Objective: To observe the morphological changes of root canals in maxillary second premolars at various ages by using cone-beam CT (CBCT) in order to provide imaging and theoretical reference for clinical treatments. Methods: The digital CBCT data of the maxillary second premolars in 440 cases from the patients in Department of Stomatology, The First Affiliated Hospital, Jinan University during March 2011 and December 2017 were collected. The CBCT images were divided into 4 groups according to the patients' ages: groups ≤20, 21-40, 41-60 and>60 years old, respectively. Changes of morphologies of root canals with aging including such parameters as types of the root canal, incidence of double root canals in single rooted teeth, distance between both root canal orifices of double rooted canals, and morphological change of the cross section of roots. Chi-square test and liner trend test were adopted in statistical analysis in the present study. Results: Most maxillary second premolars had only one root [95.2% (419/440)]. Type Ⅰ of the root canals was the most common type [57.3% (252/440)], and the following prevalent groups were type Ⅱ[16.8% (74/440)], type Ⅳ [10.2% (45/440)] and type Ⅲ [8.9% (39/440)]. The distribution of type Ⅰ~Ⅳ of the root canals were significantly different amongst various aged groups (P<0.05). Along with aging, the percentages of type Ⅰ decreased while type Ⅱ increased. However, there were no remarkable changes of type Ⅲ and type Ⅳ observed. The incidence of double canal in single rooted teeth gradually increased with aging especially in 20-year-old and above groups, e.g. 13.1% (13/99) in group of ≤20 years old and 45.0% (86/191) in group of 21-40 years old. However, there was no significant increase observed after the age of 40. The distance between two root canal orifices of double rooted canals became shorter with aging except in groups of 40-year-old and above. The morphologies of the cross sections of root canals in most groups were flat shaped [57.8% (1 121/1 938)] and oval shape [31.3% (607/1 938)]. Along with aging, the percentage of circular shape gradually increased while flat and oval shapes decreased. Conclusions: The morphology of root canal could be clearly showed by the CBCT images. Most maxillary second premolars had only one root and one apical foramen. Along with aging, the morphology of the root canals became more and more complicated.
目的： 应用锥形束CT观察不同年龄患者上颌第二前磨牙的根管形态及其增龄性变化规律，以期为临床提供影像学依据。 方法： 选择2011年3月至2017年12月就诊于暨南大学附属第一医院口腔科的323例因正畸、种植、根管等治疗需要拍摄锥形束CT的患者，男性158例，女性165例，共440颗上颌第二前磨牙锥形束CT影像资料。将440颗患牙资料按年龄分为4组：≤20岁（中位数14.0，73例）、21~40岁（中位数31.0，141例）、41~60岁（中位数49.0，83例）及>60岁组（中位数68.0，26例），各年龄组上颌第二前磨牙数依次为109、195、106、30颗。分析各组根管类型、单根牙双根管发生率、双根管两根管口之间距离、根管横断面形态4项指标与年龄的关系，对4组上颌第二前磨牙的4项指标进行卡方检验，并采用有序分组资料的线性趋势检验分析其增龄性变化。 结果： 上颌第二前磨牙主要为单根牙[95.2%（419/440）]；根管类型以Ⅰ型最多见[57.3%（252/440）]，其次为Ⅱ型[16.8%（74/440）]、Ⅳ型[10.2%（45/440）]、Ⅲ型[8.9%（39/440）]、Ⅴ型[5.0%（22/440）]、Ⅵ型[0.9%（4/440）]、Ⅶ型[0.7%（3/440）]及其他型[0.2%（1/440）]。各年龄组Ⅰ~Ⅳ型根管类型分布差异有统计学意义（P<0.05），随着年龄的增长，Ⅰ型逐渐减少，Ⅱ型逐渐增多，Ⅲ、Ⅳ型则无明显的变化规律；单根牙双根管发生率随着年龄的增加而增高，20岁以后双根管发生率的增幅较大，由≤20岁组的13.1%（13/99）上升至21~40岁组的45.0%（86/191），而40岁以后增幅显著变小（P<0.05）；双根管两根管口之间距离随着年龄的增加而缩短，40岁以后缩幅显著变小（P<0.05）；根管横断面形态以扁形[57.8%（1 121/1 938）]和椭圆形[31.3%（607/1 938）]为主，随着年龄的增长，扁形和椭圆形呈下降趋势，而圆形逐渐增多。 结论： 锥形束CT能清晰准确地显示根管形态，上颌第二前磨牙主要为单根牙单根尖孔，其中Ⅰ、Ⅱ、Ⅲ型共83.0%（365/440），随着年龄增长根管形态愈加复杂。.
Keywords: Aging changes; Cone-beam computed tomography; Premolars.