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WorksheetsBiological Apatite and Pulp
Total questions: 15
Worksheet time: 8mins
Enamel contains the largest and most crystalline apatite crystals compared to dentine and bone.
True
False
Fluoride strengthens the apatite crystal by:
Increasing the size of the unit cell
Replacing Ca²⁺ in the lattice
Replacing OH⁻ along the c-axis, making the lattice more compact
Increasing carbonate substitution
Which of the following BEST explains why biological apatite has a Ca:P ratio lower than 1.67?
It contains pure hydroxyapatite only
It contains only fluorapatite
It undergoes ion substitutions such as carbonate replacing phosphate
It has no surface ions adsorbed
Which statement BEST explains why dentine is more flexible than enamel?
Dentine crystals contain no carbonate
Dentine crystals are arranged in rods
Dentine crystals are larger and more perfect
Dentine crystals are smaller and arranged along collagen fibres
Which statement BEST describes the arrangement of ions in the small hexagonal cylinder of apatite?
Ca²⁺ ions form a square with OH⁻ in the centre
Ca²⁺ ions form equilateral triangles with OH⁻ or F⁻ along the c-axis
PO₄³⁻ ions form a hexagon around central Ca²⁺
Fluoride is located only at the corners of the small hexagon
Which tissue contains the highest carbonate content in its biological apatite?
Enamel
Dentine
Cementum
Bone
Which factor does NOT contribute to variation in the Ca:P ratio of biological apatite?
Presence of octacalcium phosphate
Ionic substitution
Ion adsorption on crystal surfaces
Increased crystal thickness
Which of the following is TRUE regarding ACP?
It is more stable than hydroxyapatite
It contains 0–5% water
It crystallises into hydroxyapatite over time
Its Ca:P ratio is always exactly 1.67
Which of the following is NOT a function of dental pulp?
Nutritive
Sensory
Protective
Keratinisation of enamel surface
The cell-rich zone of Weil contains a dense network of nerves and capillaries.
True
False
Which nerve fibres are primarily responsible for sharp, well-localised pain in the pulp?
C-fibres
A-delta fibres
Parasympathetic fibres
A-beta fibres
Which immune cell is MOST commonly found in healthy pulp tissue?
Neutrophils
Fibroblasts
Macrophages
Langerhans cells
The cell-free zone of Weil is characterised by:
Many odontoblasts arranged in a columnar layer
Large number of fibroblasts and immune cells
Nerve plexus and capillary network beneath odontoblasts
High density of collagen type I fibres
Pulp stones are:
Always pathological and require removal
Calcified masses found inside the pulp chamber
Commonly found only in primary teeth
Made entirely of enamel
Most pulpal nerve fibres enter through:
Coronal pulp
Lateral canals
Apical foramen
Dentin-enamel junction
