We see Orthodontics yield remarkable results and provide patients with the perfect smiles they seek by straightening or moving teeth. It seems simple enough, right? However, there’s more to it than meets the eye. Have you ever wondered how this movement takes place so seamlessly and positions teeth in entirely new positions without damaging the surrounding oral structures?
Today, we are going to learn about the underlying biological mechanisms that render orthodontic tooth movement possible.
The potential to move teeth through the alveolar bone is dependent on the PDL as it attaches the tooth to the bone. Orthodontic tooth movement is a synergistic consequence of physical force (orthodontic force) and biological tissue remodeling.
It’s important to understand the biology of tooth movement as it has profound clinical implications, especially in cases where dentists want to accelerate tooth movement. Our Orthodontics course at LDi delivers in-depth knowledge of the processes that bring about safe tooth movement while providing impressive results to your patients.
How Does Orthodontic Tooth Movement Occur?
Think of orthodontic tooth movement as a biological response to a mechanical force. Successful tooth movement is dependent on the coordinated tissue resorption and formation in the alveolar bone and periodontal ligament. The orthodontic force applied to the teeth creates pressure and tension zones in the alveolar bone and periodontal ligament. This, in turn, alters the homeostasis of the periodontal ligament space by disturbing the blood flow and the localized chemical environment.
The local hypoxia and fluid flow activate the biochemical and cellular events that culminate in the remodeling of bone and PDL by stimulating osteoclast resorption in areas of pressure and osteoblast deposition in areas of tension.
If the orthodontic force is sustained, as, in the case of orthodontic wires and appliances, the alteration in blood flow rapidly modifies the chemical environment by releasing certain chemical mediators. These biologically active agents include prostaglandins and cytokines that work to influence the cellular activities at the pressure and tension sides in the PDL resulting in bone remodeling.
Inflammation: A Friend or Foe for Orthodontic Tooth Movement?
We naturally tend to associate the phenomenon of inflammation with something harmful. Tooth movement, however, relies heavily on inflammatory processes for the remodeling of bone and periodontal ligament. The mechanical forces exerted on the teeth by orthodontic wires and appliances trigger a sequential immune response that consequently sets off the process of ‘aseptic inflammation.’ It is mediated by a variety of inflammatory cytokines, prostaglandins, neuropeptides, and vasoactive molecules that are released in the PDL during orthodontic tooth movement.
Inflammatory mediators are crucial for orthodontic tooth movement to occur. For example, prostaglandins help with orthodontic tooth movement by stimulating the formation of osteoclasts and accelerating bone resorption at compression sites. Cytokines such as IL-1, IL-6, IL-17, and TNF-α also induce inflammation and osteoclastic bone resorption.
In contrast, IL-10 is increased at tension sites, thereby decreasing RANK signaling and inhibiting osteoclast formation and activity, thus encouraging bone deposition.
Since NSAIDs (Non-Steroidal Anti Inflammatory Drugs) block prostaglandin synthesis in an attempt to reduce inflammation, they can interfere with orthodontic tooth movement and slow it down. Hence, it is advised for dentists to prescribe drugs other than NSAIDs for pain management following Orthodontic treatment. Acetaminophen appears to be the drug of choice for this purpose.
The importance of controlled inflammation
Optimal orthodontic force is the light and continuous mechanical force applied to teeth that leads to the maximum rate of tooth movement with minimal irreversible damage to the root, PDL, alveolar bone, and gingiva. This type of force allows for a healthy inflammatory process to take place. It is best achieved by applying a light continuous force with the help of orthodontic appliances. At the cellular level, a light force reduces blood flow and encourages quick recruitment of osteoclasts to allow for tooth movement to begin soon after.
Dysregulated tooth movement caused by heavy and prolonged forces can have dire consequences, such as tissue destruction manifested in orthodontic-induced root resorption and periodontal disease. At the cellular level, a heavy orthodontic force causes unregulated or excessive inflammation by cutting off the blood supply and causing hyalinization (cell death under pressure). Consequently, osteoclast differentiation is halted within the compressed PDL space, and tooth movement is delayed.
Since most patients desire minimal treatment duration, clinicians are always looking for safe and effective treatment techniques to hasten orthodontic movement. However, it is crucial to be wary of the fact that there exists a very delicate balance between accelerating orthodontic treatment and increasing the risk for root resorption, periodontal damage, and tooth devitalization.
Patient safety is the foundation of good patient care. A comprehensive course in Orthodontics will teach and enable you to treat malocclusion safely and effectively so you can deliver only the best to your patients!
The Bottom Line
Orthodontic tooth movement triggers inflammatory reactions in the periodontal ligament space that, in turn, stimulate the release of various biochemical signals and mediators. These are responsible for causing the alveolar bone and PDL remodeling necessary for tooth movement. However, for inflammation to play a healthy role in orthodontic tooth movement, orthodontists must bear in mind the importance of exerting only an optimal orthodontic force on the teeth. A postgraduate diploma in Orthodontics will equip you with the knowledge and skills required to improve the quality, rate, and stability of orthodontic treatment at your practice. Enroll now and learn the biological mechanisms underlying tooth movement to help guide your efforts toward new approaches to solve current challenges of Orthodontic tooth movement. At LDi, we strive to enable you to translate biological concepts into clinical practice as we dive into the world of Orthodontic together!