An investigation on the effect of humidity on the zero signal of a strain gauge measuring system / Análisis del efecto de la humedad en las lecturas de referencia de un sistema para medición de torque / Investigação do efeito da umidade nas leituras de referência de um sistema para medição de torque

Abstract Humidity is one of the most important ambient factors influencing torque calibration readings. The present study addresses the effects of relative humidity on the readings of reference torque transduction and amplification devices. The results revealed a linear effect of increasing humidity on the readings of a DMP40 torque amplifier and a torque transducer at different temperatures. Furthermore, humidity effects were smaller on the DMP40 amplifier than on the torque transducer, even at different temperatures. The results also showed that the summed effect of humidity changes on torque calibration readings of the amplifier and the torque transducer, when assessed simultaneously, but with each device under different controlled humidity conditions, is greater than the observed effect on the readings when both devices were subjected to humidity changes together. Therefore, it is recommended to test the effect of humidity in setups where these two devices are both under common humidity conditions. This is likely to lower the uncertainty parameter of the obtained torque calibration readings and is a useful consideration for inter-laboratory comparisons and performance testing.

Resumen La humedad es uno de los factores ambientales que más influyen sobre las lecturas de calibración de mediciones de torque. En este trabajo se estudiaron los efectos de la variación de la humedad relativa sobre las lecturas de aparatos de referencia para transducción y amplificación de torque. Los resultados mostraron una relación lineal y positiva entre el aumento de la humedad relativa y el componente de error de las mediciones de referencia de un transductor y un amplificador de torque DMP40 bajo cuatro temperaturas distintas. Sin importar la temperatura, las mediciones del transductor de torque fueron más susceptibles de ser afectadas por la humidad relativa que las del amplificador DMP40. Se observó también que la suma de los efectos de la humedad relativa en las lecturas de referencia del amplificador y el transductor fueron mayores cuando ambos aparatos fueron operados bajo condiciones de humedad relativa y temperatura distintas (i.e. el amplificador se encontraba en una cámara climática controlada y el transductor fuera de ella, y viceversa) que cuando ambos aparatos fueron operados bajo las mismas condiciones ambientales (i.e. ambos dentro de la cámara climática controlada). En consecuencia, se recomienda llevar a cabo evaluaciones de la humedad en espacios donde ambos aparatos estén bajo las mismas condiciones de temperatura y humedad relativa. Esto puede reducir el componente de incertidumbre de lecturas de calibración de torque y es un factor a considerar al llevar a cabo comparaciones entre laboratorios y tests de desempeño en aplicaciones industriales.

Resumo A umidade é um dos fatores ambientais que mais influenciam as leituras de calibração de medições de torque. O presente estudo analisou os efeitos da umidade relativa sobre as leituras de equipamentos de referência para transdução e amplificação de torque. Os resultados mostraram um efeito linear do aumento da umidade relativa na medição de referência de um transdutor e um amplificador de torque DMP40 em quatro temperaturas diferentes. Adicionalmente, os efeitos da umidade foram menores no amplificador DMP40 do que no transdutor de torque em todas as quatro temperaturas. Os resultados também mostraram que a soma dos efeitos da umidade relativa nas leituras de referência do amplificador e do transdutor foram maiores quando ambos equipamentos foram operados em condições de umidade relativa e temperatura distintas (p.e. o amplificador se encontrava em uma câmara climática controlada e o transdutor fora da câmara, e vice-versa) do que quando ambos equipamentos eram operados nas mesmas condições ambientais (p.e. ambos dentro da câmara climática controlada). Assim sendo, se recomenda avaliar o efeito da umidade em espaços onde ambos equipamentos estejam expostos a mesmas condições de temperatura e umidade relativa. Esso pode reduzir o parâmetro de incerteza das leituras de calibração de torque e é um fator a ser considerado ao realizar comparações entre laboratórios e testes de desempenho em aplicações industriais.

Evaluation of the effect of two different occlusal splints on maximum occlusal force in patients with sleep bruxism: a pilot study

PURPOSE: The occlusal splint has been used for many years as an effective treatment of sleep bruxism. Several methods have been used to evaluate efficiency of the occlusal splints. However, the effect of the occlusal splints on occlusal force has not been clarified sufficiently. The purpose of this study was to evaluate the effect of occlusal splints on maximum occlusal force in patients with sleep bruxism and compare two type of splints that are Bruxogard-soft splint and canine protected hard stabilization splint. MATERIALS AND METHODS: Twelve students with sleep bruxism were participated in the present study. All participants used two different occlusal splints during sleep for 6 weeks. Maximum occlusal force was measured with two miniature strain-gage transducers before, 3 and 6 weeks after insertion of occlusal splints. Clinical examination of temporomandibular disorders was performed for all individuals according to the Craniomandibular Index (CMI) before and 6 weeks after the insertion of splints. The changes in mean occlusal force before, 3 and 6 weeks after insertion of both splints were analysed with paired sample t-test. The Wilcoxon test was used for the comparison of the CMI values before and 6 weeks after the insertion of splints. RESULTS: Participants using stabilization splints showed no statistically significant changes in occlusal force before, 3, and 6 weeks after insertion of splint (P>.05) and participants using Bruxogard-soft splint had statistically significant decreased occlusal force 6 weeks after insertion of splint (P<.05). There was statistically significant improvement in the CMI value of the participants in both of the splint groups (P<.05). CONCLUSION: Participants who used Bruxogard-soft splint showed decreases in occlusal force 6 weeks after insertion of splint. The use of both splints led to a significant reduction in the clinical symptoms.

