Daranee Versluis-Tantbirojn

DENT 5302 TOPICS IN DENTAL BIOCHEMISTRY The caries process Dietary factor and cariogenic aspects of dental plaque Plaque fluid and the caries process Fluoride and dental caries Anticario mechanisms of fluoride Fluoride metabolism Fluoride toxicity Application of fluoride (& Ca P) in caries control measures

DENT 5302 TOPICS IN DENTAL BIOCHEMISTRY 28 March 2007 Objectives:

• Nature and character of dental caries • Factors influencing the caries process • Development of early caries lesion in enamel • Dentin caries

Outline

Nature of dental caries History & Epidemiology Key features of dental caries Multi-factorial Site specific Dynamic Demineralization-Remineralization Formation of early enamel lesion Microscopic features of early enamel lesion Caries free

vs

Caries controlled Dentin caries

Carious Teeth (%)

20 15 10

Epidemic

Roman 1950 Industrialize

5 0 2000 1000 0 1000 2000 Percentage of carious teeth in English population

Dental caries: the most prevalent infectious disease

• 5x > childhood asthma ; 7x > hay fever • Affects 85% of adults (>18 years old) in the US • 80% of caries occurs in 20% of the population www.surgeongeneral.gov/library/oralhealth/ Underprivileged population? Less than high school At least some college High school Total children Evans CA, Kleinman DV (2000). The Surgeon General's report on America's oral health: opportunities for the dental profession. J Am Dent Assoc. 131: 1721-8.

75% of children aged 5-11 years old were caries-free 70% of 12-17 years old had caries 94% of dentate adults (18 years or older) had caries

The nature of caries has changed:

Rapidly progressing childhood disease Slow but steadily progressing disease in adulthood

Discussion:

Give some examples of using knowledge and understanding of dental caries in your future dental practice.

Characters of caries

Traditional concept Dental caries is multifactorial

Cariogenic bacteria (dental plaque) Host factors: Tooth Saliva Diet: Fermentable carbohydrate

Characters of caries

Dental caries is multifactorial

Social class

Modern concept

Biological determinants Education

Saliva Microbial species Biofilm Flow rate Composition Buffer

Income

Fluoride Tooth Genetic Time

Behavior

Diet Composition Sugar Frequency

Attitude Socio economical factors Knowledge

Characters of caries

Dental caries is site specific

Dental caries:

Localized destruction of tooth tissues

Erosion Why localized?

Tooth morphology affects plaque accumulation Metabolism of microorganisms in dental plaque (biofilm) Microenvironment (plaque composition, thickness, diffusion properties) Access to dietary substrates, saliva, anticaries agents

Characters of caries

Dental caries is dynamic

Demineralization vs Remineralization

breakfast coffee break lunch snack

brushing

dinner snack Net loss

brushing

Brown spot (Arrested lesion)

• Change in microenvironment • Reduced plaque accumulation • Access to saliva www.recaldent.com

saliva

Formation of early enamel lesion

plaque sound enamel subsurface lesion acid

diffuse & dissociate

H + + apatite H 2 O HPO 4 2 OH Ca 2+ PO 4 3 F Ca 2+ + PO 4 3 + OH surface zone (repair)

Microscopic features of early enamel lesion

3 4 2 1 1 2 3 4 2 3 4 1 1. Surface Zone 2. Body of the Lesion 3. Dark zone 4. Translucent zone

Intact surface 20-100 m m thick, <10% mineral loss Largest zone, highest mineral loss (24%) Very small pores, <10% mineral loss Advancing front, 1% mineral loss

Clinical appearance: White spot lesion First clinical sign of enamel caries lesion Not that early!

300 – 500

m

m depth to be visible

Why are we interested in early caries lesion?

At this stage the lesion is reversible Fluoride and preventive treatment are most effective at this stage

Early carious lesions are reversible

Sound enamel White spot Cavitated lesion Age 8 93 72 19 Age 15 74 37 15 26 4 9 19 111 sound enamel 41 white spots 32 cavitated lesions

(Baker-Dirks, 1966) Study done in community with water fluoridation Only 9 of 72 white spot lesions became cavitated after 7 years More than half of early lesions regressed to ‘normal’ enamel

Dr. J.P. Byers White spot lesions around orthodontic bracketts Dr. J.P. Byers

Discussion:

‘caries-free’

vs

‘caries-controlled’

Is there a ‘caries-free’ individual?

Q1

Do you have any cavities or fillings

Q2

Do you think you have demin-remin periods?

0 3

Progression of Carious Lesion

How long?

Proximal lesions in permanent teeth can take 3-4 years through enamel, unless in caries active individuals. (Pitts, 1983)

1 2

Median survival time from stage 2 to 3 was ~ 3 years Late teen Danish population From 2 – 3: 9.2 surface % per year From 3 – 4: 2.3 surface % per year

4

Rampant caries in Mountain Dew drinker

Dentin caries

Microscopic features carious dentin

A = zone of decomposed dentin B = zone of bacterial invasion C = zone of demineralization D = sclerotic dentin E = reparative dentin

Outer carious dentin Inner carious dentin Progression of dentin caries Demineralization of inorganic substance Breakdown of organic matrix by proteolytic enzymes Bacterial invasion

Dentin caries

Two layers of carious dentin

70 -

Outer carious dentin

60 infected nonremineralizable 50 nonvital insensitive 40 30 20 10 DEJ

Inner carious dentin

uninfected remineralizable vital sensitive Turbid layer 1000 Transparent layer Sub trans parent layer 2000 Bacteria Sound dentin 3000

m

m Crystals in tubule lumen Odontoblast Pulp wall

Fusayama T, Okuse K, Hosoda H. J Dent Res. 1966;45:1033-46. Relationship between hardness, discoloration, and microbial invasion in carious dentin.

Discussion:

What do you learn today that can be used in future practice?

1.

Why underprivileged population have more caries?

2.

What should we do with white spot lesion?

3.

How much carious dentin should be removed?

Recommended references

1. Clarkson BH. Introduction to Cariology. Dent Clin North Am 1999;43(4):569-578.

2. Zero DT. Dental Caries Process. Dent Clin North Am 1999;43(4):635-664. 3. Featherstone JD. The science and practice of caries prevention. J Am Dent Assoc 2000;131:887-899.

4. Gordon Nikiforuk. Understanding Dental Caries 1. Etiology and Mechanisms, Basic and Clinical Aspects. Basel; New York: Karger 1985. Chapter 10.

5. Gao W, Smales RJ, Yop HK. Demineralisation and remineralisation of dentine caries, and the role of glass-ionomer cements. Int Dent J 2000;50:51-56.

6. Fejerskov O. Changing paradigms in concepts of dental caries: Consequences for oral health care. Caries Res 2004;38:182-191.