Preventive Dentistry
Systemic fluoride lec-4/Dr.Ayat Alshimmary
Introduction
The benefits from ingesting fluoride for controlling dental caries have
been suggested more than a century ago, Ingestion of excess fluoride, most
commonly in drinking-water, can cause fluorosis which affects the teeth
and bones. Moderate amounts lead to dental effects, but long-term
ingestion of large amounts can lead to potentially severe skeletal problems.
Paradoxically, low levels of fluoride intake help to prevent dental caries.
The dental effects of fluorosis develop much earlier than the skeletal effects
in people exposed to large amounts of fluoride.
Dental Fluorosis:
Dental Fluorosis is a developmental disturbance of dental enamel,
caused by excessive exposures to high concentrations of fluoride during
tooth development, leading to enamel with lower mineral content and
increased porosity.
Dental fluorosis is generalized within the dentition and over the entire
tooth surface which makes it easy to distinguish fluoride-induced enamel
changes from other enamel defects (non-fluoride origin) which may be
symmetrically distributed in the oral cavity. According to age and amount
of fluoride intake:
Infants and toddlers are especially at risk for dental fluorosis of the
anterior teeth since it is during the first 3 years of life that the permanent
front teeth are the most sensitive to the effects of fluoride (The central
incisor takes approximately 3 years to go through complete enamel
mineralization. Timing of chronic daily fluoride ingestion and the
corresponding dental fluorosis pattern that can be expected.). Fluoride
accumulates at the transition/ maturation stage of tooth development so that
the entire tooth surface can be affected. Children fed formula made with
fluoridated water are at higher risk to develop dental fluorosis.
1. Child from birth -3year takes excess fluoride from tap water used for
infant formula, Incisors, and first molars are most affected teeth.
2. Child from 3–6 years takes excess fluoride from early toothpaste use,
premolars, canines and second molars are most affected teeth.
3. Child from 0-6years takes excess fluoride from Fluoride supplements
and fluoridated water (drinking water >4 ppm fluoride), all teeth
affected.
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A direct relationship is present between dental fluorosis and level of F
ingested; the severity of dental fluorosis depends on:
1. Stage of tooth development.
2. Duration of exposure to fluoride.
3. Concentration of fluoride in foods and drinks.
Clinical Appearance and classification of dental fluorosis:
Dental fluorosis is characterized by staining and pitting of the teeth. In
more severe cases all the enamel may be damaged. It is difficult to
differentiate between dental fluorosis and other enamel disturbances.
Clinically dental fluorosis is characterized by a white opaque appearance
of the enamel, caused by increased subsurface porosity. The earliest sign is
a change in color, showing many thin white horizontal lines running across
the surfaces of the teeth, with white opacities at the newly erupted incisal
end. The white lines run along the ‘perikymata’, a term referring to
transverse ridges on the surface of the tooth, which correspond to the
incremental lines in the enamel known as Striae of Retzius .
At higher levels of fluoride exposure, the white lines in the enamel
become more and more defined and thicker. Some patchy cloudy areas and
thick opaque bands also appear on the involved teeth. With increased dental
fluorosis, the entire tooth can be chalky white and lose transparency.
With higher fluoride doses or prolonged exposure, deeper layers of
enamel are affected; the enamel becomes less mineralized. Damage to the
enamel surface occurs in patients with moderate- to- severe degrees of
enamel fluorosis. Teeth can erupt with pits, with additional pitting
occurring with post eruptive enamel fracture. In the individuals with
moderate dental fluorosis, yellow to light brown staining is observed in the
areas of enamel damage. In very severe cases, the enamel is porous, poorly
mineralized, stains brown, and contains relatively less mineral and more
proteins than sound enamel. Severely fluorosed enamel can easily chip post
eruptively during normal mechanical use. Although teeth with mild dental
fluorosis may be more resistant to dental decay because of the higher levels
of fluoride contained in the enamel surface, severely fluorosed teeth are
more susceptible to decay, most likely because of the uneven surface or
loss of the outer protective layer.
Dean in 1942 classified dental fluorosis as follow (Dean's Classification
of Dental Fluorosis): Criteria of index.
Normal 0 Enamel (translucent, smooth, glossy and creamy white color).
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Questionable (0.5) Enamel discolored (slight aberration from the
traclucency of normal enamel, ranging from a few white flecks to
occasional white spot.
Very mild (1) Small, opaque, paper, white area scattered irregularly
over the tooth, but not involving as much as approximately 25% of tooth
surface (no more than 1-2 mm of white opacity at the tip of cusps of
bicuspids or second molar.
Mild (2) The white opaque areas in the enamel of teeth are more
extensive, but not involve as much as 50% of tooth.
Moderate (3) All enamel surfaces of teeth are affected and subject to
attrition show wear, brown stains are a disfiguring feature.
Sever (4) All enamel surfaces of teeth are affected and hypoplasia is so
marked that general form of the tooth may be affected, discrete pitting,
brown stain wide spread teeth often present a corroded like appearance.
Pathogenesis of dental fluorosis:
Dental fluorosis is related to physiological conditions, including body
weight, rate of skeletal growth and remodeling, nutrition, and renal
function.it is widely known that F- affects the kinetics of bio
mineralization, triggering the incomplete mineralization of enamel crystals
and producing porous enamel-which is typical of dental fluorosis. Bone is
a reservoir of fluoride, as fluoride is incorporated in the forming apatite
crystals, and this ion can also be released from these crystals as bone
remodels. Therefore, rapid bone growth, as occurs in the growing child,
will remove fluoride from the blood stream, possibly reducing the risk of
dental fluorosis by lowering serum fluoride levels. Also, Nutrition is also
important for controlling the serum level of fluoride, as ions such as
calcium, magnesium and aluminum can reduce the bioavailability of
fluoride. A deficiency in these ions in food can also affect (enhance)
fluoride uptake.
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Treatment of Dental Fluorosis:
Type of fluorosis Treatment
Mild bleaching, to make the color of the
tooth surface uniform
Moderate Composite restorations combined
with micro abrasion or application
of aesthetic veneers
Sever prosthetic crowns
Incipient Caries and Fluorosis Diagnosis:
It is important to differentiate visually between incipient caries and
developmental white spot hypocalcifications (fluorosis) of enamel.
1. Dental fluorosis is common to observe and is unaffected by drying and
wetting. So, a white spot that is an incipient lesion will disappear upon
wetting and a hypocalcification will remain whether dry or moist.
2. White spot carious lesions usually occur around margins of gingival
(the favorable site for plaque deposition) Dental fluorosis and bone
fluorosis:
Skeletal or bone fluorosis affects children as well as adults. It does not
easily manifest until the disease attains an advanced stage. Symptoms of
bone fluorosis:
1. Early symptom includes sporadic pain, back stiffness, burning like
sensation, pricking, and tingling in the limbs, muscle weakness,
chronic fatigue, abnormal calcium deposits in bones and ligaments.
2. The advanced stage is osteoporosis in long bones and bony
outgrowths may occur. Vertebrae may fuse together and eventually
the victim may be crippled.
Generalized dental fluorosis of all the permanent teeth indicates that the
bone is potentially a major source of the excess fluoride that causes dental
fluorosis in children. People ingesting fluoridated water for many years
have higher levels of fluoride in their entire skeletal systems.