Root Dentin Strain and Temperature Rise During Endodontic Treatment and Post Rehabilitation

This study investigated the effects of endodontic treatment procedures and different post systems rehabilitation steps on the strain and temperature rise on apical and cervical root dentin regions. Twenty-one extracted human canine teeth had two strain gages attached to the distal root surface and two thermocouples attached to the mesial root surface (cervical and apical). The strain and temperature rise were recorded during the following procedures: root canal preparation, final rinse and drying, root canal filling and canal relief. Then the teeth were divided into three groups (n=7), according to the type of post system: CPC, cast post and core; FGP, fiberglass post; and PSP, prefabricated steel post. Data continued to be recorded during the post space preparation, post modeling (only for CPC), post trying and post cementation. Data were subjected to a two-way ANOVA followed by Tukey's test (α=0.05). The post-space preparation caused the highest temperature rise (4.0-14.9 °C) and the highest strain in the apical region during irrespective of post type. The resin cement light-activation resulted in significant temperature increases in the cervical region for all of the groups. The canal relief and the post-space preparation produced highest temperature rises. The CPC post modeling resulted in higher root strain level similarly the level of post preparation. The PSP resulted in highest strain during post trying and post cementation.

Este estudo investigou os efeitos de diferentes etapas do tratamento endodôntico e da inserção de diferentes tipos de retentores na deformação e aumento de temperatura na dentina radicular apical e cervical. Vinte e um dentes caninos humanos extraídos tiveram dois extensômetros colados à superfície da raiz distal e dois termopares ligados à superfície da raiz mesial (cervical e apical). A deformação e aumento de temperatura foram registrados durante os seguintes procedimentos: preparo do canal radicular, irrigação final e secagem, obturação do canal, alívio do canal; em seguida, os dentes foram divididos em três grupos (CPC, núcleo moldado e fundido; FGP, pino de fibra de vidro, e PSP pino pré-fabricado em aço-inoxidável, n=7). Os dados foram continuamente mensurados durante a modelagem do núcleo (somente para o CPC), inserção e cimentação dos retentores. Os dados foram submetidos a análise de variância fatorial, seguido pelo teste de Tukey (α=0,05). O preparo do canal para o retentor causou o maior aumento de temperatura (4,0-14,9 °C) e maior deformação na região apical independente do tipo de retentor. A ativação com luz resultou em significativo aumento de temperatura na região cervical, para todos os grupos. O alívio do canal e o preparo para o pino produziram maiores aumentos de temperatura. A modelagem do CPC resultou em maior nível de deformação da raiz em nível similar ao preparo para o retentor. O PSP resultou em maior deformação durante a inserção e ao final da cimentação.

Effect of fiber direction on the polymerization shrinkage of fiber-reinforced composites / 대한치과보존학회지

The aim of this study was to evaluate the effect of fiber direction on the polymerization shrinkage of fiber-reinforced composite. The disc-shaped flowable composite specimens (d = 10 mm, h = 2 mm, Aeliteflo A2, Bisco, Inc., IL, USA) with or without glass fiber bundle (X-80821P Glass Fiber, Bisco, Inc., IL, USA) inside were prepared, and the longitudinal and transversal polymerization shrinkage of the specimens on radial plane were measured with strain gages (Linear S-series 350omega, CAS, Seoul, Korea). In order to measure the free polymerization shrinkage of the flowable composite itself, the disc-shaped specimens (d = 7 mm, h = 1 mm) without fiber were prepared, and the axial shrinkage was measured with an LVDT (linear variable differential transformer) displacement sensor. The cross-section of the polymerized specimens was observed with a scanning electron microscope to examine the arrangement of the fiber bundle in composite. The mean polymerization shrinkage value of each specimen group was analyzed with ANOVA and Scheffe post-hoc test (alpha=0.05). The radial polymerization shrinkage of fiber-reinforced composite was decreased in the longitudinal direction of fiber, but increased in the transversal direction of fiber (p<0.05). We can conclude that the polymerization shrinkage of fiber-reinforced composite splint or restoratives is dependent on the direction of fiber.

Analysis on mechanical property of remedy for scoliosis by PRSS / 中国矫形外科杂志

[Objective] Scoliosis with wedging of vertebra and open-up disc space over convex side can be reversed when PRSS(plate-rod system for scoliosis)was applied.In order to study the mechanical properties of the remedy for the scoliosis by PRSS,the photoelastic test was performed.[Method] The model that consists of five vertebra bodies and four intervertebral discs was built with aluminum and polycarbonate,thus the situation of low-grade scoliosis was simulated.The axial stress was loaded 0 kg,5kg,10 kg,15 kg,20 kg respectively,and the lateral side load was 0 kg,3 kg,6 kg,9 kg,and 12 kg respectively over the spinal column.According to the factual situation,the in-situ stress was measured by using photoelastic and strain gage method.ANSYS9.0 method was also applied to simulate the experiment process and evaluate the reliability of measurement.[Result]When PRSS was placed in,compressive stress was found to exert on the convex side whereas tensile stress was found on the concave side of the curvature,thus modulating bony growth of spinal vertebra,resulted in spinal column realignment.[Conclusion]The PRSS is an effective device to treat the scoliosis of the patients,especially in young children,because it not only can correct the deformity but also allows extension along with the children's growth.