Test Bank For Illustrated Dental Embryology Histology and Anatomy 4th ed By Margaret J. Fehrenbach

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Illustrated Dental Embryology Histology and Anatomy 4th ed By Margaret J. Fehrenbach – Test Bank 

 

Chapter 01: Face and Neck Regions

 

MULTIPLE CHOICE

 

  1. Which of the following facial features is located laterally to each naris?
a. Orbit
b. Nasal ala
c. Nasal septum
d. Philtrum

 

 

ANS:  B

The nares are separated by the midline nasal septum. The nares are also bounded laterally by winglike cartilaginous structures, each ala (plural, alae) of the nose. In the orbital region of the face, the eyeball and all its supporting structures are contained in the orbit of the skull, the bony eye socket. On the midline of the upper lip extending downward from the nasal septum is a vertical groove, the philtrum.

 

REF:   Chapter 1, Nasal Region, Page 2

 

  1. The lips are outlined from the surrounding skin by a transition area called the:
a. philtrum.
b. mucogingival junction.
c. mucocutaneous junction.
d. mandibular symphysis.

 

 

ANS:  C

The vermilion zone of each lip has a darker appearance than the surrounding skin, with the lips outlined from the surrounding skin by a transition zone, the mucocutaneous junction. On the midline of the upper lip extending downward from the nasal septum is a vertical groove, the philtrum. The line of demarcation between the firmer and pinker attached gingiva and the movable and redder alveolar mucosa is the scallop-shaped mucogingival junction. The midline of the mandible is marked by the mandibular symphysis.

 

REF:   Chapter 1, Oral Region, Page 2

 

  1. Which of the following structures can be palpated in the anterior midline of the neck?
a. Thyroid cartilage
b. Parathyroid glands
c. Sternocleidomastoid muscle
d. Submandibular salivary gland

 

 

ANS:  A

Found in the anterior midline and inferior to the hyoid bone is the thyroid cartilage, which is the prominence of the “voice box,” or larynx. The vocal cords, or ligaments of the larynx, are attached to the posterior surface of the thyroid cartilage. The parathyroid glands are located close to or within the posterior aspect of the thyroid gland but cannot be palpated in a patient; the thyroid gland can be palpated on a patient within the midline cervical area. The large strap muscle, the sternocleidomastoid muscle, is easily palpated on each side of the neck. The submandibular salivary gland is in the neck region but not in the midline.

 

REF:   Chapter 1, Neck Regions, Page 8

 

  1. Which of the following statements concerning the zygomatic arch is correct?
a. The temporomandibular joint is superior.
b. The infraorbital region is inferior.
c. It overlies the mandible.
d. The external ear is posterior.

 

 

ANS:  D

Farther laterally to the infraorbital region is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The zygomatic arch extends from just below the lateral margin of the eye toward the middle part of the external ear, which is located posteriorly. Inferior to the zygomatic arch and just anterior to the external ear is the temporomandibular joint.

 

REF:   Chapter 1, Zygomatic Region, Page 2

 

  1. One of the muscles forming the cheek is the strong _____ muscle, which is felt when a patient clenches the teeth together.
a. lateral pterygoid
b. masseter
c. medial pterygoid
d. temporalis

 

 

ANS:  B

The buccal region of the face is composed of the soft tissue of the cheek. The cheek forms the side of the face and is a broad area of the face between the nose, mouth, and ear. Most of the upper cheek is fleshy, mainly formed by a mass of fat and muscles. One of the muscles forming the cheek is the strong masseter muscle, which is palpated when a patient clenches the teeth together. The pterygoid muscles are also located on each side of the face near the mouth, and the temporalis is located in the temporal region.

 

REF:   Chapter 1, Buccal Region, Page 2

 

  1. Just inferior to the zygomatic arch and just anterior to the external ear is the:
a. temporomandibular joint.
b. infraorbital region.
c. mental region.
d. parotid gland.

 

 

ANS:  A

Inferior to the zygomatic arch and just anterior to the external ear is the temporomandibular joint. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. Farther laterally is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The zygomatic arch extends from just below the lateral margin of the eye toward the middle part of the external ear. The chin is the major feature of the mental region of the face; the bone underlying the mental region is the mandible, or lower jaw. The parotid is located irregularly from the zygomatic arch down to the posterior border of the lower jaw.

 

REF:   Chapter 1, Zygomatic Region, Page 2

 

  1. The _____ salivary gland is located irregularly from the zygomatic arch down to the posterior border of the lower jaw.
a. parotid
b. submandibular
c. von Ebner
d. sublingual

 

 

ANS:  A

The parotid is located irregularly from the zygomatic arch down to the posterior border of the lower jaw. Both the submandibular salivary and sublingual are in the neck region. The von Ebner refers to minor glands located deep to the circumvallate lingual papillae on the dorsal surface of the tongue.

 

REF:   Chapter 1, Buccal Region, Page 2

 

  1. The _____ extends from just below the lateral margin of the eye toward the middle part of the external ear.
a. temporomandibular joint
b. zygomatic arch
c. labial commissure
d. infraorbital region

 

 

ANS:  B

The zygomatic arch extends from just below the lateral margin of the eye toward the middle part of the external ear. Inferior to the zygomatic arch and just anterior to the external ear is the temporomandibular joint. The upper and lower lips meet at each corner of the mouth at the labial commissure. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region.

 

REF:   Chapter 1, Zygomatic Region, Page 2

 

  1. The main feature of the _____ region of the face is the external nose.
a. infraorbital
b. zygomatic
c. nasal
d. temporal

 

 

ANS:  C

The main feature of the nasal region of the face is the external nose. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. Farther laterally is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The temporal region is on the lateral side of the head at the temple.

