Why do human jaws and teeth often have poor growth when other parts of the body are rarely affected? Occasionally a child will have ‘Club Feet’ or perhaps ‘an extra finger” but in contrast, more than half will have malocclusion. I was much impressed by the research of Horowitz on Identical Twins way back in 1960. He found that the jaws varied more than any other part of their body. It does seem that this difference can be greater than ten times, despite the genes being identical. The Illustration below shows the area open to environmental variability.
I spent a long time trying to work out why this was. I experimented with tropisms which guide plants to grow towards light or gravity and saw how identical plants with the same genes (see picture), would grow differently depending on where the sun was. I coupled this with my thoughts on the large contrasts in the growth of human jaws that sometimes occur between individuals or within the same individual over time. I then wondered if there was some kind of compensation mechanism.
Obviously it is essential for the teeth of all mammals to mesh perfectly, so perhaps the jaws are adaptive to a greater extent than other parts of the body? Based on this thought I created the ‘Tropic Premise’ (Mew,J.R.C. “The aetiology of malocclusion: can the Tropic Premise assist our understanding”. British Dental Journal. 1981:151; :296-302) which suggested that if “the tongue rests on the palate with the lips sealed and the teeth in or near contact then the growth and position of the jaws would be ideal”. This Tropic belief has subsequently proved popular and has been adopted by many millions of youngsters as ‘mewing’.
Around this time I had a nice-looking young patient with slightly prominent front teeth. Having been trained by ‘Willy’ Grossman at University College Hospital to use Funtional Appliances, I gave her an ‘Andresen Monobloc’. From the start she wore it awkwardly with her lower incisors underneath the appliance. I stopped treatment within two months but she continued to hang her mouth open. To my horror her face continued to grow down quite spoiling her appearance.
I was very concerned and took her to see my Professor but after many tests no cause was found. I now know that the appliance had disrupted her posture and with my present knowledge could have quickly reversed her growth. However at that time I could do nothing but watch and ever since have had deep feelings of guilt which have driven me to help others to avoid this. This stimulated me to design a new range of four appliances which I called the Biobloc System. Stage 1 provided room for the tongue by encouraging the suture itself to widen rather than moving the teeth and the other appliances helped to train the patient to correct their tongue and jaw posture to ensure natural growth.
Happily I got the design more or less right to begin with and they have only been changed slightly since. Many clinicians have created other expansion appliances since such as the ALF, the AGGA, and the MSE but in my opinion, few have really understood the Tropic Premise and the idea that the teeth and jaws know where they should be and only need guiding into position with the right posture. I strongly believe that they should not be pushed or pulled. Interestingly I find that the teeth often align themselves if the posture is right, although in reality I am doing no more than copying the natural growth of most mammals. Remember every cell knows where it should be and it only needs correct posture to be able to grow to that position. This is an entirely different concept of growth but I feel confident it is the right one, or very close to it.
