One common negative side effect of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets, particularly in patients with poor oral hygiene. Bio-available minerals from cement containing amorphous calcium phosphate (ACP) might facilitate remineralization and inhibit lesion development. Our objective was to compare the potential of ACP-containing resin cement, fluoride varnish, resin sealer, and MI Paste (GC America, Alsip, Ill) under similar in-vitro conditions to prevent incipient caries lesions next to brackets on teeth.
One hundred extracted premolars were randomly allocated to 5 groups (n = 20). Brackets were bonded with ACP cement (Aegis-Ortho, Bosworth, Skokie, Ill), resin (Transbond XT [3M Unitek, Monrovia, Calif], control), or resin followed by application of fluoride varnish (Vanish, 3M, St Paul, Minn), resin sealer (Pro-seal, Reliance Orthodontic Products, Itasca, Ill), or casein phosphopeptide-ACP paste (MI Paste). All groups were cycled for 15 days in demineralization solution for 8 hours a day, rinsed, placed in artificial saliva (30 minutes), brushed, and stored overnight in artificial saliva. The extent of demineralization in each group was assessed by using quantitative light-induced fluorescence and confocal laser scanning microscopy.
Only the Pro-seal and Vanish groups showed significantly smaller lesions than the controls (Kruskal-Wallis test, P <0.05) for both quantitative light-induced fluorescence and confocal laser scanning microscopy measurements. Fluorescence loss of Aegis-Ortho was similar to Vanish; Aegis-Ortho, MI Paste, and the controls were not different from each other.
Both light-cured filled resin (Pro-seal) and fluoride varnish (Vanish) might prevent enamel demineralization next to orthodontic brackets exposed to cariogenic conditions, but the observed positive effects of Aegis-Ortho and MI Paste were not significant.
One of my least favorite parts of orthodontic practice is putting my gloved fingers into the mouth of an adolescent patient with poor oral hygiene. Plaque on the teeth. Inflamed gingiva. Bleeding tissue. Enamel decalcification. Why won’t these teenagers use a toothbrush? Fortunately, I have had only a few noncompliant patients, but even one in a week of practice is too many. Although gingival edema and bleeding disappear gradually after bracket removal, the decalcification scars remain on the labial surfaces of the teeth and can be a significant esthetic compromise to the patient long after bracket removal. Over the years, researchers have developed various types of aids, both mechanical and chemical, to help patients improve their oral hygiene and minimize the destructive effects of long-standing bacterial plaque. But many of these aids require patient cooperation and regular use to have either a bactericidal effect on the plaque or a remineralizing effect on the enamel. If patients were uncooperative about tooth brushing, why would we expect them to be more cooperative about using an adjunctive material regularly? So, researchers have developed more approaches that do not depend on compliance. One is to paint a varnish containing fluoride or a resin sealer around the bracket after bonding to protect the enamel. Another is to incorporate bactericidal and remineralizing ingredients into the bonding material beneath the orthodontic bracket. If these chemical agents could be released gradually during orthodontic treatment, perhaps their preventive or rehabilitative effects could overcome the negative effects of residual plaque that remains on the teeth.
A newer type of ingredients is amorphous calcium phosphate (ACP), which has been added to bonding cement. Will this material reduce the amount of decalcification around orthodontic brackets? The purpose of this in-vitro study was to answer this important clinical question.
Q & A
Kokich: This was an in-vitro study. Please explain the advantages and disadvantages of performing this study in vivo with patients.
Peters: A well-designed and sufficiently powered controlled clinical trial to compare the new bonding material to another effective management protocol is certainly needed. However, the many clinical parameters involved, including the large variability in natural white spot lesions, introduce confounding factors and make it difficult to determine clinical comparative effectiveness in vivo. Therefore, more economical in-vitro studies with controlled variables might provide insight in the important variables to achieve efficacy before large and costly clinical studies.
Kokich: What about the contraindications to having these chemicals in the oral cavity of children? Will we regret using these agents in the future?
Peters: Calcium and phosphate ions are natural components of hard tooth tissues and healthy saliva. They play an important role in the ion exchange during the physiologic, naturally occurring demineralization and remineralization processes in the mouth. There is no additional risk associated with this bonding material beyond the normal risks of routine orthodontic care. ACP slowly releases calcium and phosphate ions. This release self-activates in a low pH oral environment and returns to a dormant state when the pH level has returned to normal. Supersaturation of calcium and phosphate ions near the enamel-plaque interface significantly accelerates the tooth’s own calcium phosphate remineralization process and prevents demineralization. Therefore, this material might have the beneficial ability to enhance the tooth’s natural repair mechanism and reduce the detrimental effects of orthodontic brackets in a noncompliant patient. This might actually give Mother Nature a helping hand in keeping teeth healthy in harsh times.
Kokich: You learned a lot about the research in this area. What will be the future directions in research to counteract enamel decalcification?
Peters: It would help a lot if there was a remedy to prevent and remineralize white spot lesions without depending on the patient’s compliance. More research is warranted to develop a bioactive bonding agent with a remineralization boost to counteract the demineralization triggered by an acidic biofilm environment.
Kokich: If you were treating your own child who had poor oral hygiene, which method described in your research would you use to prevent decalcification?
Peters: Based on current best evidence, I would insist on repeated professional application of a fluoride varnish. Fluoride varnish doesn’t need much compliance—only some chair time and a dental professional (hygienist or auxiliary) to apply the varnish. With fluoride varnish, white spot lesions are almost entirely preventable. It is a shame that such a well-known and relatively low-cost prevention isn’t included as the standard of care in orthodontics to prevent the astoundingly high prevalence of white spot lesions as an iatrogenic side effect of orthodontic treatment with fixed or bonded appliances.
I would also try to improve oral hygiene by communication techniques like motivational interviewing and explaining what goes on in the mouth, how the mechanism of demineralization works, and why a white spot lesion can’t easily be remediated once it’s there. I would make very clear that, if poor oral hygiene continues, the brackets would need to be removed and treatment halted, since I have a professional and ethical responsibility. Personally, as a medical professional, I feel responsible to prevent starting caries disease in my patients as a result of the treatment I am providing.