 

REF:   Chapter 1, Nasal Region, Page 1

 

  1. Which of the following orofacial structures is located in the midline of the face or neck?
a. Philtrum
b. Submandibular salivary gland
c. Naris and ala
d. Parotid salivary gland

 

 

ANS:  A

On the midline of the upper lip extending downward from the nasal septum is a vertical groove, the philtrum. The submandibular can also be palpated in a patient in the neck region but not in the midline. Inferior to the apex on each side of the nose is a nostril, or naris (plural, nares). The nares are also bounded laterally by winglike cartilaginous structures, each ala (plural, alae) of the nose. The parotid is located irregularly from the zygomatic arch down to the posterior border of the lower jaw and not in the midline.

 

REF:   Chapter 1, Oral Region, Page 2

 

  1. The _____ region includes the forehead and area above the eyes.
a. infraorbital
b. orbital
c. temporal
d. frontal

 

 

ANS:  D

The frontal region of the face includes the forehead and the area above the eyes. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. In the orbital region of the face, the eyeball and all its supporting structures are contained in the orbit of the skull, the bony eye socket. The temporal region is on the lateral side of the head at the temple.

 

REF:   Chapter 1, Frontal Region, Page 1

 

  1. Which of the following may be involved in the disruption of the vermilion zone and may make it hard to determine the exact location of its mucocutaneous junction between the lips and the surrounding skin?
a. Scar tissue
b. Hypercalcification
c. Cleft palate
d. Symmetry

 

 

ANS:  A

Disruption of the vermilion zone may make it hard to determine the exact location of its mucocutaneous junction between the lips and the surrounding skin. These changes may be due to scar tissue from past traumatic incidents, developmental disturbances, or cellular changes in the tissue such as occur with solar damage. These changes may also represent a more serious condition such as cancer; however, this can be verified only with tissue biopsy and microscopic examination. If this change is part of a past history of a cleft lip, this also needs to be noted in the patient record because of its impact on dental care.

 

REF:   Chapter 1, Clinical Considerations with Lips, Page 2

 

  1. The _____ region of the face is composed of the soft tissue of the cheek.
a. infraorbital
b. orbital
c. temporal
d. buccal

 

 

ANS:  D

The buccal region of the face is composed of the soft tissue of the cheek. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. In the orbital region of the face, the eyeball and all its supporting structures are contained in the orbit of the skull, the bony eye socket. The temporal region is on the lateral side of the head at the temple.

 

REF:   Chapter 1, Buccal Region, Page 2

 

  1. To palpate the lower jaw moving at the temporomandibular joint on a patient, a finger is placed into the external ear canal during:
a. rest.
b. movement.
c. swallowing.
d. eye closure.

 

 

ANS:  B

To palpate the lower jaw moving at the temporomandibular joint on a patient, a finger is placed into the external ear canal during movement.

 

REF:   Chapter 1, Zygomatic Region, Page 2

 

  1. The chin is the major feature of the _____ region of the face.
a. zygomatic
b. infraorbital
c. mental
d. oral

 

 

ANS:  C

The chin is the major feature of the mental region of the face. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. Farther laterally is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The oral region of the face has many structures within it, such as the lips and oral cavity.

 

REF:   Chapter 1, Mental Region, Page 2

 

  1. The _____ gland, an endocrine gland, can be palpated within the midline cervical area.
a. parathyroid
b. thyroid
c. parotid
d. submandibular

 

 

ANS:  B

The thyroid gland, an endocrine gland, can be palpated on a patient within the midline cervical area. The parathyroid glands are located close to or within the posterior aspect of the thyroid gland but cannot be palpated in a patient. The parotid is located irregularly from the zygomatic arch down to the posterior border of the lower jaw; the parotid has a small part that can be palpated on a patient in the buccal region as well as in the zygomatic region. The submandibular can also be palpated in the neck region but not in the midline.

 

REF:   Chapter 1, Neck Regions, Page 8

 

  1. The large strap muscle, the _____ muscle, is located on each side of the neck.
a. masseter
b. sternocleidomastoid
c. lateral pterygoid
d. medial pterygoid

 

 

ANS:  B

The large strap muscle, the sternocleidomastoid muscle, is easily palpated on each side of a patient’s neck. One of these muscles forming the cheek is the strong masseter muscle, which is palpated when a patient clenches the teeth together. The pterygoid muscles are also located on each side of the face.

 

REF:   Chapter 1, Neck Regions, Page 8

 

  1. The regions of the face include the frontal, _____, nasal, infraorbital, zygomatic, buccal, oral, and mental regions.
a. temporal
b. occipital
c. orbital
d. parietal

 

 

ANS:  C

The regions of the face include the frontal, orbital, nasal, infraorbital, zygomatic, buccal, oral, and mental regions. The other regions are regions of the head and include the temporal, occipital, and parietal.

 

REF:   Chapter 1, Face Regions, Page 1

 

  1. The _____ are separated by the midline nasal septum.
a. alae
b. nares
c. zygomatic arches
d. commissures

 

 

ANS:  B

Inferior to the apex on each side of the nose is a nostril, or naris (plural, nares). The nares are separated by the midline nasal septum. The nares are also bounded laterally by winglike cartilaginous structures, each ala (plural, alae) of the nose. Farther laterally is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The upper and lower lips meet at each corner of the mouth at the labial commissure.

 

REF:   Chapter 1, Nasal Region, Page 2

 

  1. What part of the mandible extends upward and backward from the body of the mandible on each side?
a. Coronoid process
b. Mandibular symphysis
c. Ramus
d. Coronoid notch

 

 

ANS:  C

The bone underlying the mental region is the mandible, or lower jaw. On the lateral aspect of the mandible, the stout, flat plate of the ramus (plural, rami) extends upward and backward from the body of the mandible on each side. At the anterior border of the ramus is a thin, sharp margin that terminates in the coronoid process. The midline of the mandible is marked by the mandibular symphysis. The main part of the anterior border of the ramus forms a concave forward curve, the coronoid notch.

 

REF:   Chapter 1, Mental Region, Page 2

 

  1. The lips are fleshy folds that mark the gateway of the _____ cavity proper.
a. zygomatic
b. infraorbital
c. mental
d. oral

 

 

ANS:  D

The upper and lower lips are fleshy folds that mark the gateway of the oral cavity proper. The infraorbital region of the face is located inferior to the orbital region and lateral to the nasal region. Farther laterally is the zygomatic region, which overlies the bony support for the cheek, the zygomatic arch. The chin is the major feature of the mental region of the face.

