Prospective Randomized Controlled Trial for Prevention of Demineralization During Fixed Orthodontic Treatment

Overview

Treatment with fixed orthodontic appliances is often associated with pain, which poses great challenges in the efficient brushing of the teeth thus making the teeth more vulnerable to plaque formation. Treatment duration with fixed orthodontic appliances usually extends to 18 months or even longer in some cases. This prolonged vulnerability to plaque formation frequently leads to demineralization of teeth. There is also an increase in the number of plaque retentive sites due to the fixed appliances, leading to a rapid change in the bacterial composition of the dental plaque, particularly in the number of acidogenic bacteria. The resulting enamel decalcification is also known as white spot lesions (WSLs), which is an early sign of demineralization of enamel. Enamel WSLs (EWSLs) can be observed even as early as four weeks from the start of fixed orthodontic treatment. The occurrence of EWSLs adjacent to the orthodontic brackets ranges from 15 to 85%. The incidence of EWSLs development is higher in orthodontic patients as compared to the development of similar lesions in non-orthodontic patients. These EWSLs are not aesthetically pleasing and is certainly unacceptable when it develops during fixed orthodontic treatment that is usually performed in patients who often seek such treatment to improve their aesthetics. Additionally, even if the outcome of fixed orthodontic treatment is superior from well-aligned teeth, aesthetics can be greatly compromised with EWSLs. Therefore, the prevention of such lesions is an important concern for orthodontists. Though professionally applied topical fluoride varnish helps in remineralization of EWSLs, an adequate supply of calcium and phosphate ions is essential for remineralization. Therefore, EWSLs on maxillary teeth could be prevented and remineralized by the use of advanced novel topical fluoride varnish with added calcium and phosphate-based delivery system.

Fluoride is proven caries preventive and therapeutic agent. It helps in the remineralization of early enamel caries lesions and subsequently increases its resistance to dissolution by acids produced by cariogenic microflora. Topical fluoride varnish was introduced in the 1960s. The Food and Drug Administration (FDA) in the USA approved the use of fluoride varnishes for dentistry in 1994 and presently fluoride varnish is the most commonly used professionally applied topical fluoride agent. The most popular topical fluoride varnish is Duraphat®, which contains 5% NaF varnish (2.2% Fluoride). The greatest advantage of topical fluoride varnish is its ability to adhere to tooth tissues for a longer period of time that enables improved fluoride uptake. It allows the continuous release of fluoride ions into enamel, dentine, plaque, and saliva. Additionally, the application of topical fluoride varnish is a simple procedure and does not require great patient co-operation. Topical fluoride varnish application has been reported to exhibit substantial caries inhibiting effect in both permanent and primary teeth. Among the various forms of fluoride products, such as gels, varnishes, foams, mouth- rinses, and toothpastes, varnishes do not rely on patient compliance and cooperation. The major advantage of varnishes is high retention followed by gradual release of fluoride over an extended time period, which leads to low concentrations in the liquid plaque-enamel interface. The use of fluoride diminishes demineralization and promotes remineralization, thereby balancing the process of caries formation. A recent Cochrane review has revealed moderate evidence for the prevention of EWSLs during fixed orthodontic treatment by fluoride varnish application every six weeks at the time of orthodontic review, but this finding is based on a single study. Therefore, the quality of the evidence found is moderate and the review recommendations state that additional well- conducted research is required in this area. Caries preventive and inhibiting effect of topical fluoride therapy depends on an adequate supply of calcium and phosphate ions. Though calcium and phosphate ions are supplied naturally by saliva, the concentration of such ions is low (even lower in patients suffering from reduced salivary flow). Low concentration of salivary calcium and phosphate ions leads to a mineral deposition only at the surface of the enamel as a result of a low ion concentration gradient. The deposition of minerals at the surface of enamel alone may not improve the structural properties of the deeper part of the early-stage or incipient caries lesions. This has led to the introduction of calcium phosphate-based delivery systems containing high concentrations of calcium phosphate such as tri-calcium phosphate (TCP). Tri-calcium phosphate (TCP) is a product resulting from ball milling beta-tri-calcium phosphate with sodium lauryl sulphate. ClinproTM white varnish (3M ESPE, St Paul, MN, USA), which contains TCP and NaF, is a commercially available topical fluoride varnish, which claims that the protective fumaric acid barrier facilitates co-existence of calcium and fluoride ions, however, during storage, the unwanted reaction between the ions is prevented. The protective barrier breaks upon contact with saliva, releasing the ions for effective remineralization of the tooth. At present there is no clinical study to prove the superior EWSLs-preventive effect of this newer NaF varnish with TCP when compared to conventional topical NaF varnish in patients undergoing fixed orthodontic treatment.