External root resorption after orthodontic treatment: a study of contributing factors

정연화,조봉혜 대한영상치의학회 2011 Imaging Science in Dentistry Vol.41 No.1

Purpose : The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. Materials and Methods : This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. Results : Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. Conclusion : These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth. Purpose : The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. Materials and Methods : This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. Results : Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. Conclusion : These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

부정교합 환자의 교정치료전 치근흡수에 관한 방사선학적 연구

황충주,송영윤 대한치과교정학회 1999 대한치과교정학회지 Vol.29 No.2

영구치의 치근흡수는 대개 특별한 상황, 즉 외상, 감염, 교정적 치아이동, 또는 전신질환의 경우에만 일어난다고 생각되어 왔지만, 정상적인 상황에서도 영구치의 치근흡수를 나타낼 수 있음이 보고된 이래로 치근흡수의 원인을 밝히려는 많은 연구가 있었다. 특히, 교정치료의 연관된 치근흡수의 빈도 및 심각도에 관한 많은 연구들이 있음에도 불구하고 실제로 교정치료를 위해 내원한 영구치열기의 부정교합 환자에서 교정치료전 치근흡수에 대한 연구는 없었다. 이에 본 연구는 교정치료를 위해 내원한 부정교합 환자 중에서 제3대구치를 제외한 모든 영구치의 치근 형성이 완료된 사람을 대상으로 전치부는 평행촬영법으로 촬영한 구강내 치근단 방사선 사진을, 구치부는 파노라마 방사선 사진을 이용하여 교정치료전 치근흡수의 빈도 및 삼각도를 분석하였다. 본 연구에서는 개개 치아에서 치근흡수의 빈도 및 심각도와 나이, 성별, Angle씨 분류법에 따른 부정교합 분류, 수평피개 및 수직피개, 상하악 전치부 치축각도 등의 분류에 따른 치근흡수의 빈도 및 심각도, 그리고 개개 치아에서 나타나는 부정교합의 특징 및 뚜렷한 교합마모면과 치근흡수의 빈도에 대해서 분석해 보아 다음과 같은 결론을 얻었다. 1. 본 연구에서 조사된 모든 사람에서 하나 이상의 치아에서 치근흡수를 나타내었고, 총 22.099개의 치아 중에서 7.920개의 치아, 즉 35.84%에서, 또 남성보다는 여성에서 빈도가 높았다(p<0.01). 2. 개개 치아에서의 치근흡수 감수성은 전체적인 이환치아에 대해서는 하악 전치, 상악 전치 순으로 감수성이 높았지만, 뚜렷한 치근흡수에 대해서는 상악 중절치, 상악 제 1소구치, 상악 측절치 순으로 감수성이 높았다. 3. 상하악 전치의 치축 각도에 대해서는 상악 전치 치축 각도가 클수록 상악 4전치의 치근 흡수에 미치는 영향이 컸고, 하악 전치 치축 각도가 클수록 하악 4 전치의 치근흡수에 미치는 영향이 컸다. 4. 수평피개보다는 수직피개가 치근흡수에 미치는 영향이 컸으며 개방교합의 경향이 커질수록 치근흡수의 빈도가 높았다. 5. 개개 차이에서 나타나는 부정교합의 특징에 대해서는 반대교합과 개방교합을 함께 나타내는 치아에서 치근흡수의 빈도가 가장 높았다. This study was designed to evaluate the frequency and the severity of root resorption of the permanent teeth before orthodontic treatment by means of radiograph in the malocclusion patients. In this study the author analysed the frequency and the severity of root resorption in individual teeth, the relationships of the frequency and the severity of root resorption and age, sex, Angle`s classification, overjet, overbite, and maxillary and mandibular incisor inclination, and the relationships of the frequency of root resorption and the characteristics of malooclusion and marked occlusal attrition showed in individual teeth. The results were as follows. 1. All of the persons examined showed some evidence of root resorption in one or more of the permanent teeth, 35.84% of the teeth examined and more frequent in female group than male group(p<0.01). 2. On the susceptibility of the root resorption in individual teeth in this study, the author found the mandibular incisors and the maxillary incisors, in the order named, to be most susceptible in all affected teeth, but maxillary central incisors, maxillary first bicuspids, and maxillary lateral incisors, in the order named, were more susceptible to marked root resorption. 3. The more proclined maxillary incisors the more affected root resorption in four maxillary incisors and the more proclined mandibular incisors the more affected root resorption in four mandibular incisors. 4. Overbite more affected root resorption than overjet,and the higher tender to openbite the more frequent was root resorption. 5. On the characteristics of malooclusion showed in individual teeth, the openbite teeth combined with crossbite, were most frequent in root resorption.

