Nagahara K, Yuasa S, Yamada A, Ito K, Watanabe O, Iizuka T, Sakai M, Utida H
Aichi Gakuin Daigaku Shigakkai Shi. 1989 Dec;27(4):913-24.
This investigation was undertaken to determine the causes of impacted permanent teeth and whether they have any influence on dentition, occlusion and skeletal patterns. The materials used were dental X-rays, occlusal dental X-rays, panoramic radiograms and cephalograms and dental casts of 194 cases (51 males and 143 females) which revealed impacted permanent teeth among 3979 cases (1215 males and 2764 females) from 1964 to 1985 in the Department of Orthodontics, School of Dentistry, Aichi-Gakuin University. The results obtained were as follows: 1. The incidence of impacted permanent teeth in these samples was 4.9% of the entire number of orthodontic patients. There was no significant difference between sexes. 2. The incidence according to the number of impacted permanent teeth was as follows: one impacted tooth, 74.8%; two impacted teeth; 21.1%, three impacted teeth; 3.6%, four impacted teeth; 0.5%. The incidence of two symmetrically impacted teeth was 61.5%. 3. As to the type of impacted teeth, the frequency of maxillary central incisors was the largest (33.7%), followed by 3 (25.0%), 5 (22.2%), 5 (11.9%), 2 (4.4%), 3 (1.2%), 4 (0.8%), 4 (0.4%), and 7 (0.4%). But no impacted teeth were found in the regions of 1, 2, 6, 6, 7 and 7. 4. As to impacted teeth and the type of malocclusion, the spaced arch in the anterior region had impacted teeth most frequently followed by crowding, open bite and lateral cross bite. Malocclusions with the smallest incidence were cross bite and upper protrusion. The spaced arch had a higher incidence of impacted teeth than bimaxillary protrusion. In the posterior region (impacted molar teeth), the lateral cross bite, spaced arch, and upper protrusion had impacted molars most frequently, crowding was second and cross bite had the least. 5. In the direction of long axis, the impacted tooth with a horizontal direction was found most frequently (35.2%), followed in the order of frequency by inverse direction (32.7%), labial or mesial tipping (22.0%), lingual or distal tipping (5.7%), and right-angled (4.4%). Moreover, the inverse maxillary central incisor and mesially tipped maxillary canine were found most frequently. The frequency of maxillary central incisors with crooked roots was 64.7%, which was higher than that of maxillary canines (19.0%). 6. Lack of space is the most frequently found cause of impacted teeth, and in the anterior region this was the main cause of canine impacted teeth. Eruption impediment by supernumerary teeth and trauma were found to be characteristic causes of anterior impacted teeth.
本研究旨在确定恒牙阻生的原因，以及它们是否对牙列、咬合和骨骼形态有任何影响。所用材料包括牙科X线片、咬合牙科X线片、全景X线片和头颅侧位片，以及194例（51例男性和143例女性）的牙模，这些病例取自1964年至1985年爱知学院大学牙科学院正畸科的3979例患者（1215例男性和2764例女性），其中发现有恒牙阻生。获得的结果如下：1. 这些样本中恒牙阻生的发生率为正畸患者总数的4.9%。男女之间无显著差异。2. 根据阻生恒牙的数量，发生率如下：一颗阻生牙，74.8%；两颗阻生牙，21.1%；三颗阻生牙，3.6%；四颗阻生牙，0.5%。两颗对称阻生牙的发生率为61.5%。3. 关于阻生牙的类型，上颌中切牙的发生率最高（33.7%），其次是3（25.0%）、5（22.2%）、5（11.9%）、2（4.4%）、3（1.2%）、4（0.8%）、4（0.4%）和7（0.4%）。但在1、2、6、6、7和7区域未发现阻生牙。4. 关于阻生牙与错牙合类型，前牙区牙弓间隙型阻生牙最为常见，其次是拥挤、开牙合和侧方反牙合。发生率最低的错牙合类型是反牙合和上颌前突。牙弓间隙型阻生牙的发生率高于双颌前突。在后牙区（磨牙阻生），侧方反牙合、牙弓间隙型和上颌前突最常出现磨牙阻生，拥挤次之，反牙合最少。5. 在长轴方向上，水平方向阻生的牙齿最为常见（35.2%），其次依次为反向（32.7%）、唇向或近中倾斜（22.0%）、舌向或远中倾斜（5.7%）和直角（4.4%）。此外，反向的上颌中切牙和近中倾斜的上颌尖牙最为常见。上颌中切牙根弯曲的发生率为64.7%，高于上颌尖牙（19.0%）。6. 空间不足是最常见的阻生牙原因，在前牙区，这是尖牙阻生的主要原因。多生牙和创伤导致的萌出障碍是前牙阻生的特征性原因。
