Dissertation
Dissertation > Medicine, health > Oral Sciences > Oral orthotics > Journal of Orthodontics

Changes of Crown to Root Ratio of Upper Anterior Teeth during Orthodontic Treatment between Juvenile and Adult Patients: A Preliminary Study

Author ZhongJiaYong
Tutor LinXinPing
School Zhejiang University
Course Clinical Stomatology
Keywords Crown-root ratio Preadjusted Age Root resorption Alveolar ridge absorption
CLC R783.5
Type Master's thesis
Year 2011
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Objective: To investigate straight wire appliance before and after treatment in which the role of variation of the ratio of the tooth crown and root , as well as the age factor . Methods: 46 patients were divided into two groups according to age , the 23 cases of the youth group , adult group of 23 cases . According to the orthodontic treatment panoramic radiographs , the bracket as a frame of reference , the measurement is calculated central incisors , lateral incisors and canines apical uptake before and after treatment , alveolar uptake and crown-root ratio of the amount of change , paired t test , analysis of the age factor and the crown-root ratio changes , before and after treatment . Results: The average central incisor crown -root ratio in the youth group before and after treatment were 0.62 ± 0.04,0.70 ± 0.06; the average lateral incisor crown-root ratio were 0.63 ± 0.04,0.70 ± 0.06 ; fangs average crown-root ratio were 0.54 ± 0.05 , 0.60 ± 0.06. Average central incisor crown -root ratio in the adult group before and after treatment were 0.67 ± 0.04,0.78 ± 0.06; the average lateral incisor crown-root ratio were 0.66 ± 0.05,0.77 ± 0.05 ; fangs average crown-root ratio were 0.57 ± 0.05,0.70 ± 0.06. Crown and root of each group before and after treatment than there is a significant difference , adult approached the the the crown root than the amount of change than the youth group was significantly ( P lt; 0.01 ) . Conclusion: the straight wire appliance , approached crown root ratio were significantly increased , which the adult group was significant compared to the youth group , the two groups are still within the normal range of clinically acceptable .

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