The Formation of Dental Integuments Flashcards
What is an integument?
An outer covering
Give examples of the integuments found in the mouth
Acquired pellicle, dental plaque, dental calculus (supra and subgingival)
What is the aetiological factor in major oral diseases and what diseases does this factor contribute to?
Plaque
caries, gingivitis and periodontitis
What is the pellicle considered as?
The protective covering of the enamel
How long does it take for the acquired pellicle to reach its maximum formation?
1-1.5 hrs
Explain how the pellicle forms
- Adsorption of
salivary proteins & glycoproteins onto + ve charged enamel surface - A SELECTIVE PROCESS ! - Modification of some glycoproteins in saliva by bacterial enzymes
- Loss of solubility of glycoproteins
- Pellicle layer assumes overall –ve charge
What is the function of statherin?
Statherin is a protein in humans that is encoded by the STATH gene. It prevents the precipitation of calcium phosphate in saliva, maintaining a high calcium level in saliva available for remineralisation of tooth enamel and high phosphate levels for buffering
What are the functions of the acquire pellicle?
- lubrication
- protects against acid attack
- Promotes adhesion of gingival epithelium to tooth
- Modulates growth of oral flora
What are some of the protective components in the pellicle?
- acidic proline-rich proteins (PRPs)
- Satherins and histatins
- Albumin
- Lysozymes
- IgA
- Salioperoxidase
- Proteins from gingival crevicular fluid
What are the functions of the following protective components of saliva?
1) acidic proline-rich proteins (PRPs)
2) Satherins and histatins
3) Albumin
4) Lysozymes
5) IgA
6) Salioperoxidase
7) Proteins from gingival crevicular fluid
1) The acidic proline-rich proteins will bind calcium with a strength which indicates that they may be important in maintaining the concentration of ionic calcium in saliva
2) Statherin prevents the precipitation of calcium phosphate in saliva, maintaining a high calcium level in saliva available for remineralisation of tooth enamel and high phosphate levels for buffering.
Histatin - most significant function of histatins may be their anti-fungal activity against Candida albicans and Cryptococcus neoformans
3) Ionic concentration?
4) Lyses bacteria - prevents overgrowth
5) Mucosal immunity
6) catalyses conversion of thiocyanate (SCN-) to
hypothiocyanate (OSCN–) = antibacterial
7) Contain antibodies = immunity
What are histatins and what do they contain?
Small molecular weight peptides from parotid and submandibular glands
Contain histidine
What is the purpose of histatins and what do they bind to?
anti-microbial
Bind to hydroxyapatite
Which types of histatins are present in the acquired pellicle?
1,3 and 5
Which type of histatins don’t bind hydroxyapatite?
Non-phosphorylated histatins
Explain how salivary glycoproteins are modified by bacteria
Break down oligosaccharide side chains which make protein chains insoluble and they aggregate
What are the immunological factors that lead to plaque overgrowth?
sIgA deficiency Neutrophil dysfunction Myelo-suppression (decreased ability of bone marrow to produce blood cells e.g. chemotherapy, AIDS)
What are the non-immune factors that lead to plaque overgrowth?
Xerostomia
Antibiotics
Dietary carbohydrates
Increased GCF
What are the properties of initial plaque?
Less adherent
Less potentially pathogenic
Few bacterial species
What are the properties of mature plaque?
Increased mass & thickness
– Diverse microbial composition
– Potentially more pathogenic - can react to changes in the environment
Name plaque retentive factors
– Orthodontic appliances – Partial dentures – Faulty restorations – Calculus – Deep periodontal pockets
How does calculus form?
Deposition of Ca and PO4 -containing salts into plaque • Begins within 24 - 72hrs and up to 12d to mature • Porous
When does calculus form?
• Forms when solutions of Ca and PO4
ions become “unstable”
i.e., when no longer remain in solution
• Also occurs in kidney, gall bladder, urinary bladder and salivary glands
• Calculus surface provides site for further plaque growth
What role do bacteria play in calculus formation?
Bacterial pyrophosphatase activity splits pyrophosphate in saliva to yield phosphate
Some bacterial membranes are organised into Ca-binding complexes
How does sub-gingival (serumnal) calculus form and why is it usually pigmented?
Forms from GCF and perio pocket components
Pigmented due to haem components from haemoglobin
