Enamel White Lesions (Part II): New Classification (WSTC)

Enamel White Lesions

Enamel White Lesions (Part II):
A report of three cases treated according to the new Classification (WSTC)

Dental News March 2018 


Dr. Fadwa Chtioui (cldfadwa@hotmail.com) – DDS and Postgraduate Student, Department of restorative Dentistry and Endodontics, University Hospital of Sahloul, Sousse – Tunisia
Dr. Omar Marouane – Assistant Doctor, Department of restorative Dentistry and Endodontics, University Hospital of Sahloul, Sousse – Tunisia
Dr. Nabiha Douki – Head of the department of Odontology, Professor in Restorative Dentistry and Endodontics University Hospital of Sahloul, Sousse – Tunisia 



Conventional treatment options available to treat enamel Opacitiesinclude non-invasive and invasive approaches. Resin infiltration technique has been used in cases of enamel discoloration arising from developmental defects (hypocalcification, fluorosis, and molar-incisive hypomineralization) or white spot lesions (WSL) as a minimally invasive treatment that aims to mask enamel discolorations.
The present paper presents 3 case reports of young patients with white opacities on their incisors. The lesions were topographically categorized according to the new classification of Enamel white lesions (WSTC) consecutively as superficial, mixed and deep enamel white lesions. Apart from the superficial lesion which was infiltrated after surface erosion with Icon etch (DMG,Germany), deep and mixed lesions were eventually treated with a combined use of microabrasion followed by infiltration of the lesion using Icon (DMG,Germany), during a 30-minute appointment to correct the aesthetic defect.

To overcome the difficulty in locating such enamel opacities, transillumination in this procedure was useful for a more predictable and conservative treatment.

The clinical cases illustrated in this work emphasize the major role of the new classification in insuring a more predictable treatment showing the importance of Transillumination in identifying the location but to significantly evaluate the opacity of the lesion.


Keywords: Enamel White Lesions; Resin Infiltration Technique; ICON, Transillumination



The most important aspect in diagnosis of the enamel demineralization involves accurate and reliable description of such lesions, rather than detection; which mainly requires reading certain topographic characteristics of the enamel opacity. However, the existing devices to directly assess its location within the enamel are expensiveand not well-suited for use by most of dental professionals and cannot be used in every practice.

And so, Simple, low cost, fast, chairside approach and accurate tools for a more accurate clinical inspection of white lesions by Dental professionals are always needed  (1).
This actually comes in response to the constant need of non-invasive management strategies of such lesions.
Analyzing the body and edges of the lesions examined under transillumination has provided interesting information regarding their depth and thickness and helped setting forth a new classification where Enamel lesion which maybe deep, superficial or mixed (1,2).
Studying these dark spots has brought our attention to adopt light-assisted methods towards a modified, non invasive, treatment approach (5,6).

The ‘resin infiltration technique’ was introduced with the development of highly-flowable resin material (7). To date, Icon (DMG, Hamburg, Germany) remains the most efficient product for the infiltration procedure (3). The main purpose of this therapeutic approach is to infiltrate the hypomineralized enamel with a low viscosity resin having the same optic properties as sound enamel. However, even by following the manufacturer’s instructions, the treatment outcome remains unpredictable, especially when it’s based merely on the opacity’s etiology (8).

By describing a modified treatment approach adopted for 3 clinical cases of different topographies within the enamel, the aim of this paper is to emphasize the major role of the new classification in insuring a more predictable treatment and show the importance of Transillumination, not only in identifying the location and the degree of the opacity of the enamel hypomineralization but also in significantly assessing the treatment progress and defining the appropriate time to proceed with the different treatment steps.


Case Report 1

A 19-year-old young patient consulted our department the university hospital of Sahloul, Sousse, Tunisia, to correct the white opacity on her Maxillary anterior tooth.
The clinical examination revealed a white lesion aspect on her upper right central incisor, the medical history arose suspicions of a traumatic etiology as the patient couldn’t recall any childhood dental injuries.

