Sir, I note with some interest the recent debate on the aetiology and management of malocclusions, following the letters from Drs Horobin and Broadway. As I am actively involved in orthodontic research, I understand that malocclusions are commonly encountered in modern civilisations most likely due to changes in environmental conditions, such as feeding behaviour. Malocclusions might begin at birth, as modern mothers are less likely to breastfeed a child, whereas primitive man did so exclusively. Similarly, while the young children of primitive man did not ever use pacifiers or bottle-feed their children, these recent changes in environment/behaviour might be associated with malocclusions such as anterior open bite, which was so rare even a century ago that Edward Hartley Angle omitted this malocclusion from his classification system.

In terms of cause and effect, it is likely that upper airway obstruction is associated with malocclusion, and I am currently investigating 3-D airway changes (using a non-ionising, non-invasive protocol) to establish this association. Nevertheless, there is no doubt that there is a certain genetic susceptibility to developing a malocclusion, as genes that encode for skeletal, muscular and dental tissues have been identified and sequenced. Due to temporo-spatial patterning and gene-environmental interactions, an altered maxilla has concomitant effects on the developing mandible, and these effects can sometimes be clearly seen in children who manifest malocclusion as part of a craniofacial syndrome. In order to explain these associated phenomena I developed the Spatial Matrix hypothesis1 using the Functional Matrix hypothesis as a starting point, which according to Moss2 was first formulated by van der Klaauw.3