Salivary Glands and Salivation ,

WHAT DO I NEED TO KNOW AS A DENTAL STUDENT?

Fionnuala Loy 4th Year, Dental Science Dublin Dental Hospital

Contents

1. Anatomy, Histology and Physiology of Salivary Glands

2. Saliva Functions

3. Saliva Flow Rate

4. Xerostomia – Clinical Relevance

5. Saliva as a Diagnostic Aid

Salivary Glands – Where are they?

Important to know: Relations of each gland

• Superiorly • Inferiorly • Medially • Laterally • Anteriorly • Posteriorly

Nerve supply Blood Supply Lymphatic Drainage

Submandibular and Sublingual Glands

Parotid Gland

Clinical Relevance of Parotid Anatomy Transient Facial Nerve Paralysis

Cause - Introduction of LA into the capsule of the parotid gland.

Prevention – Adhering to protocol with IDN block

Needle tip should be in contact with bone

Management – Reassure patient

Remove Contact lenses

An eye patch should be applied to affected eye

Review patient

Salivary Gland Structure Compound tubuloalveolar glands.

Structure: Closely packed acini with ducts packed in between.

Supported by CT which divides the gland into lobules.

Ducts:

Smallest , intercalated ducts – lined by simple, cuboidal epithelium.

Intercalated ducts open into striated ducts – lined by simple cuboidal/columnar epithelium.

Striated ducts open into excretory ducts - lined by simple columnar epithelium

Mescher AL: Jaqueira’s Basic Histology: Text and Atlas, 12th Edition: http://www.accessmedicine.com Copyright © The McGraw-Hill Companies, Inc.

Histological Picture

Where are the salivary ducts located intraorally?

Parotid (Stensen) duct opening Parotid Papilla. Submandibular (Wharton) duct opening Sublingual Caruncle. Sublingual duct opening – Via Duct of Bartholin Sublingual Caruncle.

OR Via smaller Ducts of Rivinus Plica Sublingualis.

Sublingual Caruncle Plica Sublingualis

Parotid Papilla

Histology • Cells lining the acini are serous, mucous or mixed. • H&E staining.

Histology by Gland Type

Serous Acini - Parotid Mixed Acini – Submandibular ‘Demilunes’ – mucous acini

capped by serous crests

Mucous Acini - Sublingual

Saliva Formation – Stage 1: Primary Saliva

©Reeves 2013

Water and ions derived from plasma

Local Vasculature

Isotonic

Primary Saliva

ACINI

DUCT

Saliva Formation – Stage 2: Final Saliva

©Reeves 2013

Concentration Gradient

Na+& Cl- K+

Hypotonic

Final Saliva

H2O

Isotonic

Primary Saliva

The Main Functions of Saliva in relation to its Constituents. Adapted from Nieuw Amerongen et al., 2004

The Main Functions of Saliva in relation to its Constituents. Adapted from Nieuw Amerongen et al., 2004

Tertiary Coloniser. Increased complexity: Gram negative, strict anaerobes.

Fusobacterium nucleatum joins in – facilitating adhesion by other bacteria (gram negative, anaerobes…)

Adhesion of primary colonisers: gram positive bacilli and cocci (S. sanguis, S. oralis…) and growth

Formation of acquired pellicle with salivary proteins on the enamel.

1.

3.

2.

4.

Salivary Biofilm Formation

Clinical Picture

Saliva Buffering Systems 1. Bicarbonate Buffering System 2. Protein Buffering System 3. Phosphate Buffering System

Saliva Buffering Systems 1. Bicarbonate Buffering System 2. Protein Buffering System 3. Phosphate Buffering System

Demineralisation

Ca10(P04)6(OH)2 Ca2+ + P043- HP04

2-

H2P04-

H3P04

Hydroxyapatite in enamel

Free ions in saliva

pH < 5.5

Remineralisation

Ca10(P04)6(OH)2 Ca2+ + P043- HP04

2-

H2P04-

H3P04

Hydroxyapatite in enamel

Free ions in saliva

pH > 6.5

Clinical Picture Early, Reversible, White Spot Lesion. Reversible caries = early enamel lesions

Late, Irreversible, Established Lesion Irreversible caries = dentine caries

It’s all a balancing act

Fluoride as a Protective Factor

Salivary Flow Rate

Salivary Flow Rate

Control of Saliva Secretion

Unstimulated Saliva Flow

The Circadian rhythm in unstimulated salivary flow rate and the idealised effect of sleep. (Dawes, 2004)

