Salivary Diagnostics – An Insight

I.IMPORTANCE OF SALIVARY DIAGNOSTICS:

1. Undemanding procedures

2. Non-invasive techniques

3. No trained medical staff is required

4. Quick process

5. Multiple samples can be collected

6. Safe to handle the sample collected

II.TYPES OF SALIVARY DIAGNOSTICS:

1. Saliva Liquid Biopsy

2. Oral Microbiome studies

3. Immune & Inflammatory markers

4. Human development (MicroRNAs)

5. Neurodegenerative Conditions

6. Measure pathogen exposure & infection

7. Biomonitering (biomedical hazards)

8. Drugs of abuse

9. Periodontal Medicine

10.Pain

11.Genetic & Epigenetic Research

12.Stress Pyshoneuroendocrinology

III.METHODS OF SALIVA SAMPLE COLLECTION:

1.Conventional Methods for Unstimulated Saliva collection:

(a) Passive Draining Method

(b) Sitting Method

(c) Carlson-Crittenden or Modified Lashley’s Method

2. Conventional Methods for Stimulated Saliva collection:

(a) Paraffin Chewing Method Fig 1.1

(b) Citric Acid Solution

3. Advanced Collection Methods for DNA:

(a) SimplOFY Collection Kit Fig 1.2

(b) DNA-SAL

4. Advanced Collection Methods for RNA:

(a) MicroSAL

(b) SuperSAL

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IV.SALIVA COLLECTION INSTRUCTIONS:

1. Swallow the leftover saliva

2. Use a timer to record salivary flow rates

3. Allow saliva to pool before collection

4. Tilt the head of patient forward & then collect saliva sample in device

5. Place cap on the vial tightly after collect & use paraffin to get a tight seal

6. Initially store in cool temperature 4ºC

7. Then transfer to -20ºC & for longer storage store at -80ºC

8. Label the vial with a marker

9. Mark the level of sample collected with a marker

V.FACTORS INFLUENCING UNSTIMULATED SALIVARY FLOW RATES:

1. Major Factors:

(a) Degree of hydration

(b) Body position – In Standing position salivary flow rate > salivary flow rate in Sitting position

(c) Exposure to light – In the dark the salivary flow rate decreases

(d) Previous stimulation

(e) Circadian rhythm – time of the day leads to variation in salivary flow rate

(f) Circannual rhythm – seasonal variation in salivary flow rate

2. Minor Factors:

(a) Gender

(b) Age

(c) Body weight

(d) Gland size

(e) Pyshic effects – thought / smell of food

(f) Functional Stimulation

VI.FACTORS INFLUENCING UNSTIMULATED SALIVARY FLOW RATES:

1. Nature of Stimulus – mechanical, gustatory, pharmacological, food intake etc….

2. Gland size

3. Vomiting

4. Olfaction

5. Smoking

6. Drugs – adrenaline, Histamine, Atropine, etc…..

VII.FACTORS AFFECTING THE COMPOSITION OF SALIVA:

1. Contribution of different glands – Unstimulated Saliva

Parotid Gland – 25%

Submandibular Gland – 60%

Sublingual Gland – 7-8%

Minor Salivary Glands – 7-8%

2. Flow Rate – if flow rate increases then pH increases & concentration of constituents increases

3. Duration of Stimulation – at constant flow rate variation in composition of saliva depending on the duration of stimulation.

4. Nature of Stimulus

5. Circadian Rhythm – Na & Cl levels are increase early morning while Protein concentration increases during late afternoon.

VIII.CLINICAL SIGNIFICANCE OF SALIVARY FLOW RATE:

1. Salivary Flow is zero during sleep.

2. Β-Blockers decrease the salivary flow rate.

3. Increase in salivary flow rate leads to increase in pH and bicarbonate concentration leading to decrease in incidence of dental caries.

4. Decrease in salivary flow rate leads to increase in incidence of dental caries as there is decrease in carbohydrate clearance from surface of teeth.

IX.DO’S AND DON’T FOR SALIVA SAMPLE COLLECTION:

1. pH of saliva – 1 hour prior to collection of saliva sample avoid intake of food, drinks, dairy products & medications & 12 hours prior avoid consumption of alcohol.

2. Dilution of Salivary biomarkers –

(a) Rinse the mouth with water before saliva sample collection

(b) Wait for 10 minutes

(c) Avoid any physical activity on the day of sample collection

3. Dental / Medical Treatment –

(a) Procedures should be avoid 48 hours prior to saliva sample collection.

(b) Complete medical history to be taken

(c) No brushing of teeth 45 minutes before collection.

4. Patient Compliance

5. Blood contamination if present or suspected then discard the saliva sample.

6. Sample handling, transport & storage –

(a) Keep in ice at 4ºC

(b) Store at -20 ºC

(c) Prolonged storage at -80 ºC

X. PROBLEMS IN SAMPLE ANALYSIS:

1. Correct anatomical site – swab to be placed next to 2nd molar between cheek & upper gum

2. Viscosity of saliva – high viscosity then aspirate slowly & avoid bubble formation. Centrifuge the sample.

3. Inadequate volumes of saliva – avoid stimulants and use show, smell & mention methods to increase salivation.

4. Change in analyte concentration due to biological rhythms

5. Transport of saliva sample – maintain a COLD CHAIN MANAGEMENT

By – Dr. Swapna Amod Patankar

Assistant Professor                                

Department of Oral & Maxillofacial Pathology & Oral Microbiology

Bharati Vidyapeeth Deemed to be University,

Dental College & Hospital,

Pune, Maharashtra, India

Dr Swapna was a participant of our Saliva Technologies and Oral Cancer Genetics Course