An appraisal of tweed's basic principles

Abstract

1. 1. Hellman's explanation of the mechanism of the growth of the face should be re-examined. According to reliable evidence, the face grows “forward” and not “from before backwards.” 2. 2. During development the alveolar processes and the dental arches grow forward more rapidly than the zygomatic processes of the maxilla. 3. 3. The basal structures giving support to the teeth continue to develop gradually under the influence of function, after the completion of the adult dentition. 4. 4. Nearly all malocclusions are characterized by an apparent forward drift of the teeth, but that condition is transitional. 5. 5. The forward tendency is a natural characteristic of all molar teeth. 6. 6. Young individuals cannot be judged by adult standards. 7. 7. There is a normal variation in the formation of the jaws between the various races; and also in the relationship of the dental arches with respect to the supporting structures. 8. 8. As a rule, neither the anterior nor the posterior teeth are placed directly over the ridges. 9. 9. The arrangement and maintenance of the lower anterior teeth in an upright position over the basal bone is not a requirement for permanent orthodontic results. 10. 10. There is a great variation in the normal axial inclination of the anterior teeth in different individuals. 11. 11. “Axial inclination of the teeth disturbed by orthodontic management, tends to correct itself following treatment.” (Brodie.) 12. 12. The extraction of four premolars for supposedly improved orthodontic results is justifiable only in very few instances. 13. 13. The extraction of third molars is recommended too frequently. 14. 14. Some arrangement should be made whereby papers read before orthodontic societies are evaluated and correlated with known facts.