Stimulated Saliva Flow

Effect of six chewing gums and gum base on flow rate of whole saliva. Unstimulated saliva was collected for 5 minutes prior to stimulation through chewing gum or gum base, which began at time zero. (Dawes, 2004)

Composition of Saliva Saliva and Oral Health Edgar M, Dawes C, O’Mullane D Eds. 4th Ed 2012

Composition Unstimulated Stimulated

Water 99.55% 99.53%

Solids 0.45% 0.47%

Flow Rate(ml/min) 0.32 0.23 2.08 0.84

pH 7.04 0.28 7.61 0.17

Sodium (mmol/L) 5.76 3.43 20.67 11.74

Potassium 19.47 2.18 13.62 2.70

Bicarbonate 5.47 2.46 16.03 5.06

Phosphate 5.69 1.91 2.70 0.55

Chloride 16.40 ± 2.08 18.09 7.38

Calcium 1.32 ± 0.24 1.47 ± 0.35

Bicarbonate as a Buffer

Main differences between Stimulated and Unstimulated Saliva

Resting Saliva

Secretion

-Submandibular - 60%

-Parotid - 25%

-Sublingual ~ 7-8%

-Minor glands ~ 7-8%

Oral Protection System

- Secretion rate: 0.3-0.4 mls/min

- Texture: Viscous (mucus)

- Rich in mucins

- pH value 5.7-7.1

-Main Functions: Coating of the teeth: salivary pellicle

- Lubrication of oral mucosa

Stimulated Saliva

Secretion

-Parotid 60%

-Submandibular 30%

-Sublingual ~ 10%

and minor glands

Oral Repair System

- Secretion rate: 1-3mls/min

- Consistency: Thin (serous)

- Rich in minerals

- pH value: 7.0-7.8

- Main Functions: Clearance, buffer system, remineralisation

Effect of Saliva Flow on Oral Clearance

Higher Salivary Flow rate = faster Oral Clearance of

Sucrose.

The effect of changes in the unstimulated flow rate on the clearance of sucrose after a 10% sucrose mouthrinse. Clearance is greatly prolonged at low flow rates. (Dawes, 2004)

Effect of Saliva Flow on Oral Clearance

Unstimulated salivary flow rate <0.2mL/min = prolonged clearance.

Prolonged clearance = > risk of caries and acid erosion.

The effect of changes in the unstimulated flow rate on the clearance of sucrose after a 10% sucrose mouthrinse. Clearance is greatly prolonged at low flow rates. (Dawes, 2004)

Effect of Saliva Flow on Buffering Capacity

Plaque pH response to a sucrose mouthrinse alone, and followed by paraffin or cheese. (Edgar and Higham, 2004. Redrawn from: Higham and Edgar, Caries Res 1989; 23: 42-48)

Effect of Saliva Flow on Buffering Capacity

Xerostomia Literally translated ‘xerostomia’ means “dry, oral cavity”.

Symptomatic description.

Patients first complain of dry mouth when salivary flow rates are less than half that of normal.

More than 50% of adults surveyed in 2000–2002 reported having some experience of dry mouth.

Dry mouth on a regular basis was reported by 12% of older people (aged 65+) compared to only 5–6% among younger adults (aged 16–24 and 35–44).*

*Whelton H, Crowley E, O’Mullane D, Woods N, McGrath C, Kelleher V, Guiney H, Byrtek M. Oral Health of Irish Adults 2000–2002.

Hyposalivation True Hyposalivation is defined as:

Unstimulated saliva flow rate of less than 0.1 ml per minute.

Stimulated saliva flow rate of less than 0.7 ml per minute.

Not everyone with xerostomia will have true hyposalivation.

Measuring salivary flow is important in diagnosing

true hyposalivation.