치근 흡수의 이해와 치료방법

황윤찬 대한치과의사협회 2021 대한치과의사협회지 Vol.59 No.6

Root resorption is very rare disease in the dental field. However, when dentist faced root resorption in the clinic without knowledge, it is very difficult situation to solve. Root resorption can be classified into external root resorption and internal root resorption according to developing place of resorption. Also, root resorption is classified into surface resorption, inflammatory resorption, replacement resorption according to developing reason of resorption. In this article, we can understand the cause and reason of root resorption development and can know how to prevent and treat the root resorption

Changes in the Titer of Tooth Root Antibodies Accompanying Root Resorption Associated with Orthodontic Tooth Movement

Park, Soo-Byung,Son, Woo-Sung 대한치과교정학회 1994 대한치과교정학회지 Vol.24 No.2

치아이동시 발생되는 치근 흡수에 관련된 특이면역반응의 역할을 연구하기 위해 치근 흡수에 따른 치근항체의 역가 변화를 관찰하였다. 생후 2년된 성견 다섯마리를 실험동물로 사용하였다. closed coil spring을 사용하여 각 실험동물의 상악 6전치에 200-250gm 의 함입력을 가하였으며, 하악6전치를 발거하여 동종항원으로 사용하였다. 발거된 하악 전치의 상아질 부의를 분리하여 6M Guanidine-HCl-10%EDTA(pH 5.0)에서 해리시킨 다음 부유물 만을 투석하여 항원을 준비 하였다. 치아를 함입시키기 전 1회 혈청을 채취하고 함입시킨 다음 부유물 만을 투석하여 항원의 근원을 제거하였다, 항체 특이성에 대한 대조군으로 혈청과 치근 항원 그리고 혈청과 관련 없는 박테리아 항원(Porphyromonas gingivalis 33277)을 섭씨 25도에서 3시간 반응시켜 모든 과정에서 항원-항체 반응을 특정하였다. 치근 흡수를 관찰하기 위하여 실험 전과 실험 후 한달 간격으로 방사선 교합사진을 촬영하였고 9주째 발거한 치아의 치근단 부위를 입체 현미경으로 관찰하였다. 치근항원에 대한 자가항원의 역가 변화를 측정하여 다음과 같은 결과를 얻었다. 자가항체의 역가는 치아가 함입되면서 즉시 감소하였다가 1주후 다시 중가하였으며 4주째 최고 수준에 도달한 다음 다시 지속적으로 감소하였다. 흡수 중인 치근을 발거한 직후 급격히 증가하는 양상을 보였다. 치근 항원과 반응시킨 혈청내에서는 항원-항체 반응이 거의 나타나지 않았으며 관련없는 박테리아 항원과 반응을 시킨 혈청에서는 활성도가 동종 치근 항원에 대한 자가항체의 활성도와 비슷하게 나타났다. 방사선 교합사진 상에서는 육안으로 구별할 수 있는 차이가 거의 없었으나 입체현미경하에서는 치근단 부위의 다양한 흡수 양상을 관찰할 수 있었다. This study was designed to measure the changes in titer of tooth root antibodies accompanying root resorption associated with orthodontic tooth movement in dogs to explore a role of the specific immune response in root response in root resorption during orthodontic tooth movement. Five adult mongrel dogs, 2 years of age, were used in the study. Six lower incisors were extracted as sources of homologous antigen in the dogs. Tooth root antigen preparations were made from a 6M Guanidine-HCL-10% EDTA(pH5.0) extract of these root dentins. Root resorption was elicited by intrusion of six maxillary incisors with 200-250gm intrusive force. In 9th week, resorbing six maxillary anterior teeth were extracted. Serum samples were taken from each dog prior to intrusion and weekly for 11 consecutive weeks. Serum autoantibody titers were determined with an enzyme-linked immunosorbent assay. As controls for antibody specificity, sera which were previously incubated with tooth root antigen as well as sera to an unrelated bacterial antigen(Porphyromonas gingivalis 33277) for 3 hours at 25 were measured in all runs. Root resorption was monitored monthly using occlusal radio-graphs. And then root resorption patterns were observed with a zoom stereo microscope(Model SZH-121, olympus optical Co. Ltd.). Incisors did not show clear radiographic evidence of significant and progressive root resorption, but periodontal ligament space had widened.But root resorption was observed on the apical regions of the maxillary incisors with a zoom stereo microscope, Teeth showed the shallow depression generally accompanying deep resorption. These demonstrate a slight tendency for an immediate decrease followed by rebound to levels above the pre-treatment baseline. Apeak titer of autoantibody to dentin antigen occurred on day 28, then steadily decreased during the 9th week period as the roots resorbed and then rapidly spiked in animals when the resorbing teeth were extracted. When sera is incubated with tooth root antigen, serum activity in the ELISA was almost absent. This is because serum activity in the ELISA could be removed by absorption of the serum with dog dentin antigen. Serum ELISA activity to the unrelated bacterial antigen remained essentially unchanged in all animals throughout the experimental period. When the time course of hanges in autoantibody to homologous tooth root antigen prepatration and unrelated bacterial antigen was compared, no significant differences were found (α=0.05). In general, the overall pattern of changes in autoantibody was similar to the two antigens. These findings suggest the possibility that these immunologic changes precede a significant development of root resorption lesions rather than merely reflecting their presence. Therefore, this suggests that the changes of antibody levels may have some predictive value for root resorption.

