Gianluca Ametrano

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.

Evaluation of surface roughness of orthodontic wires by means of atomic force microscopy

OBJECTIVE To compare the surface roughness of different orthodontic archwires. MATERIALS AND METHODS Four nickel-titanium wires (Sentalloy(®), Sentalloy(®) High Aesthetic, Titanium Memory ThermaTi Lite(®), and Titanium Memory Esthetic(®)), three β-titanium wires (TMA(®), Colored TMA(®), and Beta Titanium(®)), and one stainless-steel wire (Stainless Steel(®)) were considered for this study. Three samples for each wire were analyzed by atomic force microscopy (AFM). Three-dimensional images were processed using Gwiddion software, and the roughness average (Ra), the root mean square (Rms), and the maximum height (Mh) values of the scanned surface profile were recorded. Statistical analysis was performed by one-way analysis of variance (ANOVA) followed by Tukeys post hoc test (P < .05). RESULTS The Ra, Rms, and Mh values were expressed as the mean ± standard deviation. Among as-received archwires, the Stainless Steel (Ra  =  36.6 ± 5.8; Rms  =  48 ± 7.7; Mh  =  328.1 ± 64) archwire was less rough than the others (ANOVA, P < .05). The Sentalloy High Aesthetic was the roughest (Ra  =  133.5 ± 10.8; Rms  =  165.8 ± 9.8; Mh  =  949.6 ± 192.1) of the archwires. CONCLUSIONS The surface quality of the wires investigated differed significantly. Ion implantation effectively reduced the roughness of TMA. Moreover, Teflon(®)-coated Titanium Memory Esthetic was less rough than was ion-implanted Sentalloy High Aesthetic.

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.

Effects of intraoral aging on surface properties of coated nickel-titanium archwires

OBJECTIVE To evaluate the effects of intraoral aging on surface properties of esthetic and conventional nickel-titanium (NiTi) archwires. MATERIALS AND METHODS Five NiTi wires were considered for this study (Sentalloy, Sentalloy High Aesthetic, Superelastic Titanium Memory Wire, Esthetic Superelastic Titanium Memory Wire, and EverWhite). For each type of wire, four samples were analyzed as received and after 1 month of clinical use by an atomic force microscope (AFM) and a scanning electronic microscope (SEM). To evaluate sliding resistance, two stainless steel plates with three metallic or three monocrystalline brackets, bonded in passive configuration, were manufactured; four as-received and retrieved samples for every wire were pulled five times at 5 mm/min for 1 minute by means of an Instron 5566, recording the greatest friction value (N). Data were analyzed by one-way analysis of variance and by Students t-test. RESULTS After clinical use, surface roughness increased considerably. The SEM images showed homogeneity for the as-received control wires; however, after clinical use esthetic wires exhibited a heterogeneous surface with craters and bumps. The lowest levels of friction were observed with the as-received Superelastic Titanium Memory Wire on metallic brackets. When tested on ceramic brackets, all the wires exhibited an increase in friction (t-test; P < .05). Furthermore, all the wires, except Sentalloy, showed a statistically significant increase in friction between the as-received and retrieved groups (t-test; P < .05). CONCLUSION Clinical use of the orthodontic wires increases their surface roughness and the level of friction.

Micro-computerized tomographic analysis of premolars restored with oval and circular posts

ObjectivesThe purpose of the study was to evaluate by micro-computerized tomography (microCT) areas and volumes of post, cement, and voids/bubbles in the post space of oval-shaped premolars restored either with oval or circular posts.Materials and methodsTwelve extracted premolars were divided into two groups according to the drill-fiber post system used: (1) GC Fiber Post Drill + circular post GC Fiber Post; (2) Ellipson tipTM + oval post Ellipson postTM. Each tooth was scanned using microCT, and areas and volumes of canal, post space, post, cement, and voids at coronal, medium, and apical level were calculated by using a three-dimensional visualization software. Two-way analyses of variance and Tukey tests were used for statistical analysis (p < 0.05).ResultsThe area of voids was significantly greater at apical level of oval posts, but no difference was found between the levels among the groups. Regardless of post shape, the volume of voids and of cement was significantly higher at the coronal level. With oval posts, the total volume of cement was twice as much as with circular posts, and the difference was statistically significant.ConclusionsOur results indicate that the volume of voids does not depend on post shape. Moreover, the microCT analysis demonstrated that the volume of cement was greater with oval posts compared to circular posts.Clinical relevanceThe microCT analysis provided interesting information on voids distribution and on the ratio between post shape and cement thickness. These results might address the clinician in the reconstruction of teeth with fiber posts.

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.