Department of Orthodontics, Lithuanian University of Health Sciences, LT- 50106 Kaunas, Lithuania.
Private practice, LT- 50176 Kaunas, Lithuania.
Medicina (Kaunas). 2019 Jun 24;55(6):305. doi: 10.3390/medicina55060305.
Impacted third molars (ITM) are the most commonly-impacted teeth. There is a risk for ITM to cause a number of pathological conditions, and external root resorption (ERR) of adjacent teeth is one of the most prevalent. Retaining or prophylactic extraction of ITM is a polemic topic. External root resorption of adjacent teeth is one of possible indications for prophylactic removal of ITM. The aim of this study was to assess the relationship between external root resorption (ERR) on the distal aspect of second molars' roots and positional parameters of ITM. Methods Cone beam computed tomography scans of 109 patients (41 males, 68 females; mean age 26.4 ± 7.9 years) with 254 ITM (131 in the maxilla and 123 in the mandible) were retrospectively analyzed. Positional parameters of ITM (mesio-distal position, angulation, impaction depth, and available eruption space) were evaluated. The presence, location, and depth of ERR of adjacent second molars were assessed. Analysis showed a relationship between ITM impaction depth, mesial inclination angle, and the presence of ERR. Mesial inclination angle of more than 13.6° increased the odds of ERR occurrence by 5.439 (95% CI, 2.97-9.98). ITM presence at the level of ½ of roots of the adjacent second molar or more apically increased the odds of ERR occurrence by 2.218 (95% CI, 1.215-4.048). No significant correlation was detected between the occurrence of ERR and patient age, gender, or the available eruption space in the mandible. Depth of ERR did not depend on its location. Incidence of ERR in second molars is significantly associated with mesial inclination and a deep position of ITM.
阻生第三磨牙（ITM）是最常见的阻生牙。ITM 有引发多种病理状况的风险，其中邻牙的外吸收（ERR）是最常见的一种。保留或预防性拔除 ITM 是一个有争议的话题。邻牙的外吸收是预防性拔除 ITM 的可能指征之一。本研究旨在评估第二磨牙根远中侧的外吸收（ERR）与 ITM 位置参数之间的关系。方法回顾性分析了 109 名患者（41 名男性，68 名女性；平均年龄 26.4±7.9 岁）的 254 颗 ITM（131 颗在上颌，123 颗在下颌）的锥形束 CT 扫描。评估 ITM 的位置参数（近远中位置、倾斜角、阻生深度和可萌出间隙）。评估 ERR 对相邻第二磨牙的存在、位置和深度。分析显示 ITM 阻生深度、近中倾斜角与 ERR 的存在之间存在相关性。超过 13.6°的近中倾斜角使 ERR 发生的几率增加 5.439 倍（95%CI，2.97-9.98）。在相邻第二磨牙根的 1/2 水平或更根尖处存在 ITM 会使 ERR 发生的几率增加 2.218 倍（95%CI，1.215-4.048）。ERR 的发生与患者年龄、性别或下颌可萌出间隙无显著相关性。ERR 的深度与位置无关。第二磨牙 ERR 的发生率与 ITM 的近中倾斜和深位显著相关。