계승영구치가 선천적 결손된 유치의 치근 흡수

이정은,이제호,최형준,김성오,송제선,손흥규,최병재 대한소아치과학회 2009 大韓小兒齒科學會誌 Vol.36 No.4

유치의 정상적인 치근 흡수는 계승 영구치의 맹출 압력으로 단핵구 세포가 방출되어 파골세포로의 분화가 촉진되어 일어나며, 계승 영구치의 맹출 경로를 따라 유치의 치근이 흡수되어서 유치가 탈락하게 된다. 계승 영구치가 선천적으로 결손되었을 때에도 유치의 치근은 흡수될 수 있는데, 유치의 비정상적 치근흡수는 외상이나 염증, 교합압의 증가, 지지조직의 약화 등으로 발생할 수 있다. 치아의 선천적 결손은 인간에서 가장 흔한 발육이상이며, 영구치가 결손되었을 때 유치는 만기 잔존할 수 있다. 영구치의 선천적 결손은 전신질환이 있는 경우뿐만 아니라 국소적 원인이나 인류 진화에 따른 영향 등에 의해서도 발생한다. 이 증례들은 계승 영구치가 선천적으로 결손된 어린이에서 유치의 치근이 비정상적으로 흡수된 경우로 계승 영구치가 결손 된 유전치와 유견치, 유구치의 치근이 1/2 ~ 3/4정도까지 흡수 되었으며 흡수 부위는 불규칙적인 형태를 보였다. 원인으로는 흡수에 감수성이 높은 유치의 치주인대, 그리고 성장에 따라 증가되는 저작근육과 저작력, 혼합치열기에 유발되는 비정상적 교합 등을 생각할 수 있다. 계승 영구치가 결손된 유치가 비정상적인 치근 흡수를 보이는 경우에 유치는 유지될 수도 있지만, 여러 요인에 의하여 탈락될 경우에는 공간을 유지 할 것인지 판단해야 하며, 향후 보철치료나 교정치료를 요하므로 장기적인 치료계획을 수립해야 한다. Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.

