Challenging Age Old Definitions In Prosthodontics​

Random Thoughts
This article I am putting some random thoughts and tips together gained over last 2 decades in practice and almost quarter of a century spent with dental textbooks. Hope it may benefit some, inspire some and make some thinkers. A few of you may not agree, write to me at bodypainshelpline@gmail.com. I also give a call for a scientific board/ consensus club where contentious issues of science, mainly occlusion can be discussed and joint statement of that board could be made available to all. All are invited to online fb group, “Think Club Occlusion”. I propose such a discussions under leadership of such stalwarts like Dr. Kumarswamy or Dr. Kanir Bhatia. And who better to conduct than Famdent.
Quite by accident, while I was training a young exceptionally intelligent Dentist, I discovered that the definition of “overjet” is wrong in Dentistry. To my mind even Dawson has erred. If you disagree or want to discuss, please write to me. While I was discussing with her ill effects of “overjet” (will explain below), she inspite of being gifted with an exceptional “IQ”, although agreed with need of “zero overjet”, unlike what literature wants 2mm overjet. But she would not get –how a 2mm overjet would destroy a bite? Almost for a year I wrote her off. A year later a similar discussion and I discovered that she was right too all the while. The overjet taught to her throughout and cemented by Dawson’s book was the place she was coming from. When I saw those was left dumb founded.
Did I misunderstand, what is overjet?
Thanks to her I dig into the literature. Here’s my conclusion- either I am completely wrong or textbooks just missed this one including Dawson. Overjet is variably described as:
The projection of the upper anterior and/or posterior teeth beyond their antagonists in a horizontal direction-Farlex Partner Medical Dictionary © Farlex 2012 as given in medical dictionaries.
Clinical Cases in Orthodontics
By Martyn T. Cobourne, Padhraig S. Fleming, Andrew T. DiBiase, Sofia Ahmad, , page 13 describe it as above, except it says from upper palatal surface to lower labial surface.
It further goes on to define the goal of Orthodontic treatment as “ To create 2-4mm overjet”, this part I am going to take up next.
“The horizontal projection of maxillary teeth beyond the mandibular teeth, usually measured parallel to the occlusal plane. When not otherwise specified, the term is generally assumed to refer to central incisors and is measured from the labial surface of the lower central incisors to the palatal surface of the upper central incisors at the level of the upper incisor edge. Unique conditions may sometimes require other measuring techniques. Notice he defines, distance between surfaces, but at the incisal edge”.—Mosby’s Dental Dictionary, 2nd edition. © 2008 Elsevier.
He says 1-3mm overlap is recommended. This to my mind is close to definition of overjet but not perfect. How much should be the overjet I will discuss in next section.
Reproduced from power point/pdf by Brian Laumer, which is apparently a part of Dawson’s book.
As given in Dawson’s book apparently, a reproduction by Brian Palmer. The sentence that describes Overjet is “Overjet is a horizontal measurement”. At the Incisal edge of upper tooth seems to be erroneous and arbitrary call. A definition must be complete in all aspects.
The Book “Euro-Qual Program: Toward a Quality System for European Orthodontic …edited by GeaHeege”, describes overjet almost similarly but elaborately and specifies incisal edge of upper teeth to labial surface of lower teeth, as the measuring points. This does not seem to my mind coming from any basis.
Now you can clearly see that literature for almost two centuries of rapid development of science has not stuck to rigor in defining what is overjet and no consensus or disagreement exists on these definitions. This is against the scientific principles.
Also medicine unlike other basic sciences has discouraged “theorists” or “ logic thinkers” and I have seen authors writing their possible explanations hidden in overdetailed articles for the fear of criticism. This sometimes may lead to confusion and not aid in development of science. Fundamentally two types of thinking exists.