saliva and role of saliva in dental caries.

2. SALIVA & ITS
ROLE IN DENTAL
CARIES
Presented by-
Dr.Snehal shelke

3. Contents
 Introduction
 Definitions
 Properties of saliva
 Composition of saliva
 Functions of saliva
 Salivary glands
- classification
- anatomy
 Formation of saliva
 Nervous regulation of salivary secretion
3

4.  Role of saliva in dental caries
 Conclusion
 References
4

5.  The oral cavity is kept moist by a film of fluid
called
saliva that coats the teeth and the mucosa.
 Saliva is a complex fluid, produced by the salivary
glands.
 Individuals with a deficiency of salivary secretion
experience difficulty in eating, speaking and
swallowing and become prone to mucosal
infections and rampant caries.
5

6.  Saliva
 According to TEN CATE,
- saliva is a complex fluid , produced by the salivary
glands ,the most important function of which is to
maintain the well being of the mouth.
 According to ORBAN,
- the clear, alkaline, somewhat viscid secretion from the
parotid, sublingual and smaller mucous glands of the
mouth.
6

7.  Stimulated saliva and unstimulated saliva
 Salivary flow is termed resting (unstimulated) when no
exogenous or pharmacological stimulation is present.
 It is termed stimulated when secretion is promoted by
mechanical or gustatory stimuli or by pharmacological
agents.
7

8. Properties of saliva
 Volume: 1000-1500 ml of saliva is secreted per day
contribution by each major salivary glands:
a) parotid- 20%
b) submandibular- 65%
c) sublingual- 5%
d) minor-10%
 Mixed saliva from all the glands is slightly acidic-
pH of 6.35-6.85.
 Specific gravity: ranges from 1.002-1.012.
 Tonicity - saliva is hypotonic to plasma.
 Freezing point - 0.07 to 0.34 degree C.
8

9. Submandibular
Parotid
minor
10%
sublingual
Contribution in Unstimulated Saliva
by Salivary Glands
Submandibular Gland
Parotid gland
minor glands
sublingual glands
Ref- Orban’s 13th edition, chapter no. 11

10. Composition of saliva
10

11. Factors Influencing Composition
and Flow of Saliva
 Water Intake: If water content of body reduced to
8% salivary flow decreases to zero.
 Visual and Mental Stimulation.
 Salivary Flow Index: when salivary flow increases.
 Concentration of proteins, NaCl ,
 HCO3
 Concentration of phosphates and
Mg

12.  Body posture: individual in standing position
secret more saliva.
 Smoking and medication: Individuals those who
smoke have higher flow than non- smokers.
 Certain medications, such as antidepressants,
antihistamines, etc. (drugs having anticholinergic
action) cause reduction in salivary flow.
12

13. Functions of saliva
13
• Mucin and other glycoproteins.
• Prevents dessication of oral tissues.
• Flush away debris and other non adherent
bacteria.
Lubrication
• Bicarbonates , phosphates and salivary proteins.
• Metabolism of salivary proteins provides urea
and ammonia which help increase pH which is
not conductive for cariogenic bacteria to survive.
Buffering

14. 14
• Proline rich proteins, statherin, glycoproteins
bind to tooth surface forming enamel pellicle
which behaves as protective membrane.
Pellicle formation
• Keeps oral tissue moist and lubricated which
facilitates speech.
• Helps in vocalization and communication ability.
Speech

15. 15
• High concentration of calcium and phosphates
causes posteruptive maturation of enamel,
increases surface hardness and resistance to
demineralization.
• Remineralization of initial carious lesions by
fluoride ions.
Maintenance of tooth integrity
• Antibacterial agents: lysozymes, lactoferrin,
calprotectin, immunoglobulins.
• Antiviral agents: cystatins, mucins.
• Antifungal agents: histatins, chromogranin A.
Antimicrobial action

16. 16
• Amylase (ptyalin)- breaks down starch.
• Lingual lipase- responsible for first phase of fat
digestion.
Digestion
• Moistens the food and helps in breakdown into
small particles.
• Formation of bolus and facilitates deglutition.
Mastication and deglutition

