Effect of topical fluoride gel and fluoride varnish in the prevention of white spot lesions in patients undergoing fixed orthodontic treatment: An in vivo study

INTRODUCTION

In contemporary fixed orthodontic therapy, multibracket appliances are used as literal handles over the tooth surface enamel to bring about efficient tooth movement. Fixed orthodontic appliances comprising bands, brackets, wires, and ligatures increase the retention of debris and plaque on smooth surfaces of the tooth.^[1] One of the common side effects of this is the formation of unesthetic incipient carious lesions, known as white spot lesions (WSLs).

The pathogenesis and appearance of WSLs depend on subsurface events of demineralization and remineralization that are directly related to variation in plaque pH. When low pH is maintained for a longer period, it leads to increased demineralization and only short intervals of remineralization. Spontaneous remineralization occurs because of the simultaneous action of salivary minerals and fluoride from therapeutic intervention.^[2] The prevalence of WSLs during orthodontic treatment varies largely, from 38% to 46% from 6 to 12 months post orthodontic treatment.^[3] This increased prevalence of WSLs could jeopardize the success of orthodontic treatment.

Considering evaluation of orthodontically induced WSLs, various methods had been suggested in literature including,^[3-5] in vitro evaluation through light-induced fluorescence, polarized light microscopy, scanning electron microscopy or clinical evaluation techniques such as laser fluorescence method, use of sharp explorer tip, and most commonly used direct visual inspection method along with photographic records. The usefulness of the laser fluorescence technique is well acknowledged in the literature. It is also important to differentiate between developmental enamel lesions and orthodontically induced WSLs.^[4]

The treatment of WSLs includes various methods for both preventing demineralization as well as promoting remineralization of existing lesions. Prevention is better than cure, hence preventive steps and procedures take more importance due to the challenges involved in the treatment of already existing lesions. The preventive steps/procedures comprise oral health instructions, patient education, routine professional oral hygiene visits, and the application of fluoride protection.

Optimal protection with fluoride warrants good patient compliance, dearth of patient cooperation is an important aspect of orthodontic care. To overcome this challenge, there are multiple methods available that do not necessitate patient compliance for reducing enamel demineralization.^[6] For non-compliant patients, suitable preventive agents, such as topical fluoride application by professionals can help in decreasing the demineralization of enamel surrounding orthodontic brackets.^[7,8]

Professionally applied fluoride varnishes and fluoride gels are easy to use and studies have consistently reported a 30– 50% decrease in emerging enamel lesions following their applications.^[9] A recent randomized controlled trial and another systematic review evaluated the effect of topical fluoride and concluded a statistically significant reduction of dental caries in permanent teeth.^[10,11] However, these studies also suggested the requirement of additional research on the topic.

Keeping the various advantages and disadvantages of both fluoride gels and varnishes and the lacunae of evidence in the literature of their success potential, a study was designed to evaluate the effect of topical fluoride gel and fluoride varnish on enamel mineralization during orthodontic treatment.

The null hypothesis for the study was: There is no difference in the efficacy of topical fluoride gel and fluoride varnish in preventing the development of WSLs on enamel in patients undergoing orthodontic treatment.

MATERIALS AND METHODS

This prospective study was carried out in the Department of Orthodontics and Dentofacial Orthopedics of a tertiary care Government hospital, providing free treatment to patients. The study sample consisted of 60 adult patients with permanent dentition scheduled to undergo fixed orthodontic treatment, fulfilling the following inclusion and exclusion criteria.

Methodology

On commencement of the study all selected patients received a professional sitting of oral prophylaxis (scaling and polishing) and standard oral hygiene instructions were given to every patient.

A split-mouth study technique was adopted to conduct this study. Each of two interventions, that is, topical fluoride gel (Fluocal, Septodont, Septodont Healthcare India Pvt. Ltd. C-1/2, MIDC Industrial Area, Maharashtra, India) and topical fluoride varnish (Fluor Protector, Ivoclar Vivadent, 175 Pineview Drive Amherst, NY 14228 USA) were randomly assigned to either the right or left halves of the dentition utilizing chit system, which included one-half of the maxillary dentition and one-half of the mandibular dentition in all subjects. Central incisor, canine and second premolar in each quadrant were selected as sample teeth for evaluation, being anterior, middle, and posterior teeth respectively in the dental arch. The armamentarium used in the study is shown in the picture [Figure 1].