External apical root resorption in maxillary incisors in orthodontic patients : associated factors and radiographic evaluation

Kamonporn Nanekrungsan,Virush Patanaporn,Apirum Janhom,Narumanus Korwanich 대한구강악안면방사선학회 2012 Imaging Science in Dentistry Vol.42 No.3

Purpose: This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods: The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results: The periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p⁄0.001). Allergic condition was a significant factor at p⁄0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p⁄0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion: These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

매복된 상악 견치에 의한 전치의 치근 흡수에 대한 후향적 연구

정서현,송지수,신터전,현홍근,김영재,김정욱,이상훈,장기택,Jung, Seo-Hyun,Song, Ji-Soo,Shin, Teo Jeon,Hyun, Hong-Keun,Kim, Young-Jae,Kim, Jung-Wook,Lee, Sang-Hoon,Jang, Ki-Taeg 대한소아치과학회 2018 大韓小兒齒科學會誌 Vol.45 No.2

Root resorption of the permanent maxillary incisors can occur due to ectopic eruption of the permanent canines. Severe root resorption threatens the long-term survival of the affected incisors. The aim of the present study was to identify risk factors for root resorption of the maxillary incisors associated with impacted maxillary canines. In the present study, we retrospectively analyzed the Cone-Beam Computed Tomography (CBCT) scans of 65 children and adolescents with ectopically erupting maxillary canines (total of 88 impacted canines). Root resorption of central incisors was significantly associated with the mesiodistal position and root development of the adjacent canine. Root resorption of lateral incisors was significantly associated with sex, age, and the buccolingual and vertical position of the adjacent canine. However, enlargement of the dental follicle was not significantly associated with root resorption of adjacent incisors. Although incisor resorption is difficult to diagnose and predict, our findings suggest that changes in the dental follicles of the erupting maxillary canines do not cause resorption of the adjacent permanent incisors. CBCT should be utilized to ensure early diagnosis of impacted canines and precise evaluation of incisor root resorption. 상악 견치가 매복 시에 종종 인접 전치 치근의 치근흡수가 나타난다. 심각한 전치의 치근 흡수는 치아의 장기적인 예후를 불량하게 하기도 한다. 이 연구의 목적은 3차원 영상을 이용하여 상악 견치에 의한 전치의 치근 흡수를 관찰하고 관련된 요인을 분석하는 것이다. 연구 대상자는 상악 견치 매복을 가진 65명의 어린이로 총 88개의 치아에 대해 65개의 cone-beam computed tomography 영상을 분석하였다. 그 결과, 상악 견치의 치근 발달 정도와 치근단공의 폐쇄 및 치관의 근원심적인 위치가 중절치의 치근흡수와 유의한 관계를 나타내였다. 측절치의 치근 흡수 여부는 환아의 성별, 나이, 상악 견치의 협설 위치, 수직적 위치에 영향을 받았다. 상악 견치 치배의 확장은 중절치와 측절치의 치근 흡수 여부와 유의한 관계가 없어, 치배의 확장이 치근 흡수에 직접적인 역할을 하지 않는 것으로 나타났다. 상악 견치의 매복 시에 전치의 치근 흡수는 예측하기 어렵기 때문에, 3차원 영상을 이용한 조기 진단이 필요하다.

External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

Nanekrungsan, Kamonporn,Patanaporn, Virush,Janhom, Apirum,Korwanich, Narumanus Korean Academy of Oral and Maxillofacial Radiology 2012 Imaging Science in Dentistry Vol.42 No.3

Purpose: This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods: The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results: The periapical radiographs of 564 teeth showed that the average root resorption was $1.39{\pm}1.27$ ($8.24{\pm}7.22$%) and $1.69{\pm}1.14$ mm ($10.16{\pm}6.78%$) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion: These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