 

REF:   Chapter 1, Oral Region, Page 2

 

  1. The sharp angle of the lower jaw inferior to the earlobe is termed the angle of the:
a. mandible.
b. maxilla.
c. temporomandibular joint.
d. zygomatic arch.

 

 

ANS:  A

The sharp angle of the lower jaw inferior to the earlobe is termed the angle of the mandible. The bone underlying the lower lip is the lower jaw, or mandible. Underlying the upper lip is the upper jaw, or maxilla. Inferior to the zygomatic arch and just anterior to the external ear is the temporomandibular joint. The zygomatic arch extends from just below the lateral margin of the eye toward the middle part of the external ear.

 

REF:   Chapter 1, Buccal Region, Page 2

 

  1. Between the vermilion zone and the inner oral cavity is the:
a. philtrum.
b. mucogingival junction.
c. mucocutaneous junction.
d. intermediate zone.

 

 

ANS:  D

Between the vermilion zone and the inner oral cavity is the intermediate zone. The vermilion zone of each lip has a darker appearance than the surrounding skin, with the lips outlined from the surrounding skin by a transition zone, the mucocutaneous junction. On the midline of the upper lip, extending downward from the nasal septum, is a vertical groove, the philtrum. The line of demarcation between the firmer and pinker attached gingiva and the movable and redder alveolar mucosa is the scallop-shaped mucogingival junction.

 

REF:   Chapter 1, Oral Region, Page 2

 

  1. Which of the following orofacial structures contributes to the prominence of the neck that is also called the “Adam’s apple”?
a. Sublingual salivary gland
b. Submandibular salivary gland
c. Thyroid cartilage
d. Hyoid bone

 

 

ANS:  C

Found in the anterior midline and inferior to the hyoid bone is the thyroid cartilage, which is the prominence of the “voice box,” or larynx. The submandibular salivary gland and the sublingual salivary gland can also be palpated in a patient in the neck region superior to the hyoid bone. At the anterior midline is the hyoid bone, which is suspended in the neck; many muscles attach to the hyoid bone, which controls the position of the base of the tongue.

 

REF:   Chapter 1, Neck Regions, Page 8

 

  1. The philtrum terminates in a thicker area of the midline of the upper lip, the _____ of the upper lip.
a. septum
b. tubercle
c. symphysis
d. ramus

 

 

ANS:  B

The philtrum terminates in a thicker area of the midline of the upper lip, the tubercle of the upper lip. The nares are separated by the midline nasal septum. The midline of the mandible is marked by the mandibular symphysis. On the lateral aspect of the mandible, the stout, flat plate of the ramus (plural, rami) extends upward and backward from the body of the mandible on each side.

 

REF:   Chapter 1, Oral Region, Page 2

 

Chapter 03: Prenatal Development

 

MULTIPLE CHOICE

 

  1. The folding of the embryo during prenatal development causes _____ to be on the _____.
a. endoderm; inside of the embryo
b. ectoderm; inside of endoderm
c. endoderm; outside of the mesoderm
d. mesoderm; outside of the ectoderm

 

 

ANS:  A

After folding of the disc, the endoderm lies inside the ectoderm, with mesoderm filling in the areas between these two layers. This movement of the embryonic cell layers forms one long, hollow tube lined by endoderm from the cephalic end to the caudal end of the embryo—specifically, from the oropharyngeal membrane to the cloacal membrane. This tube is the future digestive tract and is separated into three major regions: foregut, midgut, and hindgut.

 

REF:   Chapter 3, Fourth Week, Page 27

 

  1. Which of the following tissues listed will develop from the ectoderm layer of the embryo during prenatal development?
a. Epidermis
b. Liver
c. Muscle
d. Dermis

 

 

ANS:  A

With the creation of the new embryonic cell layers of mesoderm and embryonic endoderm, the epiblast layer is now considered ectoderm. The ectoderm gives rise to the skin epidermis, the central nervous system, and other structures. The mesoderm gives rise to connective tissue, such as skin dermis, cartilage, bone, blood, muscle, and other associated tissue. The endoderm gives rise to the respiratory epithelium and cells of glands.

 

REF:   Chapter 3, Third Week, Page 25

 

  1. Which of the following structures initially forms during the third week of prenatal development?
a. Primitive streak
b. Embryoblast layer
c. Bilaminar embryonic disc
d. Trophoblast layer

 

 

ANS:  A

During the beginning of the third week of prenatal development within the embryonic period, the primitive streak forms within the bilaminar disc. This furrowed, rod-shaped thickening in the middle of the disc results from an increased proliferation of cells in the midline area. After a week of cleavage, the blastocyst consists of a layer of peripheral cells, the trophoblast layer, and a small inner mass of embryonic cells, or embryoblast layer. The trophoblast layer later gives rise to important prenatal support tissue. The embryoblast layer later gives rise to the embryo during the prenatal period that follows, the embryonic period.

 

REF:   Chapter 3, Third Week, Page 24

 

  1. From which embryonic layer is mesoderm derived during prenatal development?
a. Epiblast layer
b. Hypoblast layer
c. Endoderm
d. Neuroectoderm

 

 

ANS:  A

During the beginning of the third week, some cells from the epiblast layer move or migrate toward the hypoblast layer only in the area of the primitive streak. These migratory cells locate in the middle between the epiblast and hypoblast layers and become mesoderm, an embryonic connective tissue, as well as embryonic endoderm.

 

REF:   Chapter 3, Third Week, Page 24

 

  1. Which of the following statements concerning prenatal development is correct?
a. Most congenital malformations occur during the last prenatal week.
b. Maturation of existing structures occurs during the second to eighth week.
c. Initiation of embryonic layers occurs during the first week.
d. The fetus is the structure present during the embryonic period.

