41 research outputs found
A comparative study of smear layer removal and erosion in apical intraradicular dentine with three irrigating solutions: a scanning electron microscopy evaluation
Introduction: This study compared the efficacy of BioPure MTAD (Dentsply Tulsa, Tulsa, OK), 17% EDTA, and 42% citric acid in endodontic smear layer removal and degree of erosion in the apical third of endodontic canals. Methods: Ninety-six extracted single-rooted human teeth were randomized into four groups (n = 24) and instrumented using System GT nickel-titanium rotary instruments (Dentsply Tulsa, Tulsa, OK). Each canal was irrigated with one of the following solutions: BioPure MTAD, 17% EDTA, 42% citric acid, or 5.25% NaOCl (control). Next, all specimens were irrigated with 5.25% NaOCl. Results: Evaluation by scanning electron microscopy showed no significant differences among test irrigants in removing the smear layer. However, the efficacy of BioPure MTAD and 17% EDTA in removing the smear layer was significantly greater than 5.25% NaOCl (control). The erosive effects of irrigating solutions could not be evaluated. Conclusions: In conclusion, the protocols used in this study were not sufficient to completely remove the smear layer in the apical third of prepared root canals. © 2009 American Association of Endodontists
Dietary fluoride intake by children: When to use a fluoride toothpaste?
Fluoride is recommended for its cariostatic effect, but excessive fluoride intake may have health risks. Increased prevalence of dental fluorosis in areas with low fluoride content in drinking water has been attributed to the inappropriate excessive intake of fluoride supplements (tablets and drops) and toothpaste ingestion. The aim of the present study was to estimate the fluoride intake and the risk of fluorosis in children (6 months–6 years) in the Castelli Romani area (province of Rome, Italy), which is volcanic, therefore with a higher concentration of fluorine. Measurements of the fluoride content in drinking water, mineral waters, vegetables and commercial toothpaste for children were performed. The fluoride concentrations of all samples were determined using a Fluoride Ion Selective Electrode (GLP 22, Crison, Esp). Data were analyzed by descriptive statistics. Differences between samples were determined by Student’s t-test. The fluoride content in tap water samples collected from public sources averaged from 0.35 to 1.11 ppm. The Pavona area showed the highest content of fluoride with respect to the others (p ≤ 0.05). The fluoride content in mineral water samples averaged from 0.07 to 1.50 ppm. The fluoride content of some vegetables showed increased mean values when compared to control vegetables (p ≤ 0.05). Within the limitations of the present study, considerations should be made when prescribing fluoride toothpaste for infants (6 months–4 years) in the areas with high fluoride content, because involuntary ingestion is consistent
Valutazione microstrutturale al SEM di pervietĂ ed erosione della dentina endodontica a livello del terzo apicale, dopo pretrattamento con cinque soluzioni irriganti. Studio in vitro.
Traditional elastic ligatures versus slide ligation system. A morphological evaluation
Elastomeric materials play an important role in the orthodontic practice, including the retraction force to move teeth into extraction sites, closing diastemas, selective shifting of the midline and generalized space closure. Frictional resistance and ligating strength of archwire-bracket-ligature complex occurs during utilization of elastomeric and metallic ligatures when orthodontic forces are applicated. The aim of this study was to analyze elastic deformation of three types of elastomeric ligatures, after clinical use
PROCLO, Teologia platonica
Personalmente ho curato la traduzione dei libri III (pp. 241-327), IV (pp. 329-426) e VI (pp. 559-659)
Valutazione microstrutturale al SEM di pervietĂ ed erosione della dentina endodontica a livello del terzo apicale, dopo pretrattamento con cinque soluzioni irriganti. Studio in vitro.
