Prototyping of increased vertical dimension of occlusion using an existing removable partial denture and composite resin: a case report.

Full-mouth rehabilitation can be challenging due to the complexity of restoring the vertical dimension of occlusion (VDO) and replacing missing teeth. In partially edentulous patients, the concept of a bonded composite resin prototype for increasing the VDO has previously been applied through the use of an overlay removable partial denture (RPD) with acrylic resin covering the existing dentition. Unfortunately, this type of prosthesis does not always accurately model the function and phonetics intended for the definitive prostheses, and the esthetic result often is less than ideal. It would be advantageous if direct bonding could be used with the patient's existing RPD to model the increased VDO, but this approach has not been reported in the literature. This case report describes the direct bonding of an existing RPD to create a prototype for increased VDO in a partially edentulous patient with a skeletal Class II malocclusion. The successful outcome has been maintained for more than 1 year.

Aviation Noise Impacts: State of the Science.

Noise is defined as "unwanted sound." Aircraft noise is one, if not the most detrimental environmental effect of aviation. It can cause community annoyance, disrupt sleep, adversely affect academic performance of children, and could increase the risk for cardiovascular disease of people living in the vicinity of airports. In some airports, noise constrains air traffic growth. This consensus paper was prepared by the Impacts of Science Group of the Committee for Aviation Environmental Protection of the International Civil Aviation Organization and summarizes the state of the science of noise effects research in the areas of noise measurement and prediction, community annoyance, children's learning, sleep disturbance, and health. It also briefly discusses civilian supersonic aircraft as a future source of aviation noise.

Mortality of a cohort of workers in Great Britain with blood lead measurements.

OBJECTIVES: We examined the mortality of a historic cohort of workers in Great Britain with measured blood lead levels (BLLs). METHODS: SMRs were calculated with the population of Great Britain as the external comparator. Trends in mortality with mean and maximum BLLs and assessed lead exposure were examined using Cox regression. RESULTS: Mean follow-up length among the 9122 study participants was 29.2 years and 3466 deaths occurred. For all causes and all malignant neoplasms, the SMRs were statistically significantly raised. For disease groups of a priori interest, the SMR was significantly raised for lung cancer but not for stomach, brain, kidney, bladder or oesophageal cancers. The SMR was not increased for non-malignant kidney disease but was borderline significantly increased for circulatory diseases, for ischaemic heart disease (IHD) and cerebrovascular disease (CVD). No significant trends with exposure were observed for the cancers of interest, but for circulatory diseases and IHD, there was a statistically significant trend for increasing HR with mean and maximum BLLs. CONCLUSIONS: This study found an excess of lung cancer, although the risk was not clearly associated with increasing BLLs. It also found marginally significant excesses of IHD and CVD, the former being related to mean and maximum BLLs. The finding for IHD may have been due to lead, but could also have been due to other dust exposure associated with lead exposure and possibly tobacco smoking. Further work is required to clarify this and the carcinogenicity of lead.

Integrated understanding of urban land, groundwater, baseflow and surface-water quality--the City of Birmingham, UK.

Integrated understanding of urban land, groundwater (shallow and deep), baseflow and surface-water quality relationships is required for effective urban water-quality management. Chemical quality data from across these media have been collected for the Birmingham (UK) aquifer--River Tame conurbation to assess chemical transport from contaminated land to groundwater to baseflow to surface water. Although metals concentrations were high in soils, low leachability and attenuation caused concentrations in groundwaters and baseflow discharging to surface water to be generally low with only sporadic elevated concentrations attributed to localised point sources. Hydrocarbon VOCs (volatile organic compounds) were similarly absent or at low concentration attributable to their ready natural attenuation. Chlorinated VOCs, however, were widely encountered in groundwater, discharging as baseflow to surface water and impacting surface-water quality. This is attributed to their DNAPL (dense nonaqueous-phase liquid) properties and relative recalcitrance although there was some evidence of biodegradation, albeit insufficient to protect surface water and groundwater abstraction receptors. Some inorganic trends were evident across the various media; nitrate was the most significant quality concern. Generic conclusions are drawn on urban water-quality management and the need for risk-based management strategies to optimise use of urban, sporadically contaminated groundwater in conjunction with surface water highlighted.

Summary of recent NASA studies of human response to sonic booms.

NASA Langley Research Center has conducted three groups of studies on human response to sonic booms: laboratory, "inhome," and field. The laboratory studies were designed to: (1) quantify loudness and annoyance response to a wide range of shaped sonic boom signatures and (2) assess several noise descriptors as estimators of sonic boom subjective effects. The studies were conducted using a sonic boom simulator capable of generating and playing, with high fidelity, both user-prescribed and recorded boom waveforms to test subjects. Results showed that sonic boom waveform shaping provided substantial reductions in loudness and annoyance and that perceived level was the best estimator of subjective effects. Booms having asymmetrical waveforms were found to be less loud than symmetrical waveforms of equivalent perceived level. Subjective responses to simulated ground-reflected waveforms were fully accounted for by perceived level. The inhome study presented participants with simulated sonic booms played within their normal home environment. The results showed that the equal energy theory of annoyance applied to a variety of multiple sonic boom exposures. The field studies concluded that sonic boom annoyance is greater than that in a conventional aircraft noise environment with the same continuous equivalent noise exposure.