Life

Ask the Dentist: Misaligned jaw not confined to history books – and can be resolved

Lucy Stock, dentist at Gentle Dental Care in Belfast, says having an out-of-line lower jaw can be resolved successfully with specific treatments

Charles II of Spain had a large undershot jaw, medically known as a prognathic jaw
Charles II of Spain had a large undershot jaw, medically known as a prognathic jaw Charles II of Spain had a large undershot jaw, medically known as a prognathic jaw

FOR 184 years, from 1516 to 1700, the Habsburg family ruled Spain. The key to their success in maintaining their lineage for so long was their concept of a tight-knit family. However, sometimes you can be too close and indeed this was the case for the Habsburgs, 11 of whose marriages were incestuous.

This resulted in the infamous 'Habsburg jaw' and, ultimately, their downfall; the close genetic gene pool ended with Charles II being infertile and the end of their rule.

The Habsburg jaw was a large undershot jaw, medically known as a prognathic jaw, that sat prominently in front of the upper jaw. Ideally your top teeth sit just over the lower teeth – not too much and not meeting edge to edge. When the teeth are sitting in alignment the forces are directed evenly, allowing teeth to function and last.

A narrow gene pool is not the only cause, of course – various hormonal, genetic and congenital conditions can give rise to prognathism. About one per cent of people of European heritage have a prognathic jaw but it can affect as much as 15 per cent in Asian populations.

With a protruding lower jaw, people can feel self-conscious of their facial appearance and it's an easy target for bullies. In severe cases it causes painful jaw joints because the joint is pulled out of position.

Treatments can be successful. If the misalignment is mild then braces can push the upper teeth forward and tip the lower teeth back. In more severe cases, jaw surgery is necessary; part of the lower jaw is pulled back and stabilised with surgical plates. Many patients who undergo this procedure are very happy with the end result and feel it was worth the recovery period.

You can even correct the bite without surgery by placing crowns which can change the position of the teeth and how the jaw sits. Some people started out with a normal bite and facial appearance but after losing many teeth their lower jaw can start looking more prominent. Replacing the teeth with implants can upright the front teeth and in effect pull back the lower jaw, making eating and speaking easier and make the lips sit better.