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Diet and dental caries
Dental caries (decay): Is an oral infectious disease of the teeth in
which organic acid metabolites produced by oral microorganisms lead to
demineralization and destruction of the tooth structure.
Diet
Diet: Is the sum of the food consumed by an organism. An extensive
number of studies show that diet plays a central role in the development
of dental caries. Nutrition is related to a balance between the supply and
physiological expenditure of energy of nutrient of all the cells of the
body. Thus nutrition is concerned with the systemic, metabolic effects of
eating habits and nutrients in food. Prolonged periods of malnutrition
will affect tissues and organs in relation to their energy and nutrient
requirements. During childhood, malnutrition may restricts organ
development, ex. of the brain and salivary glands, leading to a
diminished metabolic capacity.
During adulthood, when organ formation is complete, the effect of
malnutrition mainly related to cell function.
Pre-eruptive
The enamel is non-vital tissue in the sense that after eruption into
oral cavity it does not metabolize energy or nutrients or regenerate
subsequent to injury. However, the enamel, dentin and cementum are
highly dynamic tissue. They are exposed to a contact supply of ions of
both external (oral) and internal (plaque) origin. This may for example
lead to reprecipitation of minerals after PH induced mineral loss.
The tooth development includes the formation an organic protein
matrix, followed by mineralization and maturation. The process which
Preventive Dentistry
Fifth Grade
أ.م. ساهر سامي
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follows a well-defined chronological pattern involves several critical
stages.
Nutritional insults to protein synthesis or mineralization may disturb
the tooth structure as well as the form and position of the teeth, and
delay eruption into the mouth. Nutritional disturbance, such as
deficiencies, of calcium, phosphate, vitamin D, A and C and protein
energy, affected tooth tissue formation according to their general
biological role, impair enamel and dentin quality and increase caries
process (hypoplasia caused by vit. D, calcium deficiency).
Poor nutrition is only one of many causes of enamel developmental
defects. An enamel defect that is common in undernourished
communities is linear enamel hypoplasia (LEH). This occurs in primary
incisors and is characterized by a horizontal groove usually found on the
labial surface that becomes stained post-eruptively. Enamel hypoplasia
is related to disorders in calcium homoeostatic hypocalcaemia which is
common in under nutrition. Enamel hypoplasia increase caries
susceptibility.
Vitamin D deficiency has marked effect on the development of teeth.
It causes delayed development of teeth and that were poorly calcified
and poorly aligned, cause hypoplastic teeth which have more frequently
caries than non hypoplastic teeth. Mellanby and Carr reported that
hypoplastic teeth, thought to be a result of vitamin D deficiency, were
more frequently carious than non hypoplastic teeth.
Deficiency of protein-energy, vitamin A, zinc and iron during pre-
eruptive period are reported to cause increase caries development which
is claimed to be related to impaired tooth tissue. Under nutrition may
exacerbate the development of dental caries in three ways:
1. Development of hypoplasia which in turn increase caries
susceptibility.
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2. Salivary gland atrophy which result in reduced salivary flow and
altering its composition, this reduce the buffering capacity of the
saliva and increase the acidogenic load of the diet.
3. Delays eruption and shedding of the teeth which affect the caries
experience at a given age. Poorly nourished children have been
shown to have 2-5 less teeth erupted compared to well- nourished
children of the same age, also delayed exfoliation of primary teeth
and delayed eruption of permanent teeth, this may influence the
caries prevalence at given age.
Post- eruptive
Dental caries may develop in an individual if the three pre requisites,
cariogenic microorganisms, fermentable carbohydrates and susceptible
teeth, are present for a significant time. However, the disease
development depends on factors related to enamel de- and re-
mineralization and to colonization and metabolism of plaque
microorganisms.
The progress is affected in a complex way but important
determinants are saliva secretion and composition as well as availability
of calcium, phosphate and fluoride while solubility in saliva and plaque
fluid increase or decrease as PH is lowered or, normalized respectively.
This can be illustrated in a schematic model on caries risk in the
individual.
The salivary glands and saliva composition respond to changes in
diet. Malnourished cause salivary secretion rate, the activity of salivary
antimicrobial protein and the degree of protein glycosylation impaired.
These impairment may increase plaque formation which leads to
increase in caries prevalence.
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Malnutrition also causes increased caries susceptibility as a result of
systemic effect due to protein- energy deficiency in the early post
eruptive period.
Salley et al reported that dental caries was increased in hamsters
when they were fed a vitamin A-deficient diet. This was later confirmed
in the rat by Lynch et al.