17. 17
• Food is emulsified in saliva and dissolved which
is prerequisite for the sense of perception of
taste.
• It is due to the presence of water and lipocalins.
• Also helps in maintaining taste receptors.
Taste perception
• Variety of growth factors and trefoil proteins are
present in small quantities in saliva which
promotes tissue growth, differentiation and
wound healing.
Tissue repair

18. 18
• Many substances both organic and inorganic
are excreted in saliva.
• Glucose in DM.
• Excess urea in nephritis.
Excretion

19. Salivary glands

20. Classification
 Based on size:
20
Major salivary
glands
Parotid gland
Submandibular
Gland
Sublingual gland
Minor salivary
glands
Labial and buccal
glands
Glossopalatine
glands
Palatine glands
Lingual glands

21. 21

22.  Based on the type of saliva secreted:
22

23. Anatomy of
salivary glands

24. Parotid gland
 Largest salivary glands.
 Purely serous.
 Weight: 14-28 grams.
 Pyramidal in shape.
 2 parts- a) Superficial
 b) Deep
 Superficial portion lies in front
 of external ear
& deeper portion lies
behind the ramus of
mandible.
B.D.CHAURASIA’S HUMAN
ANATOMY VOL.3

25. STENSON’S DUCT
 Length- 35-40 mm.
 Thick walled.
 Opening: opposite to
 Maxillary 2nd molar.
B.D. CHAURASIA VOL. 3 6TH EDITION

26. Blood supply
 terminal branch of external carotid artery
 & internal maxillary artery.
Nerve supply
 parasympathetic nerve supply is mainly from the
glossopharyngeal nerve and auriculotemporal
nerve.
 sympathetic innervation of all salivary gland is
provided by the postganglionic fibers from the
superior cervical ganglion.
26

27. Submandibular gland
 Second largest salivary gland
 Weight: 7-15 grams.
 Secretion is both serous and
mucous.
 Located on the medial aspect of
the body of mandible in the
submandibular triangle.
 Main excretory duct: wharton’s
duct opens at the sublingual
papillae lateral to the lingual
frenum.
27
B.D.CHAURASIA VOL.6

28.  Blood supply
- receives blood supply from the lingual and facial
branch of the external carotid artery.
 Nerve supply
- parasympathetic innervation is derived primarily
from the facial nerve reaching the gland through
the lingual nerve after synapsing in the subman-
dibular ganglion.
28

29. Sublingual gland
 Smallest of all the major salivary glands.
 Weight: 3-4 grams.
 Secretes predominantly mucous saliva.
 Located in sublingual space.
 Lies on the lingual aspect of mandible and above the
mylohyoid muscle.
29
Sublingual salivary gland

30.  Main duct: bartholin’s duct opens with or near the
submandibular duct.
 Several small ducts- ducts of rivinus open independently
along sublingual fold.
30

31.  Blood supply
-from the sublingual and submental arteries
which are branches of the lingual and facial artery
respectively.
 Nerve supply
- parasympathetic nerve supply is derived from the
facial nerve which reaches the gland via the lingual
nerve after synapsing in submandibular ganglion.
31

32. Minor salivary glands
 600-1000 minor salivary glands lie in the oral cavity and
oropharynx.
32

33.  Classified according to location:
- labial or buccal
- palatine
- glossopalatine
- lingual:
a) anterior lingual (glands of blandin & nuhn)
b) posterior lingual (von ebner’s glands)
33

34.  They are absent in: gingiva
anterior raphe of hard palate
anterior 2/3rd of dorsum of tongue
 Labial and buccal glands
- glands of lips and cheeks
- secretions are seromucous.
34

35. Glossopalatine glands
 pure mucous gland.
 localized to the region of isthmus in the
glossopalatine fold.
 May extend from the posterior extension of
sublingual gland to the glands of soft palate.
35

36.  Palatine glands
- purely mucous.
- posteriolateral region of hard palate in the
submucosa of the soft palate and uvula.
 Lingual glands
- 2 types
a) anterior lingual (glands of blandin & nuhn)
- located near the apex of tongue.
- chiefly mucous.
36

37. b) posterior lingual glands
 - mucous glands are located lateral and posterior to
the vallate papillae and their ducts open into the dorsal
surface of the tongue.
 - (von ebner’s glands): located between the
 muscle fibers of the tongue below the vallate papillae
 - wash out the trough of the papillae and ready the
taste buds for new stimulus.
37

38. Clinical importance:
For most patients, it should
technically be possible to
avoid delivering radiation to
this newly discovered location
of the salivary gland system in
the same way we try to spare
known glands.
38
Location: upper part of throat
behind the nose.
Size: 1.5 inches long.
Function: moisten the upper
part of throat.
Secretions: predominantly
mucous glands.

