Exam 4 (13, 14)

Question 1

The most common cell type in connective tissue such as pulp is the:

a. endothelial cell.
b. fibroblast.
c. white blood cell.
d. odontoblast.

Answer 1

b. fibroblast.

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.

Question 2

Which of the following is the only sensation perceived by the brain from the pulp’s sensory nerves?

a. taste
b. pain
c. temperature
d. pressure

Answer 2

b. pain

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.

Question 3

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.

Answer 3

d. vitality of the pulp.

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.

Question 4

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

Answer 4

d. accessory canal

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.

Question 5

During tooth development, both the pulp and the dentin in the mature tooth are products of the:

a. dental papilla.
b. enamel organ.
c. dental sac.
d. epithelium.

Answer 5

a. dental papilla.

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

Question 6

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.

Answer 6

a. after the completion of the apical foramen.

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.

Question 7

Dentin in a mature tooth is on the average about ______ mineralized by weight.

a. 50%
b. 65%
c. 70%
d. 96%

Answer 7

c. 70%

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.

Question 8

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

Answer 8

c. circumpulpal dentin

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.

Question 9

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

Answer 9

b. along the outer pulpal wall

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

Question 10

With increased age, the pulp tissue can become:

a. displaced by primary dentin.
b. increasingly fibrotic.
c. filled with cementicles.
d. increasingly cartilaginous.

Answer 10

b. increasingly fibrotic.

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.

Question 11

Predentin is the initial material laid down by the:

a. odontoblasts.
b. ameloblasts.
c. preameloblasts.
d. odontoclasts.

Answer 11

a. odontoblasts.

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.

Question 12

The dark, arc-like 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

Answer 12

d. interglobular dentin

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.

Question 13

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

Answer 13

c. dentinal fluid

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.

Question 14

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

Answer 14

d. contour lines of Owen

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.

Question 15

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.

Answer 15

a. from pulp tissue to the periodontal ligament.

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.

Question 16

Dentin in the mature tooth is produced as a result of secretion by:

a. cementoblasts.
b. fibroblasts.
c. osteoblasts.
d. odontoblasts.

Answer 16

d. odontoblasts

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.

Question 17

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

Answer 17

c. pulp horns

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.

Question 18

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. dead ones

Answer 18

b. unmyelinated

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%).

Question 19

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

Answer 19

a. odontoblastic layer

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.

Question 20

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

Answer 20

b. cell-rich zone

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.

Question 21

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 placing radiolucent materials.

Answer 21

c. Gingival recession may expose the opening.

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.

Question 22

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

Answer 22

c. blocking dentinal tubules

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.

Question 23

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

Answer 23

c. pinkish crown color

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.

Question 24

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

Answer 24

a. reparative dentin

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.

Question 25

In what direction do the imbrication lines of von Ebner run? a. at 45 degrees to the DEJ 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

Answer 25

b. at 90 degrees to the dentinal tubules 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.

Question 26

Sharpey's fibers are located in which of the following types of dental tissue? a. enamel b. dentin c. cementum d. pulp

Answer 26

**cementum** Sharpey fibers are a part of the collagen fibers from the periodontal ligament that are each partially inserted into the outer part of the cementum at 90 degrees or perpendicular to the cemental surface (as well as the alveolar process on their other end) as they are inserted on the other end, the alveolar process.

Question 27

which of the following types of dental tissue provides the vascular nutrition for the tooth's cementum? a. dentin b. epithelial cells c. periodontal ligament d. alveolar process

Answer 27

c. periodontal ligament The canals of the cementocytes are oriented toward the periodontal ligament and contain cementocytic processes that exist to diffuse nutrients from the ligament because it is vascularized.

Question 28

which of the following terms correctly describes the alveolar bone proper? a. lamina propria b. cancellous bone c. mucoperiosteum d. cribriform plate

Answer 28

d. cribriform plate * The alveolar bone proper makes up the lining of the tooth socket or alveolus. Although the alveolar bone proper is composed of compact bone, it may be called the cribriform plate because it contains numerous holes where Volkmann canals with their nerves and blood vessels pass from the alveolar process into the periodontal ligament. The lamina propria is the connective tissue component of the oral mucosa. A mucoperiosteum is a combined structure consisting of a mucous membrane, in the case of the oral cavity, the epithelium and lamina propria of the oral mucosa, with the periosteum of bone. The trabecular bone consists of cancellous bone or spongy bone that is located between the alveolar bone proper and the plates of cortical bone.*

Question 29

the rests of Malassez are correctly described as: a. remnants of the outer enamel epithelium b. similar to incremental growth limes in dentin c. remnants of Hertwig root sheath d. similar to the incremental growth lines in enamel

Answer 29

c. remnants of Hertwig sheath The epithelial rests of Malassez, which represent groups of epithelial cells, are stranded in mature periodontal ligament after the disintegration of Hertwig epithelial root sheath during the formation of the root.

