Rechargeable Primers and White Spot Lesions

Enamel demineralization or white spot lesions are one of the most significant risk factors during orthodontic treatment. It’s prevalence in patients after fixed orthodontic treatment ranges from 2% to 96%! It is a problem that is often swept under the carpet (bracket) and subject to the blame- game!

We know that fluoride ions can prevent white spot lesions from forming, by modifying bacterial metabolism, inhibiting the production of acids, decreasing demineralization and, promoting remineralization.

One of the recent primers introduced releases fluoride filled with 38% glass ionomer fillers, coupled with nanofillers for long-lasting strength (Opal Seal, Ultradent Products, South Jordan, Utah). It also has rechargeability, a feature that gives the clinician the chance to apply it repeatedly to increase its effectiveness.

Therefore, a fluoride-containing material would probably not have a significant preventive effect on enamel demineralisation if it was used just once.

In order to increase their effectiveness, they have to be applied repeatedly.

The article that we are going to discuss in the following post proved to be highly informative and will be retained very well in our multi-strand wired brains (All puns intended!)

Clinical effect of a fluoride-releasing and rechargeable

primer in reducing white spot lesions during orthodontic treatment

SecilComert and Abdullah Alper Oz

Am J Orthod Dentofacial Orthop. 2020 Jan;157(1):67-72.


Click on this link to access the article:

​A little information about the authors who wrote this article

Dr. Abdulla Alper Oz from the Department of Orthodontics and Dr.SecilComert, from Pediatric Dentistry work in the University of Ondokuz Mayıs

Dr. Oz is currently an associate professor and has 19 publications and 77 citations.

(Source: Researchgate)

This study compared the effect of the rechargeable primer with a conventional one in terms of prevention of WSL during orthodontic treatment, and also evaluated bond failure.

Method/Protocol- This was a prospective study with two groups- one to which ‘Opal Seal’ was applied and the other to which ‘Transbond’ was applied. Thirty patients were present in each group.

Age, sex distribution, amount of crowding, salivary flow, and buffer capacity of the patients were determined to establish any differences between the groups before the orthodontic treatment.

The patients were recalled every 4 weeks and the primer was designed for re-application during orthodontic treatment.

‘Opal Seal’ has a fluorescing agent, which helped identify the lack of primer on the tooth surface surrounding the brackets. The investigators used a UV black-light and, the new primer was added.

DIAGNOdent and digital images were used to measure the area of the white spot lesions before and after treatment.

Result ​According to the measurements taken from digital photographs, there was no significant difference between the groups. (Transbond and Opal Seal)

However, a significant difference was observed in the DIAGNOdent measurements between the groups. (Transbond and Opal Seal)

Thus, the Opal Seal group showed fewer WSLs than the Transbond group.

The number for initial demineralization was 7 (1.3%) for group 1 and 21 (3.9%) for group 2.

There was only 1 (0.2%) caries lesion in group 1, whereas there were 7 (1.3%) in group 2.

No significant difference was observed in the white spot lesion area and bracket failure rates between the primers.

Conclusions - There was no significant difference between the fluoride-releasing and rechargeable primer and the control primer.

Our thoughts

Now, we know that we may not be highly qualified to just give out opinions, but as part of our training, we are required to think out of the box!

So, as students who are just beginning to get exposed to the “bonding” world, our interest was piqued and we had a few questions.

- Would assessing the bond strength of the brackets have added greater value to the study?

- What was the area in which the primer was applied? Was it the entire tooth or only a part of it?

- What about the effects of scaling and cleaning on primer adhesion?

- What was the fluorescing agent?

- Was there any fluorosis?

- We also thought that the new brackets could have been included for bond failure assessment.

-We also wondered what protocol was followed for applying the primer? (An ideal time period of 6 months has been recommended by Proffit, before application of the primer)

This study is certainly one of a kind as it assesses the long term benefits of the primer which has not been done previously.

First of all, the use of a fluorescing agent totally grabbed our attention as it also happens to be an effective patient education tool!

The very idea behind the study- a rechargeable primer was new and highly relevant.

We thank the authors for pointing out that assessment through visual examination (by magnifying clinical photographs) was associated with a higher rate of White spot lesions than assessment with DIAGNOdent.

Lastly, of course, white spot lesions are real, problematic, and definitely require our attention.


Now if we had to design a similar study, how would we do it?

We could use a split-mouth design with 60 healthy patients after sample size calculation by using the current study as a reference. Although this has been avoided by the authord due to possibilities of cross contamination, a split mouth design may allow each patient to be their own control.

(To read about how the quality of split-mouth trials have changed over the years, click here- )

  • Two groups- conventional primer and rechargeable primer.
  • Random allocation to either the right or the left side of each jaw.
  • The conventional primer would be applied from incisors to molars on one side and the rechargeable primer would be applied on the contralateral side.
  • The teeth would be then assessed and compared for areas of white spot lesions using Diagnodent and digital images.
  • Additional assessment of any bracket failure.

Challenges- The treatment duration would not be the same for every patient. A cross over effect could happen in split-mouth study.

Thank you for taking the time to read.

Contributors to this post

Dr. Nayanika MDS Dr. Hita (II year postgraduate)