Regardless of the cause, the treatment was proceeded after assessing the depth of the lesion according to the new classification criteria (1).
The lesion in this case was superficial and the treatment consisted on alternative minimal intervention, avoiding other treatments with more predictable results that would require greater tooth structure reduction, as in using micro abrasive procedures. To solely isolate the lesion, we initially intended to, first of all protect the sound enamel tissue and then the soft tissue surrounding the tooth by covering sound tissues with a light-cured rubber dam instead of the conventional one. This step is called “lesion focolization” which also allows a more conservative and economic treatment (2,9).

The enamel infiltration technique with a resin infiltrant (Icon, DMG, Germany) was selected for this patient.
The acid gel (ICON Etch), drying agent (ICON Dry), and resin infiltrant (ICON Infiltrant), which were all applied respecting the manufacturer’s instructions (7,10).

After cleaning the tooth surface with a rubber cup and a prophylaxis paste. The next step consisted of accessing the hypomineralized lesion. Therefore, the surface area of the lesion was eroded with a15% hydrochloric acid (Icon-Etch DMG) for 120 seconds to expose the lesion’s body. Then, the etching gel was thoroughly washed away for 30 seconds using a water spray. To desiccate the lesions, ethanol was used (ICON-Dry; DMG) for 30 s followed by air drying (7,10).

The Icon infiltrant resin (ICON) was applied to the surface and its penetration within the porous enamel lesion was aided with a microbrush activated in a circular motion for 3 min per application (7). After light curing for 40 s, the application of the infiltrant resin was repeated once for 1 min and light cured for 40 s. Finally, the roughened enamel surface was polished using a composite resin polishing discs. An improvement in the esthetic appearance was achieved by adding a composite resin on the surface to repair the slight enamel loss.

Case Report 2

In our first contribution describing superficial infiltration we limited the application of the erosion/infiltration technique to cases with superficial lesions which required no dental preparation beforehand (11).

In this case, a 27-year-old young patient was chiefly complaining of the aspect of the anterior spot affecting both maxillary central incisors.

Direct visual inspection showed a creamy appearance of the enamel lesion with hardly perceivable interface between sound and hypominerlized enamel areas, while the lesionappeared homogenously opaque with ill-demarcated and dull marginsunder transillumination. Thus, deep enamel lesion was diagnosed (1,2) .

In cases of deep lesions, the lesion is covered with sound enamel tissue, thus the Infiltration takes places on the level of healthy enamel and therefore does not produce a favorable optical effect. Only a small part of the lesion is infiltrated and masking remains insufficient. This is why treating deep lesions by erosion/infiltration has been never, or almost never, successful and the results have been never satisfactory (11).

To overcome this treatment failure, the concept of infiltrating deep lesions’ category involves a mild mutilation of the enamel through an average of 10 cycles of microabrasion, around 15 seconds each, should be performed before moving ahead with the erosion/infiltration of the lesion. This will eventually ensure that the infiltration can indeed reach the body of the lesionitself.

The cycles of microabrasion, erosion and application of alcohol will continue until the optical appearance is further improved whether under transillumination as the exposed lesion shows clearly demarcated edges (1,9) or while the lesion is dried with alcohol (ICON Dry). Alcohol changes the refractive index of the surface of the enamel (3). Both tests will assist in assessing whether the further microabrasion and surface erosion will be necessary to ultimately expose the lesion almost entirely.

The infiltration can only begin if the optical change concerns the lesion in totality, the latter is now superficial more accessible by the infiltrant (3,9).
A slight loss of the enamel is inevitable in deep lesions due to the surface micro-preparation; however it can be made up with composite (7).
The choice of composite shade may differ according to the amount of tissue loss. The latter can be perceived and evaluated clinically as a concavity in the enamel will be more or less obvious with regard to the importance of enamel preparation (10,11).