Question 30

on radiographs, the periodontal ligament appears as a: a. radiopaque line covering the alveolar bone proper b. lamina dura surrounding the alveolus c. radiolucent space surrounding the alveolus d. spongy material between the alveolus and alveolar bone peoper

Answer 30

c.radiolucent space surrounding the alveolus The periodontal ligament appears on radiographs as a radiolucent area (or darker) located between the denser radiopaque (or lighter) lamina dura of the alveolar bone proper and the similar radiopaque (or lighter) cementum.

Question 31

which of the following situations can be present at the cementoenamel junction in a mature tooth? a. cementum overlaps enamel b. enamel overlaps cementum c. dentin overlaps enamel d. pulp overlaps cementum or dentin

Answer 31

a. cementum overlaps enamel Three possible types of transitional interfaces may be present at the cementoenamel junction. The cementum may overlap the enamel at the cementoenamel junction. The cementum and enamel may meet end to end, presenting no problems for either the clinician or patient. Another possible interface at the cementoenamel junction is that a gap may exist between the cementum and enamel, exposing dentin.

Question 32

which of the following fiber groups is a part of the alveodental ligament on a single- rooted adult tooth? a. circular ligamnet b. interdental ligament gingival fiber group d. apical group

Answer 32

d. apical group The main principal fiber group is the alveolodental ligament, which consists of five fiber subgroups: alveolar crest, horizontal, oblique, apical, and interradicular on multirooted teeth. The circular ligament is part of the gingival fiber groups and some consider these ligaments as a group to be part of the principal fibers but separate from the alveodental ligament. Another principal fiber other than the alveolodental ligament is the interdental ligament.

Question 33

which of the following statements concerning the oblique group of the periodontal ligament is correct? a. part of the gingival fiber group b. found only in multi-rooted teeth c. resists intrusive forces to the tooth d. resists tilting forces to the tooth

Answer 33

c. resists intrusive forces to the tooth The function of the oblique group as part of the alveodental ligament of the periodontal ligament is to resist intrusive forces, which try to push the tooth inward, as well as rotational forces; it is found on both single and multirooted teeth.

Question 34

which part of both of the jaws contains cancellous bone? a. alveolar bone proper b. cortical bone c. interdental septum d. alveolar crest

Answer 34

c. interdental septum The interdental septum consists of both the compact bone of the alveolar bone proper and cancellous bone of the trabecular bone. The alveolar bone proper is composed of compact bone. The cortical bone consists of a plate of compact bone on both the facial and lingual surfaces of the alveolar process. The alveolar crest is the most cervical rim of the alveolar bone proper.

Question 35

the most common type of connective tissue fiber in the periodontal ligament is which of the following fiber groups? a. collagen b. elastic c. oxytalan d. collagen and elastic fibers

Answer 35

a. collagen All the fibers in the periodontal ligament are collagen in structure.

Question 36

which of these fiber groups does not have any cemental insertion? a. interdental ligament b. circular ligament c. alveodental ligament d. Interradicular group

Answer 36

b. circular ligament The circular ligament encircles the tooth, as shown on a cross section of a tooth, interlacing with the other gingival fiber subgroups. Thus, it has no cemental insertion. The interdental ligament and alveodental ligament, which the interradicular group is part of on multirooted teeth, both have cemental insertions.

Question 37

the periodontal ligament directly forms from which part of the developing tooth germ? a. enamel organ b. dental papilla c. dental sac d. both enamel organ and dental papilla

Answer 37

c. dental sac Similar to the alveolar process, the periodontal ligament develops from the dental sac of the tooth germ. The enamel organ gives rise to the enamel and the dental papilla gives rise to the dentin and pulp of the tooth.

Question 38

the cementoblasts originate during tooth development from which of the following embryonic structures? a. enamel organ b. dental papilla c. dental sac d. both enamel organ and dental papilla

Answer 38

c. dental sac Cementum and its cells, the cementoblasts, develop from the dental sac and form on the root after the disintegration of Hertwig epithelial root sheath. The dental papilla gives rise to the dentin and its odontoblasts as well as the pulp and its fibroblasts. The enamel organ gives rise to the enamel and its ameloblasts.

