PRACTICE EXAM PAPER - ORAL HISTOLOGY

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?










b. 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

APPLIED ORAL HISTOLOGY CASE STUDIES FROM 1/6/11

CASE ONE

Ivor Payne has come into the surgery with a toothache in his lower left quadrant. Clinically only a small break in the enamel through an occlusal pit of 36 can be detected. A bitewing radiograph of the area shows occlusal caries well established into dentine of the 36.


Discuss the histological properties of enamel and dentine that explain how the caries appears radiographically.

Why would the patient be experiencing pain from the tooth?

What mechanisms can the pulp initiate to protect itself from the bacterial invasion?

CASE TWO
You are seeing 8-year-old Hannah Fisher who requires a fissures sealant on the occlusal surfaces of her 46. As part of the procedure you apply 37% phosphoric acid etch to the areas to be sealed


Discuss the histological basis for the above procedure and how it contributes to clinical practice.


CASE THREE
Seven year old Becky is going to the movies with her 70 year old grandmother. As a treat Granny buys them both an ice cream. Becky bites into her treat with relish and winces with ‘pain’. Granny is surprised by this as she felt no sensitivity when she bit into her ice cream at the same time.

Explain why both these reactions could be considered ‘normal’.


CASE FOUR

You are treating a carious lower molar on a 10 year old patient. The cavity prep is quite deep and extends 3mms into the dentine. Explain the histological reasons why you should place a lining material before restoring the tooth.

CASE FIVE

You are doing your Masters in Oral Health after graduating dux of your year in the BOH. Your research is based around the structure of dentine and you are giving a tute to 1st year BOH students, using the above micrograph, to demonstrate and discuss the following components of the tissue:
· Peritubular dentine
· Intertubular dentine
· Odontoblastic processes
· Dentinal tubules.

Label all these features on the micrograph and discuss their structure and function.

CASE SIX

Sixty year old Charles Long visits you for a hygiene appointment. He describes himself as ‘long in the tooth’ in more ways than way. After you look in his mouth, you are inclined to agree!


Describe the histological implications of what has occurred here, and the oral health problems that Charles is at ‘high risk’ for.