Cephalometric and clinical evaluation of Class I discrepancy cases treated by serial extraction

Abstract

0 NE of the major topics of discussion among orthodontists has been treatment in the mixed-dentition stage, especially in cases with evidence of a tooth-materialto-basal-bone discrepancy. Before 1930 treatment in the deciduous- and mixed-dentition stages was popular because the orthodontist assumed that Wolff’s law, which states that “bone grows in response to functional demand,” applied to the maxilla and the mandible as well as to the long bones. The general consensus was that early intervention could affect the dental arches with respect to growth and development. Angle’s philosophy that gentle forces in orthodontic movement would stimulate bone growth was well accepted. Soon, however, research gave the orthodontist a greater appreciation of growth and development. Broadbent, with the aid of a. cephalometer, made some of the early contributions in 1931. Schour’s14 growth study made use of vital staining, and Brodie31 * concluded : “Only alveolar processes are affected by orthodontic tooth movement.” Practitioners became more skeptical about treatment in the mixed dentition, and most orthodontic treatment of malocclusions was carried out after complete eruption of the permanent teeth. It was thought that early treatment would result in damage to the teeth and supporting structures, with no assurance of success in treatment. Early intervention was recommended only in treatment of cross-bites, oral habits, drifting permanent teeth as a result of early loss of deciduous teeth, irregularities caused by supernumerary teeth, and ectopic eruption of first molars. A few years later, other men. in the field contended that mixed-dentition treatment would permit development of the face toward greater balance and