivalis ATCC 33277; and Prevotella melaninogenica ATCC 25845. Each irrigant was kept in contact with the bacterial species used for the experiment for 10, 20, or 30 min. Results showed that all irrigants had a bactericidal effect on both facultative aerobes-anaerobes and on microaerophilic and obligate anaerobic strains, in all concentrations and even after short periods of contact.

Fracture Resistance and Deflection of Pulpless Anterior Teeth Restored with Composite or Porcelain Veneers

INTRODUCTION The aim of this in vitro study was to evaluate the influence that resin composite and porcelain veneer restorations, associated or not to fiber post placement, have on fracture resistance and deflection of pulpless anterior teeth. METHODS One hundred twenty freshly extracted human maxillary central incisors were selected. Teeth were randomly divided into 7 experimental groups (veneer preparation/resin composite veneer placement/endodontic therapy and resin composite veneer placement/endodontic therapy, fiber post and resin composite veneer placement/porcelain veneer placement/endodontic therapy and porcelain veneer placement/endodontic therapy, fiber post and porcelain veneer placement) and a control group (n = 15). Specimens were loaded to fracture recording crown deflection, and data were statistically analyzed. RESULTS Veneer preparations did not significantly influence fracture resistance of incisors. On the contrary, veneer preparation significantly increased specimen deflection values. Fiber posts seemed to significantly increase mean maximum load values for endodontically treated teeth restored with either composite or porcelain veneers. CONCLUSIONS A fiber post restoration can be suggested when endodontic treatment is associated with veneer restoration. Veneer restorations seem to be an optimal choice also for endodontically treated teeth.

In Vitro Fracture Resistance and Deflection of Pulpless Teeth Restored with Fiber Posts and Prepared for Veneers

The aim of this in vitro study was to evaluate the influence of endodontic therapy, veneer preparation, and their association on fracture resistance and deflection of pulpless anterior teeth and assess whether restoration with quartz fiber-reinforced post can influence these properties. Seventy-five freshly extracted human maxillary central incisors were selected. Teeth were randomly divided into 4 experimental groups (veneer preparation/endodontic therapy/endodontic therapy and veneer preparation/endodontic therapy, veneer preparation, and fiber post placement) and a control group (n = 15). Specimens were loaded to fracture recording crown deflection under load, and data were statistically analyzed. Veneer preparations and endodontic treatment did not significantly influence fracture resistance of maxillary incisors. On the contrary, preparation for veneer significantly increased the deflection values of the specimens. Fiber post restorations seemed to significantly increase mean maximum load values for specimens prepared for veneers. A fiber-reinforced post restoration can be suggested when endodontic treatment is associated with veneer preparation.

Localization of the e-NOS enzyme in endothelial cells and odontoblasts of healthy human dental pulp

Nitric oxide synthases (NOS) are important enzymes present in different cells such as endothelial cells, macrophages, etc. Recently, it has been found that nitric oxide (NO) is responsible for vasodilation, blood pressure regulation, platelet aggregation, cardiac contractility, and the mediation of immunity during bacterial infections and inflammation. However, the production and role of NO in various structures of the oral cavity have not been investigated extensively. The aim of this study was to evaluate the presence of e-NOS in healthy human odontoblasts and endothelial cells of the dental pulp. Twenty healthy human dental pulps were collected and frozen and pulp slices were obtained using a cryostat. The e-NOS enzyme was revealed by immunohistochemical analysis and the enzyme level was detected by Western blotting and mRNA expression by RT-PCR. The immunohistochemical results demonstrated, for the first time, the presence of e-NOS in odontoblasts and in endothelial cells. The presence of e-NOS m-RNA was confirmed by RT-PCR and the expression of the protein by Western blotting. These results clearly show that the e-NOS enzyme is present in both odontoblasts and endothelial cells of healthy human pulp. The presence of e-NOS in the odontoblast and endothelial cells of the dental pulp may mediate local vasodilation and cell proliferation.

Pro‐inflammatory cytokine release and cell growth inhibition in primary human oral cells after exposure to endodontic sealer

AIM To assay the toxicity of the single-methacrylate-based sealer urethane dimethacrylate (UDMA) (EndoRez) in terms of cell growth and pro-inflammatory cytokines release, in expanded ex vivo human dental pulp stem cells (hDPSCs), human periodontal ligament stem cells (hPDLSCs), human gingival fibroblasts (hGFs) and human osteoblasts (hOSTs). METHODOLOGY Dental pulp and periodontal ligament stem cells, osteoblasts and fibroblasts were derived from five young donors. After in vitro isolation, hDPSCs, hPDLSCs, hGFs and hOSTs were seeded to resin-based sealers for 24, 48, 72 h up to 1 week. The morphological features and the cell growth and the release of pro-inflammatory interleukin (IL)6, IL8, IL12 and tumour necrosis factor (TNF) α were analysed. Differences in cell growth and in interleukin secretion were analysed for statistical significance with two-way anova tests for multiple comparisons. RESULTS Exposure to endodontic sealer based on UDMA resulted in a 50% decrease in survival oral cells at 24 h of incubation. No evident morphological changes were present in cell cultures examined. After 48 h, 72 h and 1-week culture time, a progressive cell growth was evident. A significant up-regulation of IL6, IL8, IL12 and TNFα cytokines in cells in contact with the dental sealer compared to the control was observed. CONCLUSION In vitro, EndoRez interacted with primary human hDPSCs, hPDLSCs, hGFs and hOSTs causing damage to biological system evidenced through cell growth inhibition and up-regulation of IL6, IL8, IL12 and TNFα proinflammatory mediators.

