That Quirky Lateral

Shadeguides - Direct anteriors
8 Aug 2017

A beautiful soul voice sang: 'This is a man's world, this is a man's world. But it would be nothing, nothing without a woman or a girl.'  

Same goes for the lateral. We focus on the central incisors a lot in any restorative plan. We should, because they are important. But what would the central be without a beautiful lateral along his side? The central is the serious one, the oldest sibling, the heir to the throne, whereas the lateral can be a bit less responsible, more adventurous and creative. The quirky one. Slightly rotated? No problem. Not symmetrical with the other lateral? No problem. Slightly different colour? No problem. In fact: if you are restoring a lateral, make sure to add some excentricity. A few key points though: in general a lateral is approximately 1,5mm shorter than the central incisor. In width the cental incisor crown is approximately 2 mm wider.  The mean width/length ratio of the maxillary lateral is on average 0.8. In shape the lateral can have a square or more round form. The incisal edge in the round lateral form sometimes can be seen with a almost cuspid like tip in the middle. The lateral from the opposite side can be inspiration but absolute symmetry is not mandatory. The embrasures in the maxillary anterior region open up more from central to premolar. The angles of the lateral therefore are more rounded off than the angles of the central. The distal angle of the lateral is more rounded off than the mesial angle.

In this case a young adult patient had fallen four years ago and had suffered an enamel-dentin fracture without pulp involvement on the lateral incisor #12. The tooth had been restored with a direct composite in emergency. Patient would like to have the tooth restored in a more natural way. Direct composite was the material choosen for re-treatment. A minimally invasive choice in a relatively young patient.

 

 

 

Fig. 1

Img. 1 – Initial situation shows a restored #12 that is too dark and without any of the characteristics present in the other anterior teeth.

Fig. 2

Img. 2 – In cases of trauma, in the past, an x-ray can show periradicular lesions. In this case the x-ray taken fortunately shows no sign of that. Because of excellent periodontal health the treatment plan can be focused on the coronal part.

Fig. 3

Img. 3 – The lateral has quite a steep emergence from the gingiva. Quite characteristic and almost identical to the emergence of the cuspid. Towards the incisal the restored part of the distal contour becomes concave. A restorative goal is to change the concavity of the distal into a more straight or convex profile without creating excessive thickness on the incisal edge

Fig. 4

Img. 4 – On the palatal marginal discolouration is visible. The palatal view is a very important one to analyse before restoring any case. It tells us where to remove or add mass. In this case it can be seen that volume needs to be added in the new restoration mainly on the distal of #12. Absence of restorative material can later interfere with correct placement of the transitional lines.

Fig. 5

Img. 5 – The dark restoration clearly takes away from the beauty of the patients smile. The patient had bleached her teeth three weeks ago. Which emphasises the contrast with the darkness of the composite. Bleaching of the enamel with peroxide agents compromises bond strength. I advise patients to refrain from bleaching in a safe 2 week period before treatment.

Fig. 6

Img. 6 – White striae in parallel arrangement can be observed running from mesial to distal.In the incisal 1/3 part the perikymata are in a more translucent background

Fig. 7

Img. 7 – In the first visit impressions for studymodels and photographs were taken. The ideally shaped #12 was created in a wax-up by the lab. Silicone indices were made to be our guide through treatment.

Fig. 8

Img. 8 – Before applying the rubberdam to avoid dehydration of the enamel, a colour mock-up of lightcured composite is performed to determine the basic colour of the tooth. Notice that the central incisor is slightly lighter at the cervical and middle 1/3 than the remaining enamel of the lateral.

Fig. 9

Img. 9 – The pictures are rotated in order to mimic the operator's view. The ruberdam is installed in order to isolate the teeth from any contamination and to focus more easily.

Fig. 10

Img. 10 – After carefully removing the old composite with the help of magnification the extent of the fracture becomes more clearly. The pink glow reveals to our eyes the close proximity of the pulp.

Fig. 11

Img. 11 – A 2,0mm bevel is created in order to have a gradual transition.

