Rate of Apposition of Dentine in Upper Incisors in Normal and Hormone-Treated Rats with a Tentative Comparison of the Apposition of Dentine and Lamellar Bone

Desperately seeking stress: A pilot study of cortisol in archaeological tooth structures

OBJECTIVES

Cortisol is a glucocorticoid hormone produced through activation of the hypothalamic pituitary adrenal axis. It is known as the "stress hormone" for its primary role in the body's stress response and has been the focus of much modern clinical research. Within archaeology, only a few studies have analyzed cortisol in human remains and these have been restricted to hair (Webb et al., 2010; Webb, White, van Uum, & Longstaffe, 2015a; Webb, White, van Uum, & Longstaffe, 2015b). This study examines the utility of dentine and enamel, which survive well archaeologically, as possible reservoirs for detectable levels of cortisol.

MATERIALS AND METHODS

Then, 69 teeth from 65 individuals from five Roman and Post-Roman sites in France were tested via competitive enzyme-linked immunosorbent assay (ELISA) to assess and quantify the cortisol concentrations present within tooth dentine and enamel.

RESULTS

In both tooth dentine and enamel, detectable concentrations of cortisol were identified in multiple teeth. However, concentrations were low and not all teeth yielded results that were measurable through cortisol ELISA. Differences in cortisol values between dentine and enamel could suggest different uptake mechanisms or timing.

DISCUSSION

These results suggest that cortisol is incorporated within tooth structures and merits further investigation in both modern and archaeological contexts. Analysis of the results through liquid chromatographic-mass spectrometry would verify current results and might yield values that could be better integrated with published cortisol studies. Future studies of cortisol in tooth structures would greatly expand the research potential of cortisol in the past and could have implications for studies of human stress across deep time.

Changes in dentin appositional rates during pregnancy and lactation in rats

Dentin appositional rates were determined in pregnant and lactating rats and compared with those in non-pregnant, age-matched controls. Appositional rates were calculated from measurements of distance between fluorescent mineralized tissue markers. There were significant increases in dentin apposition during pregnancy, with the greatest increases seen in the first two weeks. Dentin appositional rates decreased significantly during mid-lactation. These results indicate that homeostatic changes during pregnancy and lactation affect mineralized tissue accretion.

Effect of pituitary hormones on dentin production in maxillary incisors in the rat

The effect of pituitary hormones on dentin production and longitudinal growth of the maxillary incisors in normal and hypophysectomized rats was investigated. Bovine growth hormone was found to increase the dentin production slightly in normal rats and significantly in hypophysectomized rats. Other pituitary hormones showed no effects on dentin apposition in the doses and periods tested. The effects of the pituitary hormones on the longitudinal growth of the tooth were small or insignificant. The effects of growth hormone on the dentin apposition and the longitudinal growth of the tooth after hypophysectomy were smaller than the effects on longitudinal bone growth and cortical bone remodeling, indicating different sensitivity to hormones between different mineralized tissues.