The purpose of this study was to investigate the micro-implant height and anterior hook height to prevent maxillary six anterior teeth from lingual tipping and extruding during space closure. We manufactured maxillary dental arch form, bracket and wire, using the computer aided three-dimensional finite element method. Bracket was .022" x .028" slot size and attached to tooth surface. Wire was .019" x .025" stainless steel and .032" x .032" stainless steel hook was attached to wire between lateral incisor and canine. Length of hook was 8mm and force application points were marked at intervals of 1mm. Four micro-implants were implanted on alveolar bone between second premolar and first molar. The heights of them were 4, 6, 8, 10mm starting from wire. We analyzed initial displacement of teeth by various force application point applying force of 150gm to each micro-implant and anterior hook. The conclusions of this study are as the following : 1. When the micro-implant height was 4mm and the anterior hook height was 5mm and below, anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, anterior teeth were tipped labially. 2. When the micro-implant height was 6mm and the anterior hook height was 5mm and below, the anterior teeth were tipped lingually. When the anterior hook height was 6mm and above, the anterior teeth were tipped labially. But lingual tipping of anterior teeth decreased and labial tipping increased when the micro-implant height was 6mm, compared with 4mm micro-implant height. 3. When the micro-implant height was 8mm and the anterior hook height was 2mm, the anterior teeth were tipped lingually. When the anterior hook height was 3mm and above, labial tipping movement of the anterior teeth increased proportionally. 4. When the micro-implant height was 10mm and the anterior hook height was 2mm and above, labial tipping of the anterior teeth increased proportionally. 5. As the anterior hook height increased, anterior teeth were tipped more labially. But extrusion occurred on canine and premolar area because of the increase of wire distortion. 6. Movement of the posterior teeth was tipped distally during maxillary six anterior teeth retraction using micro-implant because of the friction between bracket and wire. Based on the results of this study, we could predict the pattern of the tooth movement according to position of micro-implant and height of anterior hook. It seems that we can find the force application point for proper tooth movement in consideration of inclination of maxillary anterior teeth, periodontal condition, overjet and overbite
Bicuspid ; Dental Arch ; Finite Element Analysis* ; Friction ; Incisor ; Molar ; Orthodontics ; Overbite ; Stainless Steel ; Tooth Movement ; Tooth*

To evaluate the possible correlation between the origin of complete hydatidiform mole(CHM) and subsequent persistent gestational trophoblastic tumor(GTT) after molar evacua-tion, we have studied genetic origin patterns against conventional clinical parameters -pati-ent's age, gestational age, uterine size for gestational age, serum beta-hCG levels before mol-ar evacuation- in 69 patients with CHM. In our study, each of large uterine size for gesta-tional age, serum beta-hCG levels before molar evacuation, and genetic origin of CHM had a prognostic significance of subsequent persistent GTT. However, each of gestational age and patient's age is not a good prognostic indicator for subsequent persistent GTT. Among the patients with persistent GTT, there are no differences in clinical parameters- patient's age, gestational age, tumor age(the interval between evacuation of CHM and initiation of chem-otherapy), serum beta-hCG levels before molar evacuation and before initiation of chemother-apy- according to the origin of CHM. There are no differences in the analysis of sex-chr-omosome and variable number tandem repeat sequence YNZ22 and APOB gene in the extr-acted DNA from frozen tissues and paraffin blocks and from EDTA treated peripheral blood and dried blood specimen on Wartman paper. It is suggested that analysis of sex-chromo-some and polymorphism of YNZ22 and APOB gene from the extracted DNA of paraffin bl-ock and dried blood specimen on Wartman paper is the valauble experiment to evaluate the origin and the classification of hydatidiform mole and seems to be the sensitive molecular genetic method in predicting subsequent persistent GTT.
Apolipoproteins B ; Classification ; DNA ; Edetic Acid ; Female ; Gestational Age ; Humans ; Hydatidiform Mole* ; Molar ; Molecular Biology ; Paraffin ; Pregnancy ; Tandem Repeat Sequences ; Trophoblasts ; X Chromosome ; Y Chromosome