Influence of fixed orthodontic treatment on the menstrual cycle of adult females: A prospective longitudinal study.
OBJECTIVE
To investigate the influence of fixed orthodontic treatment on the menstrual cycle, including menstrual cycle length (MCL) and duration of menstrual bleeding (DMB), in adult female patients.


METHODS
This was a prospective longitudinal study conducted in Chengdu, China. A total of 164 adult women with normal menstrual cycles were recruited in the study, with 79 patients undergoing orthodontic treatment and 85 serving as controls. Data of MCL, DMB, and accompanying symptoms were collected over six consecutive menstrual cycles in each participant. Student's t test, Chi-square test, Moses extreme reaction test, and repeated measures analysis of variance were used for statistical analysis.


RESULTS
The MCL of the first menstrual cycle (T1) was significantly elongated by 2.1 ± 0.5 days compared with baseline (P  =  .003, 95% CI [-3.7, -0.5]). Variability of MCL of the orthodontic group at T1 was also significantly greater (range, 15-46 days) than that of the control group (range, 24-36 days) (P < .05). No significant difference in MCL was found in the subsequent five menstrual cycles (T2-T6) compared with baseline, and no significant differences in DMB or other accompanying symptoms were observed throughout the study.


CONCLUSIONS
Fixed orthodontic treatment may influence the MCL of adult females in the first month after bonding, but showed no effect on DMB or subsequent MCL through the follow-ups.
a  Lecturer, State Key Laboratory of Oral Diseases and Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Peipei
P
Duan
b  Senior Lecturer, Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China.
Wenwen
W
Qu
c  Professor, State Key Laboratory of Oral Diseases and Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Shujuan
S
Zou
c  Professor, State Key Laboratory of Oral Diseases and Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Yangxi
Y
Chen
d  Master's Student, West China School of Public Health, Sichuan University, Chengdu, China.
Hui
H
Lan
e  Professor, Department of Oral Sciences, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
Mauro
M
Farella
f  Senior Lecturer, Department of Oral Sciences, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
Li
L
Mei
D000328:Adult; D002681:China; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008597:Menstrual Cycle; D009967:Orthodontic Appliances; D011446:Prospective Studies
Menstrual bleeding; Menstrual cycle length; Orthodontic treatment