A up to 85%. They are more prevalent in

A white spot lesion (WSL) due to orthodontictreatment are essentially porous surface areas of enamel induced by cariousdemineralization and they appear as white opaque spots on smooth surface of thetooth.(1) Though theyrarely progress to a frank cavity, they are unesthetic and continue to be sofor years even after cessation of treatment.(2) The prevalence of WSL in patients undergoing orthodontictreatment 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 shownthat, compared with non-orthodontic patients, orthodontic patients are muchmore vulnerable to the demineralization of enamel up to 85%. They are moreprevalent in patients with fixed orthodontic appliances than in those withoutthe appliance.

(5) The increase inoccurrence of WSL during fixed orthodontic treatment is due to the irregularsurfaces of appliance components such as brackets, bands, wires, etc., whichcreate areas favorable for plaque accumulation and cause difficulty in oralhygiene maintenance. In addition, the appliance limits the movement of the oralmusculature thereby decreasing the naturally occurring self-cleansingmechanisms.(6) These WSLs canbe extremely difficult or even impossible to reverse and compromise theesthetics. Therefore, it is within the ambit ofresponsibilities of orthodontists to prevent or minimize the occurrence of WSL.

Various methods have been suggested to reduce theWSLs are (i) improving oral hygiene, (ii) minimizing the frequency ofcarbohydrate intake, and applying topical anti-microbial mouthwashes and remineralizingagents, specifically fluoride. The safety andtoxicity of fluoride use has been amply demonstrated(7), and variousmeans of topical application have been proposed including pastes(8), mouth rinses(9), and varnishes(10), but manystrategies require high concentration of fluoride and patient compliance to beefficacious (11–13). Moreover, someauthors(14–16) pointed out thatusing fluoride in high concentrations will cause remineralization mainly in thesuperficial part of the WSL. This fluoride rich layer might prevent calcium andphosphate from the saliva to penetrate and reach the deeper layers, thusinhibiting deeper remineralization and limiting the cosmetic improvement of theWSL(17,18). Recently, Casein phosphopeptides amorphous calciumphosphate (CPP-ACP) containing products were used extensively to prevent WSL (19–21). CPP-ACP  contains the active agent caseinphosphopeptide which is a nanocluster that binds to calcium and phosphate ions,stabilizes it and localize them to the tooth surface in a slow-releaseamorphous form, thus enhancing deeper remineralization of WSL whichfluoride cannot do (19).Xylitol and other polyols have been used as a cariespreventive agent in form of gum and mints(22–24). Xylitol, apolyol (a type of carbohydrate) that does not act as a metabolizing substratefor Streptococcus mutans, can be used as a low-calorie sugar substitute toprevent caries(24,25).

It isnon-cariogenic and appears to have antimicrobial properties that help toinhibit S.mutans attachment to the teeth (26).The use of xylitol chewing gum can significantly reduce the risk of cariescompared with gums that contain sorbitol and sucrose (27).

Chewingxylitol gum thrice a day for 5 minutes has shown positive results (28). One method of topical CPP-ACP application that doesnot rely heavily on patient compliance is incorporating in sugar free chewinggum, which is particularly appealing for noncompliant patients . Henceincorporating CPP-ACP in Xylitol based chewing gum could prevent the degree ofdemineralization better than other topical regimens. Pain as a result of fixed orthodontic treatment iswell recognized and considered as one of the most common adverse effect  due to the movement of tooth (29).

It has beendocumented in the literature that pain occurs in 70 to 95 percent of children.It begins  usually 2 to 3 hours after activatingthe appliance and last up to 7 days, with maximum intensity in the first two days(30–35). The reason ispossibly caused by the pressure, ischemia, and inflammation induced in theperiodontal ligament during tooth movement(36). Some recentstudies (37,38) suggested thatchewing gum may provide some pain relief and either eliminate or reduce theneed for other forms of analgesics.

However there is an increased risk associated with gum chewing, that itmay increase the frequency of appliance breakages. SPECIFIC OBJECTIVES AND HYPOTHESESThis clinical trial was planned as follows: theprimary objective was to evaluate the efficacy of use  of sugar free xylitol based chewing gum withand without CPP-ACP  for a period of onemonth in preventing the enameldemineralization near the bracket margin using cross sectionalmicrohardness analysis; the secondary objective was to investigate the effectof the use of the above chewing gums on reported pain for first two days afterseparator placement and first seven days after the bonding and activating the fullmaxillary and mandibular fixed appliances, and on the number of appliancebreakages (debonding of brackets or displacement of arch wires) over the periodof one month use of chewing gum.