Michele Simeone

Effect of Mineral Trioxide Aggregate on Mesenchymal Stem Cells

INTRODUCTION Mineral trioxide aggregate (MTA) is known to stimulate the hard tissue repair process. The purpose of this study was to evaluate the ability of MTA to support the adhesion, proliferation, and migration of human bone marrow-derived mesenchymal stem cells (hMSCs). METHODS White ProRoot MTA and white Portland cement were mixed and left to set 24 hours. MSCs were cultured on the samples and observed after 24 hours by confocal laser scanning microscopy (CLSM) by using the cytoskeleton marker CellTracker. Cell proliferation was evaluated by means of alamar blue assay in the presence and absence of differentiation medium during a period of 28 days, and cells seeded on polystyrene culture wells were the control. To assess the effect on migratory ability of hMSCs, a transwell migration assay was performed for 18 hours, positioning MTA and Portland cement in 6-well plates and the cells in 8-μm pore inserts. RESULTS hMSCs observed under CLSM showed attachment and spread activity on the upper surface of the MTA. Cell proliferation was significantly higher on MTA than on Portland cement. A rate proliferation increase of the MTA group compared with the control was observed after 14 days in presence of basic medium, whereas the same effect was reached after 21 days in presence of differentiation medium. Moreover, MTA was able to enhance cell migration significantly more than Portland cement. CONCLUSIONS Our findings suggest that MTA was able to assist hMSC adhesion, growth, and migration.

Effect of Nickel Chloride on Cell Proliferation

Objective: Metal alloys used in dentistry and in other biomedical fields may release nickel ions in the oral environment. The release of nickel might influence the normal biological and physiological processes, including tissue wound healing, cell growth and proliferation. The aim of this study was to evaluate in vitro the effects of nickel ions on cell cycle, viability and proliferation. Materials and Methods: Human osteosarcoma cells (U2OS) and human keratinocytes (HaCat) were exposed to different nickel chloride (NiCl2) concentrations (0 - 5mM) for various periods exposure. The viability of cultured cells was estimated by flow cytometry using Annexin V-FITC and Propidium Iodide (PI). Cell proliferation was evaluated by using carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and flow cytometry. Finally, the effects of NiCl2 on cell cycle were assessed and quantified by flow cytometry. Statistical analysis was performed by means of ANOVA followed by Tukey’s test. Results: NiCl2 induced a dose and time dependent decrease in cell viability. After 24h, 1mM NiCl2 caused a similar and significant reduction of viability in U2OS and HaCat cells, while higher NiCl2 concentrations and longer exposure times showed a reduced cytotoxic effect in HaCat as compared to U2OS cells. Exposure to NiCl2 caused a dose- and time-dependent inhibition of cell proliferation in both cell lines tested, with a prominent effect on U2OS cells. Furthermore, both cell lines exposed to NiCl2 exhibited significant changes in cell cycle distribution after 24h exposure 2mM NiCl2, as compared to untreated cells (p<0.05). Conclusion: Our results indicate that release of nickel ions may affect cell proliferation. The inhibition of cell growth by NiCl2 is mediated by both cell cycle arrest and by induction of cell death.

Effects of sodium hypochlorite and ethylenediaminetetraacetic acid on rotary nickel–titanium instruments evaluated using atomic force microscopy

AIM To use atomic force microscopy (AFM) to evaluate the effects of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) on the surface characteristics of ProTaper rotary nickel-titanium instruments. METHODOLOGY A total of twenty ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) instruments (S1, S2, F1, F2) were divided into five groups: no immersion, immersion in 5.25% NaOCl for 5 or 10min and immersion in 17% EDTA for 5 or 10min. Twenty surface areas along 3-mm sections at the tip of the files (perfect squares of 1x1μm) were analysed by AFM operating in contact mode under ambient conditions. Three-dimensional images (400x400 lines) were processed using Gwyddion software, and the roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova and paired samples t-test. RESULTS Three-dimensional AFM images of the surface of ProTaper instruments, including new and those immersed in NaOCl and EDTA solutions, revealed topographic irregularities at the nanometric scale. RMS and Ra values of instruments treated with NaOCl and EDTA solutions were statistically higher than that of the new ones (P<0.05). CONCLUSIONS Atomic force microscopy three-dimensional images and roughness values indicated that short-term contact between NaOCl and EDTA endodontic irrigants and ProTaper instruments caused alterations in the surface of instruments.

µCT analysis of mandibular molars before and after instrumentation by Reciproc files

Cleaning and shaping are important section for the root canal treatment. A number of different methodologies have been developed to overcome these problems, including the introduction of rotary instruments nickel-titanium (NiTi). In endodontics NiTi have been shown to significantly reduce procedural errors compared to manual techniques of instrumentation. The efficiency of files is related to many factor. Although previous investigations that have used µCT analysis were hampered by insufficient resolution or projection incorrect. The new generation of μCT performance best offer, as micron resolution and accurate measurement software for evaluating the accurate anatomy of the root canal. The aim the paper was to evaluate the efficiency of Reciproc files in root canal treatment, evaluated before and after instrumentation by using μ-CT analysis.

