Root Resorption during Orthodontic Treatment with Clear Aligners vs. Fixed Appliances—A Systematic Review

: The external apical root resorption that occurs during orthodontic treatment was the focus of this study, using either fixed appliances (FA) or clear aligners (CA). Using the Boolean keywords “APICAL ROOT RESORPTION” and “CLEAR ALIGNERS”, the study searched PubMed, Scopus, and Web of Science, with a restriction to English-language publications. A total of 50 publications were found by the computerized search, but after eliminating duplicates, completing reviews, and determining eligibility, only 9 papers could be used in the study. In conclusion, apical root resorption (ARR) is a frequent consequence of orthodontic tooth movement that mainly affects the lower incisors, which may compromise the success of the procedure and the health of the patient’s teeth. Several variables, including the type of tooth, have an impact on the severity of ARR.


Introduction
In orthodontics, the research into a more comfortable appliance that is able to meet aesthetic needs of the patient has led to the spread of aligner therapy [1][2][3][4][5][6].The classic fixed orthodontic treatment, despite its clinical efficacy, sometimes encounters poor patient acceptance, and this has led to the search for alternative therapies [7][8][9][10][11].Both appliances work on the basis of bone remodeling theory, according to which the orthodontic tooth movement is caused by bone resorption that is induced by osteoclasts in pressure zones, as well as by bone formation in the area of tension due to osteoblasts [12].The advantage of the fixed appliance is that patient compliance is not necessary, while the aligners must be worn at least 22 h a day.Furthermore, aligners are aesthetic and make home oral hygiene easier.
Among the most common adverse reactions to orthodontic treatment is the orthodontically induced apical root resorption [13,14].Although apical root resorption (ARR) can affect any tooth in the oral cavity, the teeth most susceptible to resorption are the maxillary central and lateral incisors [15][16][17].Multiple biological, mechanical, and clinical factors can provoke root resorption after orthodontic therapy, but the precise mechanism underlying this event is still unknown [18].The literature concerning the effect of clear aligners on apical root resorption is controversial.There are different stages of root resorption, and they may differ in the way we clinically approach them (in Figure 1, apical root resorption is represented by the black area of the root).This is a process not yet well understood; it might be caused by inflammation, infection, periodontal disease, or orthodontic movements that are too strong or too fast to be handled by the roots.To avoid, or lower, the chances of root resorption, it is suggested to use light and regular orthodontic forces instead of shorter and stronger ones.If root resorption occurs, it should be considered an irreversible process that can lead, in severe cases, to the extraction of the tooth (Figure 1) [19][20][21].The type of orthodontic movement, depending on the degrees and directions of forces, and on the treatment duration, can influence apical root resorption [22].
understood; it might be caused by inflammation, infection, periodontal disease, or o dontic movements that are too strong or too fast to be handled by the roots.To avo lower, the chances of root resorption, it is suggested to use light and regular orthod forces instead of shorter and stronger ones.If root resorption occurs, it should be co ered an irreversible process that can lead, in severe cases, to the extraction of the (Figure 1) [19][20][21].The type of orthodontic movement, depending on the degrees an rections of forces, and on the treatment duration, can influence apical root resorption External apical root resorption (EARR) consists of a loss of cementum or dentin companied by irreparable damage to the root structure, resulting in a reduction i length of the root apex.This adverse event could cause tooth mobility and can reduc viability of teeth [23,24].In fact, orthodontic tooth movement may result in a concentr of forces on the periodontium, mostly on the apical third of the root, causing a lo protective cells on the surface layer which consequently causes a loss of root stru that, in some cases, can be linked with episodes of orofacial pain [25][26][27][28][29][30].In the first p the damage to this structure leads to exposed denuded mineralized tissue; in the se phase, this tissue is colonized by inflammatory cells with consequent bone resorpti the inflammatory stimulus persists, root structures are damaged, as revealed by r graphic evidence [31][32][33][34].Cone beam computed tomography (CBCT), a three-dimens radiography tomography, has a demonstrably higher