The modified tooth-clearing technique allowed observation of fine morphological details in all specimens. Effective gutta-percha filling was evident in most of the wide coronal lateral canals whilst the apical narrow ramifications were often incompletely filled by cement. Overall AH-Plus demonstrated better diffusion into lateral accessory canals compared to Pulp Canal Sealer.
The use of the System-B Heat Source on root canals maintained at a constant body temperature by a thermostatic bath revealed that the increase of temperature of the gutta-percha at the apical third of the canal was negligible and that the compaction of the mass of the gutta-percha close to the apex was performed at body temperature. Minor changes in temperature of the outer surface of the root canals occurred, suggesting no danger for the periradicular tissues.
foraphane treatment protects skeletal muscle against damage induced by exhaustive exercise in rats.
Immunocytochemical analysis is a fundamental and selective technique for identifying different molecular components of human dental structure. The hypothesis tested here is that the application of different etching solutions on dentin does not hinder collagen fibrils and proteoglycans from maintaining their immunochemical antigenicity. Human dentin disks were treated with 0.5M of EDTA, citric acid, maleic acid, or phosphoric acid (for 15 or 30 s). A double-immunolabeling technique was performed to identify, simultaneously, collagen fibrils and chondroitin sulfate. The use of different acids resulted in different degrees of labeling. Maleic and citric acids revealed a diffuse and intense labeling for both collagen fibrils and proteoglycans. The use of phosphoric acid on dentin showed a massive coagulation of the proteoglycans (15 s) or very low labeling (30 s). These data clarify that the use of acids on dentin components is able to modify their antigenicity. Moreover, the double-labeling immunocytochemical technique allows understanding of the spatial relationships between the collagen fibrils and proteoglycans of the dentin matrix.
The cytotoxicity of dental composites has been attributed to the release of residual monomers from polymerized adhesive systems due to degradation processes or the incomplete polymerization of materials. 2-Hydroxyethyl methacrylate (HEMA) is one of the major components released from dental adhesives. Cytotoxic effects due to high concentrations of HEMA have already been investigated, but the influence of minor toxic concentrations on specific proteins such as type I collagen has not been studied in depth. The objective of this project was to study the effect of minor toxic concentrations of HEMA on human gingival fibroblasts (HGFs), investigating modification in cell morphology, cell viability, and the influence on type I collagen protein. Primary lines of human gingival fibroblasts were exposed to 3 mmol/L HEMA for different periods of time (24 h, 72 h, 96 h). The cell vitality was determined by MTT assay, and high-resolution scanning electron microscopy analysis was performed to evaluate differences in cell morphology before and after treatment. The presence and localization of type I collagen was determined by immunofluorescence in HGFs treated with HEMA for the same period of time. The vitality of the cells decreased after 72 h of exposure. The HGFs grown in monolayer and observed by field emission in-lens scanning electron microscopy demonstrated a preserved surface morphology after 24 h of treatment, while they showed an altered morphology after 96 h of treatment. Immunofluorescence demonstrated a reduction of type I collagen due to HEMA exposure after 96 h. From these results, we conclude that low concentrations of HEMA can significantly alter the morphology of human gingival fibroblasts and interfere with the presence of type I collagen protein.
We analyzed the incorporation of bromodeoxyuridine (BrdUrd) into DNA in exponentially growing munine erythroleukemia cells (FLC-745), using fluorescent anti-BrdUrd antibodies with light miaoscopy and flow cytometry. The fine localization of the DNA replicating sites was investigated at the ultrastructural level by using a second antibody conjugated with colloidal gold. The latter approach, which does not require acidic denaturation ofthe DNA, enables preservation ofgood morphology and obtains a better resolution power than that of electron microscopic autoradiography, the percentage oflabeled cells obtained with the two techniques being comparable.
d e n t a l m a t e r i a l s 2 3 ( 2 0 0 7 ) 513-518 a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . i n t l . e l s e v i e r h e a l t h . c o m / j o u r n a l s / d e m a Objectives. This study investigated the effects of an electric field produced by a new device for the application of etch-and-rinse adhesives on demineralized dentin surfaces. Electric device improves bonds of simplified etch-and-rinse adhesives Methods. Three simplified etch-and-rinse adhesives (Single Bond, Prime&Bond NT and One-Step) were applied with the electric device and compared with controls prepared with disposable sponges. Specimens were processed for microtensile bond strength test and nanoleakage investigation using high resolution SEM.Results. Microtensile testing revealed higher bond strengths (p < 0.05) for all adhesives tested when electricity was used. Adhesive interfaces prepared with electric impulses exhibited very homogenous hybrid layers with minimal nanoleakage compared with the controls.Significance. The use of electricity produced by a new electronic device during the application of dentin adhesives may increase adhesive adaptation to the dentin substrate and improve dentin hybridization due to the substrate modifications induced by an electric field on the demineralized dentin organic matrix. IntroductionDespite the recent developments in adhesive dentistry to reduce the number of working steps and to simplify the clinical procedure, the new simplified adhesives do not produce better results in in vitro tests [1] or improve clinical efficacy [2]. Ironically, the most user-friendly simplified adhesives, the socalled self-etching one-step adhesives, exhibited the lowest bond strengths and the least predictable clinical performances over time when compared with the multi-step etch-and-rinse and self-etch systems [2,3]. Previous reports have shown that one of the major disadvantages of the etch-and-rinse systems is incomplete infiltra- * Corresponding author at: UCO of Dental Sciences, University of Trieste, Via Stuparich, 1, I-34129 Trieste, Italy. Tel.: +39 040 3992192; fax: +39 040 912579.E-mail address: lbreschi@units.it (L. Breschi).tion of the exposed dentin matrix due to the collapse of the collagen fibrils after removal of the mineral phase [4][5][6]. A layer of disrupted collagen fibrils may interfere with adhesive penetration and the formation of the hybrid layer. Incompletely infiltrated voids within these hybrid layers may be revealed with a tracer such as silver nitrate using transmission (TEM) or scanning electron microscopy (SEM). Tracer infiltration in the absence of a physical interfacial gap has been referred to as nanoleakage [4], which may occur in interfaces bonded with either etch-and-rinse or self-etch adhesives. Field emission-SEM (FE-SEM) and TEM studies showed that entrapment of water within adhesive interfaces may create additional voids or tracks that could be revealed by these tracers [7][8][9].
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