revision pkp

Question 1

1. During root development Hertwig Epithelial Root -a.Sheath is entirely composed of:
   b. enamel organ and dental follicle
   c. enamel organ and dental papilla
   d. inner and outer cells of dental papilla

Answer 1

inner and external enamel epithelium

Question 2

2. If a tooth has two roots, how many horizontal epithelial extensions will be involved in its root formation?

Answer 2

two, one extension from left, one from right then they fuse

Question 3

3. Virulence factors are genetically controlled characteristics, that increase the ability of a pathogen to cause disease.

Answer 3

The presence of pili that permit the attachment of a bacterium to host tissues.
The production of a slimy mucus which covers the biofilm.
The production of bacterial endotoxin.
The synthesis of enzyme permitting the spread of the organism through host tissues.

Question 4

4. Which structure does not have minor salivary glands?

Answer 4

Anterior hard palate

Question 5

5. Which salivary gland produces the most unstimulated flow of saliva? *

Answer 5

submandibular

Question 6

During the late bell stage of tooth development, the
first sign of mineralisation is seen occuring in the dental tissues. Compare the mineralisation process of enamel to dentine

Answer 6

(i) Mineralisation of enamel involves non-collagenous protein matrix while that of dentine involves collagenous proteins. (ii) Enamel matrix is secreted to form a framework of the enamel and it is ~30% mineralised. During maturation it becomes 97% mineralised as calcium and phosphate replaces the organic component to form hydroxyapatite (HA). Mineralisation of dentine occurred when minerals gets incorporated into the dentinal matrix in alternate organic and inorganic phases. When matured, dentine is ~70% mineralised.

Question 7

Is the mineralisation of dentine similar to those of

cementum and alveolar bone?

Answer 7

Dentine, cementum, alveolar bone are connective tissues. It involves calcification dentinal matrix, cementum matrix/cementoid and bone matrix/osteoid

Question 8

In addition to calcium and phosphate, name ONE other micronutrient which when deficient, may impair the development of dentine, cementum and alveolar bone. Briefly explain your answer

Answer 8

Vit C - collagen is the main organic component of connective tissues. Deficiency of vit C leads to formation of weak/unstable collagen structure, hence impaired development of dentine, cementum, alveolar bone.

Question 9

Based on tissue hardness and compositions, describe

the functional significance of the enamel, dentine, cementum and alveolar bone.

Answer 9

Enamel is very hard at 97% mineralised with major inorganic component, which makes it brittle. Dentine still has ~27% organic component and ~70% mineralised. Its collagenous component gives it tensile strength. Cementum and alveolar bone are slightly less mineralised than dentine with more organic component. Thus, the forces of mastication on enamel is cushioned by the tensile dentine, received by the cementum and dissipated to the alveolar bone via the PDL.