Dental Update - Management of opacities in children and adolescents

Abstract

Enamel opacities can appear as white, cream, yellow or brown patches. They can result from developmental or acquired conditions. The diagnosis, severity of the opacity and patient's desire for treatment guide the clinician when choosing the correct management option. Microabrasion is indicated for surface opacities, whereas bleaching can treat opacities deep within the tooth. When these techniques have failed to achieve the desired result, camouflaging the opacity with composite resin may be useful. Novel techniques, such as infiltrating or sealing the opacity, can alter enamel's refractive index, offering further treatment choices.

CPD/Clinical Relevance: There are many conservative treatments available which can improve the appearance of enamel opacities.

Article

Enamel defects can present as a change in tooth colour; such as white, cream, yellow or brown opacities. The enamel structure can also be affected causing grooves or pits. The most recent UK Child Dental Health Survey (2013) found that 28% of 12-year-old children had an enamel opacity affecting one or more permanent teeth.1 Opacities can have a significant effect on a person's appearance and social wellbeing.2

Aetiology of enamel opacities

Amelogenesis is a complex process which involves three stages:

Inductive;

Secretory; and

Maturation.

Normal, fully formed enamel is comprised of hydroxyapatite crystals embedded in a protein and lipid matrix. Ameloblasts are sensitive to hereditary and environmental disturbances during amelogenesis. This can cause alterations in the enamel structure or mineral content. Disturbances in the amelogenesis process can result in an increased water and protein content compared to normal enamel. This can affect the enamel's refractive index, thereby creating an enamel opacity.

Enamel defects can be developmental or acquired. There are several conditions that can cause enamel opacities; these include:

Amelogenesis imperfecta (Figure 1);

Fluorosis (Figure 2);

Molar incisor hypomineralization (MIH) (Figure 3);

Chronological hypomineralization;

Caries; and

Secondary effects of localized primary tooth trauma or infection (Figure 4).

Figure 1. Amelogenesis imperfecta (hypocalcification type).

Figure 2. Chronological white flecks indicating fluorosis.

Figure 3. UR1 with enamel opacity and LR6 hypomineralized; this patient was diagnosed with molar incisor hypomineralization.

Figure 4. Creamy/brown opacities affecting the LL1 and LR1; the patient had a history of trauma to the primary incisors.

Some opacities can be idiopathic in origin. Clinical examination together with a thorough history from the patient and parent/guardian should help the clinician diagnose the cause of the enamel defect.

Management options

There are a number of different options available to manage enamel opacities. The clinician must firstly ascertain the individual's desire for treatment. Mild opacities may be acceptable and of no concern to the patient and therefore no treatment is required (Figure 5). The diagnosis and severity of the opacity help aid the clinician's choice as to the most suitable treatment option (Figure 6).

Figure 5. Mild opacities affecting UR2 and UL2.

Figure 6. Flow diagram of management options for enamel opacities.

Practitioners may encounter patients who have normal teeth, but complain that they are ‘yellow’ and request treatment to make them whiter. This undue concern is usually rectified by matching patients’ teeth to a shade guide to show how their teeth compare.

Prior to all procedures it is recommended that photographs and sensibility tests are completed. This should also be repeated on review post-treatment. Periapical radiographs of teeth to be treated are not normally required unless there is concern regarding vitality.

Microabrasion

Microabrasion is a relatively conservative treatment option as it removes only a superficial layer of enamel (Table 1). It involves rubbing an acid slurry on the tooth surface; the procedure therefore combines abrasion with erosion, and historically was referred to as ‘abrosion.’ This technique removes between 100–200 microns of enamel. The most widely used acid agent is 18% hydrochloric acid; however, 37% phosphoric acid can also be used. Studies have shown both acids to be equally effective with removing enamel opacities.3^,4 The advantages of phosphoric acid are that it is safe, easy to use and readily available in all general dental practices. Bassir and Golnaz, however, found that teeth treated with phosphoric acid required a longer treatment time in order to achieve similar results to hydrochloric acid.5

Table 1. Microabrasion technique.

1	Clean the teeth with a pumice/water slurry, wash and dry
2	Apply Vaseline to gingivae and isolate the teeth with rubber dam
3	Place a sodium bicarbonate/water mixture palatal to the teeth in order to neutralize any spillage
4	Mix 18% hydrochloric acid with pumice to create a slurry; rub this on the enamel surface using a wooden stick for 5 seconds. If using 37% phosphoric acid, apply this to the surface for 30 seconds
5	Then wash using high volume aspiration
6	Repeat step 4 and 5 until opacity has improved, up to a maximum of 10 cycles (3 cycles for phosphoric acid)
7	Apply fluoride to the teeth for 3 minutes
8	Remove the rubber dam
9	Some people polish the treated teeth with fine soflex discs
10	Review in a month

Microabrasion creates a dense prism-free surface layer of enamel which alters the optimal properties of the tooth; this has been described as the ‘abrosion effect.’5 In many cases, the opacity is not completely removed but an acceptable aesthetic outcome is achieved. The conservative nature of this technique means that the patient is not disadvantaged when there has been minimal improvement (Figure 7) and it may make masking the opacity with a veneer easier. Brown opacities have been found to be more easily removed than white opacities (Figure 8).