accuracy in diagnosis and mea ment of ARR (Figure 2) [35][36][37][38][39]. Being an irreversible process, it is fundamental to s this process carefully, along with its protective and risk factors [40][41][42][43].External apical root resorption (EARR) consists of a loss of cementum or dentine accompanied by irreparable damage to the root structure, resulting in a reduction in the length of the root apex.This adverse event could cause tooth mobility and can reduce the viability of teeth [23,24].In fact, orthodontic tooth movement may result in a concentration of forces on the periodontium, mostly on the apical third of the root, causing a loss of protective cells on the surface layer which consequently causes a loss of root structure that, in some cases, can be linked with episodes of orofacial pain [25][26][27][28][29][30].In the first phase, the damage to this structure leads to exposed denuded mineralized tissue; in the second phase, this tissue is colonized by inflammatory cells with consequent bone resorption.If the inflammatory stimulus persists, root structures are damaged, as revealed by radiographic evidence [31][32][33][34].Cone beam computed tomography (CBCT), a threedimensional radiography tomography, has a demonstrably higher accuracy in diagnosis and measurement of ARR (Figure 2) [35][36][37][38][39]. Being an irreversible process, it is fundamental to study this process carefully, along with its protective and risk factors [40][41][42][43].
Apart from the potential advantages of better aesthetics and comfort, the potential of predictability, reproducibility, and objectivity of aligners will potentially allow for controlling the stress derived from orthodontic forces, especially in the third apical of the radicular area [44][45][46].
The best strategy for treating root resorption is to take risk factors into account, talk to the patient in need of orthodontic treatment about the factors that were found, and include these factors in the treatment consent form.Among these risk factors is the length of the course of treatment.The longer a treatment is administered, the higher the risk of root resorption [47][48][49].Resorption is more likely to occur in roots with a thin, tapered, and dilated morphology [50][51][52][53].Furthermore, the risk of root resorption is elevated in cases of past trauma related to the anterior teeth [54].There is a chance that root resorption from prior orthodontic treatment will cause additional root shortening [55].
In these cases, conservative orthodontic re-treatment should be used, and the scope of the treatment should be constrained.Root resorption may be more likely in people who have a history of chronic bruxism, occlusal trauma, or thumb sucking [56,57].Apart from the potential advantages of better aesthetics and comfort, the poten predictability, reproducibility, and objectivity of aligners will potentially allow for trolling the stress derived from orthodontic forces, especially in the third apical o radicular area [44][45][46].
The best strategy for treating root resorption is to take risk factors into accoun to the patient in need of orthodontic treatment about the factors that were found include these factors in the treatment consent form.Among these risk factors is the l of the course of treatment.The longer a treatment is administered, the higher the r root resorption [47][48][49].Resorption is more likely to occur in roots with a thin, tap and dilated morphology [50][51][52][53].Furthermore, the risk of root resorption is elevat cases of past trauma related to the anterior teeth [54].There is a chance that root resor from prior orthodontic treatment will cause additional root shortening [55].
In these cases, conservative orthodontic re-treatment should be used, and the of the treatment should be constrained.Root resorption may be more likely in people have a history of chronic bruxism, occlusal trauma, or thumb sucking [56,57].
It is advised to assess the situation, using advancement radiographs, six to tw months following the initiation of the orthodontic treatment.Periapical or panoram diographs may be used for these assessments.The patient should be advised that th tive treatment should be stopped for a minimum of three months if root resorption is [58].The root resorption reparative process starts two weeks after the end of the a treatment [47].When severe root resorption is seen at this point, a different treat strategy should be taken into consideration, and treatment should be stopped.
The purpose of this study is the proper evaluation of the relationship between o dontically induced apical root resorption and the orthodontic treatment with alig Therefore, this study also aims to compare aligner therapy with fixed orthodontic a ances as regards apical root resorption following orthodontic treatment.

