Clinical effect of a fluoride-releasing and rechargeable primer in reducing white spot lesions during orthodontic treatment

Introduction

This study was performed to test the long-term efficacy of a highly filled resin primer (38%) that has superior fluoride release and recharge ability.

Methods

Sixty patients were divided into 2 groups. In group 1, adhesive-coated brackets (APC Plus Victory series, 3M Unitek, Monrovia, Calif) were bonded with a fluoride-releasing and rechargeable primer (Opal Seal; Ultradent, South Jordan, Utah). In group 2, the same adhesive-coated brackets were bonded with a conventional primer (Transbond XT Primer; 3M Unitek, Monrovia, Calif). In group 1, a blacklight source was used to examine the amount of adhesive remaining on enamel surfaces. This primer has a fluorescing agent and fluoresces under blacklight. If there was a lack of primer on any part of the enamel surrounding the brackets, new primer was added. Digital images of each tooth were taken to score and measure the area of white spot lesions (WSLs) after orthodontic treatment. DIAGNOdent (DIAGNOdent pen; KaVo Dental, Biberach, Germany) measurements were also used to assess WSLs after bracket removal.

Results

The WSL rate was 26.9% for group 1 and 29% for group 2. There was no significant difference between the WSL scores of the groups; however, a significant difference was observed in the DIAGNOdent measurements between the groups. According to area measurements of the lesions, there was no significant difference between the groups.

Conclusions

The results of this long-term clinical study indicated that fluoride-releasing primer has no significant advantage in reducing demineralization over the control primer over the full orthodontic treatment period.

Highlights

  • Adhesive-coated brackets were bonded with a fluoride-releasing, rechargeable primer and sealant.

  • Demineralization and white spot lesions (WSLs) were assessed and compared with that of a control group.

  • The fluoride-releasing primer did not significantly reduce demineralization or WSLs.

Enamel demineralization, called white spot lesions (WSLs), is 1 of the most significant risk factors of orthodontic treatment. When oral hygiene is poor and there has been prolonged plaque accumulation around the brackets, protection of the enamel surface is a challenge for orthodontists. The prevalence of these enamel lesions in patients after fixed orthodontic treatment ranges from 2% to 96%.

Patient education and motivation is the most important method for preventing WSL formation. Fluoride toothpaste, mouth rinses, gels, and varnishes are some of the other methods of preventing WSLs. Applying fluoride to orthodontic bonding agents is also a popular method. In recent years, new adhesives and primers that contain and release fluoride have entered the orthodontic market. Previous studies showed that these fluoride-containing glass ionomer and composite adhesives decrease enamel decalcification around orthodontic brackets. However, the fluoride-containing and releasing adhesives and primers show their highest levels during the first weeks after bracket bonding. Therefore, a fluoride-containing material would not have a significant preventive effect on enamel demineralization if it was used just once. Fluoride-releasing materials should be applied repeatedly to increase their effectiveness.

One of the recent primers releases fluoride filled with 38% glass ionomer fillers, coupled with nanofillers for long-lasting strength (Opal Seal, Ultradent Products, South Jordan, Utah). This primer also has recharge ability, and this feature gives the clinician the chance to apply it repeatedly to increase its effectiveness. However, the clinical studies about this material are limited and were only conducted over a few weeks or months after brackets were bonded to the oral cavity. The long-term clinical efficacy of this primer is unclear.

Therefore, the aims of this clinical study were to (1) compare the WSL prevention effect of this primer and a conventional one during full orthodontic treatment, and (2) evaluate the clinical survival of brackets bonded with Opal Seal and conventional primer.

Material and methods

Approval was obtained from the Regional Ethics Committee of Ondokuz Mayıs University for this long-term clinical study (OMUKAEK 2015/201). Sixty patients were divided into 2 groups. There were 30 patients in group 1 with a mean age of 15.8 years and 30 patients in group 2 with a mean age of 14.9 years. The sample sizes of the groups were calculated according to a past study. They were selected according to the following statements: (1) no visible enamel demineralization or restoration on the buccal surfaces of the teeth, (2) no morphologic crown anomalies, (3) permanent dentition, and (4) no physical disability preventing effective tooth brushing.

Special care was taken to include patients with similar characteristics in both groups. Age, sex distribution, amount of crowding, number of patients who needed extraction for orthodontic treatment, salivary flow, and buffer capacity of the patients were determined to establish any differences between the groups before the orthodontic treatment. All patients had normal salivary flow rates (>1.0 mL/min) and normal pH measurements (6.7-7.7).

