The causes of orthodontic problems (etiology of malocclusion) can be grouped into three basic groups: specific causes, genetic influences, and environmental influences.
- Disturbances in embryologic development such as cleft palate
- Skeletal growth disturbances such as birth trauma
- Muscle dysfunction such as muscular dystrophy
- Disturbances of dental development such as missing teeth, extra teeth, improper guidance of the eruption of teeth (impacted teeth), and trauma to teeth
- These specific causes account for only 5% of orthodontic problems
In the most widely used orthodontic textbook, Contemporary Orthodontics, the author, Dr. William Proffit, upon review of numerous studies, reported that the heritability of craniofacial characteristics (skeletal shapes) was fairly high but the heritability of dental characteristics (fit of the bite) was low. This means that the general shape of the facial structure has a significant genetic component but the fit of the bite and the alignment of the teeth have a little genetic basis.
Early in my orthodontic career, I would often provide the explanation for why a child’s teeth did not fit properly by saying “your child has inherited small jaws from Mom and large teeth from Dad so there is not enough room for the teeth to come in straight”. This is simply not the case. Analyses of skulls from 300 years ago find very few orthodontic problems, but, almost 85% of children in developed countries now have orthodontic problems.
Genetic changes that would be required to explain this difference in orthodontic problems would take 30,000 years or more, so over the course of 300 years there could not be genetic changes sufficient to account for the changes we see.
It appears that environmental influences on the expression of genes (epigenetics) could be the predominant cause of orthodontic problems. Proffit states that malocclusion (orthodontic problems) is a “disease of civilization” (Proffit, 2013).
The changes we have created in our environment (such as bottle feeding, and a softer diet) over the past few hundred years appear to have altered the way our faces and teeth grow. These environmental influences often result in an orofacial myofunctional disorder and include things such as:
- Changes to the transition from breastfeeding to solid foods
- Abnormal tongue rest position
- Abnormal swallow
- Mouth breathing
- Poor oral habits (thumb sucking, soothers, etc.)
- Poor posture is often related to the sedentary aspect of modern life
- Increased stress related to our fast-paced, modern life
- Increased environmental contaminants that trigger allergies
- Changes to diet such as processed foods