The dental Plano midline is one of the most important keys in the aesthetics of the patient’s smile. Before starting treatment with aligners, it is essential to carry out a correct diagnosis of the case and, among many other factors to assess, is the analysis of the dental Plano midline, which will allow us to know what movements we can and must make to achieve the desired objectives. .

We must analyze the upper dental Plano midline and the lower dental Plano midline separately.

Upper dental Plano midline

The maxillary dental Plano midline should always be centered with the facial midline, as long as there is facial symmetry. There may be a deviation of the dental Plano midline of up to 3 mm to the right or to the left without being noticeable by the general population when holding a conversation at a normal distance. Another important aspect to keep in mind is that the upper dental Plano midline must not be inclined with respect to the facial midline, it must be parallel to it, or else it could appear unsightly.

Lower dental Plano midline

The lower dental Plano midline must be centered with the upper dental Plano midline (and, therefore, with the facial midline), and, as with the upper dental Plano midline, there may be a deviation of up to 3 mm and go unnoticed. .

The deviated midline is a defect that affects a large part of the population and that, sometimes, is not given the importance it deserves.

What can cause midline deviation?

There are cases in which the occlusion of our patient is perfect and he presents a deviation from the midline. In this case, the cause may be an asymmetry in the size of the teeth, that is, Bolton’s discrepancy, where there is an alteration between the mesiodistal size of the upper and lower teeth.

Another cause, and perhaps the most common, is the presence of malocclusions such as class II or class III, where the position of the teeth can determine the deviation of the midlines.

On the other hand, there are skeletal causes where there is, for example, a mandibular deviation and the deviation from the midline is due to a component directly related to the mandibular bone.

The deviation of the midline can also be due to a dental Plano absence, either due to agenesis of the piece or its loss, which generates a movement of the remaining pieces towards the space of the dental plano absence, causing in many cases an alteration in the position of the dental plano midline.

And, finally, it may be due to a functional component, where patients make lateral or protrusive mandibular displacements, which generates an “apparent” deviation from the lower midline, but which is not real. For this reason, it is extremely important that the professional evaluate the mandibular position in centric relation, that is, in the ideal position in which the condyles are centered in the glenoid fosse, without forcing the muscles or ligaments.

How to correct the upper or lower dental Plano midline with aligners?

The deviation of the midline does not occur by itself, there will always be a base alteration that originates it. The most important thing in cases of midline deviation is to determine and diagnose what is causing it in order to attack the root problem and provide the patient with the result they are looking for.