SEM analysis of zirconium brackets using MIM technology
AIM: The need to be able to use a material with esthetic characteristics of ceramic and mechanical properties of the metallic brackets has led clinical and industrial research towards the realization of zirconium brackets. These brackets seem to respond to both the requirements of new esthetic concepts and of interesting biomechanical qualities: hardness, resistance to abrasion, resistance to compression, reduced coefficient of friction during mechanical sliding, stability in a humid temperature and to the aggression of oral fluids. METHODS: Twenty samples of zirconium brackets have been observed at SEM realized using the metal injection molding (MIM) technology: 10 new ones used as base samples and 10 used samples with the purpose of assessing the morphologic aspect and the structural variations after clinical use. RESULTS: The comparison the samples showed some structural changes regarding the surface of the body of the brackets, while slot and wings maintain an interesting stability of construction, a moderate degree of abrasion even after the application of considerable clinical strength. CONCLUSIONS: The conclusion is drawn that the positive clinical response in the use of these brackets and the limited scientific literature on the use of zirconium in orthodontics is worthy of further research
Agrumi: erosione dentale e fluoro. Prima parte
Aim of the work. The aim of the study was to evaluate erosion effectiveness and fluoride concentration of pure citrus drinks and citrus soft drinks.
Materials and methods. 7 pure citrus drinks and 12 citrus soft drinks were considered. In both cases, samples were analyzed for pH and fluoride concentration. The measurement of pH was carried out using a pH electrode connected with GLP 22 Crison® pHmeter. Fluoride concentration was carried out using a selective electrode Crison®.
Results. The study demonstrated that both pure citrus drinks and citrus soft drinks show pH values ranged between 3.6 and 1.8 and thus lower respect to critical pHs which are expected for enamel and dentine demineralization and dissolution. Regarding fluoride, measurements carried out on citrus soft drinks, generally show an absence of this ion and, only in three cases, concentrations ranged between 0.1 and 0.16 ppm.
Conclusion. Our data showed that erosive potential of pure citrus drinks and citrus soft drinks is capable of dissolving, in vitro, considerable amounts of enamel and dentine. In vivo, erosion is probably limited from many factors as calcium concentration and saliva buffering effect. Absence or very little concentration of ionic fluoride dissolved in tested drinks was observed
Agrumi: erosione dentale e fluoro. Seconda parte
Aim of the work. The aim of the study was to evaluate erosion effectiveness and fluoride concentration of pure citrus drinks and citrus soft drinks.
Materials and methods. 7 pure citrus drinks and 12 citrus soft drinks were considered. In both cases, samples were analyzed for pH and fluoride concentration. The measurement of pH was carried out using a pH electrode connected with GLP 22 Crison® pHmeter. Fluoride concentration was carried out using a selective electrode Crison®.
Results. The study demonstrated that both pure citrus drinks and citrus soft drinks show pH values ranged between 3.6 and 1.8 and thus lower respect to critical pHs which are expected for enamel and dentine demineralization and dissolution. Regarding fluoride, measurements carried out on citrus soft drinks, generally show an absence of this ion and, only in three cases, concentrations ranged between 0.1 and 0.16 ppm.
Conclusion. Our data showed that erosive potential of pure citrus drinks and citrus soft drinks is capable of dissolving, in vitro, considerable amounts of enamel and dentine. In vivo, erosion is probably limited from many factors as calcium concentration and saliva buffering effect. Absence or very little concentration of ionic fluoride dissolved in tested drinks was observed
Morphological observations and fractological considerations on orthodontics miniscrews
Aim. The purpose of this study was to evaluate morphological and biomechanical characteristics of a commercial mini-implant.
Methods. Orthodontic low head mini implants, in the two available sizes of 1,5 and 2 mm, have been used. The SEM (electronic scanning microscope) evaluation has been tested on 3 groups each one composed of 4 samples, observed in numerous enlargements and in the three dimensions of the space. The groups was composed of new mini implants, undamaged mini implants observed after their clinical use and mini implants broken at the moment of their insertion or removal after their therapeutical use.
Results. The SEM analysis of unused mini implants has shown how the diameter reduction of the neck represents the area of greater weakness; such parameter is very important in determining screw resistance to fracture. In fact the fracture observed in vivo always happened to this degree. Some micro carvings and cracks were shown on the surface, these irregularities could facilitate or promote the enlargement of the cracking itself.
Conclusion. From the results obtained it is clear that the steel is adequate for permanence in the oral cavity, and moreover the material itself is adapted to bear the pressure put on it during therapy. However, it remains advisable to make certain changes to better the surface and geometry of the miniscrews