Atlas of Human Fetal Jaw Development

By Lawrence Freilich and David Hunt

This atlas presents a study of human fetal jaw development with a primary focus on the hard tissues of the maxilla and mandible. High-definition photographs are featured throughout of the well-preserved upper and lower jaw elements from the human fetal skeletons contained in the collections of the Smithsonian National Museum of Natural History.

• Language: English
• Publisher: Quintessence Publishing Co, Inc
• Release date: Dec 18, 2019
• ISBN: 9780867157161

Book preview

PREFACE

Detailed photographic studies were carried out in order to illustrate the development of the human fetal maxilla and mandible. This photographic record was derived from known-age skeletal specimens in the collections of the Department of Anthropology, National Museum of Natural History, Smithsonian Institution. To demonstrate the developmental progression, specimens at 4, 7, and 10 lunar months of age are presented photographically to show the distinct physiologic and morphologic developmental progression of the maxilla and mandible. In brief, at 4 lunar months, the facial surface of the maxillary body displays a prominent trabecular or spongy bone topography without any cortical production; the mandibular body and ramus surfaces show more cortical bone than the maxilla. Maxillary height is limited because of early alveolar process development, but dental crypt formation is evident. The coronoid process exhibits greater development than the condyle. The 7-lunar-month maxilla and mandible display increased vertical dimension as a result of the higher alveolar processes and anterior dental crypt development. The maxillary facial surface still possesses a prominent spongiosa, while mandibular facial and lingual surfaces exhibit a mixture of spongy and cortical bone. The 10-lunar-month facial surfaces of both maxilla and mandible have more cortical composition with an abundance of small and midsized neurovascular foramina more evident in the maxilla. The alveolar processes and dental crypts of both the maxillae and mandibles are well developed, and some tooth crowns are visible.

To augment the developmental changes in fetal mandibular growth and development, a series of eight mandibles are presented in buccal and lingual orientation to show the growth and developmental stages. Also, a series of eight whole prepared fetal skulls are presented to illustrate developmental change in the skull. To put these growth and developmental changes in perspective, a series of three complete fetal skeletons are presented photographically.

Cone beam computed tomography examinations of full maxillae and mandibles and of a whole prepared skull were produced. Results reveal a relatively low bone density in the specimens at 4 and 7 lunar months. Proportional density increase is evident in the three stages of development that were studied.

Acknowledgments

The authors wish to express their indebtedness to several individuals without whose time, efforts, and invaluable editorial review this work could not have been completed:

• Stephen Mappen for his superior editing and reformatting of the photographic images in this atlas. Without his exceptional dedication and commitment, this atlas would have not been possible.

• Bruno Frohlich in the Department of Anthropology at the National Museum of Natural History, Smithsonian Institution, for his very helpful expertise and assistance with this project.

• Andrew T. Grant, chief photographic editor, for his invaluable expertise.

Capt Gerald T. Grant, Mr Shayne Kondor, and their colleagues at the Naval Postgraduate Dental School at the Walter Reed National Military Medical Center in Bethesda, Maryland, are recognized for their untiring efforts and expertise in the special imaging included in this project. Their cone beam computed tomography scans of fetal jaws and skulls offer new structural information about these osseous tissues not previously available.

CHAPTER 1

Introduction

Project Goals: Documenting Human Fetal Jaw Development by Photographic and Computed Tomographic Illustration

The goal of this project is to present an ordered study of human fetal jaw development, primarily focused on the hard tissues of the maxilla and mandible, in an image-driven format not well presented in the current scientific literature. This is an investigation of the growth and development of the human maxilla and mandible from approximately 4 months in utero until term (circa 10 months) by photographs and descriptive observations of the changes occurring in the bony tissue.

Previous studies

Although there have been numerous studies that have presented the growth and development of the human gnathic region¹–¹⁰ (see Sperber et al¹¹ for a recent in-depth volume), the results presented are generally in histologic, radiologic, or drawing formats, and few illustrations are made of dissected and cleared bone. The most relevant comparisons would be in cephalometric radiologic illustrations.⁵,⁸,¹²,¹³

In the recent past, a number of studies have employed varying techniques to examine human fetal craniofacial growth and development. Radlanski and colleagues have published several studies using three-dimensional (3D)