Nutrition Instruction in Community Dentistry

for Health Promotion of Children

TAKAYUKI KAWATODepartment of Oral Health,Nihon University, School of Dentistry

2. Dental Caries-The role of dietary carbohydrate -

OCTOBER 30, 2008

Aristotle

Sweet fig

Caries

relation?

Dental caries does notdevelop in the absence offermentablecarbohydrates in the diet.

(384 BC – 322 BC)

Effect on Caries Incidence in Rats ofIncreasing Dietary Sucrose levels

Hefti, A., and R. Schmid. (1979)Caries Res. 13:298-300.% sucrose concentration

An increase in cariesincidence with increasingsucrose dose has beenobserved at levels rangingfrom 8% to 40% of dietarysucrose.

● fissure

■ smooth surface

Cario

us

lesio

ns

Takeuchi, M. 1961., Int. Dent. J. 11:443-457.year

ye

ar

•Caries decreased in association with the severereduction in sugar supplies.•Caries increases when per-capita sugar consumptionincreases after the war.

Sugar consumption and caries incidence

10Ca2+ + 6HPO42- + 2H2O

Ca10(PO4)6(OH)2 + 8H+

DemineralisationHydrogen ion conc

RemineralisasionCalcium & phosphate level

The dissolution of the mineral salts ofthe tooth (hydroxyapatite) proceedsaccording to the formula

Saliva Saliva

tooth surface H+H+

H+

ionic seesaw

hydrogen ions ＝pH level

critacal pH=5.5

Orgainic acid metbolittes oforarl bacteria

Stephan curve

energy

glycolysis

Lactic acid(other acid)H+

H+

H+

H+

critacal pH

Stephan curve•A minimum pH being found 5-10 minutesfollowing expose to sugars.

•The minimum pH is below the critical level.•The pH then slowly returns to the baseline value

morning

↓lunch

↓dinner

↓

morning↓ lunch

↓ dinner↓

7

6

5

4

7

6

5

4

6 12 18 24

pH

pH

6 12 18 24

Frequency and time of Exposure

Frequent eating keeps the pH at the critical level belowwhich enamel demineralization can occur.

The Vipeholm study

•Dental caries appeared to be influenced more by frequency of sucroseintake than by total amount consumed.•More retensive foods were also more cariogenic.

Toffee

Chocolate

Caramel

Beverage

More cariogenic

1. Fermentable carbohydrates appear to be the only component ofthe diet capable of inducing caries.

2. The cariogenic potential of carbohydrate-containing foodsdepends on their characteristics (e.g., stickiness), and thefrequency and sequence of their consumption.

Summary-1

Highly retentive Non-retentive

Slowly solubleRapidly soluble

Sucrose

FructoseMaltoseDextrose

Lactose

Galactose

Starch

Mannose

Starch(heat treatment)

Sorbitol

Glucose

energy

glycolysis

OtherSugars Starch

H+

H+Lactic acid(other acid)

H+

H+

The influence of different sugars

Bacteria utilizes otherdietary sugars, fructose,galactose, sucrose, maltose,lactose-very efficiently, andincreasing concentrations ofhydrogen ions are measuredas a fall in pH.

Sucrose?or

Other sugar?

•The average number of decayed, missing, or filled tooth surfaces(DMFS) was twice as high in the group consuming sucrose than inthe fructose group.•The xylitol group had virtually no DMFS.

Turku Sugar Studies

0

30

60

Sucrose

Dextrose

Fructose

Maltose

Carbohydrate in Diet

Comparison of various carbohydrate in caries test fed to Rat

(Frostell G et. al 1967)fissure

buccal/lingualsurfaceproximal surface

The cariogenic potentialof sucrose is greater thanthat of equivalent amountsof glucose, fructose,dextrose and maltose.

Matrix =extracellular polysaccharides

Bacterial cells

Dental plaque

Acid

Bacterial cells synthesise extracellularpolysaccharides from sucrose, but notother sugar.

microbial metabolic by-products

Matrix

( glucan, mutan,fructan )

Deminerali-zation

Sucrose

Adhesion of bacterualcells to tooth surface

Acidproduction

Water insoluble glucan(WIG)

Water soluble glucan(WSG)glucosyltransferase

fructosyltransferase

fructan (solblue)

invertase

glycogen

Sucrose

Glucose

Fructose

glyc

olys

isSucrose metabolism inStreptococcus mutans

Streptococcus mutans・Gram-positive, facultatively anaerobic bacteria・Commonly found in the human oral cavity・A significant contributor to tooth decay.

A B C

Containing・S. mutans・sucrose (1%)

orglucose (1%)

Incubation at37℃, 5% CO2,

Angle 30°,24 hrs.

Collect supernatantand check pH

adhered cell

adhered cell

A B C

A B C

A: without sugarB: glucose (1%)C: sucrose(1%)

Carbohydrate metabolism in S. mutans

-glass tube test-

S. mutans can ferment both sucrose and glucoseS. mutans produce both water-soluble and water-insoluble glucansfrom sucrose, but not glucose

1. Among the major carbohydrates in the diet sucrose appears tohave the greatest cariogenic potential.

2. S. mutans has been the most consistently and strongly associatedbecause S. mutans produce both water-soluble and water-insoluble glucans (WIG) from sucrose.

3. WIG is necessary for the accumulation of these cells on the toothsurface.

Summary-2