Complex aesthetic cases often need more than one treatment modality, if they are to be treated in a conservative manner to preserve healthy tooth structure.
When correcting these cases which have failed, we must always look at identifying the cause of the failure. Was this due to a failure of a given material or the lack of knowledge and understanding by the clinician?
The following case highlights the need to plan correctly, and break down each clinical issue and choosing the most appropriate treatment method.

Fig.1
A 16 year old female patient presented at the practice, with her main complaint being the white and brown patches on her upper teeth. She reported that her previous dentist had tried to remove and mask her fluorosis with composite resin, 2 years previously. This did not improve matters and she became more embarrassed to smile. She was only concerned with improving her upper teeth.
On examination, a diagnosis of dental fluorosis and poorly integrated composite resin restorations was made.

Fig.2
With a cross-polarized view, it showed the huge disparity in the value and chromaticity across the hypomineralised enamel and the existing composite restorations.

Fig.3
Close up view showing the varying opacity of the white lesions.

Fig.4
Cross polarized close up view showing the varying opacity of the white lesions.

Fig.5
The reason the case was an aesthetic failure was the lack of treatment planning. Given the three differing areas to treat (i) The cervical and mid third superficial hypo-mineralisation was very diffuse – this could be treated with resin infiltration, ICON (DMG, Hamburg)
(ii) The incisal third was much more opaque and indicated a much deeper depth to the white lesion, this would require some micro/macro preparation and a single enamel composite shade.
(iii) The previous restorations were low in value indicating a single enamel shade.

Fig.6
Isolation is the key to all adhesive procedures. The upper arch was isolated from the upper first molars

Fig.7
The existing restorations were removed very carefully, so as not to further damage the teeth. The whole surfaces were cleaned with Slyc and 29 micro AluminaOxide with the Aquacare unit.

Fig.8
The lateral views shows the depth of the previous restorations and differing substrates

Fig.9
Due to the lack of bulbosity of the cingulum, the palatal floss ties we bonded insitu giving full access to the labial aspect.

Fig.10
The first stage of the resin infiltration was the use of 15% Hydrochloric acid (ICONetch, DMG) for 2 mins. Glycerine was was to protect the dentine from the etchant.

Fig.11
The etchant was thoroughly washed off. The teeth were then dried.

Fig.12
Using the Ethanol (ICON-dry, DMG) this enabled a preview of the possible infiltration result.

Fig.13
The cervical and mid thirds showed and predicted increase in chroma and a decrease in value, however the incisal third remained high in value due to the deeper nature of the white lesion.

Fig.14
Particle abrasion with 29 micron AluminaOxide (Aquacare, Velopex).

Fig.15
We decided to retain the highly opacious incisal edge as a halo. A simple dentine mamelon formation design with opalescence tint (Azure, Inspiro) to give a more youthful final appearance.

Fig.16
A cross polarized view was used to assess the effects of the resin infiltration preview.

Fig.17
The ICON-dry which is 99% ethanol was used. The preview showed an even chromaticity and a higher value incisal edge as planned.

Fig.18
The resin infiltration (ICON-infiltrate) was applied, this is an TEGDMA low viscosity monomer.

Fig.19
The dentine was layered in a simple 3 mamelon design, leaving space for incisal tints and enamel, following the Natural Layering technique.

Fig.20
Opalescence tint Azure, Inspiro was placed in-between the mamelons and incisal edge on the centrals.
On the laterals, it was placed where the surface had been air abraded

Fig.21
The enamel layer was placed to complete the restorations.

Fig.22
One week later, the patient was recalled for finishing and polishing. This allows to assess the layering and shade once rehydration has taken place. Note the uniformity of the chroma.

Fig.23
The transitional line angles were marked out and finished.

Fig.24
The secondary vertical macro texture was marked and finished.

Fig.25
The tertiary horizontal micro texture was finished.

Fig.26
The restorations were polished.

Fig.27
Right lateral view on a further review appointment.

Fig.28
Left lateral view on a further review appointment.

Fig.29
Final restorations showing good integration.

Fig.30
The patient was very pleased with her new smile.

Fig.31
At a 2 year review, there is still very good integration.
Conclusions
The preservation of sound tooth structure, especially in someone so young must be a key aim in any treatment plan. Understanding the effects of changes in chroma and value when using resin infiltration and layering composite, is critical to achieving a predictable result.
Resin infiltration, given the correct indication, is yet another another tool in our armamentarium. When managing the replacement of any aesthetic failure of a direct composite restoration, we must first figure out why it has failed and plan correctly.
Bibliography
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