Sandro Rengo | Università degli Studi di Napoli "Federico II" (original) (raw)

Papers by Sandro Rengo

Objectives: Various protective effects of N-acetylcysteine (NAC) against triethylene glycol dimet... more Objectives: Various protective effects of N-acetylcysteine (NAC) against triethylene glycol dimethacrylate (TEGDMA)-induced cell damage have been demonstrated, but so far there is no evidence on NAC direct monomer detoxification mechanism. Here, we hypothesized that NAC might reduce TEGDMA cytotoxicity due to direct NAC adduct formation. Methods: we measured the cytotoxic effects of TEGDMA in presence and in absence of NAC by MTT test. Then we analyzed the presence of TEGDMA-NAC adduct formation in extracellular and intracellular compartments by capillary electrophoresis-UV detection (CE-UV) and capillary electrophoresis\u2013mass spectrometry (CE-MS) analytical techniques. Moreover, we quantified the effective intracellular and extracellular TEGDMA concentrations through HPLC in the presence and absence of 10 mmol/L NAC. Data from all experiments were summarized as means \ub1 Standard Deviation (SD) and differences between means were analyzed by one-way analysis of variance (ANOVA) followed by Tukey\u2019s test for multiple comparisons. The level of significance was set at p<0.05. Results: TEGDMA reduced 3T3 cell vitality in a dose- and time-dependent manner, while NAC significantly decreased monomer cytotoxicity and extracellular monomer concentrations by a direct reaction with TEGDMA. The adducts between the two molecules were detected both in the presence and absence of cell. Conclusion: Our results suggest that in vitro detoxification capability of NAC against TEGDMA-induced cell damage might occur also through the formation of NAC-TEGDMA adduct

ABSTRACT Objective: Several in vitro studies have been carried out to investigate the triethyleng... more ABSTRACT Objective: Several in vitro studies have been carried out to investigate the triethylenglycol-dimethacrylate (TEGDMA) cytotoxicity. However, these studies have never focused on how the solvents used to dissolve TEGDMA in the experimental conditions might influence monomer effective concentrations and in turn its cytotoxicity. Hence, the aim of this study was to evaluate the active concentrations of the TEGDMA over the routinely experimental conditions used in biocompatibility in vitro tests and to determine any changes in cytotoxicity depending on the TEGDMA solution composition. Methods: TEGDMA dilutions were prepared directly in DMEM (in absence of cells) or were dissolved previously in DMSO or ethanol and then in medium. Monomer concentrations were quantified by an HPLC system. The cytotoxicity effects of TEGDMA dilutions (1 and 2 mmol/L, with and w/o solvents) were evaluated on 3T3-fibroblasts by MTT assay. ROS production (by FACScan flowcytometer) and intracellular and extracellular TEGDMA concentration (by HPLC) were also determined. Data were analyzed by ANOVA followed by Turkey's test for multiple comparisons. Results: Maximum solubility of TEGDMA in DMEM (in absence of cells) was 0.5 mmol/L both in the presence and absence of solvents. 2 mmol/L TEGDMA - solubilized in DMSO or ethanol and then dissolved in medium - caused a significant decrease in cell viability and an induction of ROS production compared to the same TEGDMA concentration dissolved in medium directly. Moreover when 2 mmol/L TEGDMA was added to the cells in presence of DMSO and ETOH, after 2h of incubation, TEGDMA concentration was reduced respectively 10% and 20%, while, TEGDMA added without vehicles remains constant. Conclusions: Our results showed that TEGDMA solubilization in DMEM was not complete and that the cytotoxic effects of the monomer was influenced by the method of solubilization.

Journal of Clinical Medicine

Vital pulp therapy (VPT) has been recently proposed as an alternative approach even in symptomati... more Vital pulp therapy (VPT) has been recently proposed as an alternative approach even in symptomatic mature permanent teeth with deep caries’ lesions, aiming to maintain the pulp vitality over time and/or to avoid non-surgical root canal therapy (NSRCT). However, to date, the diagnosis of reversible or irreversible pulpitis is only based on clinical pain quantity and quality, without precisely reflecting the pulp inflammation status. Therefore, the aim of the present study was to provide an overview based on the current scientific literature to demonstrate the clinical effectiveness of VPT on mature permanent teeth, validating the use of hydraulic calcium silicate-based cements and their role in pain management. VPT may be successfully applied not only in mature permanent teeth diagnosed with reversible pulpitis, but also in permanent dental elements with signs and symptoms of irreversible pulpitis. Hydraulic cements showed favorable outcomes in terms of decrease of pro-inflammatory m...