Question 39

the alveolar bone proper of the jaws in a mature adult refers to the: a. cancellous bone between the alveoli b. layer of compact bone lining the alveolus c. part of the jaw that houses the teeth d. done surrounding the lamina dura

Answer 39

b. layer of compact bone lining the alveolus The alveolar bone proper of the jaws makes up the lining of the tooth socket or alveolus, which is also considered to be the lamina dura on radiographs. The part of the jaws that contains the roots of the teeth is the alveolar process or alveolar bone. The supporting alveolar bone consists of both cortical bone and trabecular bone. The cortical bone consists of a plate of compact bone on both the facial and lingual surfaces of the alveolar process. The trabecular bone consists of cancellous bone that is located between the alveolar bone proper and the plates of cortical bone.

Question 40

which of the following structures is not considered part of the periodontium? a. alveolar process b. cementum c. basal bone d. periodontal ligament

Answer 40

c. basal bone The part apical to the roots of the teeth is the basal bone, which then forms the body of the maxilla or body of the mandible and thus is not considered part of the periodontium. The alveolar process, cementum, and periodontal ligament are all parts of the periodontium.

Question 41

which of the following tisssue types is most likely to source of cementogenic cells in adults who have undergone root planning? a. bone marrow b. periodontal ligament c. residual cementum patches d. alveolar process

Answer 41

b. periodontal ligament The periodontal ligament has a line of cementoblasts along the cemental surface of the root that can produce cementum throughout the lifetime of the tooth.

Question 42

which of the following fiber groups of the periodontal ligament foes not contribute significantly to each tooth's anchorage in the jaw? a. gingival fiber group b. interdental fiber group c. alveodental fiber group d. interradicular fiber group

Answer 42

a. gingival fiber group The gingival fiber group does not support the tooth in relationship to the jaws, resisting any forces of mastication or speech; rather, this group supports only the marginal gingiva to maintain the relationship to the tooth. Instead, the interdental and alveodental, which the interradicular fiber group is part of, supports the tooth in relationship to the jaws.

Question 43

which of the following is not a part of the gingival fiber group? a. interdental fiber group b. circular fiber group c. dentoperiosteal fiber group d. alveologingival fiber group

Answer 43

a. interdental fiber group Another principal fiber other than the alveolodental ligament is the interdental ligament. The gingival fiber group includes the fiber subgroups of the circular and dentogingival ligament, as well as both the alveologingival and dentoperiosteal ligaments.

Question 44

the anchorage of the tooth to the alveolar process is mediated through which of the following? a. interdental ligament b. sharpey fibers c. oxytalan fibers d. both sharpey and oxytalan fibers

Answer 44

b. sharpey fibers Sharpey fibers in alveolar bone proper are each inserted at 90 degrees or perpendicular to the bone to mediate the anchorage of the tooth. A principal fiber of the periodontal ligament is the interdental ligament. Oxytalan fibers are a fiber type related to elastic fibers; they appear to consist of the microfibrillar component only, thereby resembling very immature elastic fibers.

Question 45

cellular cementum is most likely found around which of the following root regions? a. cervical part of the root b. entire root of an unerupted tooth c. apical part of the root d. furcation region of the root

Answer 45

c. apical part of the root Cellular cementum consists of the last layers of cementum deposited over the acellular cementum, mainly in the apical one third of each root. At least one layer of acellular cementum covers the entire outer surface of each root with many more layers covering the cervical one third near the cementoenamel junction.

Question 46

the lamina dura noted on radiographs corresponds to which of the following structures? a. basal bone of the both jaws b. buccal and lingual cortical plates of the jaws c. supporting cancellous bone between the teeth d. alveolar bone proper of the alveolar process

Answer 46

d. alveolar bone proper of the alveolar process The part of the alveolar bone proper of the alveolar process that is present on radiographs is considered the lamina dura, which is uniformly radiopaque (or lighter).

Question 47

which of the following includes both the supporting soft and hard dental tissue between and including parts of the tooth and surrounding bone? a. periodontal ligament b. periodontium c. alveolar bone proper d. alveolar process

Answer 47

b. periodontium The periodontium consists of both the supporting soft and hard dental tissue between the tooth and the alveolar process, as well as parts of the tooth and alveolar process. Thus, the periodontium includes the periodontal ligament as well as the alveolar process, which includes the alveolar bone proper.