 

 

ANS:  C

By the end of the first week of the preimplantation period, the blastocyst stops traveling and undergoes implantation and thus becomes embedded in the prepared endometrium, the innermost lining of the uterus on its back wall. After a week of cleavage, the blastocyst consists of a layer of peripheral cells, the trophoblast layer, and a small inner mass of embryonic cells, or the embryoblast layer. Any developmental disturbances occurring during the earlier embryonic period and not the later fetal period with its fetus may give rise to major congenital malformations of the embryo. Thus, the fetal period encompasses the beginning of the ninth week or third month continuing to the ninth month, with the maturation of existing structures occurring as the embryo enlarges to become a fetus.

 

REF:   Chapter 3, Preimplantation Period, Page 21

 

  1. Which period of prenatal development is characterized by increased cellular differentiation?
a. Unattached conceptus
b. Embryonic period
c. Preimplantation period
d. Fetal period

 

 

ANS:  C

During the second week of prenatal development within the embryonic period, the implanted blastocyst grows by increased proliferation of the embryonic cells, with differentiation also occurring, resulting in changes in cellular morphogenesis. This increased number of embryonic cells creates the embryonic cell layers within the blastocyst.

 

REF:   Chapter 3, Second Week, Page 23

 

  1. Found in early prenatal development, the neural tube will form in the future which of the following structures?
a. Heart
b. Spinal cord
c. Face
d. Digestive tract

 

 

ANS:  B

As further growth of the neuroectoderm occurs, the neural tube is formed during the fourth week by the neural folds undergoing fusion at the most superior part. The neural tube forms the future spinal cord as well as other neural tissue of the central nervous system.

 

REF:   Chapter 3, Third Week, Page 26

 

  1. The primitive streak forms in the embryonic disc during prenatal development, causing:
a. initiation of palatal development.
b. bilateral symmetry.
c. fusion of the mandibular processes.
d. disintegration of the oropharyngeal membrane.

 

 

ANS:  B

The primitive streak causes the disc to have bilateral symmetry, with a right half and left half; most of the further development of each half of the embryo mirrors the other half.

 

REF:   Chapter 3, Third Week, Page 24

 

  1. The neural crest cells migrate from which embryonic structures during prenatal development?
a. Stomodeum
b. First branchial arch
c. Neural folds
d. Frontonasal process

 

 

ANS:  C

The neural crest cells migrate from the crests of the neural folds and then join the mesoderm to form mesenchyme. At the cephalic end, the oropharyngeal membrane forms, which consists of only ectoderm externally and endoderm internally, without any intermediate mesoderm. This membrane is the location of the future primitive mouth or stomodeum of the embryo and thus the beginning of the digestive tract. The first branchial arch, also called the first pharyngeal arch and mandibular arch, is the first of six arches that develops in fetal life. The frontonasal process is the midline unpaired embryonic structure that develops into the forehead.

 

REF:   Chapter 3, Third Week, Page 26

 

  1. During prenatal development, the oropharyngeal membrane of the embryo:
a. consists of three embryonic layers.
b. is located superior to the first branchial arch.
c. disintegrates during the third week of prenatal development.
d. is located superior to the maxillary process.

 

 

ANS:  B

At the cephalic end, the oropharyngeal membrane forms, which consists of only ectoderm externally and endoderm internally, without any intermediate mesoderm. This membrane is the location of the future primitive mouth or stomodeum of the embryo and thus the beginning of the digestive tract. It is located superior to the first branchial arch or mandibular arch.

 

REF:   Chapter 3, Third Week, Page 25

 

  1. During which week of prenatal development does the neural plate differentiate?
a. Second week
b. Third week
c. Fourth week
d. Fifth week

 

 

ANS:  B

A specialized group of cells differentiates from the ectoderm and is now considered neuroectoderm. These cells are localized to the neural plate of the embryo, a central band of cells that extends the length of the embryo, from the cephalic end to the caudal end, during the third week of prenatal development. This plate undergoes further growth and thickening, which cause it to deepen and invaginate inward, forming the neural groove.

 

REF:   Chapter 3, Third Week, Page 26

 

  1. By the end of the first week of prenatal development, the blastula stops traveling and undergoes:
a. implantation.
b. migration.
c. disintegration.
d. amniocentesis.

 

 

ANS:  A

By the end of the first week, the blastocyst stops traveling and undergoes implantation; thus it becomes embedded in the prepared endometrium, the innermost lining of the uterus on its back wall.

 

REF:   Chapter 3, Preimplantation Period, Page 21

 

  1. In which of the following do the final stages of meiosis occur during prenatal development?
a. Placenta
b. Ovum
c. Sperm
d. Yolk sac

 

 

ANS:  B

During fertilization, the final stages of meiosis occur in the ovum. The result of this process is the joining of the ovum’s chromosomes with those of the sperm. This joining of chromosomes from both biologic parents forms a new individual with “shuffled” chromosomes.

 

REF:   Chapter 3, Preimplantation Period, Page 20

 

  1. How many X-type chromosomes are necessary for the embryo to become of the female gender when present during prenatal development?
a. One
b. Two
c. Three
d. Four

 

 

ANS:  B

The photographic analysis of a person’s chromosomes is done by orderly arrangement of the pairs in a karyotype, with the sex known by the presence of either XX chromosomes for females or XY for males.

 

REF:   Chapter 3, Preimplantation Period, Page 20

 

  1. When does the blastocyte stop traveling and undergo implantation during prenatal development?
a. First week
b. Second week
c. Third week
d. Fourth week

 

 

ANS:  A

By the end of the first week, the blastocyst stops traveling and undergoes implantation, thus becoming embedded in the prepared endometrium, the innermost lining of the uterus on its back wall.

