Studies on the etiology of Angle's Class II malocclusal manifestations

Abstract

In summing up what has been brought forth in this contribution, the following points will become manifestly evident: That irregularity of the teeth or of any other organ is a biologic phenomenon and may occur in all living things. That malocclusions due to irregularities of the teeth, like the disturbed functions due to irregularities of other parts of animals and plants, are biologic phenomena. That attempts at classifying the irregularities and malocclusion of the teeth have been made as early as 1803. That these attempts terminated in the simple classification worked out by Angle which is accepted throughout the world. That the basis of Angle's classification does not prove satisfactory with respect to the divisions of Class II manifestations. That in skulls presenting Class II, division 1, the mandible is found to present a more acute angle than those belonging to skulls with normal occlusion. The body of the mandible therefore assumes a more posterior position in relation to the maxilla than in the normal skulls. The teeth of the mandible are therefore in distal occlusion. That in skulls presenting Class II, division 2, manifestations, there appears a reversal of this condition, i.e., the maxillary alveolar process appears to have drifted anteriorly; the teeth therein contained are consequently in mesial relation to those of the mandible. That various factors of malocclusion accepted by the modern orthodontist date back many centuries. Most of them have come down to us by tradition, and accepted on no other grounds but by the recommendations of some authority. That when put to test not one of the recommended factors is found to bear any definite relationship to a particular form of malocclusion. That the only factor found in close and positive relation to Class II, division 1, is the habit of sucking. That malocclusion is essentially an expression of some discrepancy in growth. That growth, though occurring as a constant manifestation from the fertilization of the egg to the adult size of the individual, is modified by retardations and accelerations. That accelerations and retardations when influenced by pathologic conditions result in deformities. That the development of the jaws and teeth are similarly subject to these retardations and accelerations. That 80 per cent of the individuals examined were bottle-fed. That the bottle-fed individuals present a higher incidence of diseases due to the artificial nature of the food. That of the individuals examined with reference to diseases 97 per cent had malocclusion of the teeth. That there is no correlation found between disease processes and any definite form of occlusion. That accelerations and retardation in growth influenced by pathologic conditions may explain the modified mandible in Class II, division 1, and the overdeveloped lateral portion of the upper alveolar arch and the concomitant underdeveloped premaxillary bone in Class II, division 2.. It may, therefore, be safely concluded, That mouth-breathing is not specially concerned in the production of Class II any more than it has influence to produce Class I. That the sucking habit has a positive though not exclusive relationship to Class II, division 1. That artificial feeding stands in direct relation to a higher susceptibility to pathologic conditions. That pathologic conditions have an exaggerating or activating influence upon retardation and acceleration in association with growth. And that retardations and accelerations associated with growth, influence the formation and completion of the masticatory apparatus as they do everything else that depends upon growth and development for its perfection. And, therefore, they also have an influence in the retarded development and diminutive size of the mandible with distal occlusion in Class II, division 1, and the forward drifting of the maxillary lateral halves with mesial occlusion of the maxillary teeth in Class II, division 2.