Journal of Clinical Medicine, 2022

This study assessed the electrical activity of the masticatory muscles in both children with down... more This study assessed the electrical activity of the masticatory muscles in both children with down syndrome (DS) and healthy children. After applying the inclusion and exclusion criteria, 30 patients aged between 7.9 and 11.8 years participated in the study. They were divided into two groups of 15: DS and non-DS. A DAB-Bluetooth device (Zebris Medical GmbH, Germany) was used to record the electromyographical (EMG) activity of the right and left temporal and of the right and left masseter muscles at rest and during maximum voluntary clenching (MVC). The asymmetry index between right and left masticatory muscle EMG activity was calculated for each position. The Mann–Whitney U test was applied to analyze the study results. There were no differences in the electrical activity of the temporal and masseter muscles at rest between the groups. During MVC, the asymmetry index for the masseter muscles was significantly higher in subjects with DS. The electrical potentials of the temporal and m...

The Open Dentistry Journal, 2012

Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal di... more Objective: Aim of the study was to determined by microcomputed tomography (µCT) the horizontal distance between the main (MB1) and the second mesiobuccal canal (MB2) orifices, the vertical distance between the MB1 and MB2 orifices planes, and the distance between the anatomic apex and major apical foramen (AF). Furthermore, we characterized the entire internal and external anatomy of the MB, distalbuccal (DB) and palatal (P) maxillary first molars roots. Materials and Methods: Twenty-two intact extracted first maxillary molars were scanned by X-ray computed transaxial µCT and then 2D and 3D images were processed and analyzed. Results: The results showed that 77.27% of the mesiobuccal (MB) roots presented a second MB canal, and 29.41% of the MB2 were independent from the MB1 canals. In 15 teeth, there were three root canal orifices on the chamber floor, and 10 of these teeth presented MB2 canals. The mean vertical distance between the MB1 and MB2 planes was 1.68 ± 0.83 mm. Seven teet...

Journal of Biological Chemistry, 2003

Clinical oral investigations, 2004

The aim of the present study was to investigate the cytotoxicity of two "one bottle" ad... more The aim of the present study was to investigate the cytotoxicity of two "one bottle" adhesive systems after polymerization with a conventional halogen or a light emitting diode (LED) lamp. We hypothesized that different polymerization sources might enhance the intracellular production of reactive oxygen species (ROS), leading to reduced cell survival. Two "one bottle" adhesive systems (Optibond Solo and Scotchbond One) were cured with a commercial halogen (Optilux 500) and an LED source (Elipar Freelight, 3 M). The specimens were extracted for 24 h in complete cell culture medium or in phosphate-buffered saline (PBS). Endothelial cells (ECV 304) were exposed to the extracts for 24 h and survival rates were evaluated by the MTT assay. Then, ROS generation was monitored by the oxidation-sensitive fluorescent probe 2'7'-dichlorofluorescin diacetate (DCFH-DA). Extracts from all materials except for Optibond Solo polymerized with the halogen lamp were rated si...

Journal of Endodontics, 2008

Previous investigations have revealed that dental monomers could affect intracellular pathways le... more Previous investigations have revealed that dental monomers could affect intracellular pathways leading to cell survival or cell death. Mitogen-activated protein kinase (MAPK) and protein kinase B (AKT) might mediate cell responses as well as cell survival and apoptosis. The purpose of this study was to evaluate the effects of 2-hydroxyethyl methacrylate (HEMA) on the ERK1/2 and AKT pathways in human primary pulp fibroblasts (HPCs). HPCs were treated with various concentrations of HEMA, after which viability and reactive oxygen species levels were determined by flow cytometry with Annexin V-PI staining and 2,7-dichlorofluorescine diacetate, respectively. Whole-cell extracts were immunoblotted with anti-P-Akt or anti-P-ERK1/2. Cell viability decreased in a dosedependent manner after HEMA exposure, showing a significant decrease with 10 mmol/L HEMA (p Ͻ .05). HEMA treatment resulted in a 4-fold increase in reactive oxygen species formation (p Ͻ .05). A short HEMA exposure (30 -90 minutes) increased ERK1/2 phosphorylation, whereas a decrease in the AKT phosphorylation was observed. Selective inhibitors of the ERK (PD98059) and AKT (LY294002) pathways amplified HPC cell damage after HEMA exposure. Our findings demonstrated that HEMA exposure modulates the ERK and AKT pathways in different manners, and that in turn, they function in parallel to mediate pro-survival signaling in pulp cells subjected to HEMA cytotoxicity. (J Endod 2008;34:684 -688)

Objectives. To define the inlay shading effect on the polymerization levels and kinetics of a lig... more Objectives. To define the inlay shading effect on the polymerization levels and kinetics of a light activated bonding system for an indirect restoration technique.

