Barberia-Leache Elena, Suarez-Clúa María Cruz, Saavedra-Ontiveros Dolores
Department of Preventive, Pediatric Dentistry and Orthodontics, Faculty of Dentistry, Complutense University, Madrid, Spain.
Angle Orthod. 2005 Jul;75(4):610-5. doi: 10.1043/0003-3219(2005)75[610:EEOTMF]2.0.CO;2.
The purpose of this study was to determine the characteristics and occurrence of the ectopic eruption of the maxillary first permanent molar in a sample of growing Spanish children. A descriptive, observational, retrospective study was done using the radiographs of 509 consecutive patients, who were in the first phase of mixed dentition. A method was designed to evaluate the amount of pathologic resorption of the second maxillary primary molar and the impaction of the first permanent molar measured in millimeters. Statistical analysis of the studied variables was done using chi-square, analysis of variance, and Pearson correlation coefficient. The frequency of occurrence was 4.3% with no differences in both sexes. Of these, 36.4% were unilateral and 63.6% bilateral with a right:left relation of 3:1. Of the 36 ectopic molars, 69.4% self-corrected spontaneously. In such cases, the pathological resorption of the root of the second maxillary primary molar and its adverse clinical implications were persistent. The relation between self-correction and impaction was 2.27:1. The average impaction on the right side was 2.91 mm and 1.6 mm on the left side. Correlation between the magnitude of resorption and grade of impaction was not observed. Although resorption was found on grades I and II, spontaneous self-correction could occur without arch length loss. However, on grade III or more, therapeutic intervention has to be done. The benefit of early diagnosis and treatment of the maxillary first permanent molar is the prevention of the premature loss of second maxillary deciduous molar and the resulting malocclusion.
本研究的目的是确定西班牙生长发育期儿童样本中上颌第一恒磨牙异位萌出的特征和发生率。采用描述性、观察性、回顾性研究方法，使用509例处于混合牙列第一阶段的连续患者的X线片。设计了一种方法来评估上颌第二乳磨牙的病理性吸收量以及以毫米为单位测量的第一恒磨牙的阻生情况。对研究变量进行统计学分析时使用了卡方检验、方差分析和皮尔逊相关系数。发生率为4.3%，男女之间无差异。其中，36.4%为单侧，63.6%为双侧，左右比例为3:1。在36颗异位磨牙中，69.4%自行矫正。在这种情况下，上颌第二乳磨牙牙根的病理性吸收及其不良临床影响持续存在。自行矫正与阻生的比例为2.27:1。右侧的平均阻生为2.91毫米，左侧为1.6毫米。未观察到吸收程度与阻生程度之间的相关性。虽然在I级和II级发现有吸收，但在不损失牙弓长度的情况下可能会发生自发自行矫正。然而，在III级或更高级别时，必须进行治疗干预。早期诊断和治疗上颌第一恒磨牙的益处在于预防上颌第二乳磨牙过早缺失及由此导致的错牙合畸形。
