Dental plaque and Biofilms (6) Flashcards
What is calculus?
mineralised plaque
Calcified or calcifying deposits attached to the surfaces of teeth or other solid structures in the mouth e.g. dentures
What always precedes calculus?
plaque
What are the 2 types of calculus?
Supragingival (saliva)
Subgingival (GCF)
Describe calculus formation?
Plaque deposits become the organic matrix for the subsequent mineralisation of the deposit
Small crystals appear in the intermicrobial matrix; the matrix calcifies and then the bacteria become mineralised
Mineralisation requires nucleation of crystal seeds and then crystal growth
What are the 4 crystal types of of calcium phosphate?
Octacalcium phosphate
Hydroxyapatite
Whitlockite
Brushite
Where would you find supragingival calculus?
Adjacent to the opening of salivary ducts:
Parotid
Sublingual
Where would you find subgingival calculus?
No predilection for certain parts of the mouth
Approximal and lingual parts affected more than buccal
What does subgingival plaque appear like?
Creamy-white colour Stained in smokers
Is this sub or supragingival plaque?
supragingival
Is this sub or supragingival calculus?
subgingival
What does subgingival plaque appear as?
Brownish-black due to haemorrhagic elements from GCF and black pigments from anaerobic rods
How do you detect supragingival plaque?
*Visible clinically
*Detection may be enhanced by air drying – gives a chalky appearance
How would you detect subgingival calculus?
By probing:
Tactile sensation enhanced with the use of a ball ended probe
If located at the entrance of a pocket:
-May be seen as a dark shadow under the gingival margin
-Air-jet from the 3-in-1 syringe may retract the gingivae to provide direct vision
-Following gingival recession subgingival deposits may become supragingival
-Radiopaque calculus wings may be visible on approximal wings on bitewing radiographs
How does supragingival plaque form?
- Nucleation, crystal growth and calcification are heterogeneous (non-uniform)
- Deposits build up in layers with variable mineral content in the layers
How does subgingival plaque form?
- Nucleation and crystal growth are heterogeneous
- Calcification is more homogenous compared to supragingival
- Deposits build up in layers, each with a high mineral content
What is the mineral content and source of supragingival calculus?
Mean 37% by volume Derived from saliva
What is the mineral content and source of subgingival calculus?
Mean 58% by volume Derived from GCF
What is the composition of supragingival calculus?
70-80% inorganic salts:
Mainly calcium and phosphate
Smaller amounts of:
Magnesium
Sodium
Carbonate
Fluoride
Regular distribution of fluoride
Traces of other elements
Organic matrix
–> Proteins, lipids and carbohydrates
What is the composition of subgingival calculus?
- Greater concentration of calcium, magnesium and fluoride compared to supragingival calculus
- Higher calcium to phosphate ration than in supragingival calculus
- Irregular distribution of fluoride
What is the crystal type of supragingival calculus?
Mostly octacalcium phosphate and hydroxyapatite
Some whitlockite
Some brushite
What is the crystal type of subgingival calculus?
Mostly whitlockite
Some hydroxyapatite and octacalcium phosphate
No brushite
What disease is associated with supragingival calculus?
Gingivitis
Gingival recession
What disease is associated with subgingival calculus?
periodontitis
Why is calculus always covered with an unmineralsied layer of bacteria?
Due to the rough surface
always a layer of plaque around it
Is calculus a plaque retentive factor?
YES