 

REF:   Chapter 3, Preimplantation Period, Page 21

 

  1. What best characterizes the first week of prenatal development so that the blastocyst splits into smaller and more numerous cells?
a. Implantation
b. Mitotic cleavage
c. Meiosis
d. Fertilization

 

 

ANS:  B

The first week of prenatal development is best characterized by further mitotic cleavage, in which the blastocyst splits into smaller and more numerous cells as it undergoes successive cell divisions by mitosis. During fertilization, the final stages of meiosis occur in the ovum; this process is the joining of the ovum’s chromosomes with those of the sperm. By the end of the first week, the blastocyst stops traveling and undergoes implantation, thus becoming embedded in the prepared endometrium, the innermost lining of the uterus on its back wall.

 

REF:   Chapter 3, Preimplantation Period, Page 20

 

  1. A prenatal diagnostic procedure to detect chromosomal abnormalities is:
a. mitotic cleavage.
b. bilateral symmetry.
c. amniocentesis.
d. folding.

 

 

ANS:  C

A prenatal diagnostic procedure to detect chromosomal abnormalities is amniocentesis, where the amniotic fluid is removed and its fetal cells are grown for microscopic study of the chromosomes as well as sampled for determination of other fetal complications. After fertilization, the zygote then undergoes mitosis, or individual cell division, that splits it into more and more cells due to cleavage. During the beginning of the third week of prenatal development within the embryonic period, the primitive streak forms within the bilaminar disc. The primitive streak causes the disc to have bilateral symmetry, with a right half and left half. During the fourth week of prenatal development within the embryonic period, the embryonic disc undergoes embryonic folding, which places forming tissue types into their proper positions for further embryonic development.

 

REF:   Chapter 3, Clinical Considerations for Prenatal Development, Page 18

 

  1. Which of the following can occur that mainly involves the abnormal development of one or more structures from ectoderm within the embryonic period?
a. Treacher Collins syndrome
b. Ectodermal dysplasia
c. Congenital syphilis
d. Fetal alcohol syndrome

 

 

ANS:  B

One syndrome that can occur within this period is ectodermal dysplasia, which involves the abnormal development of one or more structures from ectoderm. It has a hereditary etiology and presents with abnormalities of the teeth, skin, hair, nails, eyes, facial structure, and glands, because these are derived from ectoderm or associated tissue. If there is failure of migration of the neural crest cells to the facial region, Treacher Collins syndrome develops in the embryo. An infective teratogen causes syphilis, Treponema pallidum, because it produces defects in the incisors (Hutchinson incisor) and molars (mulberry molar), as well as blindness, deafness, and possible paralysis if not treated. Fetal alcohol syndrome is an example of the result of a teratogenic drug effect of high levels of ethanol ingested by a pregnant female during the embryonic period.

 

REF:   Chapter 3, Clinical Considerations for Embryonic Period, Page 27

 

  1. How many pairs of somites form the cuboidal segments of mesoderm within the embryo during the third week of prenatal development?
a. 12
b. 18
c. 38
d. 42

 

 

ANS:  C

By the end of the third week, the mesoderm additionally differentiates and begins to divide on each side of the tube into 38 paired cuboidal segments of mesoderm, forming the somites. The somites develop in the following weeks of prenatal development, giving rise to most of the skeletal structures of the head, neck, and trunk, as well as the associated muscles and dermis of the skin.

 

REF:   Chapter 3, Third Week, Page 27

 

  1. What exact cells are localized to the neural plate of the embryo during the third week of prenatal development?
a. Neuroectoderm
b. Mesenchyme
c. Somites
d. Endoderm

 

 

ANS:  A

A specialized group of cells differentiates from the ectoderm and is now considered neuroectoderm. These cells are localized to the neural plate of the embryo, a central band of cells that extends the length of the embryo, from the cephalic end to the caudal end. In addition, during the third week, another specialized group of cells, the neural crest cells, develop from neuroectoderm. These cells migrate from the crests of the neural folds and then join the mesoderm to form mesenchyme. By the end of the third week, the mesoderm additionally differentiates and begins to divide on each side of the tube into 38 paired cuboidal segments of mesoderm, forming the somites. The migratory cells located in the middle between the epiblast and hypoblast layers become mesoderm, an embryonic connective tissue, as well as embryonic endoderm.

 

REF:   Chapter 3, Third Week, Page 27

 

  1. What exact cells or structures develop from neuroectoderm and migrate from the neural folds to then join mesoderm to form mesenchyme during the third week of prenatal development?
a. Somites
b. Neural crest cells
c. Mesoderm
d. Yolk sac

 

 

ANS:  B

During the third week, another specialized group of cells, the neural crest cells, develop from neuroectoderm. These cells migrate from the crests of the neural folds and then join the mesoderm to form mesenchyme. By the end of the third week, the mesoderm additionally differentiates and begins to divide on each side of the tube into segments of mesoderm, forming the somites. The migratory cells located in the middle between the epiblast and hypoblast layers become mesoderm, an embryonic connective tissue. After its creation, the bilaminar disc is suspended in the uterus’s endometrium between two fluid-filled cavities, the amniotic cavity, which faces the epiblast layer, and the yolk sac, which faces the hypoblast layer and serves as initial nourishment for the embryonic disc.

 

REF:   Chapter 3, Third Week, Page 26

 

  1. If there is failure of migration of the neural crest cells to the facial region during prenatal development, _____ can develop in the embryo.
a. ectodermal dysplasia
b. fetal alcohol syndrome
c. Down syndrome
d. Treacher Collins syndrome

 

 

ANS:  D

If there is failure of migration of the neural crest cells to the facial region, Treacher Collins syndrome develops in the embryo. This results in failure of specific areas of orofacial development, presenting with downward slanting eyes, underdeveloped zygomatic bone, drooping lateral lower eyelids, and conductive hearing loss, with malformed or absent ears as well as dental developmental disturbances such as micrognathia, anodontia, and enamel dysplasia. Ectodermal dysplasia involves the abnormal development of one or more structures from ectoderm. Fetal alcohol syndrome is an example of the result of a teratogenic drug effect of high levels of ethanol ingested by a pregnant female during the embryonic period. Down syndrome occurs when an extra chromosome number 21 is present after meiotic division, leading to certain orofacial features.

