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
Section A:
ReplyDelete1. C
2. D
3. A
4. C
5. B
6. C
7. D
8. A
9. D
10. D
Part B:
ReplyDelete1. Fluoride interacts with enamel in various ways, depending on whether it occurs pre or post eruptively. During amelogenesis fluoride is absorbed by the tooth through systemic application, for example fluoridated water consumed by the mother or child. This water then is absorbed into the blood stream, which as the tooth is developing becomes a part of the crystal structure of enamel. Fluorapatite is made preferentially over hydroxyapatite as the fluoride ion is a more reactive element. The fluorapatite crystals are larger, causing there to be less intracellular space, therefore strengthening the tooth structure. The strengthened structure is now more resistant to demineralisation as fluorapatite has a lower critical pH of 4.5.
Post-eruptively fluoride interacts strongly through saliva. Saliva as we know is supersaturated with minerals, which covers the tooth surfaces. We also know that the remineralisation and demineralisation cycle occurs naturally and frequently. During the demineralisation phase, minerals are taken out of the enamel structure. If fluoride is present in the saliva (through fluoridated water) when remineralisation occurs, the fluoride ions will readily join the enamel structure, forming fluorapatite rather than hydroxyapatite. Another way in which fluoride can interact with the tooth is through its presence in fissure sealants, which causes fluoride to be given off into the tooth, strengthening it and reversing or preventing demineralisation.
2. The most external layer of enamel is known as aprismatic enamel. This means that the enamel is rodless or lacks in the uniform structure of enamel rods. This surface is commonly worn off over time; however it remains and is commonly found in the pits and fissures and also at the CEJ.
ReplyDeleteWhen placing a fissure sealant, in order for the sealant to adhere to the tooth, the surface area needs to be porous. This is not natural with aprismatic enamel. However, through the use of acid etch the layer of aprismatic enamel can be removed, exposing the uniform rod structure of enamel. The etch exposes the ends of the rods, allowing the surface area to be increased and increase in porosity. Therefore, as the etch has exposed the ends of the rods, the sealant can sink into the tops of the rods and successfully adhere to the tooth.
3. The pulp appears differently depending on the age of the patient, and is recognised through radiographs. As age increases, the size of the pulp decreases, due to fewer cells being present and secondary dentine being layed down through out life.
ReplyDeleteIn relation to caries, an older patient, therefore having a small pulp cavity, would most likely not notice the disease until it cavitated. This is due to the pulp being smaller, and having fewer cells within it. In comparison, a child with caries in the deciduous dentition would experience pain immediately as the caries process began. This is because the pulp cavities are much larger and the pulp horns reach higher up occlusally.
4. a. This patient has caused abrasion to occur on their teeth. Due to having worn away some enamel, the underlying dentine could have been exposed. Dentine is less mineralised and a vital tissue. Thus the patient may experience sensitivity on the buccal surfaces on these teeth.
ReplyDeleteb. This patient would be at an increased risk of caries as dentine is less calcified. Due to being only 70% calcified in comparison to 96% (enamel) caries will spread more readily through dentine than enamel.
5. a. Enamel and dentine are both calcified tissues within the oral cavity; however they appear to be different shades of radiopaque. This is due to their level of mineralisation. Enamel is 96% mineralised, whereas dentine is 70% mineralised. As enamel is more highly calcified, it appears whiter, hence more radiopaque. Caries is a disease in which demineralisation of the hard tissues occurs, therefore removing the amount of minerals within the tissue. As there has been a loss of mineral, the tissue appears radiolucent. In order for caries to show up radiographically, approximately 30% of the minerals must be lost. In this case, this is why the caries in dentine can be significantly recognised, however the caries within the enamel cannot be as clearly identified.
ReplyDeleteThe caries follows the path of the enamel rods, hence the directly vertical line towards the dentine. It also follows the dental tubules, which travel towards the pulp wall, therefore causing the disease to appear slightly triangular in shape.
5. b. Ivor would be experiencing pain from the tooth because the dentine is a vital tissue. Due to the infection of the tissue (a stimulus for example air, food or water), the water within the tubules would experience a change in pressure, moving towards the odontoblast heads along the pulp wall. This would then send a message to the pulp to send a stimulus to the brain in order to recognise pain.
ReplyDeletec. The pulp is lined with odontoblasts and undifferentiated cells. As a defence mechanism for protection, the pulp can stimulate the undifferentiated cells to become odontoblasts and hence produce dentine. As this dentine is in response to trauma, it is defined as tertiary dentine. This form of dentine is not structured uniformly as it is secreted rapidly to protect the pulp.
8. a. When recording the clinical appearance of gingival the three Cs should be recorded. 1. Colour 2. Contrast and 3. Contour
ReplyDeleteHealthy gingiva would appear a light coral pink colour, with stippling. It would also include knife edged papillae and not appear bulbous.
b. Stippling is a strong and reliable indicator for gingival health. The appearance of stippling is caused by Rete ridges within the basement membrane of the oral mucosa. Rete ridges are ridges which appear clinically as stippling. However, if the gingival tissue is unhealthy and thus inflamed the Rete ridges will disappear, therefore causing stippling to no longer be visible. In inflammation, the reticular layer of connective tissue experiences an influx of inflammatory cells and blood in response to infection. This influx causes the reticular layer to become level with the basal layer, therefore flattening out the Rete ridges.
c. Recession can be caused by many sources, however the most common of which is tooth brushes. Tooth brushing can be performed incorrectly through inaccurate technique and also pressure. The premolar and canine area is a difficult area to clean successfully with a toothbrush and it is commonly where the arch curves. Furthermore, the alveolar bone is thinnest at this area, causing recession to be common.
This recession could also be due to the patient having a thin gingival biotype. This therefore makes them more prone to recession as the gingiva in thinner.
The answers to q 3 and 6 in the MCQ need to be reviewed - remember that dentine is a form of connective tissue (and enamel is epithelial), so they come from different embryonic tissues.
ReplyDeleteThe short/extended answer questions have been very well completed.
ok thanks ill check those questions :)
ReplyDeleteFrom the multiple choice is question 3 supposed to be d, because pulp and dentine are forms of connective tissue, whereas enamel is epithelial tissue?
ReplyDeleteand question 6 is the answer d on the outise of the pulp wall?
Hey Veronica, I had the same answers as you for the multiple choice. I had 3 as D because dentine and pulp are forms of connective tissue. I also had D for question 6 as well. :)
Deleteawesome :) thanks
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DeleteVanessa, are you still having issues posting?
ReplyDeleteSophie
hi do you have any other resources for oral histology and embriology it covers odontogenesis, amelogenesis, dentinogenesis and pulp, oral mucosa and salivary glands.
ReplyDeletethanks heaps for posting these questions btw