Investigation Of Impacted Teeth And Impacted Supernumerary Teeth Of Patients With Malocclusion In Tianjin

Objective: To investigate prevalence and impacted condition of impacted teeth ofall teeth except the third molar and impacted supernumerary teeth of patients withmalocclusion in Tianjin. To discuss the reliability of the location of impactedmaxillary canines with the orthopantomograph. To analyse the prevalence, etiologicalfactor, direction and position of impacted maxillary canines.Methods: To collect orthopantomographs and lateral skull radiographs of 4106patients in Tianjin Stomatological Hospital from Nov.1 2005 to Oct.31 2006. Thepatients included 1783 males and 2323 females. The age of patients was from 2 to 47and the mean age was 18.7. Impacted teeth and impacted supernumerary teeth werediagnosed by radiographs. And the prevalence and impacted condition of them wereinvestigated. We chose patients with impacted maxillary canines by inclusivecriterion as object. The reliability of the location of impacted maxillary canines withthe orthopantomograph was to be discussed. And the prevalence, etiological factor, direction and position of impacted maxillary canines were to be analysed.Results:1 The prevalence rate of impacted teeth of patients with malocclusion in Tianjin was7.33％. Among the 400 impacted teeth, the teeth in order of frequency weremaxillary canines(34.00％), maxillary central incisors(16.25％), maxillary secondbicuspids(14.75％), mandibular second molars(12.25％), mandibular secondbicuspids(11.50％), maxillary lateral incisors(4.00％), mandibular canines(2.50％), mandibular first bicuspids(2.50％), maxillary second molars(1.00％), mandibularfirst molars(1.00％) and maxillary first bicuspids(0.25％). Impacted teeth ofmaxilla were more than that of mandible and its ratio was 2.36: 1. Impactedanterior teeth were more than impacted posterior teeth and its ratio was 1.31: 1.Impacted teeth occurred most frequently in maxillary-anterior teeth. The ratio of the number of impacted maxillary-anterior teeth to the number of the all impactedteeth was 54.25％. The ratio of males to females was 1: 1.08. The difference ofgender wasn't statistically significant (P＞0.05). The direction and position ofimpacted teeth occurred mostly frequently in oblique position and the ratio was54.50％. The number of impacted teeth was mostly single and the ratio was74.42％. The etiological factor was mostly abnormity of tooth germ, insufficiencyof diastemata and retained primary tooth.2 The prevalence rate of impacted supernumerary teeth of patients withmalocclusion in Tianjin was 2.51％. Impacted supernumerary teeth of maxilla weremore than that of mandible and its ratio was 9.73: 1. Impacted supernumerary teethof anterior segment were more than that of posterior segment and its ratio was6.38: 1. Impacted supemumerary teeth occurred most frequently inmaxillary-anterior segment. The ratio of the number of impacted supernumeraryteeth of maxillary-anterior segment to the number of the all impactedsupernumerary teeth was 86.44％. The ratio of males to females was 1.94: 1. Thedifference of gender was statistically significant (P＜0.05). The direction andposition of impacted supemumerary teeth occurred mostly frequently in invertedposition and the ratio was 30.51％. The number of impacted supernumerary teethwas mostly single and the ratio was 90.29％. The associated complications to thepermanent teeth were mostly displacement, rotation and diastemata of adjacentteeth.3 The bucco-palatal position of those non-rotation impacted maxillary canines thatoverlapped the coronal or middle zones of the adjacent teeth could be accuracyachieved from orthopantomographs solely, but without other radiographs. But thebucco-palatal position of the impacted maxillary canines that overlapped the apicalzone of the adjacent teeth couldn't be accuracy diagnosed fromorthopantomographs solely.4 The etiological factor of impacted maxillary canines was mostly retained primarytooth and the ratio was 37.74％. The canine angulation to the midline was mostly more than 30°and the ratio was 41.51％. The vertical canine crown height wasmostly above the cemento-enamel junction, but less than half way up the root andthe ratio was 64.15％. The canine overlap of the adjacent incisor root was mostlyno horizontal overlap and the ratio was 73.58％. The canine crown was mostlybetween the axis of maxillary lateral incisor and that of maxillary first bicuspidand the ratio was 71.70％.Conclusion: The prevalence rate of impacted teeth of patients with malocclusion inTianjin was 7.33％. Impacted teeth occurred most frequently in maxillary-anteriorteeth. The prevalence rate of impacted maxillary canine was the highest. Impactedteeth of maxilla were more than that of mandible and impacted anterior teeth weremore than impacted posterior teeth. The difference of gender wasn't statisticallysignificant. The etiological factor was mostly abnormity of tooth germ, insufficiencyof diastemata and retained primary tooth. The prevalence rate of impactedsupernumerary teeth was 2.51％. Impacted supernumerary teeth occurred mostfrequently in maxillary-anterior segment. Impacted supernumerary teeth of maxillawere more than that of mandible and impacted supernumerary teeth of anteriorsegment were more than that of posterior segment. The prevalence rate of male washigher than that of female obviously. The impacted supernumerary teeth couldinfluence the normal growth and position of adjacent permanent teeth. It was exactthat the bucco-palatal position of those non-rotation impacted maxillary canines thatoverlapped the coronal or middle zones of the adjacent teeth judged fromorthopantomographs. The etiological factor of impacted maxillary canines was mostlyretained primary tooth. The direction and position of impacted maxillary teeth hadspecificity to some extent.