Journal of applied biomaterials & biomechanics : JABB

The effects of light curing units (LCU) and energy doses on the chemical and physical properties ... more The effects of light curing units (LCU) and energy doses on the chemical and physical properties of a dental composite were investigated. The effects on the chemical and physical properties of a bisphenol A diglycidylether methacrylate (Bis-GMA) based dental restorative material were evaluated through photospectrometry, differential scanning calorimetry, and mechanical measurements. The light curing conditions associated with direct and indirect restorations were replicated in vitro using optical investigation techniques. A slight attenuation resulted independently of the LCU and a strong attenuation was measured for the cement luting a thick inlay, as well as for the deepest layer of a composite filling increment. Calorimetric measurements indicated that the curing degree is very sensitive to the light energy dose rather than to the LCU. Mechanical testing showed a transient phase during which properties increased. The delay of the composite in reaching adequate properties is stron...

Journal of Endodontics, 2010

Introduction: Mineral trioxide aggregate (MTA) is known to stimulate the hard tissue repair proce... more 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-mm 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. (J Endod

International Journal of Surgery, 2014

Carbon ®ber posts (CFP) are widely used in the restoration of endodontically treated teeth to enh... more Carbon ®ber posts (CFP) are widely used in the restoration of endodontically treated teeth to enhance the mechanical behavior in spite of metallic posts and to prevent vertical fractures of the tooth under chewing loads. The post is cemented inside the canal lumen using polymer resins with Young's modulus lower than dentine. In this conditions the stress concentration is located at the post-cement interface and in the cement bulk itself, preserving radicular dentine from dangerous stress accumulation. The mechanical resistance of CFP posts cemented in human dentine was evaluated by the means of mechanical pull-out tests assisted by the ®nite element analysis. The average bond strength and the critical stress values of the CHP-cement interface were 25 MPa and 50 MPa respectively.

Dental Materials - DENT MATER, 2010

ObjectiveThe effect of a novel light curing process, namely soft light energy release (SLER®), on... more ObjectiveThe effect of a novel light curing process, namely soft light energy release (SLER®), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated.

Molecular BioSystems, 2010

Streptococcus mutans, the main pathogen involved in the development of dental caries, is an aerot... more Streptococcus mutans, the main pathogen involved in the development of dental caries, is an aerotolerant microorganism. The bacterium lacks cytochromes and catalase, but possesses other antioxidant enzymes, such as superoxide dismutase (SmSOD). Previous researches suggested that SmSOD belongs to the 'cambialistic' group, functioning with Fe or Mn in the active site. A recombinant SmSOD (rSmSOD) with a His-tail has been produced and characterised. Studies on metal uptake and exchange proved that rSmSOD binds either Fe or Mn as a metal co-factor, even though with a consistent preference for Fe accommodation. The analysis of several enzyme samples with different values of the Mn/Fe ratio in the active site proved that the type of metal is crucial for the regulation of the activity of rSmSOD. Indeed, differently from the significant preference for Fe displayed by the enzyme in the binding reaction, its Mn-form was 71-fold more active compared to the Fe-form. The rSmSOD was endowed with a significant thermostability, its half-inactivation occurring after 10 min exposure at 71 or 73 1C, depending on the bound metal. Moreover, the enthalpic and entropic contribution to the heat inactivation process of rSmSOD were strongly regulated by the Mn content of the enzyme. The effect of typical inhibitors/ inactivators has been investigated. rSmSOD was inhibited by sodium azide, and its sensitivity increased in the presence of higher Mn levels. Concerning two physiological inactivators, the enzyme displayed a different behaviour, being quite resistant to hydrogen peroxide and significantly sensitive to sodium peroxynitrite. Furthermore, the Mn co-factor had an amplifying role in the regulation of this different sensitivity. These results confirm the cambialistic nature of SmSOD and prove that its properties are regulated by the different metal content. The adaptative response of S. mutans during its aerobic exposure in the oral cavity could involve a different metal uptake by SmSOD.

Macromolecular Bioscience, 2008

The production of PEEA microspheres with potential as carriers for protein oral delivery is descr... more The production of PEEA microspheres with potential as carriers for protein oral delivery is described. PEEAs with different hydrophilicity were synthesized and characterized. Experiments showed that an increase in copolymer hydrophilicity gave particles less prone to cell interaction. BSA release profiles from PEEA microspheres demonstrated that an increase in polymer hydrophilicity was useful in limiting protein burst and modulating drug delivery rate by increasing PEEA degradability. These results show that fine-tuning of the hydrophilic/hydrophobic properties of PCL is essential for the formulation protein-loaded microspheres with specific properties.