An individual's socioeconomic status (SES) is often viewed as a proxy for a host of environmental influences. SES disparities have been linked to variance in brain structures particularly the hippocampus, a neural substrate of learning and memory. However, it is unclear whether the association between SES and hippocampal volume is similar in children and adults. We investigated the relationship between hippocampal volume and SES in a group of children (n = 31, age 8-12 years) and a group of young adults (n = 32, age 18-25 years). SES was assessed with four indicators that loaded on a single factor, therefore a composite SES scores was used in the main analyses. Hippocampal volume was measured using manual demarcation on high resolution structural images. SES was associated with hippocampal volume in the children, but not in adults, suggesting that in childhood, but not adulthood, SES-related environmental factors influence hippocampal volume. In addition, hippocampal volume, but not SES, was associated with scores on a memory task, suggesting that net effects of postnatal environmental factors, captured by SES, are more distal determinants of memory performance than hippocampal volume. Longitudinal investigation of the association between SES, hippocampal volume and cognitive functioning may further our understanding of the putative neural mechanisms underlying SES-related environmental effects on cognitive development.

The purpose of this study was to determine the power and time parameters for an argon laser that would result in the removal of pulpal tissue without excessively elevating the external temperature of the root. External temperatures were measured by attaching thermistors to the surfaces of the teeth at the cemento-enamel junction (CEJ) areas and at the root apices. Results indicate that a 1-W power setting with a pulse duration of 0.1 sec and a 1 sec interval between pulses produced a mean temperature rise of 0.89 +/- 0.27 degrees C at the cemento-enamel junction area and a mean temperature increase of 2.04 +/- 0.47 degrees C at the apex. A 2-W power setting with a 0.1 sec pulse duration and a 1 sec interval between pulses resulted in a mean temperature increase of 1.58 +/- 0.45 degrees C at the CEJ and a mean temperature rise of 2.59 +/- 0.20 degrees C at the apex. Based upon the results of this study, it was concluded that an argon laser operating at 1 or 2 W of power with a 0.1 sec pulse duration could be used to remove pulpal tissue without creating an excessive increase in the external temperature of the tooth.

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