In Vitro Effect of Bromelain on the Regenerative Properties of Mesenchymal Stem Cells.

BACKGROUND: Bromelain belongs to a group of protein-digesting enzymes obtained commercially from the fruit or stem of pineapple. Several studies demonstrated that bromelain exhibits various fibrinolytic, anti-edematous, antithrombotic, and anti-inflammatory activities supporting its application for many therapeutic benefits. The aim of this study was to analyze the effects of bromelain on the pro-wound healing activities and the regenerative properties of mesenchymal stem cells. METHODS: Mesenchymal stem cells were treated in vitro with bromelain alone or combined with dexamethasone sodium phosphate. Real-time polymerase chain reaction was performed to profile the expression of extracellular matrix components and remodeling enzymes, and cytokines. RESULTS: The combination of bromelain and dexamethasone sodium phosphate induced a great activation of mesenchymal stem cells with an increase in hyaluronan and collagen production and anti-inflammatory cytokines release. CONCLUSION: Based on the results of this in vitro study, the combined use of bromelain and dexamethasone sodium phosphate stimulated the pro-wound healing activities and the regenerative properties of mesenchymal stem cells better than bromelain and dexamethasone alone.

Shaping ability of four nickel-titanium rotary instruments in simulated S-shaped canals.

INTRODUCTION: The purpose of this study was to compare the shaping ability of ProTaper, Mtwo, BioRaCe, and BioRaCe + S-Apex instruments in simulated canals with an S-shaped curvature. METHODS: Canal transportation and aberrations were assessed by comparing the preinstrumentation and postinstrumentation images under a stereomicroscope. Analysis of variance and post hoc Student-Newman-Keuls test were used for statistical analysis. RESULTS: ProTaper instruments caused more pronounced canal transportation in the apical curvature (P < .01) than all other instruments. The use of ProTaper, Mtwo, and BioRaCe instruments resulted in more canal aberrations compared with BioRaCe + S-Apex (P < .05). CONCLUSIONS: NiTi systems including less tapered and more flexible instruments like S-Apex seem to be favorable when preparing S-shaped canals.

Chemical analysis of nickel-titanium rotary instruments with and without electropolishing after cleaning procedures with sodium hypochlorite.

The aim of this study was to chemically analyze rotary nickel-titanium instruments with and without electropolishing after cleaning procedures with NaOCl. To evaluate the effect of 5.25% NaOCl on electropolished RaCe instruments, a total of 18 instruments were tested. A control group of 18 nonelectropolished RaCe instruments was used. The surface of each instrument was analyzed before and after cleaning in NaOCl by using energy dispersive x-ray analysis, Auger electron spectroscopy, and scanning electron microscopy. Surface defects were recorded, and a chi(2) test was used for statistical analysis. After immersion in NaOCl, the nonelectropolished and electropolished files showed a significant increase of iron deposits as a result of galvanic corrosion of the shaft (P < .05). The nonelectropolished files showed marked presence of NaCl deposits in the machining marks and microcracks. As regards the chemical nature of the surface, the electropolished files had an oxide increase compared with the low oxide concentration (mainly TiO2) before cleaning. The nonelectropolished files already possessed higher oxides concentration (TiO2 and NiO) before NaOCl cleaning. NaOCl treatment affects the chemical composition of the surface and, in particular for nonelectropolished instruments, of the bulk exposed through machining marks and fabrication microcracks.

Pitting corrosion resistance of nickel-titanium rotary instruments with different surface treatments in seventeen percent ethylenediaminetetraacetic Acid and sodium chloride solutions.

This study evaluated the pitting corrosion resistance of nickel-titanium (NiTi) rotary instruments with different surface treatments in 17% ethylenediaminetetraacetic acid (EDTA) and NaCl solutions. Electropolished RaCe instruments were allocated to group A, non-electropolished RaCe instruments to group B, and physical vapor deposition (PVD)-coated Alpha files to group C (10 instruments per group). Electrochemical measurements were carried out by using a potentiostat for galvanic current measurements. On the basis of electrochemical tests, no localized corrosion problems are to be expected in EDTA. In NaCl, pitting potential occurred at higher values for the electropolished and PVD instruments, indicating an increased corrosion resistance. There appears to be a risk of corrosion for NiTi instruments without surface treatments in contact with NaCl. NiTi files with PVD and electropolishing surface treatments showed an increase corrosion resistance.

Cyclic fatigue of different nickel-titanium endodontic rotary instruments.

OBJECTIVE: A comparative study of the fatigue resistance of rotary nickel-titanium endodontic instruments was performed with the aim of assessing the influence of both instrument design and surface treatment on flexural fracture. STUDY DESIGN: To evaluate fatigue resistance of different rotary instruments, a total of 120 instruments were tested; these came from different sources: ProFile, RaCe, K3, Hero, and Mtwo. To compare the effect of electro-polishing procedures on fatigue resistance, a group of RaCe instruments (which are normally electro-polished) without surface treatment was used. A scanning electron microscope (SEM) study for each instrument was performed before and after fatigue study to determine the mode of fracture and the aspect of tips and cross-sectional surface areas. RESULTS: ProFile instruments gave the best values for fatigue resistance. It was seen that for RaCe instruments the surface treatment reduces the presence of micro-cracks, surface debris, and machining damage. CONCLUSIONS: This study shows that the instrument design often proves to be an important factor in the fatigue resistance of NiTi rotary instruments. In RaCe instruments the electro-polishing surface treatment increases the fracture-related fatigue resistance.