39. Formation of saliva
 Occurs in 2 stages:
39
• Cells of the secretory end pieces and intercepted ducts
produce primary saliva.
• It is isotonic in nature containing most of the organic
components and water.
1st
stage
• Primary saliva is modified as it passes through the ducts,
mainly by reabsorption and secretion of electrolytes.
• The final saliva that reaches the oral cavity is hypotonic.
2nd
stage

40. Nervous regulation of salivary secretion
 Saliva secretion is regulated by nervous mechanism
- parasympathetic fibers
 stimulation of these fibers activate the acinar cells and
 dilate the blood vessels of salivary glands leading to
 secretion of large quantity of watery saliva with lesser
 organic constituents.

40

41. - sympathetic fibers
stimulation of these fibers activate acinar cells and
cause vasoconstriction by secreting nonadrenaline
leading to secretion of less saliva which is thick and
rich in mucous.
41

42. Normal Flow of saliva
42
Flow rate
(ml/min)
Whole saliva
Resting 0.2-0.4
Stimulated 1.5-2.0
If resting flow rate is <0.1ml/min : Hyposalivation.
If stimulated flow rate is <0.7ml/min : Hyposalivation.

43. Collection of saliva
43
Saliva can be collected in different forms
Resting or unstimulated whole
saliva
Stimulated whole saliva
Glandular saliva(mainly parotid)-
with or without the stimulation

44. 44
• Mixture of secretions which enters the mouth in
the absence of exogenous stimuli.
• In salivary diagnosis, unstimulated saliva is
often preferred since stimulated contains only a
diluted concentration of biomarkers.
Unstimulated saliva

45. 45
• Secreted in response to either masticatory or
gustatory stimulations.
• Masticatory-paraffin wax, rubber bands,
unflavoured chewing gum base, cotton puff.
• Gustatory-citric acid, sour candy drops.
Stimulated saliva

46. Methods of collection of whole saliva
46
Spitting method
Suction method
Swab method
Draining method

47. Recent techniques of collection of
saliva
47
• Preservatives are added to protect the
sample integrity.
Orangene
• Uses collection tubes into which saliva is
expectorated for a predetermined
volume.
Saligene
• Collection through an absorbent foam
swab which picks up 1 ml of saliva.
• Use in diagnosis of HIV, hepatitis A and
B, mumps and rubella.
Oracol
• Utilises high quality immuno-
chromatographic strips for delivery of
immediate results.
Verofy

48. Role of saliva
in dental
caries

49. Saliva and dental caries
 In addition to moderating microbial factors and
encouraging preventive dietary behaviors , a core
goal in caries prevention is promoting the natural
protective mechanisms of saliva.
 The pH of the dental plaque is the key factor in the
balance between acid demineralisation of teeth and
Remineralisation of the initial dental caries.
49

50. Dental caries-
 According to Shafer: microbial disease of the
calcified tissues of the teeth, characterized by
demineralization of the inorganic portion and destruction
of the organic substance of the tooth.
50
Key’s triad for contributing factors for dental caries

51. SALIVA ROLE IN CARIES CONTROL
Saliva is well known to have specific protective
effects against dental caries.
 ex : Rampant caries followed by irradiation.
The principal properties of saliva that protect the
teeth against caries are:
 Dilution and clearance of dietary sugars
 Neutralization and buffering of acids in plaque
 Supply of ions for remineralization
 Antiplaque and antimicrobial factors
51

52. 1) Dilution and clearance of dietary
sugars and bacteria
 The most important function of saliva is the clearance of
oral micro organisms for a healthy balance between host
defense and endogenous and exogenous microbial attack
in the mouth.
 The disturbance in this balance can be due to extensive
growth of bacteria or some systemic disease or reduced
salivary secretion rate.
 A high saliva stimulation rate will result in rapid clearance.
52