Materials and Methods
In order to achieve the aims presented above, a literature review was carried o described in the following subsections.It is advised to assess the situation, using advancement radiographs, six to twelve months following the initiation of the orthodontic treatment.Periapical or panoramic radiographs may be used for these assessments.The patient should be advised that the active treatment should be stopped for a minimum of three months if root resorption is seen [58].The root resorption reparative process starts two weeks after the end of the active treatment [47].When severe root resorption is seen at this point, a different treatment strategy should be taken into consideration, and treatment should be stopped.
The purpose of this study is the proper evaluation of the relationship between orthodontically induced apical root resorption and the orthodontic treatment with aligners.Therefore, this study also aims to compare aligner therapy with fixed orthodontic appliances as regards apical root resorption following orthodontic treatment.

Materials and Methods
In order to achieve the aims presented above, a literature review was carried out as described in the following subsections.

Protocol and Registration
This review was conducted in accordance with the standards of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and it was submitted to PROSPERO (International Prospective Register of Systematic Reviews) with the number 460,848 [59].

Search Processing
APICAL ROOT RESORPTION and CLEAR ALIGNED were the terms with which databases (Scopus, Web of Science, and PubMed) were searched to identify the papers under evaluation.Searches were combined using the Boolean operator "AND".
The search was restricted to include only items published in English and during the previous ten years (2013-2023) (Table 1).

Eligibility Criteria
Working in pairs, the reviewers selected publications that met two criteria for inclusion: (1) research using human subjects only; and (2) clinical studies or case reports.
The review was conducted using the PICO criteria: Population: adult patients in need of orthodontic treatment, both male and female; Intervention: fixed orthodontic appliances or clear aligners for orthodontic therapy; Comparison: apical root resorption following fixed orthodontic therapy or clear aligners; Outcome: root volume variation before and after treatment.

Data Processing
Any publications that deviated from the themes examined were excluded through the screening process, which involved reading the titles and abstracts of articles selected in the previous identification step.After that, the full texts of publications that met the preset inclusion requirements were perused.Disagreements among reviewers regarding the article selection were resolved through discussion.

Results
A total of fifty articles were found using keyword searches in the Web of Science (21), Scopus (14), and PubMed (15) databases.Twenty-four articles were included after duplicates (26 total) were eliminated.Fourteen of these twenty-four studies were eliminated because they did not meet the predetermined inclusion criteria.Of the 14, 10 were systematic reviews, 2 were in vitro studies, and 2 were animal research studies.Nine publications were chosen for this work at the end of the screening process (Figure 3).Each study's findings are presented in Table 2.

Authors (Year) Type of the Study Aim of the Study Materials Results
Gay et al. [31] 2017 Radiometric study The study's goal was to look at the prevalence and severity of root resorption in adult patients wearing aligners.
Panoramic radiographs taken at the start (T0) and end (T1) of the clear aligner therapy were used to measure the lengths of 1083 teeth's roots and crowns.
Root resorption (RR) could result from Invisalign ® orthodontic treatment.However, it turned out that its incidence was extremely comparable to that which was described for orthodontic mild forces.

Case-control genetic association study
To evaluate risk factors of EARR after CAT or FOT.
Genetic and clinical factors were evaluated in 172 patients treated with CA or fixed appliances.Similar results were obtained after both treatments.and post-treatment (T1) CBCT pictures were collected.
During aligner therapy, the majority of incisors had mild to moderate resorption; a very small proportion displayed severe resorption.

Randomized clinical trial
To compare the amount of ARR after orthodontic therapy (fixed appliances vs. CA).
Intraoral radiographs of anterior teeth from 40 patients before (T0) and after 6 months (T1) of CAT or FOT.
Intraoral radiographs showed how both techniques resulted in a comparable ARR that does not affect the longevity of the teeth.

Almagrami et al. [64] 2023
Retrospective study The study's goal was to examine the severity of orthodontically caused root resorption of maxillary incisors in those who used transparent aligners vs. fixed appliances.
Treatments with clear aligners and fixed appliances appeared to cause increased root resorption in the maxillary incisor, with a higher incidence in fixed appliance treatments.

Gay et al. [31] 2017
Radiometric study The study's goal was to look at the prevalence and severity of root resorption in adult patients wearing aligners.
Panoramic radiographs taken at the start (T0) and end (T1) of the clear aligner therapy were used to measure the lengths of 1083 teeth's roots and crowns.
Root resorption (RR) could result from Invisalign ® orthodontic treatment.However, it turned out that its incidence was extremely comparable to that which was described for orthodontic mild forces.Iglesias-linares et al. [44] 2017

Case-control genetic association study
To evaluate risk factors of EARR after CAT or FOT.
Genetic and clinical factors were evaluated in 172 patients treated with CA or fixed appliances.
Similar results were obtained after both treatments.

Aman et al. [60] 2018
Retrospective study The aim of the study was to investigate the incidence and severity of orthodontically induced root resorption with clear aligner therapy.
Maxillary incisor root lengths were measured using CBCT before and after treatment in 160 patients treated with clear aligners.
Minimal root resorption was the consequence of thorough treatment with clear aligners.

Eissa et al. [19] 2018 Pilot study
The aim of this study was to evaluate the root resorption of maxillary incisors after Thirty-three patients were divided into three groups.group 1: patients treated with clear aligners; group 2: patients Root resorption after orthodontic treatment was a complication with various orthodontic techniques.