Temperature Profiles Along the Root with Gutta-percha Warmed through Different Heat Sources

Objectives: To evaluate temperature profiles developing in the root during warm compaction of gutta-percha with the heat sources System B and System MB Obtura (Analityc Technology, Redmond, WA, USA). Thirty extracted human incisor teeth were used. Root canals were cleaned and shaped by means of Protaper rotary files (Dentsply-Maillefer, Belgium), and imaging was performed by micro-CT (Skyscan 1072, Aartselaar, Belgium). Methods: Teeth were instrumented with K-type thermocouples, and the roots were filled with thermoplastic gutta-percha. Vertical compaction was achieved through the heat sources System B and System MB, and temperature profiles were detect-ed by means of NI Dac Interface controlled by the LabView System. With both heat sources, higher temperature levels were recorded in the region of the root far from the apex. When the warm plugger tip was positioned at a distance of 3 mm from the root apex, temperature levels of about 180°C were used to soften gutta-percha, and no statistically significant differences were observed between peak temperatures developed by the two heating sources at the root apex. However, a temperature level higher than 40°C was maintained for a longer time with System MB. Results: Statistically significant differences were observed in peak temperature levels recorded far from the root apex. Thus, with a temperature of about 180°C and the warm plugger positioned at 3 mm from the root apex, both heating sources led to a temperature slightly higher than 40°C at the apex of the root, suggesting that the gutta-percha was properly softened. Significance: A temperature level higher than 40°C was maintained for a longer time with System MB, thus providing an ad-equate time for warm compaction of the gutta-percha.

Polyacrylic resins regulate transcriptional control of interleukin-6, gp80, and gp130 genes in human gingival fibroblasts

Studies have failed to identify the molecular mechanisms that regulate the genotoxic and cytotoxic effects of methacrylate resins, which are important in the biocompatibility of dental materials. Interleukin (IL)-6 has a crucial role in the control of acute-phase protein response during inflammation. In humans, the synthesis and release of two major acute-phase proteins, C-reactive protein and serum amyloid A, are regulated by IL-6. This study focused on IL-6 and activation of its receptors gp80 and gp130 in human gingival fibroblasts in order to assess the effects of the commercial acid resins Jet Kit, Unifast, and Duralay on control of inflammation.

The IG- file use to Gauge the Apical Diameter in Endodontics: An In Vitro Study

Aim: The aim of this study was to evaluate the efficacy of the IG-file, a new instrument designed for apical diameter gauging. Materials and Methods: After shaping with F1 Universal Protaper, 60 roots were randomly divided into two groups and assigned to two operators, One Expert in Endodontics (EO) and One Unexpert (UO). In each sample, after canal curvatures have been detected, the apical diameters were measured with the IG-file and the K-NiTi. The results were compared with the reference value obtained by retrograde apical gauging. The data were statistically analyzed. Results: Among 60 samples, 10% of errors were recorded when the IG-files were used; in the K-NiTi group the incorrect measurements were 70%. In both groups (expert and unexpert) the IG-file measurements were more accurate than the K-NiTi (90 vs 33 and 90 vs 26,7). The differences were statistically significant. In curved canals, the difference between measurement rates performed with both instruments was statistically significant (85,7% IG-file vs 28,6% K-NiTi) as well as for the samples without curvatures (92,3% IG file vs 30,8% NiTi file). In root canals without curvatures overestimation errors in K-NiTi file group are more frequent than underestimation errors. This difference was statistically significant. Conclusion: A proper gauging of the apical diameter has a key role in endodontic therapy; an incorrect measurement can lead to clinical failures. This “in vitro” study highlights that IG-file improves measurement accuracy independently from clinician experience. Furthermore, in curved canals, the IG-file is more accurate than K-NiTi.

Numb chin syndrome: A reflection of malignancy or a harbinger of MRONJ? A multicenter experience

INTRODUCTION Numb chin syndrome (NCS) or mental neuropathy (MN) is a disorder characterized by sensory neuropathy on the distribution of the inferior alveolar nerve or mental nerve. The most frequent causes are of odontogenic origin (infections, wrong therapies). Other etiologies are related to primary tumor, metastasis, osteoradionecrosis and medication-related osteonecrosis of the jaw (MRONJ). The aim of this study is to highlight the clinical importance of NCS as one of the first symptoms of cancer or as consequence of drug therapy. MATERIALS AND METHODS The present study was conducted from 2010 to 2016 by recruiting patients who present NCS as one of the symptoms, having excluded those in which it depends on a clear odontogenic cause, on systemic degenerative diseases or metabolic disorders. Data collection included suspected diagnosis at the time of presentation of the symptom, final diagnosis, mandibular localization, treatment performed and diagnostic delay between the first medical examination and the definitive diagnosis. RESULTS This study included 29 patients in which NCS had not a clear odontogenic cause. NCS was the first symptom of malignancy in 11 cases and the clinical sign of metastasis in 4 cases. In a single patient, it was the first symptom of an immune-mediated disease. In the remaining 13 patients, NCS represented the symptom of MRONJ. CONCLUSION NCS can be the first symptom of malignancy, especially in patients with a previous history of cancer, but also a prodromal sign of MRONJ. It should be recognized in order to require deeper examinations for early diagnosis of the disease.

Dentizione decidua: Studio della complessità anatomica mediante μtC

Endodontics is the branch of deciduous teeth pediatric dentistry that deals with the treatment of the root canal system. The goal of therapy is to maintain as long as possible the element in the dental arch to prevent alterations of orthognathodontic, infectious, and functional history and eruptive sequence. Although manual instrumentation has been widely used and still preferred by some practitioners, has limitations that affect the actual ability to clean the channel, the ability to create steps, perforations, dentinal plugs and fractures of the instrument. On the other hand, the disadvantages are the high cost of the instruments in nickel-titanium, which must be frequently replaced, and the risk of compromising the stability of the tooth due to an excessive consumption of dentinal tissue. The use of computed microtomography (μCT) of extracted elements has a considerable advantage in the study of dental hard tissues. The purpose of this study was to analyze the anatomy of the endodontic system of the elements deciduous.