Invasive cervical resorption: treatment challenges

김유경,이찬영,김의성,노병덕 대한치과보존학회 2012 Restorative Dentistry & Endodontics Vol.37 No.4

Invasive cervical resorption is a relatively uncommon form of external root resorption. It is characterized by invasion of cervical region of the root by fibrovascular tissue derived from the periodontal ligament. This case presents an invasive cervical resorption occurring in maxillary lateral incisor, following damage in cervical cementum from avulsion and intracoronal bleaching procedure. Flap reflection, debridement and restoration with glass ionomer cement were performed in an attempt to repair the defect. But after 2 mon, more resorption extended apically. Considering root stability and recurrence potential, we decided to extract the tooth. Invasive cervical resorption in advanced stages may present great challenges for clinicians. Therefore, prevention and early detection must be stressed when dealing with patients presenting history of potential predisposing factors. Invasive cervical resorption is a relatively uncommon form of external root resorption. It is characterized by invasion of cervical region of the root by fibrovascular tissue derived from the periodontal ligament. This case presents an invasive cervical resorption occurring in maxillary lateral incisor, following damage in cervical cementum from avulsion and intracoronal bleaching procedure. Flap reflection, debridement and restoration with glass ionomer cement were performed in an attempt to repair the defect. But after 2 mon, more resorption extended apically. Considering root stability and recurrence potential, we decided to extract the tooth. Invasive cervical resorption in advanced stages may present great challenges for clinicians. Therefore, prevention and early detection must be stressed when dealing with patients presenting history of potential predisposing factors.

한국인에서의 교정치료로 인한 상악 중절치 치근 흡수에 영향을 미치는 요소

정동화(Dong-Hwa Chung),박영국(Young-Guk Park),김광원(Kwang-Won Kim),차경석(Kyung-Suk Cha) 대한치과교정학회 2011 대한치과교정학회지 Vol.41 No.3

치근 흡수는 백악질과 상아질의 부분적인 상실로 특징되어지는 상황이며, 치근의 길이 감소를 야기하고 치아의 기능에 심각한 영향을 줄 수 있다. 일반적인 병리적인 치근 흡수와 구별하여 교정치료와 관계된 치근 흡수를 orthodontically induced root resorption (OIRR)이라고 부른다. 이번 연구의 목적은 한국인을 대상으로 하여 교정 치료 후에 나타나는 치근 흡수와 관련된 환자 요인과 교정치료 요인을 찾고, 그 양상에 대해 알아보는 것이다. 판별될 요소들은 발치 치료 여부, 성별, 나이, 치근첨의 변위량과 방향, 총 치료 기간, 치아 길이, 치근의 형태였다. 이번 연구는 단국대학교 치과대학병원 교정과에서 2007년 11월부터 2008년 12월 사이에 포괄적인 교정치료가 종결된 환자의 상악 중절치를 대상으로 하였다. 선정된 대상자 수는 137명이었다. 각각의 기록은 치근단 사진과 측모 두부 방사선사진으로 구성되어졌다. 전체 대상치아에 대한 평균 치근 흡수량은 1.63 ㎜였으며 표준편차는 1.58 ㎜였다. 이변량적인 비교에서 발치 치료군에서는 2.10 ± 1.64 ㎜, 비발치 치료군에서는 1.18 ± 1.39 ㎜로 나타났다. 발치 치료 군에서 흡수량이 0.92 ㎜ 컸으며, 통계적으로 유의한 차이를 나타냈다. 초기 치아의 길이가 길수록 흡수량이 컸으며, 4 ㎜ 이상의 심한 치근 흡수를 보이는 그룹에서 blunt, pointed, eroded 형태의 비정상적인 치근 형태의 비율이 높았다. OIRR에 영향을 줄 수 있는 요소로 발치 여부, 초기 치아의 길이, 치근의 형태가 있었다. Objective: Orthodontically induced root resorption (OIRR) involves partial loss of cementum and dentin of teeth caused by routine orthodontic treatment. It decreases root length and influences the function of affected teeth. In this study, the treatment and patient factors causing apical root resorption in Koreans were determined. The observed factors were extraction, gender, age, displacement of root apex, total treatment period, total teeth length, and shape of the root. Methods: The records of 137 patients treated with full, fixed edgewise appliances were obtained from the Department of Orthodontics, Dankook University Dental Hospital, from November 2007 to December 2008. Periapical radiographs of the maxillary central incisors and cephalometric radiographs of each patient were used to assess apical root resorption and type of tooth movement. Results: The mean amount of resorption was 1.62 ± 1.58 ㎜. The amount of resorption in the extraction and non-extraction groups was 2.10 ± 1.64 ㎜ and 1.18 ± 1.39 ㎜, respectively. The amount of root resorption increased with the total tooth length. Severe root resorption (> 4 ㎜) was related to abnormal root shape (blunt, pointed, or eroded). Conclusions: The variables significantly related to OIRR were extraction, initial tooth length, and root shape.