A Clinical Study Of The Risk Factors For Orthodontically Induced Inflammatory Root Resorption Of Maxillaryanterior Teeth

Objective: To examine the risk factors related to the orthodontically inducedinflammatory root resorption (OIIRR) of the maxillary anterior teeth, and try toconfirm the predicted factors of the tendency of OIIRR based on the study of clinicalcases analysis.Materials and methods: According to the sample selection criteria, choosingeligible cases127(male:38cases, female:89cases; mean age:16.38years; meantime of treatment:19.75months), totally762teeth. Examine the length of the dentalcrowns and roots from the surface fault of the6front teeth before and after thetreatment. Besides, measure the length of the crowns of the patients with plastermodel, and then calculate the amount of root resorption of each tooth. At the sametime, input all data into statistical software spss17.0, using t test, analysis of variance,correlation analysis and multiple regression analysis to test it according to theinformation such as the started age、course of treatment、with or without extraction ofthe patients.Results: The maxima、minimum and mean value of the amount of root resorptionof the maxillary anterior teeth after the treatment are: central incisor:3.99mm,-2.15mm,1.1898mm;lateral incisor:4.13mm,-1.71mm,1.4327mm;canines:3.45mm,-4.76mm,0.3487mm. The results of T test and single factor variance analysis showedthat the root length of each tooth has a significant statistical difference (P <0.01) before and after the treatment. There were statistical differences of the amount of rootresorption of maxillary anterior teeth among the started age、with or without toothextraction、application of microimplant anchorage and time of treatment. While therewere no statistical differences in vertical facial skeletal types and occlusal contactsituation of mandibular anterior teeth.In addition, there were statistical differences ofthe the amount of root resorption of maxillary lateral incisor、incisor and canines indiagonal line traction、lingual root torque and root development, respectively.Pearson correlation analysis showed that the amount of root resorption of maxillaryanterior teeth is related to the started age、time of treatment、with or without toothextraction、the application of microimplant anchorage and occlusal contact situationof mandibular anterior teeth,respectively.In addition, the amount of root resorptionof maxillary incisor、lateral incisor and canines has significant correlation with thelingual root torque、diagonal line traction and root development, respectively.Multiple regression analysis showed that root development、time of treatment and theapplication of microimplant anchorage can be used as the prediction factors of theabsorption tendency of the root of maxillary anterior teeth.Conclusion:1. The amount of root resorption of maxillary anterior teeth is bigrelated to the started age、time of treatment、with or without tooth extraction、theapplication of microimplant anchorage and occlusal contact situation of mandibularanterior teeth,respectively;2. The amount of root resorption of maxillary lateralincisor has big significant correlation with the diagonal line traction;3. The amountof root resorption of maxillary incisor has big significant correlation with the lingualroot torque;4. The amount of root resorption of canines has huge significantcorrelation with the root development;5. Root development、time of treatment and theapplication of microimplant anchorage can be used as the prediction factors of theabsorption tendency of the root of maxillary anterior teeth.