CORRECTION OF MIDLINE CANT WITH A SINGLE CENTRAL INCISOR
The primary objective of treating a single central incisor is to create a restoration that blends in with the surroundings. The two front teeth – upper central incisors -are the most dominant part of the smile, and they are used to determine the position and cant of a facial and dental midline.
Studies suggest that the most important relationship to evaluate the aesthetics is the mediolateral inclination of the maxillary incisors. If the incisors are inclined by 2mm right or left, laypeople regard this as unesthetic.
Figs 1 & 2 show a trauma case with damaged right upper central incisor – 11. The assessment of the facial midline can only determine with a full-face photo; however, the images suggest enough to indicate the existing midline cant.
The treating clinician sent the patient to me – the dental ceramist for a consultation at the temporary stage (Fig 3). The midline cant is still apparent, and the patient had expressed his wish to have it corrected (Fig 4).
There are two ways of correcting the midline cant:
1. To clinically shave off the undamaged dentition – the left upper central incisor (21) in this situation, or
2. To overlap over 21 to create the illusion of straighter midline.
Option 1 adds additional clinical challenges at the time of try-in and insertion, which requires a meticulous level of precision.
Option 2 can be technically challenging and hard to get acceptance from the patient in general for not wanting to have one tooth more prominent than the other.
Now, who decides? The patient, of course. He permitted me to go with option 2, and then I informed the treating clinician accordingly.
Fig 5 shows the completed restoration in a close-up smile photo. Fig 6 indicates the levelled and straightened tooth, smile as a whole, correcting the midline cant.
In this particular case, I was confident (and thus pushed the patient accordingly) that option 2 was the best option due to the position of the left upper lateral incisor (22). Fig 7 shows how prominent the 22 is, compared to its counterpart of the right upper lateral incisor (12). 11 – upper right central incisor – can be more pronounced to balance things out, and this is called ‘contrapposto’ – an Italian term that means ‘counterpoise’ used in visual arts (see below – a video explaining the concept). Fig 8 shows the final result – retracted frontal view, perfectly balanced in harmony with the surroundings!
You might notice that the value is slightly low and chroma is somewhat high on the 11, but I did this on purpose. Because I overlapped the 11, it is more prominent than the position of the 21. What’s at the front appears brighter/whiter, and thus, it makes sense for me to reduce the brightness and increase the intensity in colour. In real life, it looks perfect (I don’t say that often, but I’m thrilled with the outcome).
Watch Video (4.22 minutes): Contrapposto explained
I want to thank the treating clinician – Dr Fiona Gallagher from Family Dental Practice in Brighton-Le-Sands NSW, Australia, for her clinical excellence. https://www.familydentalpractice.com.au/
This case was issued in February 2012 with no remakes or adjustments.
See another great example of addressing the midline cant in the Before and After section – click here to read.
Boksman, L. Simplifying Laboratory Communication. https://www.oralhealthgroup.com/features/simplifying-laboratory-communication-the-dental-midline-position-incisal-cant-and-incisal-horizontal/