Initial status showing white lesion on both teeth #21 & 11 according to the new classification, the Lesion is located deep within the enamel (an ivory-white aspect with blurry edges)


Visual examination after Ten cycles of microabrasion applied to the lesion for 15 secnds each (activated with a micro brush) : hypomineralized enamel became intensely white


In transillumination, the lesion appears opaque with ill-demarcated and dull margins. The body of the lesion is smooth, showing a heterogeneous opaqueness


Under transillumination, well-demarcated limits are seen between sound and hypominerilized enamel after abrasive & erosive cycles


Post-operative clinical view and under transillumination just after the erosion and infiltration procedure shows the disappearance of most of the opaqueness

Case Report 3

A 16-year old male patient consulted for an unpleasant aspect of his maxillary Central Incisors.
Intra oral examination revealed the presence of a huge hypomineralized lesion occupying almost 2 thirds of both central incisors.
The lesion was defined as mixed according to the new classification (1). Therefore, microabrasion will be focused on deep areas to expose them to the surface and thus assuring the efficacy of the infiltration step.
Added to the alcohol test, inspecting the lesion under transillumination also plays a major role in guiding us towards initiating (1,3,9,12). The enamel loss was repaired with composite resin.

We only showed the treatment results of the right incisor in this case.

Initial status showing white lesion on tooth #11

Topographic Localization under transilluminatio confirm that both central incisors represent a Mixed Enamel lesion

Microabrasion (activated with a micro brush)

Lesion Examination under Transillumination after Surface treatment and Erosion (Icon Etch)

Visual examination after abrasive and erosive cycles shows well-demarcated limits between sound and hypomineralized enamel, which became intensely white

Post operative clinical view

Inspection of the treatment outcome and lesion disappearance under transillumination


In a previous article, it was established a new classification for enamel white lesions showing a high reliability in categorizing those lesions according to their topography and depth within the enamel. As the complete infiltration of the lesion remains the key to assure the success of the technique, the present paper aimed to highlight the major role of this classification in aiding a more predictable treatment outcome thanks to the use of direct visual inspection and light-based observation under transillumination.
Thus, this topographic classification has a marked prognostic effect even in cases where the etiology was ill- or not even defined.
The main difficulty with this technique is judging at what moment it is possible to perform the infiltration. Sometimes, the infiltration is performed after a large number of cycles of sandblasting or microabrasion cycles and erosion, but never before alcohol producing a clear optical effect and masking the lesion homogenously. The alcohol can also be the fine line between the moment where the body of the lesion is attained and the infiltration is allowed. In fact, the alcohol applied onto the surface of the lesion will change the refractive index of the surface of the enamel as it dries it out. This will assist in assessing whether the resin will make a difference in erasing the white lesion completely of whether further sand blasting and hydrochloric acid etching will be necessary.

However, transillumination can play a major role as well. Added to the Alcohol test already recommended by multiple authors, transillumination also offered a good indicator in this present one to preview the edges resolution and the opacity of the lesion. Following microabrasion, if the lesion doesn’t show well-demarcated margins with a clear interface undertransillumination, either chemical erosion should be repeated or further cycles of microabrasion should be performed (7,13), specifically in the zones where the lesion boards remains fuzzy and no optical modification is visible.

Infiltrating deep and superficial areas are complementary procedures in cases of mixed lesions. In return for a very slight mutilation of the tooth, deep infiltration makes it possible totreat all white spot lesions of the enamel, whatever their etiology or depth once they were correctly identified according to the new classification.
The dark hallow which might be seen around the lesion by the end of the treatment, marks areas where the infiltration wasn’t achieved, and may present the limitation of the infiltration technique in cases of deep and mixed lesions.

Adopting conservative treatment approaches remains a priority before having recourse to any substantial enamel preparation. The new classification of enamel white lesions allows a fast, easy and a more predictable and conservative treatment. We also tended to assure the lesion focalization during the treatment procedure in order to obtain a more conservative and economic treatment.

A Simplified Scheme showing the Treatment Protocol following the new classification


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12. Alwafi A. Resin Infiltration May Be Considered as a Color-Masking Treatment Option for Enamel Development Defects and White Spot Lesions. J Evid Based Dent Pract. 2017;17(2):113–5.

13. Son J-H, Hur B, Kim H-C, Park J-K. Management of white spots: resin infiltration technique and microabrasion. J Korean Acad Conserv Dent. 2011;36(1):66. 

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