 

REF:   Chapter 3, Clinical Considerations for Embryonic Period, Page 30

 

  1. Implantation of the zygote may also occur outside the uterus during prenatal development with a(n):
a. infection with rubella.
b. infection with syphilis.
c. ectopic pregnancy.
d. case of ectodermal dysplasia.

 

 

ANS:  C

Implantation the zygote may also occur outside the uterus with an ectopic pregnancy, most occurring within the fallopian tube. This disturbance has several causes but is usually associated with factors that delay or prevent transport of the dividing zygote to the uterus, such as scarred uterine tubes due to pelvic inflammatory disease. Examples of an infective teratogen for the embryo is the virus causing rubella, which can result in cataracts, cardiac defects, and deafness or the bacterial spirochete causing syphilis, Treponema pallidum, because it produces defects in the incisors (Hutchinson incisor) and molars (mulberry molar), as well as blindness, deafness, and possible paralysis if not treated. Ectodermal dysplasia involves the abnormal development of one or more structures from ectoderm.

 

REF:   Chapter 3, Clinical Considerations for Preimplantation Period, Page 22

 

  1. What is the exact term for the process that affords the development of specific tissue structure or differing form due to embryonic cell migration and inductive interactions?
a. Folding
b. Morphogenesis
c. Proliferation
d. Appositional or interstitial growth

 

 

ANS:  B

Morphogenesis is the process of development of specific tissue structure or shape. This process occurs due to the migration or proliferation of embryonic cells, which is followed by the inductive interactions of those cells. During the fourth week of prenatal development within the embryonic period, the embryonic disc undergoes anterior and lateral embryonic folding, which places forming tissue types into their proper positions for further embryonic development. Proliferation describes the controlled levels of cellular growth present during most of prenatal development. Growth may be by appositional growth, in which tissue enlarges by the addition of layers on the outside of a structure. In contrast, growth may be by interstitial growth, which occurs from deep within a tissue type or organ.

 

REF:   Chapter 3, Embryonic Period, Page 22

 

  1. What is the prenatal organ that joins the pregnant woman and the developing embryo during the second week of prenatal development?
a. Placenta
b. Amniotic cavity
c. Yolk sac
d. Primitive streak

 

 

ANS:  A

The placenta is a prenatal organ that joins the pregnant female and developing embryo during the second week of prenatal development. It develops from the interactions of the trophoblast layer and endometrial tissue. Its formation and the associated developing umbilical circulation permit selective exchange of soluble bloodborne substances between them. After its creation, the bilaminar disc is suspended in the uterus’s endometrium between two fluid-filled cavities: the amniotic cavity, which faces the epiblast layer, and the yolk sac, which faces the hypoblast layer and serves as initial nourishment for the embryonic disc. During the beginning of the third week of prenatal development within the embryonic period, the primitive streak forms within the bilaminar disc, a furrowed, rod-shaped thickening in the middle of the disc.

 

REF:   Chapter 3, Second Week, Page 24

Chapter 13: Dentin and Pulp

 

MULTIPLE CHOICE

 

  1. The most common cell type in connective tissue such as the pulp is the:
a. endothelial cell.
b. fibroblast.
c. white blood cell.
d. odontoblast.

 

 

ANS:  B

As in all forms of connective tissue, the fibroblasts are the largest group of cells in the pulp. The odontoblasts are the second largest group of cells in the pulp, but only their cell bodies are located in the pulp. The pulp contains white blood cells in its tissue and vascular supply, but levels are normally low, unless the cells are ready to be triggered by an inflammatory or immune reaction. Endothelial cells line the blood vessels within the pulp.

 

REF:   Chapter 13, Pulp Histology, Page 168

 

  1. Which of the following is the only sensation perceived by the brain from the pulp’s sensory nerves?
a. Taste
b. Pain
c. Pressure
d. Temperature

 

 

ANS:  B

The brain perceives all sensations directed to the pulp as sensations of pain. Therefore, changes in temperature, vibrations, and chemical changes that affect the pulp or dentin by way of the pulp’s nerves are perceived only as painful stimuli.

 

REF:   Chapter 13, Pulp Properties, Page 167

 

  1. During cavity preparation of a tooth, care must be taken to preserve the:
a. enamel rod fluid.
b. support of the dentinal tubules.
c. cemental vascularity.
d. vitality of the pulp.

 

 

ANS:  D

Dental professionals must do their utmost to prevent injury and preserve the vitality of the pulp during preventive and restorative procedures. Such iatrogenic injury to the pulp can result from the heat or vibrations emitted by dental handpiece during cavity preparation.

 

REF:   Chapter 13, Clinical Considerations for Pulp Pathology and Repair, Page 171

 

  1. Which of the following pulp structures is formed when Hertwig epithelial root sheath encounters a blood vessel?
a. Pulp horn
b. Pulp chamber
c. Apical foramen
d. Accessory canal

 

 

ANS:  D

Accessory canals form when Hertwig epithelial root sheath encounters a blood vessel during root formation. Root structure then forms around the blood vessel, forming the accessory canal. The coronal pulp is located in the crown of the tooth. Smaller extensions of coronal pulp into the cusps of posterior teeth form the pulp horns. The large mass of pulp is contained within the pulp chamber of the tooth. The apical foramen is the opening from the pulp into the surrounding periodontal ligament near each apex of the tooth.

 

REF:   Chapter 13, Pulp Anatomy, Page 168

 

  1. During tooth development, both the pulp and dentin in the mature tooth are products of the:
a. dental papilla.
b. enamel organ.
c. dental sac.
d. epithelium.

 

 

ANS:  A

Dentin and pulp tissue have similar embryologic backgrounds because both are originally derived from the dental papilla of the tooth germ during tooth development.

 

REF:   Chapter 13, Dentin Matrix Formation, Page 159

 

  1. Secondary dentin usually forms within the tooth:
a. after the completion of the apical foramen.
b. before the completion of the apical foramen.
c. nearest to the dentinoenamel junction.
d. in response to tooth trauma.