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.

Morphological analysis and interleukin release in human gingival fibroblasts seeded on different denture base acrylic resins.

The development of different types of materials with application in practice dentistry is an area of intense growth and research due to its importance in oral health. Among the diverse materials currently used in restoration or in dentures, the acrylic based resins have been widely employed. The release of toxic components and the changes on their physical and mechanical properties actually represent a goal of intensive research. In vivo analysis showed that the surface roughness of the acrylic resin represents a factor that could stimulate bacteria colonization and soft tissue inflammation. For this purpose, in this work, we have analyzed the cell response to acrylic based resins Ivoclar, Tokuso and Coldpack in basal conditions, unpolished, and after the polished procedure performed to reduce the surface roughness. Our in vitro results using human gingival fibroblasts (HGFs) showed a decrease of cell growth, evaluated by MTT assay starting at 24 h of incubation, in samples seeded on resins in basal conditions and after the polished procedure. This cell growth reduction was associated to evident morphological changes in unpolished materials. After 24 h of culture in presence of polished and unpolished resins a spontaneous release was present of pro-inflammatory cytokines such as Interleukin-6 (IL-6) and −8 (IL-8), which was higher in unpolished resins, indicating that the polished procedure, minimizing the cytotoxicity process, could contribute to reduce the gingival inflammation processes.

Wear properties of a novel resin composite compared to human enamel and other restorative materials.

The purpose of this in vitro study was to compare the two-body wear resistance of human enamel, a pressable glass-ceramic (Imagine PressX), a type 3 gold alloy (Aurocast8), three resins composites currently available on the market (Enamel plus HRi, Filtek Supreme XTE, Ceram.X duo), and one recently introduced resin composite (Enamel plus HRi-Function). Resin composites were tested after simple light curing and after a further heat polymerization cycle. Ten cylindrical specimens (7 mm in diameter) were manufactured with each dental material according to standard laboratory procedures. Ten flat enamel specimens were obtained from freshly extracted human molars and included in the control group. All samples were subjected to a two-body wear test in a dual-axis chewing simulator over up to 120,000 loading cycles, against yttria stabilized tetragonal zirconia polycrystal cusps. Wear resistance was analyzed by measuring the vertical substance loss (mm) and the volume loss (mm(3)). Antagonist wear (mm) was also recorded. Data were statistically analyzed using one-way analysis of variance (ANOVA) (wear depth and volume loss) and Kruskal-Wallis one-way ANOVA on ranks (antagonist wear). Heat-cured HRi function and Aurocast8 showed similar mean values for wear depth and volumetric loss, and their results did not statistically differ in comparison with the human enamel.

Influence of a repeated preheating procedure on mechanical properties of three resin composites.

The aim of this study was to assess the flexural strength, flexural elastic modulus and Vickers microhardness of three resin composites prepared at room temperature or cured after one or repeated preheating cycles to a temperature of 39°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium), Opallis (FGM), and Ceram X Duo (Dentsply DeTrey). For each trial, one group of specimens of each material was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 1, 10, 20, 30, or 40 preheating cycles to a temperature of 39°C in a preheating device. Ten rectangular prismatic specimens (25 × 2 × 2 mm) were prepared for each group (N=180; n=10) and subjected to a three-point bending test for flexural strength and flexural modulus evaluation. Vickers microhardness was assessed on 10 cylindrical specimens from each group (N=180; n=10). Statistical analysis showed that, regardless of the material, the number of heating cycles was not a significant factor and was unable to influence the three mechanical properties tested. However, a significant main effect of the employed material on the marginal means of the three dependent variables was detected.

NF-κB and NOS may play a role in human RPMI-8402 cell apoptosis

Apoptosis is a fundamental process that is required for the normal development and functioning of the immune system. It can be induced in different ways depending on cell type and acquired signal. Since the NF‐κB transcription factor complex is believed to be involved in nitric oxide‐induced apoptosis, the aim of this study was to investigate NF‐κB and nitric oxide synthase (NOS) activity during dimethyl sulphoxide (DMSO)‐dependent cell death of RPMI‐8402 human pre‐T cells. Our results show that NF‐κB activation is associated with a significant up‐regulation of NOS activity and induction of apoptosis. Furthermore, the inhibition and reversal of these effects by parthenolide treatment or DMSO removal indicate that these molecules are directly involved in the progression of cell death.