Fig. 12

Img. 12 – Peroperatively, in accordance with the patient, it was decided to also correct the chipped off enamel on the distal angle of the central incisor #11.

Fig. 13

Img. 13 – Therefore the silicone index had to be adjusted. Before proceeding with the lateral it was checked if the index could be seated exactly. The fracture line was marked on the index. The composite is then applied in the index extraorally. The line helps to avoid excess of the material on the palatal.

Fig. 14

Img. 14 – The palatal wall is built up with a white enamel composite.

Fig. 15

Img. 15 – A sectional matrix and a wedge are put into place to guide the approximal into a beautiful, naturally rounded shape. The mesial and distal are done separately to ensure an optimal visibility.

Fig. 16

Img. 16 – The Box is ready! From here we can start to play with the colours and shape.

Fig. 17

Img. 17 – The opaque dentin-like composite is applied, and mamelons are sculpted. In between, there a small amount of a translucent composite is accurately placed to have a subtle note of blue/grey in the incisal one third.

Fig. 18

Img. 18 – To mimic the white striations seen in the other maxillary anteriors small grooves are made with a tiny, sharp instrument (Fissura LM-Arte) in the following composite layer before it is lightcured. The small white bands can now be created by applying a very small amount of white colour diluted with modelling resin to lower the intensity of the white. The lines can be drawn with the instrument. After lightcuring the restoration was wrapped in a bow with the final layer of white enamel composite applied. In the same colour that was used for the palatal wall.

Fig. 19

Img. 19 – All the composite is applied. Next step is to remove any surplus of material and establish the correct outline. The silicone index should seat perfectly.

Fig. 20

Img. 20 – A pencil line on the incisal edge can compare the thickness to the initial goal defined in the index. In most cases the final layer of composite is a bit too thick and needs to be aligned with the index.

Fig. 21

Img. 21 – With a small polishing disc the composite is thinned out until the pencil line and slicone index run parallel.

Fig. 22

Img. 22 – During the treatment the contralateral lateral is there to be consulted.The transitional lines can easily be seen because of the natural gloss of the enamel. They have an almost omega shape.

Fig. 23

Img. 23 – After the correct placement of the omega shaped transitional lines, the mesial and distal angles are rounded off a bit more and the embrasures are opened up more to give it a more lateral like appearance.

Fig. 24

Img. 24 – Adding to the quirkiness of the lateral a little notch is made in the incisal edge.

Fig. 25

Img. 25 – The final result shows a lateral incisor that is more in harmony with the other maxillary anteriors.

Fig. 26

Img. 26 – In close-up the transition from composite to enamel is invisible. The colour of the restoration matches with the remaining enamel. Characteristics seen in the cuspid and central incisor are copied into the lateral.The white small bands and cloudy like white spots, the blue/grey background in the incisal one third and the warmth of the underlaying dentin in the middle one third.

Fig. 27

Img. 27 – The original concave distal wall is now more straight in line with its neighbouring teeth.

Fig. 28

Img. 28 – The patient's beautiful smile is restored.

 

Conclusions

To answer the original question: but what would the central be without a beautiful lateral along his side? Or: what would a smile be without a lateral full of character? Incomplete to say the least.
The use of composite to restore gives us the freedom to simulate in a minimally invasive way as precisely as possible any kind of natural structure. To complete a smile again.

Bibliography

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Sterrett JD, Oliver T, Robinson F, Fortson W, Knaak B, Russell CM.Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man.J Clin Periodontol. 1999 Mar;26(3):153-7.
Chu SJ.Pract Proced Aesthet Dent. 2007 May;19(4):209-15.Range and mean distribution frequency of individual tooth width of the maxillary anterior dentition.
Manauta J, Salat A. Layers, An atlas of composite resin stratification. Chapter 4 Mid and chapter 10 Surface and polishing Quintessence Books, 2012
Unlu N, Cobankara FK, Ozer F.J Biomed Mater Res B Appl Biomater. 2008 Feb;84(2):363-8.Effect of elapsed time following bleaching on the shear bond strength of composite resin to enamel.