In both groups, all teeth had been cleaned and polished before the fixed appliances were bonded. Thereafter, the teeth were acid-etched with 32% phosphoric acid (Scotchbond Universal Etchant, 3M Dental Products, Germany) for 15 seconds, rinsed, and dried. In group 1, a thin layer of Opal Seal primer was applied to the etched enamel surface. Before bracket bonding, the primer was cured for 5 seconds with a light-emitting diode unit (Elipar S10; 3M Unitek, Monrovia, Calif). Adhesive-coated brackets (APC Plus Victory series, 3M Unitek, Monrovia, Calif) were used for all patients. The adhesive remaining around the bracket margins was removed, and all bonding procedures were performed by the same investigator (S.C.). The patients were recalled every 4 weeks during the orthodontic treatment. This primer was designed for re-application during orthodontic treatment. Opal Seal has a fluorescing agent and fluoresces under blacklight. Shining a UV blacklight on the enamel surface will indicate the presence of the sealant ( Fig 1 ). If there was a lack of primer on any part of the enamel surrounding the brackets, new primer was added.

Fig 1
A, The color change and uniform coating of the adhesive; B, Opal Seal fluoresces under blacklight.

In group 2, a conventional primer (Transbond XT Primer; 3M Unitek, Monrovia, Calif) was applied to the etched enamel surfaces. The same adhesive-coated brackets were bonded, too. These adhesive-coated brackets have a pink, color-changing adhesive. This color change and uniform coating of adhesive on each tooth allows easy flash clean-up.

The same investigator gave brushing training and oral hygiene instructions to the patients in both groups. The patients were reminded of these suggestions if their oral hygiene motivation decreased during the orthodontic treatment.

After the fixed orthodontic appliances had been removed, and adhesive remaining on enamel surfaces was cleaned with a tungsten carbide burr. Digital images of each tooth were taken to score and measure the area of WSLs before and after orthodontic treatment (EOS 600D, Canon Macro Ring Lite MR-14EX flash, 100 mm f: 2.8 macro lens; Canon, Tokyo, Japan). All photographs were taken directly without a mirror ( Fig 2 ).

Fig 2
Digital images of each tooth were taken to score and measure the area of WSLs.

All separate digital images were examined, and the presence and severity of WSLs were recorded according to a modified WSL scoring system as follows: (0) no WSLs, (1) slight WSLs, (2) severe WSL formation, (3) WSLs with cavitation.

After the fixed orthodontic attachments had been removed, the buccal surfaces of the teeth in both groups were dried and then measured with a DIAGNOdent device (DIAGNOdent pen; KaVo Dental, Biberach, Germany). The buccal probe was used; every tooth was tested twice, and the mean value was recorded. Scores of 0-12 show normal and healthy enamel, 13-24 suggest incipient caries, and 25 or above indicate dental caries.

The areas of the WSLs were also measured. For this purpose, mesiodistal lengths of the teeth with WSLs were measured from orthodontic models, and images were scaled according to these measurements. The areas were calculated by open source software (ImageJ, version 2.0, National Institutes of Health, Bethesda, Md) ( Fig 3 ).

Fig 3
The areas of WSLs were calculated with the software.

The patients were recalled every 4 weeks during the orthodontic treatment for a routine appointment, and the clinical failure rates were recorded. Only first-time bracket failures were recorded. New brackets were bonded with the same bonding protocols as used at the beginning of the treatment according to the investigation groups. However, new brackets were not included in the bond failure part of the study.

Two patients in each group did not attend the appointments regularly during the orthodontic treatment, and the final data were analyzed with 28 participants per group. All the statistical analysis was performed using SPSS statistical software (version 23; IBM, Chicago, Ill). The paired sample t test and Mann-Whitney U test were used according to the distribution of the data. Categorical data were assessed using Pearson chi-square test. Differences in bracket survival according to primer type, patient’s sex, and dental arch and tooth type were evaluated with Kaplan-Meier and log-rank tests. The level of significance was set at P < 0.05.

Results

The distributions of the sample characteristics of the groups are given in Table I . The patients were similar in the 2 groups, and there was no significant difference in patients’ ages, amount of crowding, duration of treatment, salivary flow, or buffer capacity ( Table I ). After the fixed orthodontic treatment, 305 of the 1090 teeth showed WSLs according to the digital images. The WSL rate was 26.9% for the Opal Seal group and 29% for the control group. There was no significant difference between the WSL rates of the groups.

Table I
The distributions and comparisons of the sample characteristics of the groups
Characteristics Opal Transbond Test statistics (t) P
Age (y) 15.89 ± 2.86 14.96 ± 1.43 1538 0.132
Treatment duration (mo) 12.82 ± 3.53 13.75 ± 4.77 –0.828 0.411
Amount of crowding (maxillary) 3.9 ± 1.83 3.71 ± 1.64 0.415 0.679
Amount of crowding (mandibular) 3.03 ± 1.6 2.82 ± 1.56 0.482 0.632
Salivary pH 6.99 ± 0.18 7.01 ± 0.22 –0.468 0.642
Salivary flow rate (mL/dk) >1 >1
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Jan 7, 2020 | Posted by in Orthodontics | Comments Off on Clinical effect of a fluoride-releasing and rechargeable primer in reducing white spot lesions during orthodontic treatment
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