A longitudinal study of the stability of the dentition following orthodontic treatment

[摘要] ENGLISH ABSTRACT:The maintenance of dental alignment following orthodontictreatment has been, and continues to be, a challenge for theorthodontist (McReynolds and Little, 1991). Orthodontistsshould endeavour to establish normal occlusions andfunction to the end that physiologic balance and retentivestability may be achieved (Goldstein, 1953). Manyphilosophies and theories have been formulated in responseto this challenge, but few have successfully withstood thetest of rigorous post-orthodontic evaluation.The present study comprises longitudinal assessments ofdentofacial changes which occurred in South AfricanCaucasian subjects during their orthodontic treatment aswell as a mean of 7 years following active treatnent. Thesample consists of 88 Caucasian subjects; 33 males and 55female sUbjects who have undergone conventional edgewiseorthodontic treatment (Lindquist; 1985). The treatmentincludes extraction (56%) and nonextraction (44%) therapy.Due to the intricate structure of the craniofacial complex,it is deemed important to discuss the major components ofthis complex separately and then to compare the variablesdescribing the area with post-orthodontic lower incisorcrowding. Lower incisor crowding or irregularity, mostoften referred to as relapse when occurring in thepost-orthodontic dentition, is a phenom~non that is clinically visible and easily assessed using the LittleIrregularity Index (Little, 1975). A variety of orthodonticstudy cast and cephalometric variables represent the changeswhich occur at the three time intervals selected for thisstudy, namely pre-treatment (T1), post-treatment (T2) andfollowing active treatment (T3). statistical analysis of th~data was undertaken by the Institute for Biostatistics ofthe Medical Research Council, Tygerberg, RSA utilising theSAS (1985). The significance level of the results of thisstudy is set at p = 0.05.xNo previous study has documented theevaluated and described the variouscraniofacial skeleton in this format.literaturepartsor hasof theThe thesis is divided into thirteen chapters.

[发布机构] Stellenbosch University