Figure 7. (a, b) Hydrochloric acid microabrasion on UR1 and UL1 provided minimal improvement of white opacities.

Figure 8. (a, b) Significant improvement of brown opacities affecting UR1 and UL1 with hydrochloric acid microabrasion.

Microabrasion is quick and easy to perform, and is extremely acceptable to the patient. The major disadvantage is the risk of soft tissue damage from using an acid within the oral cavity. In addition, it has a limited effect on opacities deep within enamel. Microabrasion can be successful treating surface opacities such as hypomineralization and fluorosis.

Infiltration

Icon® caries infiltrant (DMG) is a novel product which can be used to mask carious and non-carious white opacities (Table 2). It is a micro-invasive technique. It fills the lesion and refracts the light in a similar manner to natural tooth tissue.

Table 2. Infiltration technique.

1	Clean the tooth/teeth and isolate with rubber dam
2	Attach the smooth surface tip to the Icon®-Etch (15% hydrochloric acid), apply Icon®-Etch to the lesion for 2 minutes
3	Wash for at least 30 seconds and dry
4	Mix 18% hydrochloric acid with pumice to create a slurry; rub this on the enamel surface using a wooden stick for 5 seconds. If using 37% phosphoric acid, apply this to the surface for 30 seconds
5	Wash for at least 30 seconds and dry
6	Attach the smooth surface tip to the Icon®-Dry (99% ethanol), apply Icon®-Dry to the lesion, allow to set for 30 seconds then dry
7	Attach the smooth surface tip to the Icon®-Infiltrant (methacrylate-based resin matrix), apply Icon®-Infiltrant to the lesion, allow to set for 3 minutes
8	Remove the excess material then cure for 40 seconds
9	Repeat steps 7 and 8, allowing the infiltrant 1 minute to set
10	Remove the rubber dam and polish

The refractive index (RF) of sound enamel is 1.62; demineralized enamel when wet has a RF of 1.33 and when dried the RF drops to 1.0.6 White spots become more apparent once a tooth is dried; this is due to the difference in the refractive indices. When the resin infiltrates the porous enamel by capillary forces, the RF increases to 1.52, which is similar to sound enamel. The change in RF is reflected by an improved appearance of the lesion as it loses its whitish appearance.

Kim et al studied the effect of resin infiltration on teeth with a developmental defect of enamel and teeth with post-orthodontic decalcification. They found the post-orthodontic decalcification lesions were more successfully masked compared to teeth with a developmental defect of enamel. They thought this may be due to lesion depth and surface layer thickness.6 The available evidence shows promising results, however, further high quality research is needed to assess its success and colour stability in the long term.

Bleach, etch and seal

Another conservative option is the etch-bleach-seal technique (Table 3).7 The penetration of clear fissure sealant into the treated enamel surface, similar to Icon®, may alter the enamel's reflective index, thereby improving the aesthetics.

Table 3. Bleach, etch and seal technique.

1	Isolate tooth/teeth with rubber dam and etch the enamel surface with 37% phosphoric acid for 60 seconds
2	Bleach the etched enamel with 5% sodium hypochlorite for 5–10 minutes
3	Re-etch with 37% phosphoric acid for 60 seconds
4	Apply clear fissure sealant over the treated surface and cure

Vital bleaching

Vital bleaching can be carried out by the clinician in the surgery and also by the patient at home using a nightguard. It is recommended as a treatment option for mild fluorosis (Figure 9). Bleaching using a nightguard can be used in conjunction with microabrasion to manage moderate fluorosis.

In October 2012, the European Union changed the law relating to tooth whitening. The regulation stipulates that products containing or releasing up to 6% hydrogen peroxide can be used, as long as certain conditions are followed:

‘The first use to be only done by dental practitioners or under their direct supervision’; and

Products are ‘not to be used on a person under 18 years of age.’8

The GDC released a statement in May 2014 stating that ‘products containing or releasing between 0.1% and 6% hydrogen peroxide cannot be used on any person under 18 years of age except where such use is intended wholly for the purpose of treating or preventing disease.’9

Bleaching is not a procedure without risks. Transient pulpal sensitivity, gingival ulceration and deterioration of colour improvement are associated with whitening. A review of studies using 10% carbamide peroxide as the bleaching agent found that 15–65% of patients reported tooth sensitivity.10 Stopping treatment or increasing the time between bleaching cycles can relieve these symptoms. Desensitizing toothpastes/mousses or toothpastes/gels with a high concentration of fluoride can be applied to the sensitive teeth directly or via a prefabricated nightguard. In order to reduce the risk of gingival ulceration, soft tissue protection with rubber dam for chairside bleaching is essential and an appropriately extended nightguard for at home bleaching.

