The white spot lesions on the enamel are caused by a defect in its structure and mineralization. These optical changes occur mainly due to the presence of empty spaces between the hydroxyapatite crystals and which are now occupied by organic fluids. The difference in the RI of the fluid, basically composed of water (1.33) and enamel (1.62), leads to the visual identification of the porous area of the enamel as a white spot.¹ The increased porosity located in the enamel can have a preeruptive etiology, due to alterations such as dental fluorosis; traumatic hypomineralization or molar and incisor hypomineralization; or posteruptive, as dental caries.

The diagnosis of enamel defects can be performed through visual examination, considering the shape, size, color, and location of these defects.¹ The deep of the lesion is also an important factor to be analyzed in order to define the treatment.² For this, the white lesion must be transilluminated, and where the darker the transilluminated spot appears, the deeper it is.²,³

Traditionally, the treatment options for preeruptive white superficial spots were tooth whitening or microabrasion, and the restorative technique, for deep spots.⁴ However, such techniques can cause, respectively, sensitivity and thickness reduction of the enamel and even the beginning of the restorative cycle.⁵

The use of infiltrant, a low-viscosity fluid resin that penetrates the body of the white stain lesion due to capillarity, has been proposed to mask the appearance of this enamel defect, as it has a RI around 1.52, which is closer than healthy enamel RI.⁵ This is considered a microinvasive treatment since it requires only a previous erosion of the healthy enamel for application.⁵ Initially indicated for the treatment of incipient caries lesions, infiltrants had their indications expanded for the treatment of white spots of fluorosis and traumatic hypomineralization.⁶ However, when indicated for hypomineralization white spots of molars and incisors or in other deep hypomineralization spots, some authors suggest the association with more significant wear of the dental structure, although still superficial, followed by restorative procedures, in order to guarantee satisfactory esthetic results.²

Although the diagnosis is decisive for the choice of treatment, the patient's agreement to wear his/her tooth for esthetics needs to be considered. Thus, the objective of this work is to describe the microinvasive approach for deep white spot lesion of molar and incisor hypomineralization, present in an upper central incisor, using resin infiltration. This case report was structured based on the Care Checklist, the case report guideline.

A female patient, 20-year-old, denying allergies and systemic diseases, was seen at the Dentistry Service of the School of Dentistry of the Federal University of Bahia (FO-UFBA), after presenting an esthetic complaint due to the presence of an extensive white spot, located in the incisal third of the buccal face of her right upper central incisor. The patient also described that she had already sought esthetic treatment for that white spot and that, as she always received treatment indications that included wearing out her tooth, she never felt comfortable to accept them. On clinical examination, the presence of an extensive white spot with a high degree of opacity, with defined margins, and with an elongated shape is noted, occupying a large part of the incisal third of the buccal face of tooth 1.1. In the mesial, still in the incisal of the buccal face, the presence of two smaller and less opaque white spots is noted Figure 1a. To assess the depth, a tooth transillumination was performed, with the aid of a photoactivating device emitting LED light (light emitted by diode) (VALO^® Cordless-Ultradent, South Jordan, USA). It is observed that the most opaque and centralized part of the stain was darker when transilluminated, showing more depth Figure 1b. The two less opaque white spots and the marginal part of the spot were lighter, characterizing less depth Figure 1b. The diagnosis was a deep white spot due to molar and incisor, hypomineralization due to the location, and clinical characteristics of the mentioned spot and the fact that molar teeth 2.6 and 2.7 also present hypomineralized spots.Figure 1

(a) Clinical aspect of the white spot lesion. (b) Transillumination of the white spot with photopolymerizer device, showing that the deeper the stain, the darker it appears when being transilluminated. (c) Rubber dam isolation from the first upper right premolar to the upper left first premolar