53. Sreebny et al noted
that sugar solutions
were cleared in two
stage pattern.
 rapid clearance-
over first 6 minutes
 followed by slower
clearance rates.
53

54. Bacterial Clearance
 The flushing effect of this salivary flow is, by itself,
adequate to remove virtually all microorganisms
not adherent to an oral surface.
 Because the flow of saliva is combined with the
swallowing reflex, the clearing effect is highly
increased due to actual elimination of substances
away from the oral cavity into the esophagus.
 Bacterial clearance is also related to the
composition of saliva.
54

55. Agglutinins
• Clumping of
bacteria into
large
aggregates.
• Increased oral
clearance.
• More easily
flushed.
Mucin
• Aggregate oral
bacteria.
• Easy clearance.
sIg A
• Specific defence
factor.
• Aggregates oral
bacteria for easy
swallowing.
Components of saliva which help
in the clearance of bacteria are:

56. Conclusion:
The total salivary
concentration of sIg A is
significantly higher in the
low caries-active children
group than caries-active
children group. There is
a negative correlation
between sIg A level and
dental caries activity in 6
to 9 year-old children.

57. 2) Neutralization and buffering of
acids in plaque
 Role of saliva: to restore the pH to the normal range as
quickly as possible.
 The primary buffering system of saliva is formed by
bicarbonates (HCO3).
 To some extent phosphate ion (HPO4) and salivary
proteins contribute to the buffering action.
 The bicarbonate in saliva is able to diffuse into the dental
plaque to neutralize the acid formed from carbohydrate
by the microorganisms.
57

58. Bicarbonate buffer
system
Phosphate buffer
system
Protein buffer system
composed of :
•bicarbonate (HCO3-)
•carbonic acid (H2C03)
•dissolved carbon
dioxide gas (CO2)
contributes to the
buffer capacity from
pH 6-8.
Act as buffers when the
pH is above or below
their isoelectric point
(pH 5).
•maximum buffer
capacity is obtained at
pH 6.
Buffer below pH 5,
where neither
phosphate nor
bicarbonate
contributes much to
the buffer capacity .
•“Chief Determinant” of
pH of saliva.
Buffering effect of
proteins is least.
Phase buffering -the
bicarbonate buffer system
is also in equilibrium with
gaseous C02 in the
surrounding air
-adds an actual pH-rising
capacity to the buffer
system.

59.  The buffering effect of saliva is measured by laboratory
method or a chair side Dentobuff strip system.
59
Dentobuff system

60. 3) Demineralization and re-
mineralization of tooth surfaces
 The main factors governing the stability of enamel are pH and free
active concentration of CALCIUM,PHOSPHATE and FLOURIDE.
 The carious process is initiated by bacterial fermentation of
carbohydrates leading to formation of acids and fall in pH.
 Initially H+ will be taken up by buffers in plaque and saliva.
 Inspite of that if pH continues to fall due to continuous release of
H+ the fluid medium will be depleted of OH- and PO3 4.
60

61.  In summary, hydroxyapatite crystals dissolve in acid
because the surrounding solution becomes unsaturated
owing to the removal of phosphate and hydroxyl ions
from solution.
61

62. Salivary calcium and phosphate ions
act by 2 mechanisms on carious
process:
62
Solubility of
enamel
surface
• Salivary calcium and phosphate ions
suppress tooth mineral dissolution
through mass action, and if the pH is high
enough, they remineralize lost tooth
mineral.
Deposition Of
A Salivary
Aggregate
• consists of calcium phosphate-carbonate-
protein complex (salivary precipitin).
• When acid is produced by the plaque
bacteria from fermentable carbohydrate
and the pH drops, these salivary precipitin
in plaque, dissolves before the
hydroxyapatite of the tooth.
• Surrogate source of calcium and
phosphate ions.

63.  Conclusion:
• Individuals who have
increased salivary inorganic
calcium, phosphate, pH,
flow rate and maintain poor
oral hygiene could be at a
higher risk for developing
periodontitis and have less
dental caries and more
number of intact teeth.
63

64. 64
ROLE OF SALIVARY FLUORIDE:
 Diffuses from saliva into plaque as calcium
fluoride.
 Fluorapatite layer is much more acid-resistant
than the original hydroxyapatite and is formed
more quickly than ordinarily remineralized
enamel.
Mechanism of action of fluoride
1. Increases the enamel resistance and reduces.
the enamel solubility.
2. Increases the rate of post eruptive maturation.
3. Remineralisation of incipient caries.
4. Interfere with microorganisms.

