**1. Introduction**

Many orthodontic patients complain about the physical and social discomfort which is associated with prolonged use of fixed appliances [1]. There are also numerous studies which report that dental and periodontal complications such as apical root resorption, subsequent

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

gingivitis, periodontitis, enamel demineralization, increased levels of dental caries, and open gingival embrasure spaces may occur during orthodontic treatment [2].

The first step of the biological response to orthodontic force is "tension and compression in the periodontal ligament" which constricts and deforms blood vessels damaging cells in the periodontal tissues. The initial aseptic acute inflammatory response is realized by releasing chemokines and cytokines from localized cells such as osteoblast, fibroblast, and endothelial cells. Most of these cytokines are pro-inflammatory providing the continuity of the inflammatory response by activating osteoclast precursors of periodontal ligament in extravascular range and inflammatory cells. Infiltration of inflammatory cells causes the increase of chemokine and cytokine levels. This enables differentiation of osteoclast precursors to multinucleated giant cells which will realize alveolar bone resorption that is required for tooth movement. The continuity of the existence of anti-inflammatory chemokines and cytokines is essential in order to suppress destructive pro-inflammatory and osteolytic processes [4]. Therefore; the pro- and anti-inflammatory responses of alveolar bone, periodontal ligament, and inflammatory cells to orthodontic force are required to be known in order to develop safe

Micro-Osteoperforations

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http://dx.doi.org/10.5772/intechopen.81419

The methods which accelerate tooth movement can be classified in three groups:

In this method, substances such as prostaglandins, corticosteroids, vitamin D, cytokines, neuropeptides, leukotrienes, nitric oxide, diazepam, and vasoactive medications, which are considered as physiological agents that transform mechanical forces into cellular response, are used to decrease the resistance to the strength applied during tooth movement that occurs

Taking systemic effect rather than being limited to the applied area and affecting other target cells in the body are reported as a common side effect of using these hormones and medications [17]. Therefore, there is no medication treatment which safely accelerates tooth move-

It was reported that stimulating periodontal ligament mechanically or physically can increase alveolar bone remodeling and tooth movement accordingly. Physical methods frequently include equipment-assisted treatment methods [6] such as low-dose laser applications, electromagnetic field, direct electrical current, and vibrational applications. These methods take effect by inducing signal molecules such as receptor activator of nuclear factor-kappa

methods to shorten orthodontic treatment period.

**1.** Chemical applications (local or systemic applications)

within the cells and to change the environmental factors [15, 16].

**3. Accelerated tooth movement**

**2.** Mechanical-physical stimulations **3.** Surgical-assisted techniques [14]

**3.2. Mechanical-physical stimulations**

**3.1. Chemical applications**

ment [18].

However, a major challenge in orthodontics is to shorten treatment time by avoiding undesirable side effects without compromising treatment outcome. The rate of orthodontic tooth movement is primarily determined by the remodeling of tissues surrounding the roots; this in return is under the control of molecular mechanisms regulating cellular behaviors in the alveolar bone and periodontal ligament [3]. Assuming that the clinician optimized mechanics and cooperation for any patient, the main factor controlling the treatment time and rate will be the patient's biological response to the orthodontic forces [4, 5]. Therefore, identifying and controlling the cellular regulators are essential to shorten orthodontic treatment time safely.

The concept of accelerating tooth movement has received increased attention recently [6] with the introduction of various clinical techniques; including local injection of cellular mediators [7], physical or mechanical stimuli [8] and surgically assisted orthodontics [9, 10]. Local or systemic pharmaceutical administration and physical or mechanical stimulation methods might not be applicable to daily clinical practice because of their possible side effects and their outcomes that await validation [11]. Over the past decade, the regional acceleratory phenomenon induced by surgical trauma has received emphasis for accelerating orthodontic tooth movement and reducing the treatment time [11]. However, many techniques which are surgically assisted involve considerably high surgical trauma limiting application of the technique currently.

A new method which uses micro-osteoperforations (MOPs) to stimulate alveolar bone remodeling without the disadvantages of surgery such as the requirement of corticotomies, cuts in cortical bone, raising split-thickness flap, and decorticating the bone has recently been identified [5, 12]. Animal studies revealed that micro-osteoperforations significantly stimulate expression of inflammatory markers and increase the number of osteoclasts and bone resorption. The increase in bone remodeling contributes to the rise in both rate and magnitude of tooth movement [4]. In addition to the requirement of additional studies, similar results are reported in clinical trials [4, 5].

In this chapter, we focused on the biologic basis of orthodontic tooth movement, accelerated tooth movement techniques and application methods, advantages, disadvantages, effects, and possible side effects of micro-osteoperforations as a new, reliable, repeatable and minimally invasive method for accelerating orthodontic tooth movement.
