**4.3. The relation of micro-osteoperforations with pain and root resorption**

There is a limited number of studies that evaluate patients' pain and discomfort levels among the clinical studies in which micro-osteoperforations are applied. Alikhani et al. [5] asked their patients to scale their pain and discomfort levels via a numeric rating scale on the day they replaced the device, the day they began canine distalization, 24 h, 7th and 28th days after canine distalization in their study in which they evaluated the effect of micro-osteoperforations on canine distalization. In this scale, which is reported as having high credibility, "0" presents no pain, while "10" stands for the existence of the worst pain. Data analyses showed that the patients had the most pain in 24 h following canine distalization but no significant difference was observed between experimental and control groups. The patients defined a slight and resistible pain on the micro-osteoperforation side which does not require taking painkillers but no statically significant difference was found. The similar feedbacks were taken in Boz's thesis study in 2018 concluding that micro-osteoperforations did not cause a significant pain or discomfort [64]. In line with these findings, it is possible to state that microosteoperforations are easily tolerated by the patients and can be applied to routine clinical use.

of upper molar teeth which was moved [12]. Although all findings support the idea that micro-osteoperforations do not increase root resorption risk showing that mini-implants can be safely used for MOP procedures in terms of root resorption, it is clear that there is a need

Micro-Osteoperforations

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

Cheung et al. [12] included 20 patients whose upper primary premolars are planned to be extracted for orthodontic purposes in their study which is known as the initial clinical study to evaluate the effects of MOPs on OIRR. About 150 g buccal tipping force was applied to premolar tooth which was planned to be extracted and micro-osteoperforations of 5 mm depth were applied to mesial and distal parts of the premolar teeth on the experimental side via Propel device (Propel Orthodontics, San Jose, Calif) evaluating the patient's opposite side as the control group. Following 28 days of tooth movement period, premolar tooth on both sides was extracted and examined by microcomputed tomography, volumes of root resorption craters were calculated and compared. Volumetric root loss average of the premolar tooth on the side which micro-osteoperforations are applied was found to be 42% more than the premolars on the control side. The researchers represented that the side to be applied micro-osteoperforations was not randomly selected (decision was taken in accordance with the availability of the distance between the roots) and evaluation was carried out following a short-term tooth movement as the limitations of the study and suggested further studies with treatments of longer terms and larger sample numbers. Nonetheless, when the findings of the study are considered, it can be stated that special attention shall be paid on planning

micro-osteoperforations with patients who are individually prone to root resorption.

As a result, there are studies which report that micro-osteoperforations can cause positive and negative effects on root resorption. Their relations were not clearly explained so there is

• Among several techniques which are defined to accelerate orthodontic tooth movement and treatment periods accordingly, due to numerous studies, surgical techniques that have

• Micro-osteoperforations are outstanding as a minimal invasive, easy-to-use, repeatable, and efficient new method that can eliminate some disadvantages of surgery among the

• Experimental studies have proved that micro-osteoperforations accelerated bone remodeling process and orthodontic tooth movement accordingly together with an increase in osteoclast number and new bone formation and a decrease on bone volume and density. A

• Different techniques are defined to apply micro-osteoperforation in the literature but there is a need for studies that evaluate differences between techniques in order to determine the

the most predictable results have been an essential part of modern orthodontics.

limited number of clinical studies also support the findings.

for further supportive studies with increased sample number.

a need for further studies.

defined invasive techniques.

**5. Conclusions**

ideal method.