 

 

ANS:  A

Secondary dentin is formed after the completion of the apical foramen(s) and continues to form throughout the life of the tooth. Primary dentin is formed in a tooth before the completion of the apical foramen(s) of the root, which is the opening in the root’s pulp canal. Mantle dentin is the first predentin that forms near the dentinoenamel junction. Tertiary dentin forms quickly in localized regions in response to a localized tooth trauma to the exposed dentin.

 

REF:   Chapter 13, Dentin Types, Page 162

 

  1. Dentin in a mature tooth is on the average about ____% mineralized by weight.
a. 50
b. 65
c. 70
d. 96

 

 

ANS:  C

Mature dentin is by weight 70% inorganic material or mineralized. The alveolar process is by weight 50% inorganic material. Mature cementum is by weight 65% inorganic material. Mature enamel is by weight 96% inorganic material.

 

REF:   Chapter 13, Dentin Properties, Page 158

 

  1. Which of the following terms associated with dentin can be used to correctly describe the type that makes up the largest part of the tooth’s dentin?
a. Tomes granular layer
b. Mantle dentin
c. Circumpulpal dentin
d. Interglobular dentin

 

 

ANS:  C

Deep to the mantle dentin is the layer of dentin around the outer wall of pulp, the circumpulpal dentin, which makes up the bulk of the dentin in a tooth. Tomes granular layer is most often found in the peripheral part of dentin beneath the root’s cementum. Mantle dentin is the first predentin that forms near the dentinoenamel junction. Interglobular dentin is found in those areas where only primary mineralization has occurred within the predentin, and the globules of dentin do not fuse completely and appear as dark arclike areas in a stained section of dentin.

 

REF:   Chapter 13, Dentin Types, Page 162

 

  1. In which location is the cell body of the odontoblast found in a mature, healthy erupted tooth?
a. Along the dentinoenamel junction
b. Along the outer pulpal wall
c. Near the dentinocemental junction
d. Near the pulpal core

 

 

ANS:  B

The odontoblasts are located only along the outer pulpal wall. Only their cell bodies are located in the pulp.

 

REF:   Chapter 13, Pulp Histology, Page 168

 

  1. With increased age, the pulp tissue can become:
a. displaced by primary dentin.
b. increasingly fibrotic.
c. filled with cementicles.
d. increasingly cartilaginous.

 

 

ANS:  B

With increased age, the pulp undergoes a decrease in intercellular substance, water, and cells as it fills with an increased amount of collagen fibers and thus becomes fibrotic.

 

REF:   Chapter 13, Aging Pulp, Page 170

 

  1. Dentin in the mature tooth is produced as a result of secretion by:
a. cementoblasts.
b. fibroblasts.
c. osteoblasts.
d. odontoblasts.

 

 

ANS:  D

Apposition of dentin by odontoblasts, unlike enamel, occurs throughout the life of the tooth, filling in the pulp chamber of both the crown and root.

 

REF:   Chapter 13, Dentin Matrix Formation, Page 160

 

  1. Predentin is the initial material laid down by the:
a. odontoblasts.
b. ameloblasts.
c. preameloblasts.
d. odontoclasts.

 

 

ANS:  A

Predentin is a mesenchymal product consisting of nonmineralized collagen fibers produced by the odontoblasts. Ameloblasts form from preameloblasts and then later produce enamel. Odontoclasts are active during eruption, removing parts of the primary tooth.

 

REF:   Chapter 13, Dentin Matrix Formation, Page 159

 

  1. The dark, arclike areas in histologic sections of a tooth are what type of dentin?
a. Tomes granular layer
b. Mantle dentin
c. Circumpulpal dentin
d. Interglobular dentin

 

 

ANS:  D

The dark, arclike areas in a stained histologic section in a tooth are considered interglobular dentin. In these areas, only primary mineralization has occurred within the predentin, and the globules of dentin do not fuse completely. Tomes granular layer is most often found in the peripheral part of dentin beneath the root’s cementum. Mantle dentin is the first predentin that forms near the dentinoenamel junction. Deep to the mantle dentin is the layer of dentin around the outer wall of pulp, the circumpulpal dentin, which makes up the bulk of the dentin in a tooth.

 

REF:   Chapter 13, Dentin Matrix Maturation, Page 160

 

  1. Which of the following includes the tissue fluid surrounding the cell membrane of the odontoblast?
a. Lymph
b. Gingival crevicular fluid
c. Dentinal fluid
d. Synovial fluid

 

 

ANS:  C

The dentinal fluid in the tubule includes the tissue fluid surrounding the cell membrane of the odontoblast. The lymph is found within the lymphatic system. The gingival crevicular fluid is located within the gingival sulcus. The synovial fluid is found within the temporomandibular joint, surrounding the disc of the joint.

 

REF:   Chapter 13, Mature Dentin Components, Page 160

 

  1. Which of the following are a number of adjoining parallel imbrication lines that are present in stained dentin?
a. Lines of Retzius
b. Reversal lines
c. Arrest lines
d. Contour lines of Owen

 

 

ANS:  D

The contour lines of Owen are a number of adjoining parallel imbrication lines that are also present in a stained section of dentin. These specific imbrication lines demonstrate a disturbance in body metabolism that affects the odontoblasts by altering their formation efforts, and they tend to appear together as a series of dark bands. The lines of Retzius are incremental lines noted in stained enamel. Both reversal lines and arrest lines are stained lines noted in both cementum and repair due to repair and apposition of the hard tissue, respectively.

 

REF:   Chapter 13, Dentin Histology, Page 166

 

  1. Lateral pulp canals within the pulp chamber extend:
a. from pulp tissue to the periodontal ligament.
b. vertically toward the cementum.
c. between two pulp canals, as a bridge.
d. from the chamber, parallel to another canal.

 

 

ANS:  A

Accessory canals may also be associated with the pulp and are extra openings from the pulp to the periodontal ligament Accessory canals are also called lateral canals, because they are usually located on the lateral surface of the roots of the teeth, but this is not always the case because they can be found anywhere along the root surface.