Quality Assessment and Risk of Bias
Figure 4 reports the risk of bias in the included studies.One study shows a significant risk of bias with regard to the randomization procedure and allocation concealment.Low risk of bias is ensured by all other studies.Of the included studies, two display an increased risk of detection bias (self-reported outcome); two show a low risk of detection bias (objective measures); and only one study exhibits performance bias (Figure 4).Two studies ensure a low risk regarding attrition and reporting bias.The ARR on each tooth was calculated as the difference in root length before and after orthodontic treatment.
Clear aligner patients had lower prevalence and severity of ARR than fixed appliance patients, as determined by CBCT.

Liu et al. [62] 2021
Retrospective study The purpose of the study was to investigate the prevalence and severity of root resorption with clear aligner therapy using CBCT.
During aligner therapy, the majority of incisors had mild to moderate resorption; a very small proportion displayed severe resorption.

Randomized clinical trial
To compare the amount of ARR after orthodontic therapy (fixed appliances vs. CA).
Intraoral radiographs of anterior teeth from 40 patients before (T0) and after 6 months (T1) of CAT or FOT.
Intraoral radiographs showed how both techniques resulted in a comparable ARR that does not affect the longevity of the teeth.

Almagrami et al. [64] 2023
Retrospective study The study's goal was to examine the severity of orthodontically caused root resorption of maxillary incisors in those who used transparent aligners vs. fixed appliances.
Treatments with clear aligners and fixed appliances appeared to cause increased root resorption in the maxillary incisor, with a higher incidence in fixed appliance treatments.

Quality Assessment and Risk of Bias
Figure 4 reports the risk of bias in the included studies.One study shows a significant risk of bias with regard to the randomization procedure and allocation concealment.Low risk of bias is ensured by all other studies.Of the included studies, two display an increased risk of detection bias (self-reported outcome); two show a low risk of detection bias (objective measures); and only one study exhibits performance bias (Figure 4).Two studies ensure a low risk regarding attrition and reporting bias.

Discussion
Although numerous works can be found in the literature comparing these two orthodontic therapies, answers to several questions are still missing, including whether the amount of apical root resorption is predictable, and whether therapy with aligners brings advantages in terms of apical resorption compared to fixed therapy.Therefore, a broader review is important.
One of the most undesirable effects of orthodontic therapy is apical root resorption (ARR), which is a permanent loss of hard tissue on the root apex of a tooth.The incidence of ARR in orthodontic patients ranges from 20% to 100% [60].Severe ARR is uncommon, with a frequency of 1 to 5%; however, resorption can be greater than 5 mm, or one-fourth of the root length [60].ARR can result in an uneven crown-to-root ratio in the afflicted teeth, as well as tooth loss, thus compromising patients' quality of life and orthodontic

