Acknowledgements - UCSF School of Dentistry - University of ...

#43 Title: The Function of Leucine Rich Amelogenin Peptide (LRAP) in tooth formation.
J STAHL, Y NAKANO, T LE, P DEN BESTEN
UCSF Department of Orofacial Sciences
Background: LRAP, or leucine rich amelogenin peptide (LRAP) is a 59 amino acid alternatively spliced amelogenin, which includes
the first 33 and the last 26 amino acids from the full-length amelogenin. LRAP has been shown to have cell signaling properties,
though its function in enamel formation remains unknown.
Objective: To determine the effects of LRAP in mouse tooth formation, using a transgenic mouse, which overexpresses LRAP.
Methods: Hemi-maxillas of wild-type (WT), and LRAP overexpressor in wild-type background (LRAP/WT) mice (0 and 5 days postnatal)
were fixed in 4% paraformaldehyde, and demineralized in 8% EDTA (Ph 7.6) AT 4˚C. The jaws were embedded in paraffin for
longitudinal sectioning. The localization of various matrix, differentiation, and signaling proteins in the developing tooth organ were
compared by immunohistochemistry (IHC). Immunoreactivity was detected with a Vecastatin ABC kit. Right dry hemimandibles
were scanned with a microCT to characterize the mineral density of the dental tissues in WT and transgenic mice.
Results: In both newborn and day 5 mice, ameloblast morphology was disrupted, suggesting an interference with cell polarization.
IHC In newborn LRAP/WT mice revealed a transient upregulation of amelogenin in secretory ameloblasts and adjacent
odontoblasts, with no similar upregulation in WT mouse molars. In the maxillary first molar of postnatal day 5 LRAP/WT mice,
ameloblasts were poorly organized and enamel matrix formation was almost completely absent. Amelogenin immunostaining in the
cell cytoplasm of LRAP/WT mice was increased as compared to controls, and Lamp1 was upregulated in both ameloblasts and
odontoblasts of postnatal day 5 LRAP/WT mice. Initial microCT data showed an overall delay in mandibular incisor and molar
development in the LRAP/WT mice at the early post-natal stage.
Conclusions: Early overexpression of LRAP interferes with ameloblast function and tooth development.
# 44 Title: Are Dental Caries in Adolescents Associated with Health Insurance?
S SUNDARRAJAN (1), J CHENG (2), S HYDE (2)
(1) Graduate Division UCSF, (2) UCSF Department of Preventive and Restorative Dental Sciences
Objective: To determine the association between health insurance and dental caries among adolescents aged 12-19 years from a
national sample of a diverse population.
Methods: This secondary data analysis of the continuous National Health and Nutrition Examination Survey (NHANES) data set
from 2005-2008 focuses on the oral health exam component, health insurance, and demographic variables. The primary outcome
measure is the presence of dental caries, and the predictor of interest is health insurance. Covariates in the analyses include age,
gender, race/ethnicity, country of birth, annual family income, and presence of dental sealant. Data were analyzed using STATA 11.
Since NHANES was a multistage, complex survey, Stata’s survey commands and pweight option were used to handle the sampling
weights and clustering.
Results: Teenagers without dental sealants, born outside the US, who were Mexican American, Other Hispanic, or Non-Hispanic
Black, and whose families did not have health insurance had twice the number of decayed teeth as those with sealants, born in the
US, Non-Hispanic Whites, and whose families did have health insurance (all p