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Published on: April 15, 2021
The Impact of Acute and Chronic Stress and Cannabinoid Extract Injection on Orthodontic Tooth Movement: An
Amin Golshah1, Mohammad Moslem Imani1, Fatemeh Azizi1
1Department of Orthodontics, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran, kums.ac.ir.
Background And Objectives:
Knowledge about the effects of medications and supplements on orthodontic tooth movement (OTM) is imperative for orthodontists. This study aimed to assess the effects of acute and chronic stress and cannabinoid extract (CE; marijuana) injection on OTM in rats.
Materials And Methods:
In this animal experimental study, 220 male Wistar rats were randomly assigned to 22 subgroups (n = 10) in two main groups of acute and chronic stress. The rats in the acute group were evaluated over a 21-day period in the following 11 subgroups (1) no orthodontic treatment/no medication (2), orthodontic treatment/no medication (3), no orthodontic treatment/intraperitoneal CE injection (4), orthodontic treatment/CE injection (5), no orthodontic treatment/saline injection (6), orthodontic treatment/saline injection (7), no orthodontic treatment/no medication under stressful conditions (8), orthodontic treatment/no medication under stressful conditions (9), no orthodontic treatment/CE injection under stressful conditions (10), orthodontic treatment/CE injection under stressful conditions (11), no orthodontic treatment/saline injection under stressful conditions. The rats in the chronic group were studied over a 40-day period in the following 11 subgroups with the same subgroups of the acute group. All rats were then sacrificed, their maxilla was resected, and OTM, the mean number of blood vessels, osteoclasts, and Howship's lacunae, bone volume/total volume (BV/TV) ratio, and bone mineral density (BMD) were assessed.
Results:
OTM was significantly greater under chronic stress (0.23 ± 0.19 mm) than acute stress (0.21 ± 0.16 mm, p < 0.001), and in rats receiving CE injection (0.29 ± 0.19 mm) compared with controls (0.20 ± 0.17 mm, p < 0.001). The mean number of Howship's lacunae (10.74 ± 5.27 vs. 8.52 ± 6.31, p < 0.001), osteoclasts (14.69 ± 7.53 vs. 11.06 ± 8.45, p < 0.001), and blood vessels (12.45 ± 3.19 vs. 10.81 ± 2.69, p < 0.001) were also significantly higher in stressed rats receiving CE. BV/TV and BMD were significantly lower in CE-treated stressed rats (BV/TV: 17.56% ± 2.20% vs. 27.79% ± 5.68%, p < 0.001; BMD: 1.76 ± 0.39 vs. 2.54 ± 0.46 g/cm3, p < 0.001) compared with controls. All parameters were further enhanced by orthodontic treatment.
Conclusion:
Daily CE injection combined with acute and chronic stress significantly enhances OTM in rats, accompanied by increased osteoclastic activity, vascularization, and decreased bone density. Quantitative data and statistical significance provide robust evidence of these effects.
