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Abstract：
OBJECTIVE: To elucidate the relationships and factors affecting the proximity between the incisive canal (IC) and maxillary central incisors and to predict the probable outcomes after anterior tooth retraction using cone beam computed tomography (CBCT).
METHODS: Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction.
RESULTS: All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC.
CONCLUSIONS: Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.
METHODS: Retrospective CBCT data taken before and after maxillary anterior retraction in 36 patients were used in this study. The incisive canal length (ICL), maxillary central incisor length (TL), angles between the palatal plane and axes of the maxillary alveolar border (θ1), IC (θ2), and maxillary central incisor (θ3), retraction distance (TDE), distance from the maxillary central incisors to the IC (D), cross-sectional area of the IC (CSA), and volume of the IC were evaluated. Comparison of the parameters between contact and noncontact groups were examined. Logistic regression was performed to analyze the probable outcome prediction.
RESULTS: All parameters significantly decreased after anterior retraction, except for the ICL. Eighteen roots in 12 patients contacted the IC. The θ1, θ2, θ3, and D values at all levels were significantly lower, whereas the TDE, midlevel and oral opening CSA, and volume were significantly higher in the contact group compared with the noncontact group. The larger the pretreatment θ1 and θ3 were, the higher was the chance of incisors not contacting the IC.
CONCLUSIONS: Maxillary central incisors not contacting the IC after anterior retraction was positively associated with larger degrees of pretreatment maxillary alveolar bone angle and maxillary central incisor angle.
摘要：
目的：阐明影响切牙管（IC）与上颌中切牙之间接近的关系和因素，并使用锥形束计算机断层扫描（CBCT）预测前牙回缩后的可能结果。
方法：本研究使用了36例患者上颌前退缩前后的CBCT数据。切缝管长度(ICL),上颌中切牙长度(TL),腭平面和上颌牙槽缘轴之间的角度（θ1），IC(θ2),和上颌中切牙（θ3），缩回距离(TDE),从上颌中切牙到IC的距离（D），IC的横截面积(CSA)，并对IC的体积进行评价。检查了接触组和非接触组之间的参数比较。进行Logistic回归分析可能的结果预测。
结果：前回缩后所有参数均显着降低，除了ICL。12名患者的18个根部接触了IC。各层次的θ1、θ2、θ3和D值均显著降低,而TDE,中级和口头开放CSA，与非接触组相比，接触组的体积明显更高。预处理θ1和θ3越大，门牙未接触IC的机会越高。
结论：上颌中切牙前缩后未接触IC与上颌牙槽骨角和上颌中切牙角预处理程度较大呈正相关。
方法：本研究使用了36例患者上颌前退缩前后的CBCT数据。
结果：前回缩后所有参数均显着降低，
结论：上颌中切牙前缩后未接触IC与上颌牙槽骨角和上颌中切牙角预处理程度较大呈正相关。