It is advised to over bleach the tooth so that it is a shade lighter than the ideal colour as there is frequently an initial shade regression. Haywood carried out a study on 38 patients who received nightguard bleaching using 10% carbamide peroxide. The study found 74% and 62% of patients reported no or slight shade regression after 18 months and 36 months, respectively.11 If shade regression does occur then the bleaching procedure can easily be repeated.

Chairside bleaching

The clinician applies hydrogen peroxide, a high level bleaching agent, to the tooth surface; this is further activated with a light or laser source. This technique can achieve rapid results, however, it generally requires repeat visits to achieve the optimum aesthetic outcome. In addition, by using an agent of higher concentration, the potential risks may be increased. A review of activated external bleaching systems by Buchalla and Attin concluded that bleaching activated by light, heat or laser may have adverse effects on the pulp and should be used with caution.12

At home bleaching

The patient places carbamide peroxide gel, a low level bleaching agent, in a custom-fabricated nightguard. Initially this is carried out daily (Table 4). The carbamide peroxide breaks down to hydrogen peroxide and urea. The concentration of hydrogen peroxide that is released from carbamide peroxide gel is around a third; for instance 10% carbamide peroxide will yield 3.6% hydrogen peroxide. The custom-made tray has a reservoir to contain the bleach constructed either by placing composite resin (without etching) over the opacity before taking the impression or by placing wax on the model before constructing the tray.

Table 4. At home bleaching technique.

1	Take an alginate impression of the arch that requires bleaching
2	Construct a nightguard which does not cover the gingivae; with or without reservoirs for the bleaching gel
3	Provide the patient with instructions of use and advise daily use
4	Review in 2 weeks

Direct composite resin

The aesthetical properties of composite resins have improved significantly over the past 15 years. Composite can be used as a localized restoration or as a veneer to help camouflage opacities (Table 5).

Table 5. Direct composite resin technique.

1	Select a shade
2	Apply rubber dam
3	Select and adjust a crown former, if required
4	Etch the enamel
5	Apply bonding agent and cure
6	Shape the composite resin over the localized area or the entire labial surface, with or without the crown former, and cure
7	Polish with composite finishing burs, soflex discs and interproximal polishing strips
8	Emphasize the importance of excellent oral hygiene instruction

Composite resins require maintenance over time; they can accumulate staining which can be easily polished away and they can fail, requiring replacement. They can become a plaque retentive factor within the oral cavity so excellent oral hygiene measures should be in order prior to placement and must also be maintained. This should be conveyed to the patient and parent/guardian during the consent process.

In the past, a minimal chamfer margin was cut in enamel. This would help improve retention of the composite resin and the interface between tooth and composite. Current practice has now shifted to minimally invasive dentistry and, owing to the advances of bonding agents and composite resin materials, the preparation of a finishing margin is not required.

The beauty of composite resin is that it can be adjusted, and additions made to it over time. Composite opaquers can be used to try and mask the opacity and then more translucent shades placed on top (Figure 10). A combination of different shades can be utilized to try and achieve a more natural result.

Figure 10. (a, b) Enamel opacity on UR1 failed to improve with microabrasion; a composite veneer was subsequently placed.

Their use is indicated in patients with amelogenesis imperfecta, moderate/severe fluorosis and opacities which have failed to achieve a satisfactory result with microabrasion or vital bleaching. When bleaching has been carried out, it is advised to delay composite placement for two weeks in order to attain a stable tooth colour for shade matching. Secondly, a waste product from the breakdown of hydrogen peroxide is oxygen; this can affect the bond between composite and tooth tissue.13

Removal of opacity

Dark opacities can be difficult to mask completely. Removal of the localized opacity down to the amelodentinal junction with a diamond bur and subsequent composite resin coverage may help achieve a more acceptable result. With this option, tooth tissue is irreversibly removed.

Indirect composite resin

Laboratory fabricated composite veneers can be used for dark opacities that are unsuccessfully masked with indirect composite resin (Table 6). With this option there is an increased cost due to the involvement of the laboratory. Like direct composite resin, they can accumulate staining, encourage plaque retention and fail, requiring replacement.

Table 6. Indirect composite resin technique.

1	Select a shade
2	Take a detailed impression of the teeth to be veneered
3	Cement the laboratory fabricated veneer to the tooth using an appropriate bonding system
4	Polish with composite finishing burs, soflex discs and interproximal polishing strips
5	Emphasize the importance of excellent oral hygiene instruction

Porcelain veneers require tooth preparation. They are contra-indicated in the paediatric population as they have large pulp chambers and immature gingival margins.

Conclusion

Clinicians working in general practice will regularly see children and young people with enamel opacities affecting their permanent incisors. If they cause the patient concern then appropriate management options should be discussed. Microabrasion is indicated for surface opacities, whereas bleaching can treat opacities deep within the tooth. When these techniques have failed to achieve the desired result, camouflaging the opacity with composite resin may prove successful. Novel techniques, such as infiltrating or sealing the opacity, can alter enamel's refractive index, offering further treatment choices.

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References

Management of opacities in children and adolescents

Authors

Ann Wallace

Chris Deery