Orthodontically induced inflammatory root resorption (OIIRR) is included in negative side effects of orthodontic tooth movement as a frequent research subject. Although its etiology and predictors are not fully understood, it is considered to be resulted from complex interaction of individual sensitivity [68], applied mechanics [69, 70], and specific dental predisposition [71]. Orthodontically induced inflammatory root resorption was stated to be related with periodontal ligament remodeling which is a result of the pressure applied to tooth root during tooth movement and removal of hyalinized necrotic tissues after trauma. Excessive pressure that causes ischemic necrosis [72] of periodontal ligament and root resorption related to orthodontic tooth movement is reported to be frequently observed in the areas in which excessive pressure is applied to periodontal ligament [73]. The underlying biological process of both orthodontic tooth movement and root resorption covers local inflammatory response. Animal studies show that many pro-inflammatory cytokines are common in both pathways. Cytokines such as IL-1, TNFα, and chemokines as IL-8 and MCP-1 are known to have significant roles to initiate and ease root resorption process [74]. These inflammatory mediators have significant roles on activation of tooth movement and osteoclast activity [75]. Inhibition of cytokine activity decreases osteoclast and odontoclast rate as well as tooth movement and root resorption [76]. It is known that accelerated tooth movement techniques increase inflammatory cytokine activation.

In the literature, there are several studies that evaluate the effects of accelerated tooth movement and decortication on root resorption [5]. The cytokines which promote inflammation are also reported to activate cementoclasts which cause root resorption increasing root resorption risk accordingly [77]. On the contrary, there are findings in the literature which state that decortication and demineralization of alveolar bone decrease the pressure toward tooth movement enabling an ease for the movement and decreasing root resorption risk accordingly [12]. It was found out that the effects of tooth movement accelerated via corticotomy on orthodontically induced inflammatory root resorption were similar to conventional orthodontic treatment but it was also reported that periapical radiographies may not be reliable for assessing root resorption in two studies which was carried out by evaluation of periapical radiographies [78, 79]. In an animal study which evaluates the effects of corticotomies on tooth movement, it was found out that there were not any differences between control and experimental groups in terms of root resorption [80].

In the literature, there is a limited number of studies which evaluates the effects of microosteoperforations on root resorption. Tsai et al. reported in their study in which they compared the efficiency of micro-osteoperforations and corticisions that root resorption creation risk of minor surgical interventions is lower when compared with conventional orthodontic treatments. The hematoxylin and eosin analysis of the researchers showed that micro-osteoperforation-assisted accelerated tooth movement was resulted in decreased root resorption [11]. Similarly, in the study in which Cheung et al. evaluated effects of microosteoperforations on experimental tooth movement in rats, root resorption was observed on the MOP application side on the samples which were colored with hematoxylin eosin reporting that 3D volumetric analysis did not show any volumetric difference in the root of upper molar teeth which was moved [12]. Although all findings support the idea that micro-osteoperforations do not increase root resorption risk showing that mini-implants can be safely used for MOP procedures in terms of root resorption, it is clear that there is a need for further supportive studies with increased sample number.

Cheung et al. [12] included 20 patients whose upper primary premolars are planned to be extracted for orthodontic purposes in their study which is known as the initial clinical study to evaluate the effects of MOPs on OIRR. About 150 g buccal tipping force was applied to premolar tooth which was planned to be extracted and micro-osteoperforations of 5 mm depth were applied to mesial and distal parts of the premolar teeth on the experimental side via Propel device (Propel Orthodontics, San Jose, Calif) evaluating the patient's opposite side as the control group. Following 28 days of tooth movement period, premolar tooth on both sides was extracted and examined by microcomputed tomography, volumes of root resorption craters were calculated and compared. Volumetric root loss average of the premolar tooth on the side which micro-osteoperforations are applied was found to be 42% more than the premolars on the control side. The researchers represented that the side to be applied micro-osteoperforations was not randomly selected (decision was taken in accordance with the availability of the distance between the roots) and evaluation was carried out following a short-term tooth movement as the limitations of the study and suggested further studies with treatments of longer terms and larger sample numbers. Nonetheless, when the findings of the study are considered, it can be stated that special attention shall be paid on planning micro-osteoperforations with patients who are individually prone to root resorption.

As a result, there are studies which report that micro-osteoperforations can cause positive and negative effects on root resorption. Their relations were not clearly explained so there is a need for further studies.