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Figure 1:

Study Armamentarium (a) Lip and cheek retractor (b) Application trays for fluoride gel (c) Dappen dish with brush applicator sticks for fluoride varnish (d) Fluocal fluoride gel (e) Fluor Protector fluoride varnish (f) DIAGNOdent pen 2190 with autoclavable tips (g) Magnifying surgical loupe.

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The selected patients were subjected to standard orthodontic bonding procedures and measurements for enamel mineralization of sample teeth were obtained T0 (at the time of bonding/baseline), using the following two methods [Figure 2]:

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Figure 2:

DIAGNOdent scoring.

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Evaluation using laser fluorescence

Mineralization of all sample teeth (maxillary and mandibular central incisors, canines, and second premolars) was measured with a DIAGNOdent pen 2190 (Kaltenbach and Voigt GmbH, KaVo Dental GmbH, Biberach). The laser was calibrated for each patient according to the manufacturer’s guidelines and readings were taken at 04 labial sites: M-mesial, D-distal, O-occlusal, and G- gingival. Each 1 mm distance from the bracket. Laser fluorescence from the wand tip is reflected off the tooth surface to measure the mineralized content of the enamel, higher readings indicate greater demineralization. Usually, DIAGNOdent score for healthy tooth substance = 10–12, initial demineralization = 13–24, strong demineralization = >25, However, any readings from 2 to 9 can signify incipient decalcification.^[13]

Evaluation by direct visual observation under magnification

Using surgical loupe for visual evaluation under magnification (×2.5), decalcification scores in each of the four areas (gingival, occlusal, mesial, and distal edges of the bracket) on all sample teeth were recorded as per the following index:

Enamel decalcification index

Score 0 = no decalcification.

Score 1 = mild, but clinically visible decalcification affecting <50% area.

Score 2 = moderate to severe decalcification more than 50% area.

Score 3 = decalcification covering the complete area or surface breakdown and caries.

Total score per tooth was calculated by adding up individual area scores for each sample tooth.^[14] After baseline observations were recorded on the day of bonding T0, the dental arches were isolated for following topical fluoride intervention [Figure 3].

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Figure 3:

Split-mouth application of fluoride gel and varnish.

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Fluoride gel half (A) - topical fluoride gel was applied to the enamel around the brackets of one-half of the maxillary dentition and one-half of the mandibular dentition as per the manufacturer’s recommendations at T0 under controlled clinical settings, high volume suction utilizing split carrier gel trays.

While in, fluoride varnish half (B) - topical fluoride varnish was applied to the other remaining half of maxillary and mandibular dentition as per manufacturer’s recommendations at T0 under controlled clinical settings, high volume suction utilizing applicator tips. In follow-up visits, enamel demineralization was evaluated using above mentioned two methods (laser fluorescence and direct visual observation) at T1 = at 3 months of fixed orthodontic therapy, T2 = at 6 months of fixed orthodontic therapy.

The direct visual observation and readings of Laser fluorescence were recorded after cleaning the labial surfaces of all teeth using a brush mounted on a low-velocity handpiece.

RESULTS

Analyzing the data considering in maxillary and mandibular arches, all selected teeth and all quadrants combined following are the results.

DISCUSSION

WSLs are incipient enamel caries and one of the clinically significant side effects of fixed orthodontic therapy. Preventing the development of these lesions would be the best possible strategy to deal with WSLs. Various preventive measures have been suggested in the past; however, the most commonly used prevention protocol includes the use of topical fluorides in their different forms, apart from patient education and oral hygiene practices.^[15,16]

The present split-mouth study involved the application of two different forms of fluoride, that is, fluoride in Gel form (Fluocal, Septodont [active fluoride nearly 11,900 ppm]) and Varnish form (Fluor Protector, Ivoclar Vivadent [active fluoride nearly 10,000 ppm]). As both forms of fluoride are professionally applied, they do not rely on patient compliance and also deliver relatively high fluoride concentrations.^[10] Most studies suggest that biannual/annual applications are effective in the prevention of demineralization.^[10,13,17]

