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
This study aimed to measure irreversible DNA damage in the offspring of rats exposed to contaminated soil. Bone marrow cells were removed from the femurs of the offspring of rats that were exposed to contaminated soil via gavage during three different periods: 21 days prior to detection of pregnancy, during pregnancy and 21 days after birth, during the lactation period. For each group, we also had a control group under the same experimental conditions but exposed to uncontaminated soil. The results showed that pups borne of rats exposed to contaminated soil had an increase in the number of micronuclei in the different exposure groups compared with their respective control groups. This suggests a potential risk of mutagenic damage to the offspring of pregnant women who live at the sampling site.
Este estudo objetivou medir os danos irreversíveis de DNA na prole de ratas expostas a um solo contaminado, através do teste do micronúcleo. O mesmo foi realizado na medula óssea retirada do fêmur de filhotes de ratas expostas, via gavagem, em três diferentes períodos, ratas expostas durante 21 dias antes da detecção da prenhez, durante a prenhez e 21 dias após o nascimento, durante o período de aleitamento. Para cada grupo foi utilizado um grupo controle, mantido nas mesmas condições experimentais e expostos a um solo não contaminado. Os resultados obtidos nos filhotes expostos ao solo contaminado mostraram um aumento no número de micronúcleos nos três diferentes grupos expostos quando comparados aos seus respectivos grupos controle. Assim, os dados sugerem um potencial risco de dano mutagênico aos descendentes das gestantes residentes no local de amostragem.