A up to 85%. They are more prevalent in

A white spot lesion (WSL) due to orthodontic
treatment are essentially porous surface areas of enamel induced by carious
demineralization and they appear as white opaque spots on smooth surface of the
tooth.(1) Though they
rarely progress to a frank cavity, they are unesthetic and continue to be so
for years even after cessation of treatment.(2)

The prevalence of WSL in patients undergoing orthodontic
treatment has been reported to be 38% in 6 months and 46% in 12 months,
compared with 11% in control group.(3) Studies (4,5) have shown
that, compared with non-orthodontic patients, orthodontic patients are much
more vulnerable to the demineralization of enamel up to 85%. They are more
prevalent in patients with fixed orthodontic appliances than in those without
the appliance.(5) The increase in
occurrence of WSL during fixed orthodontic treatment is due to the irregular
surfaces of appliance components such as brackets, bands, wires, etc., which
create areas favorable for plaque accumulation and cause difficulty in oral
hygiene maintenance. In addition, the appliance limits the movement of the oral
musculature thereby decreasing the naturally occurring self-cleansing
mechanisms.(6) These WSLs can
be extremely difficult or even impossible to reverse and compromise the
esthetics. Therefore, it is within the ambit of
responsibilities of orthodontists to prevent or minimize the occurrence of WSL.

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Various methods have been suggested to reduce the
WSLs are (i) improving oral hygiene, (ii) minimizing the frequency of
carbohydrate intake, and applying topical anti-microbial mouthwashes and remineralizing
agents, specifically fluoride. The safety and
toxicity of fluoride use has been amply demonstrated(7), and various
means of topical application have been proposed including pastes(8), mouth rinses(9), and varnishes(10), but many
strategies require high concentration of fluoride and patient compliance to be
efficacious (11–13). Moreover, some
authors(14–16) pointed out that
using fluoride in high concentrations will cause remineralization mainly in the
superficial part of the WSL. This fluoride rich layer might prevent calcium and
phosphate from the saliva to penetrate and reach the deeper layers, thus
inhibiting deeper remineralization and limiting the cosmetic improvement of the
WSL(17,18).

Recently, Casein phosphopeptides amorphous calcium
phosphate (CPP-ACP) containing products 
were used extensively to prevent WSL (19–21). CPP-ACP  contains the active agent casein
phosphopeptide which is a nanocluster that binds to calcium and phosphate ions,
stabilizes it and localize them to the tooth surface in a slow-release
amorphous form, thus enhancing deeper remineralization of WSL which
fluoride cannot do (19).

Xylitol and other polyols have been used as a caries
preventive agent in form of gum and mints(22–24). Xylitol, a
polyol (a type of carbohydrate) that does not act as a metabolizing substrate
for Streptococcus mutans, can be used as a low-calorie sugar substitute to
prevent caries(24,25). It is
non-cariogenic and appears to have antimicrobial properties that help to
inhibit S.mutans attachment to the teeth (26).
The use of xylitol chewing gum can significantly reduce the risk of caries
compared with gums that contain sorbitol and sucrose (27). Chewing
xylitol gum thrice a day for 5 minutes has shown positive results (28).

One method of topical CPP-ACP application that does
not rely heavily on patient compliance is incorporating in sugar free chewing
gum, which is particularly appealing for noncompliant patients . Hence
incorporating CPP-ACP in Xylitol based chewing gum could prevent the degree of
demineralization better than other topical regimens.

Pain as a result of fixed orthodontic treatment is
well recognized and considered as one of the most common adverse effect  due to the movement of tooth (29). It has been
documented in the literature that pain occurs in 70 to 95 percent of children.
It begins  usually 2 to 3 hours after activating
the appliance and last up to 7 days, with maximum intensity in the first two days
(30–35). The reason is
possibly caused by the pressure, ischemia, and inflammation induced in the
periodontal ligament during tooth movement(36). Some recent
studies (37,38) suggested that
chewing gum may provide some pain relief and either eliminate or reduce the
need for other forms of analgesics. However there is an increased risk associated with gum chewing, that it
may increase the frequency of appliance breakages.

SPECIFIC OBJECTIVES AND HYPOTHESES

This clinical trial was planned as follows: the
primary objective was to evaluate the efficacy of use  of sugar free xylitol based chewing gum with
and without CPP-ACP  for a period of one
month in preventing the enamel
demineralization near the bracket margin using cross sectional
microhardness analysis; the secondary objective was to investigate the effect
of the use of the above chewing gums on reported pain for first two days after
separator placement and first seven days after the bonding and activating the full
maxillary and mandibular fixed appliances, and on the number of appliance
breakages (debonding of brackets or displacement of arch wires) over the period
of one month use of chewing gum.