title: Genetic and clinical risk factors of root resorption associated with orthodontic treatment.
abstract: BACKGROUND
  External apical root resorption (EARR) is a common complication in orthodontic treatment. Despite many studies on EARR, great controversies remain with regard to its risk factors. The objective of this study was to explore the relationship among sex, root movement, IL-1RN single nucleotide polymorphism (SNP) rs419598, IL-6 SNP rs1800796, and EARR associated with orthodontic treatment.
  
  
  METHODS
  Altogether 174 patients (with 174 maxillary left central incisors) were selected for this study. Cone-beam computed tomography was performed before the start of the treatment and at the end of the treatment. Cone-beam computed tomography data were used to reconstruct a 3-dimensional image of each tooth; the volume and the root resorption volume of each tooth were calculated. Three-dimensional matching was used to measure the amount of movement of each root. Genomic DNA was extracted from buccal swabs, and genotypes of SNP rs419598 and SNP rs1800796 of each subject were determined using TaqMan polymerase chain reaction genotyping (Applied Biosystems, Foster City, Calif). The data were analyzed with multiple linear regression analysis.
  
  
  RESULTS
  The statistical analysis indicated no relationship between sex, tooth movement amount, and IL-1RN SNP rs419598 with EARR. The IL-6 SNP rs1800796 GC was associated with EARR, and root resorption differed significantly between SNP rs1800796 GC and CC.
  
  
  CONCLUSIONS
  IL-6 SNP rs1800796 GC is a risk factor for EARR. The amount of root movement, IL-1RN SNP rs419598, and sex as risk factors for EARR need further study.
authors.affiliation: Postgraduate student, State Key Laboratory of Oral Disease, Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China; clinician, Department of Orthodontics, Stomatology Hospital of Guangzhou Medical University, Guangzhou, China.
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Lecturer, State Key Laboratory of Oral Disease, Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Shushu
authors.initials: S
authors.lastname: He
authors.affiliation: Postgraduate student, State Key Laboratory of Oral Disease, Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Gu
authors.affiliation: Postgraduate student, State Key Laboratory of Oral Disease, Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Professor, State Key Laboratory of Oral Disease, Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China. Electronic address: songchen882002@hotmail.com.
authors.forename: Song
authors.initials: S
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D054893:Cone-Beam Computed Tomography; D005260:Female; D005838:Genotype; D006801:Humans; D021621:Imaging, Three-Dimensional; D015850:Interleukin-6 / Q000235:genetics*; D008297:Male; D009971:Orthodontics, Corrective / Q000009:adverse effects*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D012391:Root Resorption / Q000000981:diagnostic imaging / Q000209:etiology* / Q000235:genetics; D012737:Sex Factors; D019227:Tooth Apex
chemical_list: D015850:Interleukin-6