A new approach to accelerate orthodontic tooth movement in women: Orthodontic force application after ovulation

Correlation of salivary cytokine IL-17A and 1,25 dihydroxycholecalciferol in patients undergoing orthodontic treatment

The management of malocclusion has developed greatly in terms of treatment simulation and biomechanics, but treatment duration has been a great concern to the clinician as well as the patient. 1-25dihydroxycholecalciferol (biologically active form of Vitamin D) stimulates both osteoclasts and osteoblasts and was found to be the most significant in Orthodontic Tooth Movement acceleration. Inflammatory cytokines like IL-17A also play an important role in osteoclastogenesis and can enhance the rate of Orthodontic Tooth Movement.To perform a simultaneous evaluation of pro-inflammatory salivary cytokine IL-17A and salivary 1-25dihydroxycholecalciferol and to correlate their role on orthodontic tooth movement.A prospective cohort study was conducted among n = 97 patients. Saliva samples were collected from the patients at three phases of the orthodontic treatment, centrifuged and stored at 4℃ for evaluation of salivary 1-25dihydroxycholecalciferol levels and Pro-inflammatory cytokine IL-17A using ELISA.The mean salivary 1-25dihydoxycholecalciferol levels were 41.250 ng/ml, 33.246 ng/ml and 35.043 ng/ml during the initial phase, lag phase and post lag phase of orthodontic treatment. The mean pro-inflammatory cytokine IL-17 A levels were 107.79 pg/ml, 102.98 pg/ml and 66.156 pg/ml during the initial phase, lag phase and post lag phase of orthodontic treatment. There was a correlation between the salivary 1-25dihydroxycholecalciferol level and salivary cytokine IL-17A levels during the various phases of orthodontic treatment using Spearman's correlation rho test and linear regression analysis. There was no significant difference (p > 0.05) between 1-25dihydroxycholecalciferol levels and gender during the various phases (initial phase, lag phase and post lag phase) of Orthodontic treatment.There was a negative correlation between salivary 1-25dihydroxycholecalciferol level and salivary cytokine IL-17A levels during the various phases of orthodontic treatment. The level of 1-25dihydroxycholecalciferol and salivary cytokine IL-17A have been quantified during the various phases of Orthodontic treatment and this can be used clinically for the supplementation of Vitamin D in patients with low vitamin D levels and can enhance the treatment duration for the patient with less damaging effects to the surrounding tissues.

Does the rate of orthodontic tooth movement change during the estrus cycle? A systematic review based on animal studies

BACKGROUND

As the fluctuation of sex hormone levels in menstruating women results in periodical effects in bone metabolism, understanding the implications for tooth movement could be of benefit to the orthodontist. This type of research presents practical and ethical problems in humans, but animal models could provide useful information. Our objective was to systematically investigate the available evidence on the question whether the rate of orthodontic tooth movement varies between the different stages of the estrus cycle in animals.

METHODS

Unrestricted searches in 7 databases and manual searching of the reference lists in relevant studies were performed up to February 2021 (Medline [PubMed], CENTRAL [Cochrane Library; includes records from Embase, CINAHL, ClinicalTrials.gov, WHO's ICTRP, KoreaMed, Cochrane Review Groups' Specialized Registers, and records identified by handsearching], Cochrane Database of Systematic Reviews [Cochrane Library], Scopus, Web of Knowledge [including Web of Science Core Collection, KCI Korean Journal Database, Russian Science Citation Index, SciELO Citation Index and Zoological Record], Arab World Research Source [EBSCO] and ProQuest Dissertation and Theses [ProQuest]). Our search focused on prospective controlled animal studies, whose samples included female subjects of any species that were quantitatively comparing the amount of tooth movement in the different stages of the estrus cycle. Following study retrieval and selection, relevant data was extracted, and the risk of bias was assessed using the SYRCLE's Risk of Bias Tool.

RESULTS

From the finally assessed records, 3 studies met the inclusion criteria. Two of the studies experimented on Wistar rats, whereas the other on cats. Tooth movement was induced by expansion or coil springs. The rate of orthodontic tooth movement was increased during the stages of the estrus cycle when oestrogen and/or progesterone levels were lower. The risk of bias in the retrieved studies was assessed to be unclear.

CONCLUSION

Hormonal changes during the estrus cycle may affect the rate of orthodontic tooth movement. Although these animal experiment results should be approached cautiously regarding their translational potential, it could be useful to consider the possible impact of these physiological changes in the clinical setting until more information becomes available. Registration: PROSPERO (CRD42021158069).

Estrogen effects on orthodontic tooth movement and orthodontically-induced root resorption

Estrogen is an essential regulator of the bone tissue. The remodeling of the alveolar bone and periodontal ligament is the basis of orthodontic tooth movement (OTM). There is a negative coregulation between physiological estrogen levels and the rate of OTM. As a possible inhibitory factor of OTM, estrogen suppresses bone resorption by inhibiting osteoclastic differentiation and restraining osteoclast lifespan though multiple pathways and cytokines, leading to the suppression of the initiation step of bone remodeling. On the other hand, estrogen stimulates osteoblastic differentiation and function. Estrogen receptor-α (ERα) involves in the osteogenic responses to mechanical stimulation, and the ERα expression is regulated positively by the levels of circulatory estrogen. Orthodontically induced root resorption (OIRR) is a common side-effect of orthodontic treatment. Estrogen may have some inhibitory effects on OIRR, but more studies are needed to get an effective conclusion.

