ABSTRACT
Abstract Introduction: one of the main factors for discomfort in users of removable partial prosthesis is the presence of visible retainers in the anterior zone. In Kennedy Class III arches, that is, exclusively dental loading pathways (in which the functional forces reach their final receptor: the alveolar bone), anterior zone retainers may be eliminated by selecting an appropriate prosthetic insertion and removal axis, and mainly by carving guiding planes that should provide retention by mechanical rubbing. This in vitro experimental study aimed to prove the hypothesis that it is possible to obtain functional retention in a dental-loading pathway removable partial prosthesis without using retainers in the anterior zone. Methods: 7 maxillary models with different types of toothless process were used. As a common characteristic, they all were classified as Kennedy Class III with partial denture arches. A Cr-Co metallic base was built for each model according to their clinical situation. Their design allowed them to be exposed to traction in a universal traction machine (Tinius Olsen H5K-S). Results: the proposed hypothesis was confirmed as expected. The traction force needed to displace the metallic bases with retainers in the anterior zone was 16.93 Newton in average. On the other hand, the metallic bases without retainers in the anterior zone showed an average of 12.84 N. The average values obtained for both groups are higher than those reported in the literature (4.903 N). Conclusions: in Class III removable partial dentures it is possible to use metallic bases with no retainers in the anterior zone.
Resumen Introducción: un factor que incomoda a los usuarios de prótesis parciales removibles es la presencia de retenedores visibles en la zona anterior. En clases III de Kennedy, es decir, vías de carga exclusivamente dentarias, sería posible eliminar los retenedores del sector anterior mediante un adecuado tallado de planos guías que brinde retención por roce mecánico y la elección de un eje de inserción y remoción protésico. Este trabajo es un diseño experimental in vitro que tiene por finalidad validar la hipótesis propuesta por nuestro equipo de investigación, que es posible obtener retención funcional en una prótesis parcial removible de vía de carga dentaria sin utilizar retenedores en el sector anterior. Métodos: se utilizaron 7 modelos maxilares en yeso tipo IV, con distinto tipo de desdentamiento, cuya característica común era que correspondían a clases III de Kennedy de arcos parcialmente desdentados. A cada modelo se le confeccionó una base metálica de Cr-Co, de acuerdo con sus características clínicas individuales, las cuales presentaron un diseño que permitió utilizarlas en una máquina de tracción universal para someterlas a fuerzas de tracción. Resultados: la fuerza de tracción necesaria para desalojar las bases metálicas que contaban con retenedores en el sector anterior fue del orden de 16,93 N en promedio. En cambio, las bases metálicas sin retenedores en el sector anterior presentaron un valor promedio para su desalojo de 12,84 N. Conclusiones: los valores promedio obtenidos para ambos grupos son superiores a los que se señala en la literatura (4,903 N) como válidos para una retención adecuadamente funcional para una prótesis parcial removible.
Subject(s)
Denture, Partial, Removable , Orthodontic Retainers , Esthetics, DentalABSTRACT
Background Ethylene is capable of promoting seed germination in some plant species. Mobilization of metals such as Fe, Cu, Mn, and Zn in mature seeds takes place when seeds are germinating. However, whether ethylene is involved in the regulation of soybean seed germination and metal element mobilization during early seed germination stage remains unknown. In the present study, seeds were treated with ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG) and ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), and double distilled H2O (ddH(2)0) treatment was used as control. Ethylene emission, ACC synthase (ACS) expression, ACS enzyme activity and Ca, Zn, Mn, Cu and Fe content in hypocotyls were qualified to analyze the relationship between ethylene and mobilization of these elements. Results The results showed that ACS expression, ACS enzyme activity and ethylene emission peaked at 1 and 7 d after sowing. AVG inhibited ethylene production, promoted the hypocotyls length, ACS expression and its activity, concentrations of total and HCl-extractable Zn, and HCl-extractable Fe in hypocotyls, while ACC caused opposite effects. AVG and ACC treatment had no significantly effects on total and HCl-extractable Ca, Cu and HCl-extractable Mn. Total Mn concentration was promoted by AVG at 1, 3, and 5 d significantly, while ACC treatment tended to have no significantly effects on Mn concentration. Conclusion These findings suggested that ethylene is at least partly involved in the regulation of soybean seed germination. Remobilization of Zn and Fe may be negatively regulated by ethylene.
Subject(s)
Seeds , Soybeans , Germination , Ethylenes , Lyases/metabolism , Metals/metabolism , Zinc/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Iron/metabolismABSTRACT
Objective:To establish the methods for the determination of Mg,Al,K,Ca,Cr,Cu,Zn,As,Se,Ag,Cd,Sn,Ba,Pb,Na and Hg in water for injection. Methods:The sixteen metallic elements in water for injection were determined by ICP-MS. The collision cell technology ( CCT) was used to minimize the multiple atomic interference, and the matrix effect and signal drift were compensated by using Li, Sc, Ge, In, Ir and Bi as the internal standards and the samples were directly acidified to detect the metallic elements. Results:The detection limit range of the 16 metallic elements were from 0. 009 to 0. 165 ng·ml-1. The calibration curves showed good linearity (r≥0. 999 0). The recoveries were within the range of 80%-120%(n=6). Conclusion:The method is simple, rapid and accurate. It can be used to determine the contents of metallic elements to reduce the potential exceeding limit risk of toxic metal el-ements in water for injection. The methods also can provide reference for the more strict quality evaluation of water for injection.
ABSTRACT
Although the efficacy of complexon Ⅲ (EDTA), complexon Ⅳ (CDTA) and HMP-Na (hexametaphosphate) as complex compounds of metallic elements of cholelith has been reported in many papers, it is still a question on deciding which is the best one. This article describes an experimental study of comparing the influence of 2% EDTA. 2% CDTA, 5%HMP—Na and deionic water on Ca, Mg, Cu, Fe, Mn and Zn of 30 cholelith samples. These elements were measured with atomic absorption spectroscopy. The results were compared to the group which was not treated. Our results demonstrate that 5% HMP-Na is the best complex compound for metallic elements of a pigment stone. This study provides an experimental basis for using an ideal complex compound in clinic to dissolve bile pigmental stones.