Salivary Biology and Dental

Practice Mark Hector

University of Dundee

University of Dundee

Why is knowledge of saliva important for

the dentist (and doctor)? Normal state – anatomy, control of secretory processes, biochemistry/

inorganic and organic components, maintenance of oral and dental health

Disease processes, impact of medicines, young and older people

Xerostomia – impact on soft and hard tissues

Quality of life impact

Dental team leader and team education leader

Patient education

The Functions of Saliva

Normal abnormal

Xerostomia in the older patient

Post radiotherapy, targeted at

mandible, but affecting

submandibular gland

Several other causes

Xerostomia – soft

tissues

• Reduced quality of life – a major impact for

most patients.

• Normal everyday functions severely disrupted

• Speech, chewing dry foods, swallowing, oral

clearance, taste perception

• Other mucosae may well be affected if

systemic aetiology

Xerostomia -

Significant additional risk of damaging mucosa

Need to discuss with patient/carer, especially in elderly patients need to maintain full hydration if salivary function adequate to avoid symptoms of dry mouth.

If wearing complete upper prosthesis significant difficulty in maintaining stability – loss of ‘peripheral seal’ by saliva.

Tooth Decay and Erosion

At 5 years: 52% had erosion affecting primary incisors

At 5 years 40% had decayed teeth

NHS Dentistry: ~4% of GDP in UK

Relative susceptibility of teeth to decay – link

to saliva distribution and flow

Courtesy of A Danchaivijitr Courtesy of A Danchaivijitr

Rapid development of dental / root

caries

Salivary flow across teeth

Salivary highways

Salivary byways

Iatrogenic stagnation areas

Continuous one-sided chewing on gum base

Distribution of Saliva Around the Mouth

Adult – student practical Children – part of MSc project

The older patient

Healthy – no effect

Special senses

Tooth loss

Posture/disability

Medication

Drugs that Produce Xerostomia

ANALGESICS

ANTIARRHYTHMICS

ANTICONVULSANTS

ANTIDEPRESSANTS

ANTIEMETICS

ANTIHISTIMINES

ANTIHYPERTENSIVES

ANTINAUSEANTS

ANTINEOPLASTICS

ANTIPARASITICS

ANTI-PARKINSON’S

ANTIPSYCHOTICS

ANTISPASMODICS

ANXIOLYTICS

APPETITE SUPPRESSANTS

DECONGESTANTS

DIURETICS

EXPECTORANTS

MOI’s

MUSCLE RELAXANTS

SEDATIVES

TRANQUILLISERS

Caries risk – Flow – resting / stimulated

Buffering capacity

Plaque pH

not funded by UK NHS

Buffering intra-oral acids Rest

Contra

chewing Ipsi chewing

Sleep

Dietary causes of Enamel

Demineralisation:

Dental Caries and Erosion

Huge threat from acidic and

sugary drinks, sweets

and foods

2010

2.9 billion bags/packets/boxes of sweets sold in 2011 From Tesco, Asda, Morrisons and Sainsbury (1 pppw = 225g per week per person)

5 ltr per person per week

2010

Drinks Relative titratable

acidity pH

Erosive

potential

Grapefruit juice 9.3 3.2 High

Orange juice 4.8 3.8 High

Apple juice 4.5 3.3 High

Schweppes 2.6 2.6 Moderate

Sunpride 2.4 3.7 Moderate

Carbonated orange

drink 2.0 2.9 Moderate

Ribena ‘Toothkind’ 1.0 2.8 Moderate

Cola 0.7 2.5 Moderate

Diet Cola 0.5 2.9 Moderate

Sparking Water 0.1 5.3 Low

Plaque pH following glucose rinse

Na+

K+

Na+

K+

Na+

K+

Na+

K+ Cl-

Result: Saliva HCO3-, Cl-

Cl- K+

Na+

Connective

Tissue Lumen

Striated Duct Cell Activated

• Cl- / HCO3- Exchanger

HCO3-

Cl-

HCO3-

Modification of primary saliva in the

striated duct

Paradigm of dental enamel mineral preservation

demineralisation remineralisation

Continuous and dynamic processes

Balancing Act

driven by under/supersaturation wrt HAP

Variation in critical pH: de- or re-mineralisation

pH

Ca

2+ c

on

cen

tra

tio

n m

mo

l l-

1

Salivary Calcium

Saliva is supersaturated with respect

to hydroxyapatite (enamel)

Ca

Ca

Ca

Ca

Ca

PO4

PO4

PO4

Ca Ca

Ca PO4

PO4

PO4

Ca

PO4 X

Ca10(PO4)6(OH)2

Tooth Solution adjacent to

tooth surface

Evolution of Statherin (STN43)

Kawasaki and Weiss, PNAS 2003 (100); 7: 4060

STN43 STN21

Statherin: DpSpSEEKFLRRIGRFGYGYGPYQPVPEQPLYPQPYQPQY

QQYTF

N-terminus

Binds hydroxyapatite

Binds Ca 2+ (SXE motif)

Inhibits secondary precipitation

(crystal growth)

Inhibits primary precipitation

(crystal nucleation)

Salivary protein Statherin and the enamel pellicle

'statheropio' meaning 'to stabilise

Adhesive

Dentistry

Frosting of enamel following acid etch Saliva must be kept off enamel surface

Fissure sealant successfully placed Excellent retention possible.

Promote good / beneficial habits

Should we stop this?

University of Dundee