No abstract

Forty extracted human third molar teeth were divided into four groups, each of 10 teeth, to test the hypothesis that dentine thickness variation influences diffusion of the monomers 2-hydroxyethylmethacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) from light-cured bonding resin-composite resin restorations to the pulp space. An occlusal cavity 6 mm in diameter was prepared in each tooth of four groups with remaining dentine thickness of 3.4-3.6, 2.4-2.6, 1.4-1.6 and 0.4-0.6 mm, respectively. A polypropylene chamber was attached to the cemento-enamel junction of each tooth to contain 1 mL of distilled water. Each cavity was treated with Scotchbond Multipurpose (3 M, U.S.A.) then restored with Z100 (3 M) and light activated for 30 s. Water samples were retrieved over a time course up to 30 days and analysed by high performance liquid chromatography. Both HEMA and TEGDMA were detected in the pulp samples for all teeth. Decreasing dentine thickness substantially increased pulpward diffusion rate of both HEMA and TEGDMA during the first day after placement, as well as the total release of both components from a bonding resin-composite combination in vitro.

The purpose of this study was to identify and quantify any component released from seven commercially available light-cured or resin-modified glass ionomer and compomer cements. Twenty-one separate cylindrical stainless steel moulds 6 mm in diameter and 1.0 mm deep were filled with one of seven glass ionomer or compomer cements, light activated and then immediately immersed in separate containers of distilled water. Water samples were retrieved over a time period of up to 30 days and retained for analysis. An occlusal cavity 6 mm in diameter was prepared in extracted human third molar teeth with a remaining dentin thickness of 1.6-2.0 mm. A polypropylene chamber was attached to the cemento-enamel junction of each tooth to contain 1 mL of distilled water. Ten teeth were each filled with one of three cements and light activated. Water samples (eluates) were retrieved over a period of time. All samples were analysed by high performance liquid chromatography. Only one component, hydroxyethyl methacrylate (HEMA), was detected in the eluates from both tooth and mould samples. Analysis of diffusion of the HEMA through dentin showed a relatively sustained movement into the pulp space during the first day, with exponential decline thereafter. Our data show that HEMA was released from all of the light activated glass ionomer cements studied and from the compomer, both directly into water and through dentin. This release may be relevant both to the risk of adverse pulpal responses in patients and to the risk of allergy in patients and dental personnel.

The diffusion of 2-hydroxyethylmethacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) from light cured bonding resin-composite resin restorations through human carious dentin was investigated. Extracted human molar teeth with different degrees of caries were obtained from consenting donors. Teeth were classified into three groups according to caries severity (mild, moderate and severe) using subjective criteria. The outer carious lesions were then removed guided by a proprietary caries detector dye. Teeth with exposure of the pulp space after caries removal were excluded from the study. A polypropylene chamber was attached to the cemento-enamel junction of each tooth to contain 1 ml distilled water. Each cavity was restored with a HEMA containing bonding resin then a TEGDMA-containing resin composite. Water samples were retrieved over a time course and analyzed by high performance liquid chromatography. There was great variation between teeth in HEMA and TEGDMA permeability. The cumulative amounts released were of similar magnitude to those observed in non-carious teeth for the mild and moderately-severe groups. However, the cumulative amounts released were markedly greater in severely carious teeth than in those with moderate or mild caries.

Abstract. In this paper, we present our work, which is doing an energy audit on alternator's current output and battery's voltage based on alternator speed. Up until today, the demand for power in automobile is ever increasing. As technology advances, more and more electrical devices were produced and being installed in vehicles. To cope with the demand, alternator has been designed and modified so that it can produce enough power. This research is to study the effect of alternator speed to the charging system. The car used in this experiment is Proton Preve 1.6 Manual. In both ISO 8854 and SAE J 56, alternator testing and labelling standards indicate that the rated output an alternator is the amount of current that it is capable of producing at 6,000 RPM. Three different constant speed of engine which is 750 RPM as idle speed, 1500 RPM and 3000 RPM as cruise speed were taken as parameter. The speed of the alternator was measured using tachometer, digital multi-meter was used to measure battery's voltage, and AC/DC Clamp was used to measure alternator current output. The result shows that the faster the alternator spin, the more power it can produce. And when there is more power, the faster the charging rate of the battery.