Staircase-pattern neonatal line in human deciduous teeth is associated with tooth type.

OBJECTIVE: The staircase (Sc) pattern enamel microstructure is an expression of an impaired ameloblast function. It has been reported to appear in the neonatal line (NNL), the accentuated stria evincing live birth in deciduous tooth enamel. Our objective was to investigate the prevalence of Sc NNL in deciduous tooth types and its possible association with perinatal circumstances. DESIGN: Sc in the NNL of 88 teeth, a collection derived from a long-term, prospectively followed population cohort, was recorded with linear polarised transmitted light and analysed for tooth type, duration and mode of delivery, and pain medication used during labour. RESULTS: Sc prevalence in the NNL differed highly significantly between tooth types (p < 0.0001). An increase in Sc prevalence was significantly associated with an increased ratio of prenatal to total crown enamel (p < 0.001), when buccal and lingual crown walls were analysed separately. No significant association was found between Sc prevalence and duration or mode of delivery or pain-relieving medication (p = 0.57, p = 0.65, p = 0.58, respectively). CONCLUSION: This research indicates that the NNL location within tooth crown enamel has a strong impact on microstructural changes along the NNL. Considering our results of Sc prevalence, deciduous canines, having the least Sc appearance, could be used in studies that aim to investigate factors associated with NNL width. In addition, Sc prevalence variation in first deciduous molars might enable to investigation of physiological stressors strong enough to cause ameloblast impairment, such as Sc.

Deciduous neonatal line: Width is associated with duration of delivery.

The delivery-related neonatal line (NNL) appears into the enamel of primary teeth and first permanent molars at birth and is a marker of live birth process. It varies in width and its location, is different in each deciduous tooth type, and is indicative of gestation time. It is unclear which triggers determine NNL at birth. Our objective was to investigate the effect of the duration and mode of delivery on NNL width. NNL of 129 teeth, a collection derived from a long-term, prospectively followed population cohort, was measured under light microscope. Altogether, 54 sections with most optimal plane of sectioning were analysed for the duration and mode of delivery. NNL was detected in 98% of the deciduous teeth with the median width of 9.63µm (min 3.16µm, max 27.58µm). A prolonged duration of vaginal delivery was highly significantly associated with a narrower NNL (r=-0.41, p=0.0097). No significant association was found between the width of NNL and mode of delivery (p=0.36). NNL is demonstrable in virtually all deciduous teeth. The width seems to be inversely proportional to the duration of delivery. Causes of the inverse proportion are speculated to result from altered amelogenesis induced by prolonged and intensified delivery-associated stress. Further research is needed to clarify the underlying mechanisms.

Scenes from the past: multidetector CT of Egyptian mummies of the Redpath Museum.

As a nondestructive method of historical and anthropologic inquiry, imaging has played an important role in mummy studies over the past several decades. Recent technologic advances have made multidetector computed tomography (CT) an especially useful means for deepening the present understanding of ancient cultures by examining preserved human remains. In April 2011, three ancient Egyptian human mummies from the Redpath Museum of McGill University were examined with 320-section multidetector CT as part of the IMPACT Radiological Mummy Database project headquartered at the University of Western Ontario. Whole-body scanning was performed with a section thickness of 0.5 mm and a peak voltage of 120 kVp, and the raw CT datasets were postprocessed by using smooth body and high-resolution bone convolution filters. Two of the mummies were scanned at different energy levels (80 and 135 keV). The high-resolution CT scans revealed the details of mummification and allowed observations about the socioeconomic and health status of the human subjects based on both the mummification technique used and the appearance of the remains, particularly the bones and teeth. The paleopathologic information obtained from the scans confirmed some findings in studies performed in the same mummies in the late 19th and 20th centuries. The CT scans also demonstrated a high degree of variability in Egyptian mortuary practice, variability that is not generally recognized in the literature. Unusual features that were observed included a relatively uncommon retained heart in mummy RM2718, retained lungs in a mummy from which the heart had been extracted (RM2720), and a cartonnage plaque placed over the left abdomen of a mummy that had been eviscerated transperineally (RM2717).

Early dental intervention in the Redpath Ptolemaic Theban Male.

A computed tomography study of the remains of a Ptolemaic male mummy from Thebes (RM2718; 350-60 BCE), one of three ancient Egyptian human mummies curated at McGill University's Redpath Museum, demonstrates the packing of a large interproximal carious lesion with a protective linen barrier. The dental packing described here is unique among ancient Egyptian mummies studied to date, and represents one of only a few recorded dental interventions in ancient Egypt. Such a finding lends further support for the existence of a group of dental specialists practicing interventional medicine in ancient Egypt. While the physical evidence, to date for other interventions, may be scarce, the findings presented here should underline the need to continue to look for evidence of dental packing as well as other therapeutic dental interventions in the ancient world.