| ObjectiveBased on different development stages of orthodontic treatment for maxillary inverted impacted central incisors of mixed dentition,and the contralateral teeth with the same name were selected as control teeth,analysis of before and after treatment of the root lengths of maxillary impacted central incisors and contralateral central incisors,the angle of the crown and root,the condition of alveolar bone and dental pulp of maxillary impacted central incisors,to discuss the effect and the optimal timing of orthodontic treatment of maxillary inverted impacted central incisor in different development period.MethodsA total of 36 patients diagnosed with maxillary inverted impacted central incisor in the First Affiliated Hospital of Zhengzhou University from June 2015 to June 2020,aged 7～12 years,were selected and divided into early tooth age group(19 cases)and late tooth age group(17 cases)according to the degree of dental calcification of impacted teeth.All patients received surgical fenestration and orthodontic traction.The contralateral maxillary central incisors were used as the control teeth.The root length of the impacted teeth of the two groups and the control teeth were analyzed and the alveolar bone absorption height,the thickness of the alveolar bone in the apical area,the angle of the crown and root and the pulp activity of the impacted teeth of the two groups were compared.by oral cone-beam CT.Results1.Root length:① In the early tooth age group,the root length of the impacted teeth and the control teeth were 6.81 ±1.42mm and 7.91±0.52mm,respectively,before orthodontic treatment,and there was a statistical significance between them(P<0.05).At the end of treatment,the root lengths of the impacted teeth and the control teeth were 8.75 ± 1.15mm and 10.06 ± 1.39mm,respectively,with statistical significance(P<0.05).② In the late tooth period group,the root lengths of the impacted teeth and the control teeth were 7.96±1.05mm and 9.59±1.09mm,respectively,before treatment,and the difference was statistically significant(P<0.05).At the end of treatment,the root lengths of the impacted teeth and the control teeth were 8.68±0.89mm and 10.97±0.78mm,respectively,and the difference was statistically significant(P<0.05).③The maxillary inverted impacted central incisors between the two groups:before orthodontic treatment,the root length of the maxillary inverted impacted central incisors teeth in the late tooth age group was longer than that in the early tooth age group,and after orthodontic treatment,the root length increment of the maxillary inverted impacted central incisors in the early tooth age group was longer than that in the late tooth age group,with statistical significance(P<0.05).2.The alveolar bone condition:After orthodontic treatment,the alveolar ridge absorption height of the impacted labial teeth in the early age group and the late age group were 2.34±1.13mm and 3.5 8±1.54mm,respectively,with statistical significance(P<0.05).The absorption height of alveolar ridge on the lingual side of the impacted teeth was 2.05± 1.01mm and 2.07±1.03mm in the early and late tooth age groups,respectively,and there was without statistical significance(P>0.05).There was without significant difference in the labial bone thickness and lingual bone thickness between the two groups(P>0.05).There was without signif cant difference in the labial and lingual bone thickness between the two groups(P>0.05).3.Root curvature:Before treatment,the angle of the crown and root of impacted teeth in the early tooth age group was(151.30±11.51)°,and that in the late tooth age group was(122.15±18.68)°,and the difference between them was statistically significant(P<0.05).After treatment,the angle of the crown and root of impacted teeth in early and late tooth age groups was(162.26±12.46)°and(127.98±18.74)°,respectively,and the difference was statistically significant(P<0.05).The difference of the angle of crown and root before and after the treatment of impacted maxillary central incisor was(10.86±4.37)° and(5.84±1.70)° in the early and late tooth age groups,respectively,with statistical significance(P<0.05).4.Pulp activity:There was without significant difference in the pulp activity of the impacted teeth between the two groups after treatment(P>0.05).Conclusion1.The inverted impacted maxillary central incisor is still developing during orthodontic traction treatment.The earlier the treatment(That is,7～8 tooth age when traction treatment),the better the root development.2.After orthodontic traction treatment,the dental pulp activity of the impacted teeth could reach the normal level.After early traction treatment,the inverted impacted maxillary central incisor had less labial alveolar bone attachment loss,less root curvature,more upright root,and better periodontal stability.3.CBCT should be taken early for diagnosis and treatment after the eruption of the oppositely named maxillary central incisor with inverted impacted teeth. |
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