Aetiology of Xerostomia

Classification of Salivary Gland Disease Salivary Gland

Diseases

Developmental Sialadenitis Obstruction &

traumatic lesions Sjogren

Syndrome Sialadenosis

HIV-associated salivary gland

disease

Salivary Gland Tumour

Age related changes

•Atresia •Aplasia •Heterotopic Salivary tissue

•Bacterial •Chronic •Acute

•Viral •Mumps •CMV

•Post-irradiation •Sarcoidosis •Sialadenitis of minor glands

•Salivary Calculi •Necrotizing Sialometaplasia

•Adenoma: •Pleomorphic adenoma •Warthin’s tumour

•Carcinoma: •Mucoepidermoid •Acinic Cell •Adenoid Cystic •Carcinoma arising in PA •Pleomorphus, low- grade adenocarcinoma

Diagnosis - History ALWAYS: •History

•Medical •Social •Pain - SOCRATES

• IMPORTANT QUESTIONS RELATED TO SALIVARY GLANDS: • History of Swelling/changes over time? • Trismus? • Pain? • Variation with meals? • Bilateral? • Dry mouth/Dry eyes?

• Does the amount of saliva in your mouth seem to be too little? • Does your mouth feel dry when eating a meal? • Do you sip liquids to aid in swallowing dry food? • Do you have difficulty swallowing?

• Recent exposure to sick contacts (mumps)? • Radiation therapy • Current medications

Diagnosis - Inspection

• Asymmetry (glands, face, neck)

• Diffuse or focal enlargement?

• Erythema extra-orally? • Trismus? • Medial displacement of

structures intraorally? • Examine external auditory

canal (EAC)

Diagnosis - Palpation • Palpate for cervical

lymphadenopathy • Bimanual palpation of FOM in a

posterior to anterior position. • Have a patient close mouth

slightly and relax musculature to aid in detection

• Examine for duct purulence • Bimanual palpation of the gland

(firm or spongy/elastic)

Diagnosis-Intraoral

Diagnosis – Special Tests Measuring Salivary Flow Rate:

Standardised conditions.

Best measured in morning: 9am-11am.

Px should not eat, smoke, drink or clean his/her mouth 1 hour beforehand.

Px should sit with head forward slightly and swallow saliva before measurement.

Px allows saliva to drip into container for 5 minutes (without mechanical movements) into suitable collecting vessel.

At end point px spits remaining saliva from oral cavity into vessel.

Calculate flow rate per minute.

Diagnosis: Special Tests B) If tumour suspected - • Refer to Oral Surgery

department for assessment and possible biopsy

C) If medications are the suspected cause - • Liase with GP and see if

an alternative can be prescribed

Other Special Tests: •Biopsy •Blood Tests

•FBC •Anitbody screening: (Ant-La, Anti-Ro, ANA, RF)

•Candida smear or culture

A) If Salivary Calculi suspected - • Lower occlusal radiograph Other imaging techniques - • CT Scan • US • Sialography • Scintigraphy Refer to oral surgery if stone cannot be removed non-surgically. NB: Not all salivary calculi are radio-opaque

D) If Sjogren's Syndrome or other systemic condition is suspected - • Refer to oral medicine for

assessment.

Symptomatic Treatment for Patient • Sip water frequently

• Use ice sticks

• Restrict caffeine intake

• Avoid mouth rinses

containing alcohol

• Humidfy sleeping area

• Coat lips with a lubricant

• Maintain good OH

• Bruch twice daily with

fluoride toothpaste

• Avoid tobacco, spicy, salty

and acidic foods that can

irritate the mouth.

• Sugar free gum.

Stimulation of Salivary Flow Local:

Masticatory-gustatory stimulation e.g: sugar-free gum.

Pharmacological "sialogogues.":

Pilocarpine - 5 milligrams four times per day.

Cevimeline - 30 mg three times per day.

NB: Common Side Effects:

Sweating, nausea and rhinitis.

Contraindicated in px with:

Hypersensitivity

Narrow-angle glaucoma

Uncontrolled asthma

Caution with β-blocker use

Saliva Replacements Best method – frequent lubrication with water.

Saliva Substitutes:

Negatives

Calcium, Phosphate and other ions

compared to saliva – remineralisation.

Bad taste.

Complicated administration.

Cost.

More viscous than natural saliva – Carboxymethylcellulose

Examples: Oral Balance, Xerostom

Management of Hyposalivation Education.

Fighting infection eg: CHX mouthrinse, nystatin suspension

Dietary History and advice.

Professional Tooth Cleaning as needed.

Fluoridation (toothpaste, gels, varnish and mouthwash)

Restorative Treatment.

Periodontal treatment.

Future of Saliva – A diagnostic Aid? Measuring buffering capacity

Microbial testing

Diagnosing systemic disease?

Thank You for Listening

Any Questions?