 

REF:   Chapter 13, Pulp Anatomy, Page 168

 

  1. What are the smaller extensions of coronal pulp into the cusps of posterior teeth termed?
a. Accessory canals
b. Lateral canals
c. Pulp horns
d. Pulp canals

 

 

ANS:  C

The coronal pulp is located in the crown of the tooth. Smaller extensions of coronal pulp into the cusps of posterior teeth form the pulp horns. Accessory canals may also be associated with the pulp and are extra openings from the pulp to the periodontal ligament; accessory canals are also called lateral canals. The radicular pulp, or root pulp, is the part of the pulp located in the root of the tooth; it is also called the pulp canal by patients.

 

REF:   Chapter 13, Pulp Anatomy, Page 167

 

  1. Which is the most common type of nerves associated with the pulp in a mature erupted tooth?
a. Myelinated
b. Unmyelinated
c. Myelinated and unmyelinated are in equal numbers
d. Neither myelinated and unmyelinated nerves are found in pulp

 

 

ANS:  B

Two types of nerves are associated with the pulp, which includes mainly unmyelinated nerves (70% to 80%) and in lesser amounts, myelinated nerves (20% to 30%).

 

REF:   Chapter 13, Pulp Histology, Page 169

 

  1. Which of the following zones in pulp is closest to the dentin?
a. Odontoblastic layer
b. Cell-rich zone
c. Pulpal core
d. Cell-free zone

 

 

ANS:  A

The first zone of pulp closest to the dentin is the odontoblastic layer. The next zone, nearest to the odontoblastic layer, inward from the dentin, is considered the cell-free zone. The next zone, nearest to the odontoblastic layer, inward from the dentin, is considered the cell-free zone. The final zone of pulp is the pulpal core, which is in the center of the pulp chamber.

 

REF:   Chapter 13, Pulp Zones, Page 169

 

  1. Which zone in the pulp contains a nerve and capillary plexus?
a. Odontoblastic layer
b. Cell-rich zone
c. Pulpal core
d. Cell-free zone

 

 

ANS:  B

A nerve and capillary plexus are also located in the cell-free zone of the pulp. The odontoblastic zone consists of a layer of odontoblasts. The cell-rich zone has an increased density of cells compared with the cell-free zone but still does not contain as many cells as the odontoblastic layer. This zone also has a more extensive vascular supply than does the cell-free zone. The pulpal core, which is in the center of the pulp chamber, consists of many cells and an extensive vascular supply; except for its location, it is very similar to the cell-rich zone.

 

REF:   Chapter 13, Pulp Zones, Page 169

 

  1. Which of the following statements is correct when considering accessory canals?
a. Teeth have a standard number.
b. Radiographs always indicate the number and position.
c. Gingival recession may expose the opening.
d. They are examined by placement of radiolucent materials.

 

 

ANS:  C

Gingival recession may expose the opening of an accessory canal. Teeth have a variable number of these canals. Radiographs do not always indicate the number or position of these canals, unless they are examined with instruments using radiopaque materials.

 

REF:   Chapter 13, Pulp Anatomy, Page 168

 

  1. Which of the following is not associated with dentinal hypersensitivity?
a. Enamel and cementum do not meet
b. Dentin exposed due to caries process
c. Blocking dentinal tubules
d. Branching of dentinal tubules

 

 

ANS:  C

Dentinal hypersensitivity can be treated somewhat successfully with solutions applied either by professionals or within over-the-counter dentifrices available to patients; these desensitizing agents temporarily block the exposed open ends of the dentinal tubules. When dentin is exposed as a result of caries, the open dentinal tubules may be painful, causing dentinal hypersensitivity. However, many times it is the microscopic anatomy of the tooth that is the culprit; the enamel and cementum do not meet, leaving a gap with dentin exposed. Branching of the dentinal tubules containing the live odontoblastic processes throughout dentin adds to the overall level of exposure.

 

REF:   Chapter 13, Clinical Considerations for Dentin Pathology, Page 166

 

  1. The resorption process within the dentin can result in a clinically presentation of a:
a. silver-hued tooth.
b. pulp with stones.
c. pinkish crown color.
d. carious tooth.

 

 

ANS:  C

Dentin can become resorbed in permanent teeth, but the cause is idiopathic and can involve either an internal or external resorption process. It can be noted radiographically, but it is hard to discern between the two processes. In contrast, when the process begins on the external surface of the root and then penetrates through the cementum into dentin, it can lead to a pinkish crown color noted clinically from the granulation tissue seen beneath the translucent enamel.

 

REF:   Chapter 13, Clinical Considerations for Dentin Pathology, Page 162

 

  1. What type of dentin occurs when odontoblasts in the area of the traumatized tubules may perish because of the injury, but neighboring undifferentiated mesenchymal cells of the pulp can move to the area and become odontoblasts?
a. Reparative dentin
b. Reactive dentin
c. Sclerotic dentin
d. Mantle dentin

 

 

ANS:  A

Odontoblasts in the area of the traumatized tubules may perish because of the injury, but neighboring undifferentiated mesenchymal cells of the pulp can move to the area and become odontoblasts, forming a type of tertiary dentin, reparative dentin. If the tertiary dentin is formed by existing odontoblasts, it is considered to be reactive dentin. A certain type of tertiary dentin, sclerotic dentin occurs when the odontoblastic processes die and leave the dentinal tubules vacant. Mantle dentin is the first predentin that forms.

 

REF:   Chapter 13, Clinical Considerations for Dentin Pathology, Page 163

 

  1. In what direction do the imbrication lines of von Ebner run?
a. At 45 degrees to the dentinoenamel junction
b. At 90 degrees to the dentinal tubules
c. At 45 degrees to the inner pulpal wall
d. At 90 degrees to the periodontal ligament

 

 

ANS:  B

The imbrication lines of von Ebner are incremental lines or bands that stain darkly in a section of dentin. They run at 90 degrees to the dentinal tubules.

 

REF:   Chapter 13, Dentin Histology, Page 166

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