65. 4) PROTECTIVE AND
ANTIMICROBIAL
PROPERTY
65
1.Mucous glycoproteins
 Produced by minor salivary glands.
 Serous glycoproteins.
 They help in super saturation of the calcium and phosphate
reduces dissolution and promotes remineralization of the tooth
enamel.
 Statherins and acidic proline-rich proteins in saliva inhibit
spontaneous precipitation of calcium phosphate salts.
 Maintaining the physical-chemical integrity of tooth.

66. 66
2. Pellicle Formation
 Thin (0.5 μm) protective diffusion barrier formed on
enamel by the salivary proteins.
 Statherins and certain of the proline rich proteins bind to
the tooth surface, forming the acquired enamel pellicle.
 Its functions include not only protection and lubrication,
but also Remineralisation and hydration.
 It also functions as a diffusion barrier and possess
buffering ability.

67. Antimicrobial action
1. Salivary Ig A:
 is the largest immunologic component of saliva.
 Inhibits bacterial colonization by agglutination.
 Inhibits bacterial adherence to oral tissues.
 Affects enzymes essential for bacterial metabolism.
 Neutralize viruses, bacterial, and enzyme toxins.

68.  2. Lactoferrin:
 Causes bactericidal or bacteriostatic effects on
various microorganisms.
3. Lysozyme:
 It is an enzyme that hydrolyzes the polysaccharide
of bacterial cell walls, resulting in cell lysis.
 It is a positively charged enzymatic protein.
 It alters aggregation and inhibits of bacterial
adherence.

69. 4. Mucin:
 MG1- High molecular weight glycoprotein,
Adsorbed on tooth surface and contributes to
enamel pellicle formation and protect tooth surface
from chemical and physical attack including acid
attack.
 MG2- Low molecular weight, Also adsorbed on
tooth surface but is easily displaced.
69

70. 70
5.Proline rich protein-
 Binds tightly to hydroxyapatite Prevent precipitation
of Calcium phosphate Protect enamel surface and
prevents demineralization.
6.Histatins-
 Bind to hydroxyapatite crystals in Supersaturated
saliva and Prevent calcium phosphate precipitation.

71. Impact of saliva on restorative
dentistry
 Amalgam – Delayed expansion in amalgam alloys.
 GIC –contamination – Dissolution of matrix.
 Composite – Bond failure.
 Re-etching – if contaminated.
 Impressions – Disinfection protocol to prevent cross
infection.
71

72. conclusion
 Saliva has an important role in patents quality of life.
 Dental professionals need to be aware of problems that
arise when there is over production or underproduction
of saliva.
 It is advantageous for dental professionals to check the
salivary flow rate on regular basis.
72

73.  Saliva contains many important substances and also
acts as a transporter of many important ions, such as
calcium, phosphate and fluoride.
 Saliva helps to maintain a constant reservoir of ions that
help to neutralize the pH and prevent demineralization.
73

74. References
1. Orban’s oral histology and embryology. 13th edition.
2. Dentistry for child and adolescent-MC Donald and Avery-
 9th edition.
3. Essential of medical physiology – Sembulingam 6th edition.
4. Shafer’s Textbook of oral pathology, 8th edition.
5. Chaurasia B D. In Human anatomy vol 3.4th edition.
6. Priya Y, pratibha M. methods of collecting saliva- A review. Int.
Dent oral health 2017;3(3):149-53.
74

75.  7. ghoms SA. Textbook of oral medicine. 3rd edition.
 8. Soesilawati P, Notopuro H, Yuliati Y, Ariani MD, Alwino Bayu
Firdausi M. The role of salivary sIg A as protection for dental caries
activity in Indonesian children. Clin Cosmet Investig Dent.
2019;11:291-295.
 9. A potential new organ at risk for radiotherapy. Radiotherapy and
oncology : journal of the European Society for Therapeutic Radiology
and Oncology, 154, 292–298.
75

76. 76