Sex differences in the effects of the moon on ischemic stroke incidence: new findings from Beijing, China

Stroke is a major cause of death and disability in China, and no therapies have proven effective to prevent it. Popular belief holds that the lunar cycle affects human physiology, behavior, and health. The aim of our study is to determine whether the lunar cycle impacts the incidence of stroke subtypes [intracerebral hemorrhage (ICH), transient ischemic attack (TIA) and ischemic stroke (IS)]. We retrospectively extracted the discharge registry data of all patients with first-ever acute stroke hospitalized in the affiliated hospital of Beijing University of Traditional Chinese Medicine during 2002-2015. The onset times of stroke were assigned to four primary lunar phases based on NASA definitions. Chi-square tests and multiple logistic regression analyses were used to estimate the association between the lunar cycle and stroke incidence with adjustment for age, sex and season. A total of 5,965 patients with stroke (4,909 admissions for ischemic stroke IS, 754 admissions for ICH, and 302 admissions for TIA) were evaluated in our study. Subgroup analysis indicated that the admission rates of different sexes for IS tended to have opposite variation during the four moon phases. More female patients were admitted during the new moon than in the first and third quarters, while fewer male patients were admitted during the new moon than in the first and third quarters (χ2 = 15.589, P = .001). Multiple logistic regression analyses revealed that men were more likely to be admitted for IS in the first quarter than during the new moon (odds ratio [OR] = 1.252, 95% confidence interval [CI] = 1.076-1.456) (P = .004), and a corresponding trend was also identified for the third quarter (OR = 1.235, 95% CI = 1.062-1.437) (P = .006). No significant gender differences were shown in ICH or TIA. No sex difference is obvious during the full moon. Moon phases seem to affect both genders, but in very different ways. It seems that the new moon is a protective factor for male ischemic stroke patients and a risk factor for female ones. Woman tends to be more vulnerable than ever at the new moon, so deserves more attention and care. The mechanisms underlying this observation are worth studying further.

Effect of combined oral contraceptives on orthodontic tooth movement in a female rat model

Background

To investigate the effect of combined oral contraceptives (COC) on orthodontic tooth movement (OTM) and periodontal remodelling in a female rat model.

Methods

A total of 80 three-month-old female, Sprague-Dawley rats were randomly divided into experimental and control groups. The maxillary first molars were moved mesially using nickel-titanium coil springs (50 g force). The experimental group (N = 40) ingested 1.5 ml COC (Marvelon, 0.12 mg/d, N.V. Organon, Oss, The Netherlands) daily. The control group (N = 40) ingested 1.5 ml saline (0.9% sodium chloride) daily. After 7, 14, 21 and 28 days of force application, 10 rats in each group were euthanased and a vernier calliper was used to measure the orthodontic movement of the first molar. Root resorption at pressure areas was assessed by H and E staining. Micro-CT was used to detect alveolar bone mineral density.

Results and conclusion

The amount of OTM in the experimental group (0.46 ± 0.16 mm) was significantly less than in the control group (0.85 ± 0.25 mm; p = 0.003) during the 28 days of observation. There were significantly smaller (p = 0.002) root resorption lacunae in the experimental group (111710 ± 4037 pixels) compared with the control group (204962 ± 21318 pixels) after 28 days. There was no statistically significant difference in the bone mineral density between the experimental and control groups throughout the study period (p > 0.05 at each time point). The short-term administration of COC may retard tooth movement and reduce the level of root resorption during OTM in female rats.

Effects of piezosurgery in accelerating the movement of orthodontic alveolar bone tooth of rats and the expression mechanism of BMP-2

The aim of the study was to investigate the effects of piezosurgery in accelerating the movement of orthodontic alveolar bone tooth of rats and the expression mechanism of bone morphogenetic protein-2 (BMP-2). Adult male Wistar rats (n=30), with an age range of 14–15 weeks, and an average weight of 250±16 g were used. The animals were randomly divided into the control and observation groups. The rats in the control group were injected with 25-dihydroxyvitamin (1,25-dihydroxycholecalciferol) into their dental ligament. The rats in the observation group were placed with an orthodontic device between the first molar and central incisor in the maxillary. On the first day after animal treatment, piezosurgery stimulation was performed on the first molar in maxillary. The changes of the movement distance of the first molar and gum surface temperature on days 1, 3, 5, 7 and 14 were then compared. Immunohistochemical staining was performed to detect the expression of BMP-2 of periodontal tissue in the tension side of the first molar. Tooth movement distance in the observation group on days 5, 7 and 14 was significantly longer than that in the control group (p<0.05). The gum surface temperature of the observation group was elevated to some extent, peaking after 20 min. BMP-2 mRNA and protein levels in the observation group were significantly higher than those of the control group at days 3, 5, 7 and 14 (p<0.05). In conclusion, piezosurgery may significantly accelerate the movement of orthodontic alveolar bone tooth of rats and be associated with an increasing BMP-2 expression.

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.

Materials and 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 &lt; .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.

Conclusion: 

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.