Bleaching of fluorosis stains using sodium hypochlorite.

Fluorosis staining is commonly considered an esthetic problem because of the psychological impact of unesthetic maxillary anterior teeth. Numerous treatment approaches have been proposed, ranging from bleaching to enamel reduction to restorative techniques. Bleaching of hypomineralized enamel lesions, using 5% sodium hypochlorite, has been useful clinically. The technique described, in this case, appears to have advantages over other methods for improving the appearance of fluorotic lesions. It is simple, low cost, noninvasive, so the enamel keeps its structure, relatively rapid, and safe; it requires no special materials, and it can be used with safety on young permanent teeth.

Esthetically distressing discolorations of permanent incisors have multiple etiologies that comprise both the genetic and environmental factors.[12] Dental fluorosis, is a demineralization of enamel because of the effects of excessive fluoride intake, results in opaque white areas or discolorations ranging from yellow to dark brown, together with porosities on the enamel surface.[3] Fluorosis staining is commonly considered as an esthetic problem because of the psychological impact of unesthetic maxillary or mandibular anterior teeth.[4]

In the past, dental fluorosis cases were encountered in settlements with an elevated concentration of fluoride in the drinking water. Fluorosis stains are generally treated in the light of three concepts: Removing the stained enamel, bleaching the stained tooth, and/or covering the stained area.[5]

The most conservative approaches involve bleaching the teeth. This can be accomplished using a variety of materials that are mostly based on chemicals that produce peroxide ions. The use of peroxide-based bleaching materials can cause dental sensitivity and less frequently, gingival irritation.[6] Microabrasion and removal of the outer enamel surface have also been advocated to manage enamel discolorations.[7]

Even very young patients can be highly concerned over discoloration of their anterior teeth. Therefore, suitable treatments are needed for young permanent teeth that are partially erupted and have large pulp chambers and incomplete root formation. To overcome this problem, a conservative treatment approach for the management of yellow-brown intrinsic staining of dental enamel is presented.

Case Report

A 10-year-old boy is complaining of brown stains on the upper front tooth region since 2 years reported to the clinic [Figure 1]. After a clinical examination and taking the patient's medical history, the stains were diagnosed as fluorosis. In consideration of his age, we should not recommend the treatment options that involve significant removal of tooth structure, such as porcelain or composite resin veneers. A conservative treatment plan was presented to the patient that would fulfill his request, which is bleaching with sodium hypochlorite.

Figure 1

Preoperative photograph

The teeth are cleaned with flour of pumice using a rubber cup to remove all plaque and any extrinsic surface discolorations. The teeth are then isolated with a rubber dam, and each tooth is ligated to protect the soft tissues from the bleaching agent. To allow better penetration of the bleaching agent, the enamel surface is etched for 60 s with 37% phosphoric acid. Sodium hypochlorite (5%) is applied to the entire tooth surface using a cotton applicator. The bleach is continuously reapplied to the tooth as it evaporates. The teeth were bleached in a single appointment for 25–30 min. After the bleaching, the previously stained lesions will have a white mottled appearance, which is much more esthetically acceptable.

To prevent organic material from re-entering the porous enamel, the bleached and etched teeth can be sealed after achieving the optimal bleach result. Sealing of the hypomineralized surface is accomplished by rinsing and drying the tooth to removal all bleaching agent. Etch the tooth for 30 s with 37% phosphoric acid, rinse with water and treat the bleached and etched surface with a highly penetrating clear resin like composite bonding agent. The resin will perfuse the etched and porous enamel, creating resin tags that occlude the porosities and prevent re-staining of the hypomineralized lesion. We have observed marked degree of success even after 6 months [Figure 2].

Figure 2

Postoperative photograph

Discussion

More than a century of experience has shown bleaching to be an effective treatment for the conditions of fluorosis, tetracycline staining, and acquired external and internal discolorations.[8]

Bleaching of discolored teeth in young patients may offer advantages over more conventional treatment involving partial or complete coverage restorations.

Microabrasion and removal of the outer enamel surface have also been advocated to manage enamel discolorations.[7] This technique can be successful for lesions that are mild and relatively superficial and do not extend to deeper enamel layers, such as might occur with moderate-to-severe fluorosis.[79]

Microabrasion, either alone or coupled with bleaching, has the disadvantage of requiring the removal of some enamel. However, this approach is more conservative than reducing the enamel surface for the placement of facial veneers. Bleaching and microabrasion also have the benefit of being applicable for partially erupted, young permanent teeth. The placement of facial veneers is typically not considered until a patient's teeth have fully erupted, and the gingival height has stabilized. Thus, definitive restorative management for enamel discolorations is typically delayed until the child is in mid to late adolescence; even though substantial concern over the appearance of discolored teeth can begin many years earlier when the teeth partially emerge and visible.

The sodium hypochlorite technique has several advantages over peroxide-based protocols for the specific application of removing stains from localized hypomineralized lesions in young teeth. It is known to be highly effective at removing organic material by oxidizing it and allowing the smaller degraded molecules to be washed away. Applying sodium hypochlorite to bleach discolored, hypomineralized enamel lesions can degrade and remove the chromogenic organic material that is, located in the enamel.[10]

The second critical step in this bleaching approach lies in the resin perfusion of the hypomineralized lesion to prevent future chromogens from entering the porous enamel causing a re-staining of the lesion. The use of 16% hydrochloric acid alone or followed by hydrogen peroxide bleaching can successfully remove intrinsic yellow-brown stains.[11]

We prefer the use of phosphoric acid for two reasons. First, it is readily available in most dental offices 37% phosphoric acid removes less enamel compared with 16% hydrochloric acid. It has long been known that 37% phosphoric acid (most commonly supplied for resin boding) is highly effective at etching the enamel crystallites and increasing enamel porosity. Therefore, the etch/bleach technique presented in this paper uses materials that are readily available in the dental office and that have been shown to be clinically safe and effective. Studies show that sodium hypochlorite can effectively remove proteins from the enamel crystallite surfaces.[12] It has been shown that pretreatment of the enamel with sodium hypochlorite to remove the enamel proteins can enhance the ability of acid to etch the surface, thereby improving the likelihood that resins can bond successfully to the surface.[13]

Conclusion

The above technique uses readily available materials that show a high level of safety and can be used on young permanent teeth. Permanent incisor teeth that are only partially erupted can be treated, allowing older children and very young adolescents to benefit from this approach. This technique provides a conservative alternative treatment for yellow-brown hypomineralized enamel that shows a good clinical success. The application of conservative treatment approaches should be considered prior to applying techniques that require substantial enamel removal for the treatment of enamel discolorations.