Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin controversia, as a composite of controversus - "turned in an opposite direction, " from contra - "against" - and vertere - "to turn, " hence, "to turn against." The field of orthodontics is broad. It covers a wide scale from biology to mathematics, from the understanding of growth and interaction of the orthodontic appliances and the oral environment into which it is applied, to the mathematical models for the establishment of the desired force systems. Why are controversies anticipated? Why is their existence crucial? Significant differences in treatment philosophies exist among those who provide orthodontic treatment. In such circumstances there is a tendency to accept the new in preference to the old simply because in the material world of perishables, new is better and old is worse. A critical evaluation of the rationality and utility of treatment principles should be less a matter of taste and more of an appreciation of the development of ideas and the estimation of their practical application.