A Retrospective Study Of The Condition Of Impacted Teeth

Impaction of teeth is a common malocclusion that occurs in our clinicalwork.Sequelae of impacted teeth include the following clinicalramifications:migration of the adjacent teeth, loss of arch length,root resorptionof the adjacent teeth.The existence of impacted teeth seriously affect the patient’smasticatory function.Any permanent teeth can become impacted.There isconsiderable variation in the condition of impacted teeth due to ethnic group,raceand respondents.It is crucial to allocate the impacted teeth for a successfultreatment.Three-dimensional reconstruction of spiral CT can accurately andeffectively check the spatiallocation of the impacted teeth and the anatomicalrelationship with the surrounding organization structure.The impacted maxillarycanines can result in root resorption of the adjacent teeth,especially the maxillarylateral incisors.Conventional2D radiographic imaging is limited in evaluating theroot resorption of the adjacent teeth,while three-dimensional reconstruction ofspiral CT can observe the degree of root resorption. The study aimed to enrich the data of the condition of impacted teeth,takeadvantage of the three-dimensional reconstruction of spiral CT to allocate theimpacted teeth and estimate the degree of root resorption of the adjacentteeth,while the factors that affect the duration of forced eruption of the impactedmaxillary canines were also estimated.The study is composed of three experiments as following:Experiment1: An Epidemiological Study of Impacted Teeth in OrthodonticPatients.Objective: To make an epidemiological and descriptive study of the basiccharacteristics of patients with impacted teeth. Methods: The records of6876patients from orthodontic department were examined and those who werediagnosed as impacted teeth from panoramic radiograph were investigated. Thevariables of gender, age, location and number were taken into account. Results:The prevalence of the impacted teeth in orthodontic patients was estimated to be8.56%.Among these impacted teeth, the maxillary canines occurred mostfrequently,followed by supernumerary teeth.The maxillary region waspredominant.Most cases presented only one impacted teeth. The female patientswere more frequently affected than male patients,and the difference betweengender was significant (p<0.05).Conclusions: The incidence of the impacted teethwas high in orthodontic patients, especially the maxillary canines. Early detectionand early treatment of the impacted teeth are important for the orthodontists.Experiment2: Spatiallocation assessment of the impacted maxillary caninesand observation of root resorption of the adjacent incisors.Objective: Toinvestigate the spatiallocation of the impacted maxillary canines and rootresorption of the adjacent incisors. Methods: Spiral CT Scans of240patients with304impacted maxillary canines were included in this study.The DICOM fileswere imported into the Mimics software.The location of the impacted maxillary canines was assessed and quantified in three dimensions.In addition,rootresorption of the adjacent incisors was investigated.Results: Among theseimpactions,91.1%were impacted mesially with the average degree of10.59mm;49.7%were impacted labially with the average degree of1.45mm;Theaverage distance of impacted cusp tips to the occlusal plane was11.50mm.Theincidence of root resorption of the adjacent teeth due to impacted maxillarycanines was29.6%.Conclusions: The location of impacted maxillary caninesvaries greatly in three dimensions.The most frequent location of impactedmaxillary canines was mesial,labial and gingival.The phenomenon of rootresorption of the adjacent incisors induced by the impacted maxillary canines wascommon,and the orthodontists should pay attention to it.Experiment3:An analysis of factors related to the duration of forcederuption of impacted maxillary canines.Objective: The aim of this study was toidentify the factors that affect the duration of forced eruption of the impactedmaxillary canines. Methods: Data of46successfully treated impacted maxillarycanines with forced eruption were analyzed.The duration of forced eruption wasrelated to the following factors:age of the patients(y),the distance between theimpacted maxillary canine cusp tip and the occlusal plane(d),the angle betweenthe axis of the impacted maxillary canine and the occlusal plane(α),mesiodistalposition of the canine cusp tip in relation to the adjacent teeth(ZB),the anglebetween the canine axis and the lateral incisor axis(β).Results: The resultsindicated a direct correlation of the duration of forced eruption with the age andd,the more mesially located with the canine cusp tip to the midline,the longertreatment time needed.In contrast,there was an inverse correlation between theduration of forced eruption and α.Conclusions: The patient’s age and the positionof the impacted maxillary canines can be provided as important predictors of the duration of the forced eruption.