Download White Spot Lesions

summaries
annual session
White Spot Lesions
Demineralization and Remineralization
Presented by Eric Reynolds, AO, at the PCSO Annual Session, October 10, 2010.
Summarized by Dr. Bruce P. Hawley, PCSO Bulletin Northern Region Editor.
I
n Dr. Eric Reynolds’ home country of Australia, the
prevalence of dental caries is increasing in the 6- to
12-year-old child populations. Rather incredibly, oral
disease has moved in recent years from the seventh to the
second most expensive disease group in Australia, behind
cardiovascular disease. This change appears to be related
to increased consumption of flavored bottled beverages
(resulting in a higher level of sugar consumption), as well
as of bottled water, which does not include fluoride. Also,
plasticizers in bottles may have a metabolic effect on the
porosity of enamel.
MECHANISM OF DENTAL CARIES
Oral biofilms, which are really films of bacteria, take
on a low pH when mature, and on enamel this becomes
acidogenic. Glucose, fructose, and other fermentable
carbohydrates in the diet can also lower the pH level,
like sucrose.
The white spot lesion is completely reversible in the
initial stage, and of course our aim is to reverse the
demineralization process whenever possible. White spot
lesions can be detected in orthodontic patients as early
as four weeks into orthodontic treatment. The inverse
relationship between fluoride and caries is well known,
and the conversion of hydroxyapatite to fluorapatite is
desirable. Fluoride remineralizes predominantly at the
tooth surface, but remineralization at the subsurface body
of the demineralized lesion is needed to obtain general
improvement. Net remineralization to form fluorapatite
is believed to be calcium phosphate limited. The clinical
application of calcium phosphate is not particularly successful due to a low solubility factor. Insoluble calcium
phosphate is not easily applied or effectively located at
the tooth surface. In studies going back to the 1940s and
50s, milk and cheese have been shown to cause anti-
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cariogenic activity in animals and in situ caries models.
The anticariogenic agents in milk have been identified as
casein, calcium, and phosphate.
REMINERALIZATION
STUDIES
The combination of casein phosphopeptides (CPP) and
amorphous calcium phosphate (ACP) is now marketed
under the brand name Recaldent. CPP-ACP prevents
caries in rat models, with 55% caries reduction at the 1%
concentration level and 78% reduction at the 5% level.
The inhibition of strep mutans’ in vitro adherence to the
enamel surface by CPP-ACP has also been demonstrated.
Several studies have been carried out in Australia comparing the use of sugar-free gum vs. sugar-free gum with
CPP-ACP. In a randomized double-blind study of 12-yearolds in Melbourne, the experimental and control groups
chewed their gum three times daily for a 24-month study
period, with one of these daily sessions being supervised
in the school setting. The gum with Recaldent showed a
53% increase of carious lesions, and the control group
had a 20% decrease in lesions. This was true even in an
environment of fluoridated water and fluoride toothpaste.
CPP-ACP localizes calcium phosphate at the tooth surface
and is still present three hours following the chewing
session. In another randomized comparative mouthrinse
study, the incorporation of fluoride into plaque via combined 2% CPP-ACP plus 1100ppm fluoride was better
than with the fluoride only or the CPP-ACP alone, even
under acid-challenged conditions. On a microscopic level,
the defects do indeed get smaller, with acid-soluble apatite converting to fluorapatite. Intra- and inter-crystalline
defects begin repairing, with preferential binding of the
peptides to the faces of the hydroxapatite crystals.
PCSO Bulletin • WINTER
2010
summaries
annual session
CLINICAL USE
OF RECALDENT
In Australia, Recaldent is available commercially as
Tooth Mousse/MI, while in North America the only product with CPP-ACP is MI Paste (made by GC America).
The esthetic improvement of demineralization requires
the agent to get into the lesion. Dr. Reynolds likes first to
remove the protein, which blocks ion diffusion. Rather
than acid etching or microetching the tooth, he prefers
bleaching with hypochlorite, though peroxide bleaching can also be done. Improvement often takes weeks or
months to occur. There is enough clinical trial evidence
to advocate short-term as well as long-term CPP-ACP use
for caries prevention. Combined CPP-ACP with fluoride
results in a greater regression of white spot lesions over a
12-week period than CPP-ACP alone or fluoride application alone (comparable to the mouth rinse study above).
Subsurface remineralization is needed for post-orthodontic remineralization of white spot lesions.
U.S.) can be used in the morning and evening, with the
special CPP-ACP chewing gum after meals and snacks
(this gum is not available in North America).
Active demineralized lesions have a porous surface layer,
which will show a rapid visual change to air drying. Inactive lesions, conversely, have a mineralized surface layer,
and there is little to no change to air drying. In very severe
cases of demineralization, the use of bleaching, acid etch,
microabrasion, or strong acid application in the dental
chair followed by the application of MI Paste can help to
achieve an esthetic improvement.
S
It is possible to damage a demineralized area of enamel
adjacent to a bonded orthodontic bracket while debracketing, and remineralization before bracket removal has been
found to help reduce this damage in an in vitro study.
During active treatment, Dr. Reynolds will have the atrisk patient apply the Recaldent agent with fingers around
the wires and brackets before going to bed. During treatment or at deband, Tooth Mousse Plus (or MI Paste in the
WINTER
2010 • PCSO Bulletin
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