Discussion
Although numerous works can be found in the literature comparing these two orthodontic therapies, answers to several questions are still missing, including whether the amount of apical root resorption is predictable, and whether therapy with aligners brings advantages in terms of apical resorption compared to fixed therapy.Therefore, a broader review is important.
One of the most undesirable effects of orthodontic therapy is apical root resorption (ARR), which is a permanent loss of hard tissue on the root apex of a tooth.The incidence of ARR in orthodontic patients ranges from 20% to 100% [60].Severe ARR is uncommon, with a frequency of 1 to 5%; however, resorption can be greater than 5 mm, or one-fourth of the root length [60].ARR can result in an uneven crown-to-root ratio in the afflicted teeth, as well as tooth loss, thus compromising patients' quality of life and orthodontic treatment outcome [63].Clear aligners are becoming increasingly popular for orthodontic treatment; nevertheless, ARR during clear aligner therapy is still poorly understood.
The ARR in patients treated with clear aligners and conventional fixed appliances was evaluated and compared in this study [63].The type of tooth movement can contribute to an increased occurrence of root resorption [65,66].The removal of the hyaline zone is believed to be necessary to initiate natural tooth movement, but it can also lead to the absorption of the root's cement, making the exposed dentine more vulnerable to resorption by scavenger cells.To avoid or lower the chances of root resorption, it is suggested to use light and regular orthodontic forces instead of shorter and stronger ones.Some argue that intermittent forces, such as those exerted by aligners, versus continuous forces from fixed appliances, result in distinct types of pressure [67][68][69].According to certain sources, intermittent pressure may permit the cementum around the root to repair itself.In a randomized controlled clinical trial, Toyokawa-Sperandio et al. compared the amount of root resorption six months into orthodontic treatment between fixed appliances and orthodontic aligners (OA) [63].Intraoral X-rays of the front teeth demonstrated that both methods resulted in comparable root resorption rates that did not impact tooth longevity.Similar findings were reported by Iglesias-Linares et al., who considered various clinical, genetic, and radiographic factors [44].However, Yi et al. suggested that external apical root resorption (EARR) was lower in non-extraction patients treated with OA compared to those treated with fixed appliances, indicating that OA might be more effective in safeguarding teeth from root resorption [61].
Given that ARR is a three-dimensional topographical change, the accuracy of ARR assessment is limited in two-dimensional radiography, such as in panoramic and periapical radiographs [60].Cone beam computed tomography (CBCT), on the other hand, has demonstrated considerably higher accuracy in the diagnosis and quantification of ARR [60].
Li et al. conducted a study analyzing the prevalence and severity of root resorption using fixed orthodontic treatment and aligners.They used cone beam computed tomography (CBCT) to measure root resorption, defined as the difference, in millimeters, between tooth lengths before and after orthodontic [35].A total of 373 roots from 70 subjects were considered.The prevalence of root resorption was significantly lower in the clear aligner group (56.30%) compared to the fixed appliance group (82.11%).In the fixed appliance group, all teeth examined before and after treatment showed a statistically significant reduction in root length, whereas in the clear aligner group, only the maxillary incisors and mandibular central incisors exhibited a statistically significant change in root length [35].Li et al. compared the severity of root resorption in individuals undergoing treatment with fixed braces versus transparent aligners.The maxillary canine and lateral incisor in the fixed appliance group experienced the most severe root resorption, while the mandibular canine and lateral incisor in the transparent aligner group displayed the least severe root resorption [35].They observed reduced severity and lower prevalence of root resorption in patients who were treated with aligners.
In contrast, Gay et al. employed panoramic X-rays to compare the lengths of 1083 teeth (incisors, canines, and premolars) before and after aligner therapy [31].All 71 adult patients examined in their study showed a minimal reduction in root length, where root length is considered the distance between the apex and the cement-enamel junction.However, only 3.69% of the assessed teeth (41.81%) had roots shorter than 20% of their original pre-treatment length.This incidence of root resorption can be compared to any orthodontic therapy with light orthodontic forces.Upper lateral incisors, lower lateral incisors, and central incisors were the teeth most affected by severe root resorption [31].
Liu et al.'s study exclusively evaluated incisors in patients who used aligners to address class II malocclusion.They defined root resorption as the difference in root volume before and after treatment [62].Following treatment with clear aligners, most teeth exhibited mild to moderate resorption, with only a few displaying severe resorption.Risk factors for root volume loss included tooth type and intrusion-extrusion changes [62].
In 2023, Ibtehal Almagrami et al. conducted a retrospective study to assess the dimensions of alveolar bone alterations associated with orthodontic tooth movement (OTM), as well as the prevalence and severity of orthodontically induced inflammatory root resorption (OIIRR) in maxillary incisors treated with clear aligners (CA) or fixed orthodontic appliances (FA) [64].The secondary goal of this study was to compare post-treatment alveolar bone alterations and root resorption in maxillary incisors treated with either approach.A total of 40 patients were randomly assigned to one of two groups (CA or FA).In the CA group, 20 patients were treated with Invisalign (Align Technology, San Jose, CA, USA).The FA group included 20 patients (29.67 ± 7.71 months) who had fixed orthodontic appliances (Victory Series; 3 M Unitek, San Jose, CA, USA).Baseline characteristics and treatment duration were identical across both moreover, both groups were treated with mild to moderate crowding on a non-extraction basis.Crowding was reduced by posterior teeth distalization, dental arch expansion, and anterior tooth proclination.Pre-treatment (T0) and post-treatment (T1) CBCT was used to assess dentoalveolar quantitative alterations.Alveolar bone thickness (ABT), alveolar bone height (ABH), root length (OIIRR), and maxillary incisor inclinations were among the parameters assessed.CA and FA treatments appeared to generate a substantial reduction in ABT, and both treatment methods reduced ABH significantly, with the greatest reduction reported on the labial side of the lateral incisors in the CA group.FA and CA treatments resulted in statistically significant increases in OIIRR in the maxillary incisor area, with FA patients displaying a greater frequency and severity of OIIRR.
CBCT was also used in Aman et al.'s study to investigate the occurrence and severity of OIIRR in patients who had undergone complete treatment with clear aligners (Invisalign; Align Technologies, Santa Clara, CA, USA), and to identify potential risk factors for OI-IRR [60].The root lengths of 160 patients who had completed orthodontic treatment with clear aligners were assessed, using orthogonal images from pre-treatment and posttreatment cone-beam computed tomography exams.
The proportion of change in root length was strongly impacted by gender, malocclusion, crowding, and post-treatment approximation to the cortical plates.Based on the results of this study, comprehensive treatment with clear aligners resulted in minimal root resorption, and the best predictor of root resorption was the post-treatment location of the root apices relative to the palatal cortical plate [60].
Osama Eissa et al. used CBCT to compare the root lengths of upper incisors as an indicator of orthodontically induced apical root resorption following treatment with Smart Track ® aligners versus two different types of fixed orthodontic appliances-regular and Damon brackets [19].The research featured 33 patients with class I malocclusion (4-6 mm crowding) who were randomly assigned to one of three groups: Smart Track ® aligners, Damon brackets, or conventional brackets.Using Dolphin imaging software, the lengths of maxillary incisor teeth were measured before and after treatment.When compared to typical pre-adjusted edgewise appliances in instances of class I malocclusion with mild to moderate crowding, Smart Track ® aligners showed less reduction in root length, indicating reduced root resorption.In terms of root resorption, there was no statistically significant difference between aligners and passive self-ligating Damon Q devices [19].

