Crown Size-Arch Space Relationships During Human Prenatal Dental Development

As shown in composite reconstructions made from optically-projected measurements of 10μ frontal maxillofacial sections of 20 histologically normal fetuses and embryos in the 70-255 mm CRL range, individual differences in relative tooth size and interdental spacing are evident by 10.5-11 weeks of gestation, and age-corrected crown-size correlations (r=0.40) approximate those in postnatal life. Despite an eight-fold increase in crown dimensions, interdental spacing remains approximately constant after 150 mm CRL, suggesting that the tooth organs or the periodontal membranes are able to maintain spacing, into the third trimester.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67036/2/10.1177_00220345790580020301.pd

Re-visiting the embryogenesis of the human lower lip: An overlooked paradigm

The rare opportunity to study a human fetus showing bilateral clefting of the lower lip along with other associated anomalies resembling those of the equally rare Pena-Shokeir phe-notype prompts this report. The scarcity of reports on bilateral clefts of the lower lip has strengthened the conventional understanding or, perhaps even dogma that the lower lip and jaw develop from the progressive midline merging of just two mandibular prominences in the embryo. On the basis of observations stemming from this case report, it is proposed that yet another developmental event or process (in addition to the midline merging of the mandibular prominences) may be operable in the normal morphogenesis of the lower lip and anterior mandibular region. The bilateral paramedian clefting observed provides evidence that another distinct developmental region, a small medial process complements mandibular morphogenesis

Prenatal Ordering and Postnatal Sequence in Dental Development

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67226/2/10.1177_00220345710500060701.pd

Crown Area as an Indicator of Changing Crown Size in Human Pre-natal Teeth

This study deals with correlations of tooth size in human primary teeth. Traditionally, mesiodistal or buccolingual measurements have been used to express crown size. However, in this study, crown area was used as a reference parameter. Graphic reconstructions of 38 histologically prepared human fetuses with Crown-Rump Length (CRL) between 54 and 280 mm were used to obtain linear and area measurements. Based on clinical records and physical examinations, these fetuses were considered typical-for-age, or "normal". Correlation matrices indicated high levels of concordance among all developing deciduous tooth crowns and arch measurements. It was concluded that crown area is a statistically better trait to use in comparison of teeth rather than the traditional mesiodistal measurement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66806/2/10.1177_00220345840630111001.pd