This month our blog will we will cover a physiological topic.
Recently, several studies raise the hypothesis that diabetes affects the speed of orthodontic movement. However, a simple consultation with the literature is not able to give us a definitive answer on the question. While some studies indicate that diabetes accelerates orthodontic movement, [1,2] others indicate the opposite.[3,4] And there are those who found no influence of the disease on the speed of orthodontic movement. Faced with so much controversy, I decided to discuss this topic due to its great relevance.
Diabetes and its major complication
The prevalence of diabetes has increased rapidly in the world, with approximately 9% of the adult population suffering with the disease. The prevalence among children and adolescents is also significant, especially in relation to diabetes Type 2, whose main risk factor is obesity. In type 1 diabetes, the problem is of autoimmune origin. In these two major types of diabetes, the big villain is the same: the excess of glucose in the blood. Hyperglycemia is responsible for the complications that cause heart attacks, strokes, blindness, amputations, among other problems. This is because excess blood glucose binds with various components of the endothelial cells and collagen in the blood vessels, causing changes that culminate in the fragility and destruction of the capillaries that irrigate the tissues. This complication is called microangiopathy.
Why could diabetes accelerate orthodontic movement?
We know that orthodontic movement depends on the remodeling of the alveolar bone, in which the activities of osteoclasts (resorption) and osteoblasts (deposition) interfere with the speed of tooth movement. As diabetes is normally characterized by a pro-inflammatory state, the increase of pro-inflammatory mediators in the periodontal tissues could increase the activity of osteoclasts, facilitating the resorption of the alveolar bone and, consequently, accelerating tooth movement.[1,2]
And why could diabetes slow orthodontic movement?
Although the studies cited above demonstrate an increase in proinflammatory mediators in periodontal tissues, we must not forget that bone remodeling induced by orthodontic force requires a series of other local responses. For example, removal of the hyalinized tissue in the areas of compression, regeneration of the fibers of the periodontal ligament and bone deposition in the traction areas of the ligament. All this requires adequate vascularization of the region, and in diabetes, microangiopathy can impair all these responses, thus delaying tooth movement.[3,4]
But does diabetes even affect the speed of orthodontic movement?
A careful analysis of the studies and mechanisms of the disease allows us to state the following: 1) the increase in inflammation in the periodontium of diabetics does not necessarily indicate a higher rate of tooth movement – what may be occurring is a greater destruction of the periodontal tissues, which causes not only increased tooth mobility, but could also lead to tooth loss. It is worth remembering that studies that demonstrate an acceleration of movement induced by diabetes were performed in rodents, usually with excessive forces, and the tooth movement was evaluated only for a short period of time. 2) Diabetic microangiopathy is more compatible with a retard in tooth movement – since adequate circulation of periodontal tissues is essential for the recruitment, activation and functioning of the cells involved in the remodeling of the tissues of the periodontal ligament and alveolar bone.
Final considerations and alert
The experiments cited in the post were performed in rodents, that is, we do not have evidence from clinical studies to confirm if diabetes actually changes the speed of orthodontic movement. However, the criteria adopted by the studies (force and anchorage control, appropriate analysis of the results, etc…), as well as the pathophysiological mechanism of the disease, point more coherently to the possibility that diabetes per se (ie without associated periodontal disease) could delay the orthodontic movement.
In those studies in which the hyperglycemia was treated, the normalization of glycemia reversed the aforementioned changes. This means that diabetes can only affect orthodontic treatment in uncontrolled patients. And in these cases, the patient becomes more susceptible to periodontal disease (by the microangiopathy already cited), and the combination of orthodontic force plus periodontal disease is extremely damaging to the periodontium. The orthodontist must therefore be extremely careful to the health conditions of the periodontal tissues, controlling the degree of dental mobility and bleeding. The application of forces in an unhealthy periodontium is obviously contraindicated.
ALERT: Finally, we highlight the importance of anamnesis and the clinical follow-up of the periodontal health of ALL patients. Diabetes is considered a silent, undiagnosed disease in one-third of dental patients. In addition, about 30% of diabetic patients do not perform adequate glycemic control. The chance of attending uncontrolled patients is therefore very high. Our greatest care in these cases must then focus on the health of the characters of orthodontic movement, ie the periodontal tissues.
If you have experience or doubts about this or any other systemic disease, leave your comment here. If you have questions about how other systemic conditions or drugs interfere with orthodontic treatment, we suggest the reading of our review article. 
1. Braga SM et al. Effect of diabetes on orthodontic tooth movement in a mouse model. Eur J Oral Sci. 2011;119:7-14.
2. Sun J et al. Histological evidence that metformin reverses the adverse effects of diabetes on orthodontic tooth movement in rats. J Mol Histol. 2016 Dec 15. [Epub ahead of print]
3. Arita K et al. Effects of diabetes on tooth movement and root resorption after orthodontic force application in rats. Orthod Craniofac Res. 2016;19:83-92.
4. Villarino ME et al. Bone response to orthodontic forces in diabetic Wistar rats. Am J Orthod Dentofacial Orthop. 2011;139(4 Suppl):S76-82.
5. Plut A et al. Bone remodeling during orthodontic tooth movement in rats with type 2 diabetes. Am J Orthod Dentofacial Orthop. 2015 Dec;148(6):1017-25.
6. Global report on diabetes. World Health Organization, Geneva, 2016
7. Rhodus NL, Vibeto BM, Hamamoto DT. Glycemic control in patients with diabetes mellitus upon admission to a dental clinic: considerations for dental management. Quintessence Int. 2005;36:474-82.
8. Gameiro GH et al. The influence of drugs and systemic factors on orthodontic tooth movement. J Clin Orthod. 2007 Feb;41(2):73-8;