White spot lesions may be the result of incipient caries lesions, dental fluorosis, and hypomineralization of dental enamel, and its diagnosis is essential for establishing the treatment plan for them.⁴,⁷,⁸ The differential diagnosis of these lesions is not simple and should be performed through visual inspection of the stain, during the clinical examination, after prophylaxis. For an easier and more detailed examination, clinical microscopes can be used to increase the visualization of the operative field.³ There is also the method of transillumination in which a light-curing device is positioned on the lingual face of the tooth, and when the light is activated, it crosses better healthy regions or superficial spots, while deeper regions of the lesion appear darker because they allow little light to pass through them, as shown in Figure 1b. In the present clinical case, the opaque and irregular lesion was diagnosed as enamel hypomineralization, caused by molar and incisor hypomineralization, being classified as deep both by the etiology and by means of transillumination, since it was darkened on that examination Figure 1a and Figure 1b.¹,³,⁹,¹⁰

Esthetic treatments for deep white spots are usually restorative, since more conservative alternatives such as whitening and/or microabrasion are more effective for more superficial white spots.⁴ Esthetic restorations, in turn, are invasive procedures that require considerable wear of the dental structure and insert the tooth into the restorative cycle that leads to further additional dental wear.⁵,¹¹ It is noteworthy that the patient, in the present case, declined from restorative esthetic treatments previously proposed to her, due to her option to avoid any more significant wear of your teeth. Therefore, the restoration of this white spot would not be considered as a therapy for this case.

Thus, aiming at an individualized treatment, less invasive, and with a minimum of dental wear, we opted for the use of infiltrants, as it is an alternative that has shown promising and interesting results for the masking of white spot lesions.²,⁷,¹¹,¹²,¹³,¹⁴,¹⁵ The mechanism of action of the infiltrant occurs from the initial application of 15% hydrochloric acid, similar to microabrasion, followed by washing and application of a solvent that removes water from the spaces that should be occupied by hydroxyapatite. In this way, the resinous monomers of the infiltrant (RI = 1.52) can penetrate through the enamel porosities, and the spaces previously occupied by water (RI = 1.33) and/or air (RI = 1.00) are now filled by resin in a hybridization process, changing the RI of the white spot in order to make it closer to the healthy enamel (RI = 1.62) and thus making the color of the lesion similar or closest to the tooth color.⁷

Despite the clinical descriptions of esthetic success in masking white spot lesions, the majority reports the treatment of superficial white spots, which are best achieved and infiltrated by fluid resin.⁷,¹¹,¹⁴,¹⁵ The infiltrant has also been indicated in deep lesions, when associated with an increase in the number of acidic cycles applied or even associated with superficial restorations, after dental microwear on the body of the lesion.² For the present clinical case, an increase in acidic cycles was chosen in order to avoid additional wear of the tooth, as requested by the patient herself, even if this resulted in not completely eliminating of the white spot. The possibility of not completely masking the white spot was previously discussed and accepted by the patient, the most interested and active agent in this decision.

The most relevant doubts regarding the indication of this treatment refer to its longevity and the color stability of the infiltrated resin, since there are no reports of side effects in the literature.¹² Cazzolla et al.⁷ reported satisfactory and stable results after 4-year follow-up of infiltrated white spot, using a protocol similar to that described in this clinical case.⁷ It should be noted that the esthetic result of infiltrated white spots seems to improve over time and that improvement seems to be justified by the rehydration of the enamel and the spot, previously dehydrated by the use of alcohol.⁵,¹⁵ In the present case report, the infiltrating product was able to mask the entire length of the white spot, which lost the opaque aspect and started to appear brighter and with a color closer to the tooth. Although the treatment was not able to completely eliminate the white spot, its esthetic result contemplated the patient's desires for improvement in her smile, without the need to receive esthetic restoration in composite resin.

The use of resin infiltrant has been reported as a safe, microinvasive approach with stable results for masking superficial white spot lesions in dental enamel, although this is not an indication of the manufacturer. In the present clinical report, the application of the resin infiltrant was able to mask a deep white spot caused by molar and incisor hypomineralization, without the need for additional dental wear, being effective in the esthetic and conservative treatment of the lesion.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or nonfinancial in this article.