Vitamin A deficiency is known to impair enamel and dentin
formation, impair immune function, reduce synthesis of specific
glycoproteins, such as a salivary bacteria – agglutinating glycoprotein
(BAGP) and in case of sever deficiency, to reduce salivary secretion
rate.
There is a wealth of evidence to show the role of dietary sugar in the
etiology of dental caries, sugar are undoubtedly the most significant
factor in the etiology of caries.
There is evidence to show that many groups of people with
habitually high consumption of sugar also have level of caries higher
than the population average, ex. include confectionary industry workers
and children with chronic diseases require long term -sugar containing -
medicines. Some medical conditions such as phenyl keton urea require
diet that are high in refined sugars.
Low dental caries experience has been reported in groups of people
who have a habitually low intake of dietary sugars, ex. children in
institutions where strict dietary regimens are followed and children with
hereditary fructose intolerance (HFI) which is a congenital deficiency of
fructose phosphate aldolase and consumption of fructose result in nausea
and, and children of dentists.
Despite reports by parent dentists of restricted intake of sugar by
their children, the low dental caries experience of these children cannot
be assumed to be due to low sugar intake alone as oral hygiene and other
preventive care are likely to be greater in these children.
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Frequency of sugar intake
Dental caries experience increases with increasing frequency of
intake of sugars. Some human studies show that the frequency of sugar
intake is a more important etiological factor for caries development than
the total consumption of sugar, as Holbrook et al (1995): 5 years old
children in Iceland reported 4 or more times intakes of sugar/ day or 3 or
more intakes of sugar between meals/ day have more caries than other
population.
Type of sugars (cariogenicity of sugars)
1. Monosaccharide include glucose and fructose which are found
naturally in fruits, vegetables and honey while galactose occur only
as a result of the breakdown during digestion of lactose.
2. Disaccharide: three main disaccharides are found in food include:
a. Sucrose (refined from sugar cane or sugar beets, it is a major part
of dietary sugar) formed when one molecule of glucose combine
with one molecule of fructose.
b. Lactose (milk sugar) is formed when a molecule of glucose
combine in a molecule of galactose. Lactose is the sugar found in
milk which is of animal rather from plant origin, and is the only
disaccharide obtained primarily from animal-based food.
c. Maltose is formed from a combination of two molecules of
glucose, it is mainly derived from hydrolysis of starch.
3. Polysaccharide. Unlike the monosaccharide and disaccharide, it is
not sugar. Polysaccharide are known as the complex carbohydrates
because their molecules are much larger and more complex than
those of mono and disaccharides. All polysaccharides are made up
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of many individual sugar molecules, usually glucose, joined
together. Four types of polysaccharides are nutritionally
significant: starch, glycogen, dextrin and fiber. The digestible form
includes starch which is composed of glucose found in rice,
potatoes, peas, about half of dietary carbohydrates are composed of
starch.
The cariogenicity of all are similar except for the lactose which has
lower.
The sweetness of sugars
All sugar contribute sweetness to food, but the relative sweetness
power varies among sugars. In general, the more easily the sugar
dissolves in water the greater is sweetness power. For example, fructose
is 75% sweeter than any other sugars. It is soluble in water, difficult to
crystallize, as a result it is expensive it is useful in syrup. At the other
extreme, the least sweet, least soluble sugar is lactose. Lactose is seldom
if ever used as sweetener because it almost impossible to dissolve in
food to be sweetened.
Factors affecting food cariogenicity
1. Type of carbohydrate
oral bacteria metabolize all mono and disaccharide sugars to produce
acid. Physical location of sugars in foods affect their cariogenicity,
sugars have been classified into intrinsic and extrinsic sugars.
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Classification of sugars for health purposes: Classification of the Department of
Health COMA UK, (1989), (Committee on Medical Aspect of Food Policy)
Intrinsic sugars are located within the cellular structure of the food and
are not thought to be harmful to the teeth.
Extrinsic sugars are located outside the cellular structure of the food and
include milk sugars and non-milk sugars (free sugars).
Milk sugars, when naturally present in milk or milk products, are not
harmful to teeth (as lactose).
Non-milk extrinsic sugars (free sugars) are harmful to teeth.
In term of dental caries, the intake and frequency of intake of non-milk
extrinsic sugar (free sugars) are need to be reduced.
Not harmful to teeth
Not harmful to teeth Harmful to teeth
Non-milk sugars: all sugars added by
manufacturer, cook or consumer
plus sugars present in fruits juices,
honey and syrups
Intrinsic sugar: sugars physically
located within the cellular
structure of fruits, vegetables and
cereals
Total sugars
Extrinsic sugars: sugars physically
located outside the cellular
structure of the food
Milk sugar: sugars naturally
present in milk and milk
products