Question 48

when many of the cementoblasts become entrapped by the cementum they produce, they become: a. odontoclasts b. odontoblasts c. cementocytes d. dental sac cells

Answer 48

c. cementocytes During the later steps within the stage of apposition of cementum, many of the cementoblasts become entrapped by the cementum they produce, becoming cementocytes. After the appositional growth of cementum in layers, the cementoblasts that do not become entrapped in cementum line up along the cemental surface along the length of the outer covering of the periodontal ligament. When the undifferentiated cells of the dental sac come into contact with the newly formed surface of root dentin, these cells are induced to become cementoblasts. Odontoblasts are cells that produce dentin. Odontoclasts resorb dentin, cementum, and enamel during tooth shedding and eruption.

Question 49

the alveolar process between two neighboring teeth is specifically called the _____ bone a. interdental b. basal c. interradicular d. trabecular

Answer 49

a. interdental The alveolar process that separates two neighboring teeth is the interdental septum or interdental bone. The part apical to the roots of the teeth is the basal bone, which then forms the body of the maxilla or body of the mandible. The alveolar process that separates the roots of the same tooth is the interradicular septum or interradicular bone. The trabecular bone consists of cancellous bone that is located between the alveolar bone proper and the plates of cortical bone.

Question 50

the most common cell in the periodontal ligament is the: a. cementoblast b. fibroblast c. odontoclast d. osteoclast

Answer 50

b. fibroblast Like all connective tissue, the fibroblast is the most common cell in the periodontal ligament, producing fibers and intercellular substance. The cementoblast and odontoclast as well as the osteoclast are present in the periodontal ligament. The cementoblast produces cementum and the odontoclast resorbs parts of the tooth during tooth shedding and eruption. The osteoclast resorbs the alveolar process.

Question 51

with occlusal trauma, there can be a widening of the: a. periodontal space b. periodontal ligament c. lamina dura d. periodontal space, periodontal ligament, and lamina dura

Answer 51

d. periodontal space, periodontal ligament, and lamina dura Early occlusal trauma can be viewed on radiographs as a widening of the radiolucent (or darker) periodontal ligament space between the radiopaque (or lighter) lamina dura of the alveolar bone proper and the similar radiopaque (or lighter) cementum. Because the periodontal space represents the periodontal ligament, the ligament can double and the individual principal fiber bundles also become thicker. Thickening of the lamina dura, which represents the alveolar bone proper, is also possible with occlusal trauma in response to overall alveolar process loss.

Question 52

which part of the periodontal ligament is noted to be wider in a healthy adult tooth? a. near the apex b. near the cervix c. both near the apex and cervix d. between the apex and cervix

Answer 52

c. both near the apex and cervix The periodontal ligament is wider near the apex and cervix of the tooth and narrower between these two end points.

Question 53

in which part of the alveolar process is the loss of bone from periodontitis first evident? a. interradicular bone b. basal bone c. supporting alveolar bone d. alveolar crest

Answer 53

d alveolar crest The bone loss from periodontitis is first evident in the most coronal part of the alveolar bone proper, the alveolar crest, which looks moth eaten both microscopically and radiographically. The alveolar process loss of the jaws, which involves the presence of the roots of the teeth, progresses apically to involve the interradicular bone if the tooth is multirooted, as well as the surrounding supporting alveolar bone, but does not involve the inferior bone of the jaws, the basal bone.

Question 54

which of the following is not bisible at least somewhat on bitewing radiographs? a. periodontal space b. lamina dura c. cortical bone d. trabecular bone

Answer 54

c. cortical bone The cortical bone is not visible on periapical or bitewing radiographs but only on occlusal radiographs as a uniformly radiopaque (or lighter) bony sheet, facial and lingual to the teeth. The periodontal space and lamina dura are both present somewhat. Only the parts of trabecular bone between the teeth and between the roots are ever present on any type of radiograph.

Question 55

which type of bone is only present in an area of anodontia? a. cortical bone b. basal bone c. alveolar bone proper d. trabecular bone

Answer 55

b. basal bone The developmental dental anomaly of anodontia, in which tooth germs are congenitally absent, may affect the development of the alveolar process of either jaw. Proper development is impossible because the alveolar unit of each dental arch only forms in response to the tooth germs in the area. Only basal bone will be present in each one of the involved areas of the jaws. The alveolar process, which includes the alveolar bone proper and the supporting alveolar bone, the latter of which consists of the cortical bone and trabecular bone, will not have developed due to the anodontia.