Composite discoloration

12 Feb 2018 - 10164

Discoloration of composites of anterior restorative work is an aesthetic disaster for the patient. And many times it’s a reason for retreatment of previous dental work. Composite discoloration can be quite common and can be caused by various reasons. One of the main reasons discoloration of the composite over time can occur is inadequate polishing of the composite. A multistep, accurate, polishing system is mandatory to keep the composite color stable as much as possible. Other (co-) factors in discoloration are patient habits (food, drinks, smoking e.g.), inadequate or no etching around and beyond the preparation or fracture line or insufficient polymerisation of the composite. In this clinical case none of the reasons above was considered applicable.Presumed reason of discoloration and solution is presented in the case. When a case of discoloured composite is presented in daily practice, repeating the polishing sequence over time can remove superficial staining of the composite and reestablish the luster of the restoration. More elaborate is the removal of the outer and/or inner layers and applying a new composite layer(s). The framework, being the palatal shell and defined mesial and distal angles and embrasures can be maintained, therefore making the retreatment less comprehensive.

 

Fig. 1

Four years ago, a young woman came into the dental office I worked at the time with an aesthetic problem. The right central incisor had been restored multiple times by different dentists after a trauma caused the loss of tissue.

Fig. 2

The transition line from tooth surface to restoration was visible and slightly discoloured.

Fig. 3

The incisal edge was without the beautiful characterisation of the unmatched left central incisor.

Fig. 4

Most disturbing and eye-catching to the patient was the darkness of the restoration. She requested treatment to change the colour of the restoration and create a more lifelike appearance.

Fig. 5

A glimpse of the treatment performed four years ago. After the first consultation a wax-up on study models was made and with the help of silicone matrices the composite was replaced. The matrices would be of great help to recreate the natural curve of the three facial planes of the tooth and thereby putting the incisor edge at the exact right spot for layering.

Fig. 6

A layering composite restoration was then made to enhance the color and give the incisor some incisal edge character.

Fig. 7

Here the photostory of four years ago ends. The final colour of the composite restoration cannot be judged accurately because of the dehydration of all neighbouring teeth. But even in this whiter, dehydrated state of the enamel the colour of the restoration appears to be a match. Final multistep polishing was performed and the patient was happy with the end result. Until….

Fig. 8

Four years after finishing the treatment in the practice I worked occasionally at that time the patient came to my own dental office. The patient told me the restoration had been quite sufficient aesthetically in those years. The restoration had been slightly darker than the other teeth from the beginning, but not in a disturbing way. Recently the color had darkened to the extent that it was distracting.

Why had the restoration discoloured? In quite a short time period. A multistep polishing procedure had been followed at the time, the patient’s habits were not unordinary and the restoration was light cured abundantly. The only difference I could think of was the fact that at the time I did this treatment in a clinic without  all of my regular material present. With in retrospect the use of an adhesive containing a hydrophilic monomer (2-hydroxyethyl methacrylate: HEMA) as liquid on my instruments to model the composite. The use of adhesive does not alter the mechanical properties of the composite. But those containing hydrophilic HEMA and/or solvents can better be avoided to be used as instrument wetting agent.

 

Fig. 9

In a close-up of the upper right anterior region the color of the restoration looks within the color range naturally present in the dentition. On the dark side of the palette though.

Fig. 10

A close-up of the two centrals shows the vast difference in colour. In this anterior region there is a diffuse colour spectrum comparing cuspid, lateral and incisor. But the two centrals require symmetry, in shape but also in colour, in order to please the eye.

 

 

Fig. 11

A new colour mock-up was made. Emphasizing the milky whiteness of the left central by using a whiter dentin and an achromatic white enamel. A fast partial silicone index was made from the existing restoration.

Fig. 12

The central is isolated by rubberdam and a clamp was installed to clear the whole surface  to ensure good labial access despite a fixed retention bar being present on the palatal. 

Fig. 13

The composite will be removed back to the palatal shell. To fully recreate the colour but to also take advantage of the already correctly formed length and outline. A bonding procedure including the use of silane was performed.

Fig. 14

The approximal walls were made with the use of a matrix. The matrix was put in place with the hollow side on the palatal and the round side towards the labial following the desired natural shape of the incisor.

Fig. 15

The distal build up following the shape of the matrix. The use of brushes  facilitates the merging of the composite.

Fig. 16

Back to ‘The Box’. 

Fig. 17

Shaping of the mamelons. At this stage the transition from restoration to tooth should already be virtually invisible.

Fig. 18

After applying the last layer of achromatic enamel composite the finishing can start according to The Power of Pencil. First step is guaranteeing that the facial curve of the element is correct. By reducing the thickness of the composite incisally with the silicone matrix as a guide.

Fig. 19

A little surplus of composite can mostly be found towards the palatal.

Fig. 20

A very thin polishing disc can help to carefully go in between.

Fig. 21

The pencil lines will help us see the transitional lines. To check if they are symmetrical with those of the other central incisor.

Fig. 22

Final polishing consists of a multistep procedure. From thermoplastic wheels to felt with aluminium oxide paste.

Fig. 23

The final smile after rehydration of the enamel. 

Fig. 24

Beautiful youthful display of teeth with the lips at rest. The subtle surface structure that can be seen adds onto the natural appearance of the restoration.

Fig. 25

In close-up the restoration is in harmony with the rest of the anteriors because now there is harmony of the two centrals.

 

Conclusions

Discoloration of a composite restoration occurs in any dental practice. First of all an analysis of the performed treatment and patients habits can bring to light the most likely causes that were mentioned in the introduction. Another polishing sequence in many cases can lighten and bright up the restoration considerably. If not, a retreatment can be performed less comprehensive by using the palatal outline of the existing restoration. Sometimes it is smart in the retreatment to do another colour mock-up and choose for the lightest option.

Bibliography

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