How does arch form and interproximal contact size affect the 3D displacements and rotations of teeth: a finite element analysis

ABSTRACT Objective: The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF). Methods: Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar. Results: Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models. Conclusions: Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.

RESUMO Objetivo: O objetivo deste estudo foi determinar como o formato da arcada e o tamanho do contato interproximal deslocam os dentes inferiores submetidos a um componente anterior de força (CAF). Métodos: Nove modelos de elementos finitos (MEF) da arcada inferior foram desenvolvidos utilizando o software Ansys® v. 16.0. Eles foram projetados para avaliar os efeitos de três formatos de arcada (triangular, oval e quadrado) e três tamanhos de contato interproximal (ponto a ponto, 1 mm de diâmetro e 2 mm de diâmetro). Todos os nove modelos foram submetidos a um CAF de 53,8 N (5486 gm). Foram avaliados tridimensionalmente as rotações dentárias e os deslocamentos dos dentes inferiores, do primeiro molar direito ao primeiro molar esquerdo. Resultados: A forma da arcada teve um efeito maior no movimento dos dentes do que o tamanho do contato interproximal. Arcadas triangulares e contatos ponto a ponto produziram os maiores deslocamentos e rotações dos dentes. Arcadas ovais com pontos de contato interproximal de 2 mm de largura apresentaram maior estabilidade. O primeiro pré-molar direito apresentou os maiores deslocamentos em todos os modelos. Conclusões: O formato da arcada e o tamanho do contato interproximal afetam a estabilidade dos dentes. Os dentes foram menos estáveis nas arcadas estreitas com contatos interproximais ponto a ponto, e mais estáveis nas arcadas mais largas com contatos maiores.

Assessment of Post-mortem Processing Methods on Quality and Shelf Life of Mutton

This study was carried out to assess the influence of post-mortem processing methods on quality and shelf life of two breeds of sheep meat. A total of twelve sheep, six each from Balami and Ouda (two prominent breed of Sheep in Nigeria) were weighed, slaughtered and allotted to three processing methods which are scalding, singeing and skinning in a completely randomized experimental design in a 2 × 3 factorial arrangement (2 breeds and 3 post-mortem processing methods). The carcass characteristics, primal cuts, physico-chemical properties, sensory and microbial counts were assessed. The results showed that Ouda breed gave the highest (p<0.05) dressing % (36.43%), preferred (p<0.05) primal cuts in rounds (15.13%), Marbling score, lipid profile (Total cholesterol, LDL), and Lipid peroxidation, Balami sheep was however rated higher (p<0.05) in juiciness, tenderness and overall acceptability. The Scalded sheep had the highest dressing % (35.45%), with preferred marbling score (5.80), and microbial counts. The scalded samples were also the lowest (p<0.05) for crude Fiber, CF, total cholesterol (276.40 mg/dL) and LDL (183.89 mg/dL). Minimal exudate loses (cooking loss and drip loss) were recorded in singeing samples and was rated highest (p<0.05) with organoleptic properties. The microbial and fungi loads increased with the storage days. Conclusively, Ouda breed and Scalding method of post-mortem dressing gave the preferred values for optimum nutrients and shelf-life of sheep meat.

Myotonia congenita: mutation spectrum of CLCN1 in Spanish patients

Myotonia congenita (MC) is a Mendelian inherited genetic disease caused by the mutations in the CLCN1 gene, encoding the main skeletal muscle ion chloride channel (ClC-1). The clinical diagnosis of MC should be suspected in patients presenting myotonia, warm-up phenomenon, a characteristic electromyographic pattern, and/or family history. Here, we describe the largest cohort of MC Spanish patients including their relatives (up to 102 individuals). Genetic testing was performed by CLCN1 sequencing and multiplex ligation-dependent probe amplification (MLPA). Analysis of selected exons of the SCN4A gene, causing paramyotonia congenita, was also performed. Mutation spectrum and analysis of a likely founder effect of c.180+3A>T was achieved by haplotype analysis and association tests. Twenty-eight different pathogenic variants were found in the CLCN1 gene, of which 21 were known mutations and seven not described. Gross deletions/duplications were not detected. Four probands had a pathogenic variant in SCN4A. Two main haplotypes were detected in c.180+3A>T carriers and no statistically significant differences were detected between case and control groups regarding the type of haplotype and its frequencies. A diagnostic yield of 51% was achieved; of which 88% had pathogenic variants in CLCN1 and 12% in SCN4A. The existence of a c.180+3A>T founder effect remains unsolved.

Paediatric admissions and outcome in a general intensive care unit

Background: It is believed that intensive care greatly improves the prognosis for critically ill children and that critically ill children admitted to a dedicated Paediatric Intensive Care Unit (PICU) do better than those admitted to a general intensive care unit (ICU). Methods: A retrospective study of all paediatric (< 16 years) admissions to our general ICU from January 1994 to December 2007. Results: Out of a total of 1364 admissions, 302 (22.1%) were in the paediatric age group. Their age ranged from a few hours old to 15 years with a mean of 4.9 ± 2.5 years. The male: female ratio was 1.5:1. Postoperative admissions made up 51.7% of the admissions while trauma and burn made up 31.6% of admissions. Medical cases on the other hand constituted 11.6% of admissions. Of the 302 children admitted to the ICU, 193 were transferred from the ICU to other wards or in some cases other hospitals while 109 patients died giving a mortality rate of 36.1%. Mortality was significantly high in post-surgical paediatric patients and in patients with burn and tetanus. The length of stay (LOS) in the ICU ranged from less than one day to 56 days with a mean of 5.5 days. Conclusion: We found an increasing rate of paediatric admissions to our general ICU over the years. We also found a high mortality rate among paediatric patients admitted to our ICU. The poor outcome in paediatric patients managed in our ICU appears to be a reflection of the inadequacy of facilities. Better equipping our ICUs and improved man-power development would improve the outcome for our critically ill children. Hospitals in our region should also begin to look into the feasibility of establishing PICUs in order to further improve the standard of critical care for our children