WSLs cause changes in the fluorescence value of enamel and when a clean enamel surface is subjected to irradiation of a specific wavelength, tooth structure emits fluorescence related to the amount of mineralization. This phenomenon was utilized for the evaluation of demineralization in the laser fluorescence method (DIAGNOdent pen 2190 [KaVo]), which functions at 655 nm wavelength. Minimal or no fluorescence was shown on clean and healthy enamel surfaces. Whereas, demineralized enamel surface showed increased fluorescence proportionate to the amount of demineralization. DIAGNOdent is a valuable tool to evaluate WSL.^[13,16]

Another method used for evaluation of WSLs was a clinical visual examination that has been used classically in various studies, Geiger et al. have given basic scoring for assessing the severity of acquired WSLs.^[18] The present study employed the Enamel Decalcification Index^[14] as recommended by Banks and Richmond, along with surgical loupe magnification (×2.5) for better visual inspection around the orthodontic bracket. The baseline evaluation of DIAGNOdent and visual scores showed no significant difference between the two groups studied (Gel and Varnish). This suggests that both the groups were comparable and there was no selection bias in the present study.

The results of inter-group comparisons in the present study showed that DIAGNOdent and visual scores are significantly higher in the gel group than in the varnish group both at 3-months (T1) and 6-months (T2). These results indicate lesser demineralization with varnish application compared to the gel application. However, results of intragroup comparisons for both gel and varnish groups showed that DIAGNOdent and visual scores are significantly higher at T1 and T2 compared to baseline (T0) values, also the scores at T2 are significantly higher compared to T1. Indicating that demineralization occurred in both the groups, and it increases with the duration of fixed orthodontic treatment after initial one-time baseline application at the time of bonding. Adriaens et al.^[19] showed high effectiveness of Fluor Protector fluoride varnish for preventing WSL; the present study also indicates that Fluor Protector fluoride varnish is highly effective in reducing enamel demineralization.

A report from American Dental Association which was based on various systematic reviews and clinical trials related to in-office fluoride interventions, suggested that half-yearly fluoride varnish is very effective in reducing caries incidence.^[20] Similarly, Hawkins and Locker^[21] also recommends the six-monthly application of professionally applied topical fluoride. Agrawal et al.^[22] concluded that the biannual application of APF gel significantly reduces enamel demineralization. The results of the present study corroborate with the findings of the above-mentioned studies and both Fluocal Gel and Fluor Protector varnish reduces the caries incidence during the first 6 months after one-time application.

Comparative evaluation between the fluoride gel and fluoride Varnish was carried out by Seppa et al.^[23] in terms of caries preventive effect of both the agents. They concluded that the difference between varnish and gel was statistically not significant and larger studies were required for comparative evaluation. In the present study, a significant difference between both the group in terms of reducing demineralization is evident. It may be because of the sensitivity of methods used for the evaluation of WSLs.

As evident with the results and also during the examination, laser fluorescence is more sensitive compared to visual examination under magnification as a detection method for enamel demineralization. DIAGNOdent was able to detect changes on the enamel surface and the demineralization scores were reproducible. Findings of DIAGNOdent were corroborated with the visual findings of WSLs. However, many incipient lesions were detected by DIAGNOdent that were clinically not visible even under ×2.5 magnification. The findings of the present study are in tandem with the findings of Aljehani et al.,^[24] they reported a high correlation between DIAGNOdent and visual findings and concluded that DIAGNOdent is a valuable, objective and quantitative detection tool whereas visual examination is a subjective method. DIAGNOdent can be used for quantification of demineralization and to find out long-term changes with WSL prevention protocols.

CONCLUSION

This prospective clinical study was conducted to evaluate the efficacy of topical fluoride gel and fluoride varnish in preventing the development of WSLs on enamel in patients undergoing orthodontic treatment using PEA by testing the null hypothesis that there is no difference in the efficacy of two materials being tested. The following conclusions can be drawn from the study:

1. The null hypothesis is rejected as there is a significant difference in the two materials studied to prevent the development of WSLs.

2. Fluoride varnish (Fluor Protector) is more efficacious than fluoride gel (Fluocal) in reducing enamel demineralization, but both the agents could not completely eliminate chances of enamel demineralization.

3. Initial application of fluoride varnish around the orthodontic bracket at bonding appointment may be recommended for every patient as a standard prophylactic procedure to reduce the chances of development of WSLs.