Proliferative activity in periapical lesions.

The identification of proliferative activity in periapical lesions may be useful in discovering the biological behaviour of different cell types. Proliferant cell nuclear antigen (PCNA), Ki67, CD3 and p53 have been used for the evaluation of the proliferative ability of many lesions. In this study, 16 periapical granulomas and 8 radicular cysts were analysed. A semi-quantitative method was used for evaluation of each lesion and antigen. According to the intensity of staining the following scores were assigned: 0 = no reactivity; 1 = reactivity above background; 2 = moderate reactivity; 3 = strong reactivity. Ki67 positive cells were present in all the periapical lesions. The antibody Ki67 was positive in pathological keratinic cells, while it was only slightly positive in normal epithelial cells. PCNA positive cells were present in 22 of the 24 cases examined. CD3 reactivity was also highly positive in periapical lesions. The reaction of oncoprotein p53 in periapical lesions was negative. The expression of the positive reaction of Ki67 and PCNA in periapical lesions is therefore an indicator of cell proliferation as a result of a chronic irritative stimulus.

Fabrication of hard coatings on NiTi instruments.

The present study was designed to compare the nature of modified surface layers obtained by two different procedures on endodontic files made of NiTi alloy: the procedures were arc evaporation physical vapor deposition and thermal metal organic chemical vapor deposition (MOCVD). Experimental samples were GT Rotary Instruments. The first method was based on the physical deposition of elemental titanium in the presence of nitrogen. The second technique is a typical MOCVD procedure which adopts Ti(Et2N)4 as a titanium and nitrogen precursor. Control samples were not exposed to any process. The chemical composition of the surface and in-depth layers of each sample were examined by X-ray photoelectron spectroscopy and X-ray diffraction measurements. The instruments showed surface chemical compositions that were different from those seen in the control group; samples treated with the first method show a surface Nitrogen/Titanium ratio of 1; MOCVD instruments show a surface Nitrogen/Titanium ratio of 1.7; control samples show a Nitrogen/Titanium ratio of 0.2. Both techniques can produce a high nitrogen concentration on the surface. However, data showed that the morphologies, the in-depth nitrogen distribution, and the chemical nature of the coatings obtained with the two procedures were different. The paper also reports the effects of the two deposition procedures on the nickel/titanium ratio of the surface.

Depositions of nitrogen on NiTi instruments.

This study was designed to obtain nitrogen-rich layers on the surfaces of endodontic files made of nickel-titanium (NiTi) alloy by chemical vapor deposition. Experimental samples (GT rotary instruments) were deposited by using two different methods. The first one was based on the reaction of wet NH3 with NiTi under high temperatures (300 degrees C). The second technique is a typical MOCVD (metal organic chemical vapor deposition) procedure that uses Ti(Et2N)4 as a titanium and nitrogen precursor. Control samples were not exposed to any process. The chemical composition of the surface layers of each sample was determined by means of X-ray photoelectron spectroscopy and X-ray diffraction measurements. The experimental instruments showed surface chemical composition that was different from that seen in the control group; samples treated with gaseous NH3 showed a surface nitrogen/titanium (N/Ti) ratio = 0.9; MOCVD instruments showed a surface N/Ti ratio of 2; control samples showed a N/Ti ratio = 0.2; MOCVD of nitrogen ion of nickel-titanium files produced a higher concentration of nitrogen on the surface.

A comparison of the adhesion of three restorative materials.

This study compared the adhesion of three different composite restoration resins. For this investigation, 45 extracted lower wisdom molars were selected and 45 Class I cavities were prepared by the same operator, and were randomly divided into three groups of 15 samples each. GROUP A: the molars of this group were filled with Surefil and the adhesive used was Prime & Bond NT. GROUP B: the molars of this group were filled with Prodigy Condensable and the adhesive used was Optibond Solo. GROUP C: for the molars of this group, Enamel Plus was used as composite and Prime & Bond NT was used as adhesive. As a negative control, twenty teeth were used without Class I preparations. Teeth were embedded in cold-cure acrylic resin and sectioned longitudinally. Dye penetration at the enamel and dentin margins were scored at 30 x magnification. Evaluations were rated from 0 to 3 (0 = no leakage; 1 = dye penetration up to one-half of the preparation depth; 2 = dye penetration more than one-half of preparation depth, but less than the axial wall; 3 = dye penetration along the axial wall). All the samples were analyzed with SEM at the following magnifications: 80 x (I micrograph), 220 and 740 x (II micrograph), 1200 x and 4200 x (III micrograph). The samples of Groups B and C showed no dye penetration. The samples of Group A showed either a level 2 or a level 3 dye penetration.