Date of Award

2019

Document Type

Thesis - MUSC Only

Degree Name

Master of Science (MS)

Department

Orthodontics

College

College of Dental Medicine

First Advisor

Timothy Tremont

Second Advisor

Zachary Evans

Third Advisor

Loring Ross

Abstract

Objective: The purpose of this study was to investigate the effects of in utero nicotine exposure on anterior-posterior craniofacial development in a mouse model. Materials and Methods: To determine the effects of in utero nicotine exposure on anterior-posterior craniofacial development, pregnant mothers of C57BL6 mice were exposed to nicotine via their water supply. Maternal water supply exposure was initiated from conception and continued to term (E1-E20). Three exposure groups were identified and received the following levels of nicotine: 1) low-dose (50ug/mL); n=26, 2) medium-dose (100 ug/mL); n=12, and 3) high-dose (200 ug/ml); n=13. The control group consisted of 24 unexposed mice; n=24. All mice were sacrificed day 15 post-natal. Their skulls were fixed in a solution of 4% paraformaldehyde, then switched to 70% ethanol prior to exposure to microCT imaging. Lateral cephalograms were constructed from the microCT images and a customized cephalometric analysis was performed using Dolphin Imaging Software. Results: Nicotine exposed mice demonstrated a statistically significant change in the maxillary anterior-posterior jaw development. Palatal length was greatest in the low-dose (50ug/mL) exposure group (4.21mm ± 0.30), and shortest in the high-dose (200ug/mL) exposure group (4.05 ± 0.18). Maxillary anterior-posterior position value was lowest for the high-dose (200ug/mL) group (104.16 ± 2.41), showing a decrease of about two degrees when compared to the control group (106.4± 2.45). This change illustrates a tendency for maxillary retrusion. Mandibular measurements for ramus length, corpus length, and anterior mandibular length in the exposure groups did not show a statistically significant difference when compared to control group measurements. Conclusions: In utero nicotine exposure has an effect on craniofacial development. Nicotine exposure can predispose offspring to variations in palatal length and maxillary position. Nicotine exposure did not result in statistically significant mandibular changes – namely, changes in the ramus length, corpus length, and anterior mandibular length. Educational information on the potential effects of nicotine exposure from nicotine products (including newer products) should provide information to their patients of child-bearing age. Providers, such as primary care physicians, obstetricians, and dental professionals, should have information made available to their patients regarding 1) smoking cessation and 2) the potential negative effects of nicotine products, including e-cigarettes.

Rights

All rights reserved. Copyright is held by the author.

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