This study was carried out in order to findout the amount of tooth movement, the changes arch size and the changes in arch morphology following orthodontic treatment and to provide a guideline for to predict post-treatment arch morphology. The sample group for this study consists of 15 males and 22 females, totalling in 37 persons, who received orthodontic treatment at Orthodontic Department of DanKook Univ. Dental Hospital. They are classified into Extraction Class I treatment group (E I), Non-extraction Class I treatment group (N I), and Non-extraction Class III treatment group (N III), according to their pre-treatment malocclusion state and methods of treatment.
Following conclusions and averaged dental arch form for each group were obtained by cephalometric linear measurements and dental arch measurements using pre- and post-treatment .lateral cephalograms and plaster study models.
I . Intercanine width were reduced in max. of both EI. and NI during the period of treatment. 2. Intermolar width were reduced in max. of El and increased in max. of NI. Therefore although
there was no difference between these two groups before the treatment, intermolar width of
the max. of NI was wider than that of E I after the treatment.
3. PMV-incisor distance and PMV-canine distance were decreased in both max. and mand. of El and that of NI, during the period of treatment. PMV-molar distance was decreased in both max. and mand. of NI and in mand. of NIII.
4. Items that showed stability during the treatment were: max. & mand. PMV-molar distance, mand. intercanine and intermolar width in El; mand. intercanine and intermolar width in NI; mand. & max. PMV-incisor distance, PMV-canine distance, max. PMV-molar distance and
max. & mand. intercanine and intermolar width in NIII.
S. The differences in averaged canine and molar variances to post-treatment dental arch form were present only in El and in NI. There was no variance between maxilla and mandible in each group.
|