Conclusions
In conclusion, orthodontic therapy, while highly effective in achieving desired tooth movements, is associated with the potential side effect of apical root resorption (ARR).This permanent loss of hard tissue at the root apex can range in severity, with severe cases compromising the crown-to-root ratio and, in extreme instances, leading to tooth loss.The incidence of ARR in orthodontic patients varies widely, and its impact on patients' quality of life and treatment outcomes underscores the need for a comprehensive understanding and effective management of ARR.
Clear aligners have gained popularity as an alternative to conventional fixed appliances for orthodontic treatment.The mechanism of tooth movement during clear aligner therapy and its association with ARR remain areas of ongoing research and debate.The nature of forces exerted, whether intermittent forces from aligners, or continuous forces from fixed appliances, may influence the occurrence and severity of root resorption.Studies comparing ARR in patients treated with clear aligners versus fixed appliances have yielded varying results, indicating the complexity of this phenomenon.
The assessment of ARR is crucial for accurate diagnosis and treatment planning.Traditional two-dimensional radiography has limitations in capturing the three-dimensional topographical changes associated with root resorption.Cone beam computed tomography (CBCT) emerges as a valuable tool, offering higher accuracy in the diagnosis and quantification of ARR.Recent studies utilizing CBCT have provided insights into the prevalence and severity of ARR in patients undergoing orthodontic treatment with clear aligners or fixed appliances.
Comparative studies, such as the one conducted by Li et al., revealed differences in the prevalence and severity of root resorption between clear aligner and fixed appliance groups.The choice of treatment modality and its impact on ARR may vary depending on tooth type and other factors.Additionally, investigations into the dimensions of alveolar bone alterations and orthodontically induced inflammatory root resorption (OIIRR) further contribute to our understanding of the consequences of orthodontic tooth movement.Recent research, such as the retrospective study by Ibtehal Almagrami et al., highlights the importance of considering post-treatment alveolar bone alterations and root resorption when comparing different orthodontic approaches.Comparing clear aligners with fixed orthodontic appliances, the study demonstrated distinct effects on alveolar bone thickness, height, and root length, emphasizing the need for careful evaluation in treatment planning.
In summary, while ARR remains a concern in orthodontic therapy, ongoing research, particularly with the use of advanced imaging techniques like CBCT, contributes to a better understanding of the factors influencing root resorption.Clinicians should weigh the risks and benefits of different treatment modalities, considering individual patient characteristics and the potential impact on root health.As orthodontic techniques continue to evolve, addressing and minimizing the risk of ARR will be crucial for optimizing treatment outcomes and ensuring long-term oral health for patients undergoing orthodontic therapy.
The variability in treatment protocols, patient populations, and orthodontic techniques across different regions and practices may limit the generalizability of the results and should be considered in future research endeavors.

Figure 1 .
Figure 1.Different stages of root resorption.The part of the root that is colored black repre apical root resorption.

Figure 1 .
Figure 1.Different stages of root resorption.The part of the root that is colored black represents apical root resorption.

Figure 2 .
Figure 2. Length difference between a normal root and one with resorption.The white line ind the length of the healthy dental root, while the blue line indicates the length of the dental roo sorbed.

Figure 2 .
Figure 2. Length difference between a normal root and one with resorption.The white line indicates the length of the healthy dental root, while the blue line indicates the length of the dental rooteriassorbed.

Table 1 .
Database search indicators.