Practice exam for Oral Histology

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SECTION A

MULTIPLE CHOICE QUESTIONS – circle the correct answer in this test booklet.

1. Enamel is formed by which type of cell?

A) Odontoblasts
B) Enameloblasts
C) Ameloblasts
D) Fibroblasts

2. Enamel is usually % mineralised by weight:

A) 50
B) 65
C) 70
D) 96

3. Which of the following dental tissues are derived from the same embryonic source?

A) Enamel and dentine
B) Enamel and pulp
C) Enamel, dentine and pulp
D) Dentine and pulp

4. The peritubular dentine found surrounding each tubule is:

A) not true dentine
B) less calcified than intertubular dentine
C) more calcified than intertubular dentine
D) not different from intertubular dentine

5. In a healthy, mature tooth where is the location of the cell body of an odontoblast?

A) at the dentino-enamel junction
B) in the outer wall of the pulp
C) in the centre of the dentinal tubules
D) within the pulpal core

6. Secondary dentine forms:

A) before the completion of the apical foramen
B) in response to trauma
C) at the dentino-enamel junction
D) on the outside wall of the pulp

7. Enamel rods are longest:
(i) cusps tips
(ii) at the CEJ
(iii) incisal edges
(iv) at the bottom of fissures

A) i and ii
B) i and iv
C) ii and iii
D) i and iii


8. Incremental lines within the enamel that appear to transverse the rods are known as:

A) Lines of Retzius
B) Imbrication lines of Von Ebner
C) Enamel spindles
D) Perikymata


9. Which of the following properties is NOT characteristic of enamel?

A) Dynamic tissue
B) Highly mineralised
C) Nonvital
D) Highly vascular


10. Partially calcified enamel faults, which often extend from the DEJ to the outer surface, are known as:

A) Enamel tufts
B) Gnarled enamel
C) Enamel spindles
D) Enamel lamellae

PART B Short Answer Questions

1. Describe how fluoride interacts with enamel during amelogenesis and post-eruptively (5 marks)

2. You are placing a fissure sealant in a molar tooth. A step in the process is applying an acid etching solution to the enamel area to be sealed. Describe how the histology of enamel tissues enables the sealant to adhere to the tooth using the acid etch technique
(8 marks)



3. Describe the age changes that occur in the dental pulp? How do these changes affect the response of the dental pulp to an injury such as dental caries? (6 marks)

4. You are examining a patient and note that due to using a hard toothbrush and a vigorous action, they have worn away some of the enamel on the buccal surfaces of their molars.
4a What symptoms may these patients be experiencing and explain why?
(3 marks

4b What would this patient be at higher risk for on these affected surfaces? Give reasons for your answer.
(2 marks)
5. Ivor Payne has come into the surgery with a toothache in his upper left quadrant. Clinically only a small break in the enamel through an occlusal pit of 26 can be detected.

A bitewing radiograph of the area shows occlusal caries well established into dentine of the 26
5a Discuss the histological properties of enamel and dentine that explain why the caries appears radiographically.
(6 marks)
5b Why would Ivor be experiencing pain from the tooth?
(4 marks)
5c What mechanisms can the pulp initiate to protect itself from the bacterial invasion?
(3 marks)

6. The following diagram shows the developing dentine and enamel tissues during the apposition stage of tooth development.
Developing enamel
Diagram from Bath-Balogh M and Fehrenbach MJ (2006) Illustrated Dental Embryology, Histology and Anatomy, 2nd edition, Elsevier Saunders: St Louis
Developing dentine


6a Label the diagram where indicated. Then in the space below, discuss the purpose of each labelled feature (9 marks)

6b Describe what occurs to the ameloblasts and odontoblasts after formation of their relevant dental tissues, and what implications this has for the tooth.
(4 marks)
7. The junctional epithelium (JE) is considered to be the first line of defence that protects the underlying connective tissue from onslaught from bacterial toxins. How does the JE performs this function from a histological perspective.
(5 marks)

8. During a clinic session a patient presents with clinically healthy gingival tissues. (6 marks)

a. Describe how you would record the appearance of healthy gingival tissues on your examination sheet?
The presence of stippling is one indicator of gingival health. Explain what causes stippling on a histological level.
c. You notice that in one area, around the 34, there is an isolated area of 4-5 mm of recession. Outline any possible cause/s of this isolated case.


9. Explain how the periodontal ligament performs the following functions:
(7 marks)
Formative/regenerative
Nutritive
Sensory
Adaptive
Supportive

10. What radiographic indications could give you evidence of a healthy attachment apparatus? (4 marks)






11. Draw a series of clearly labelled diagrams to represent a tooth and its supporting structures. The following must be included: (pencil can be used to answer this question) (18 marks)

Enamel Alveolar crest
Dentine CEJ
Cementum Apex
Junctional epithelium Lamina dura
Sulcular epithelium Free gingiva
Gingival margin Attached gingiva
Mucogingival junction Alveolar mucosa
Free gingival groove Gingival col area