Department of Pedodontics and Preventive Dentistry, Christian Dental College, Ludhiana, Punjab, India.
Department of Pedodontics and Preventive Dentistry, Maharishi Markendeshwar College of Dental Sciences and Research, Ambala, Haryana, India.
J Indian Soc Pedod Prev Dent. 2024 Jul 1;42(3):226-234. doi: 10.4103/jisppd.jisppd_86_24. Epub 2024 Sep 9.
Contemporary imaging methods and quickly advancing technologies have increased the number of diagnostic tools available in medicine and orthodontics. The current study aimed to determine three-dimensional (3D) space changes that occurred after the extraction of either the maxillary or mandibular primary molars during the mixed dentition period.
The present study was a longitudinal split-mouth study with a study group and a control group. The sample consisted of 20 children aged between 6 and 9 years. Clinical examination, radiological analysis, and 3D digital images of the plaster casts were used sequentially to gather all the data. The dental cast measurements recorded were arch width, arch length, hemi-perimeter, dental space at the extraction site, and angulation of the first permanent molar. The children were recalled for follow-up after 9 months, and all dental cast measurements were repeated using nondestructive 3D computed tomography software. For repeated measurements, the test applied was a paired t-test, and for independent samples, the test was a Student's t-test.
A significant decrease in arch width (P = 0.001), arch length (P < 0.001), hemi-perimeter (P < 0.001), D-space (P < 0.001), and E-space (P = 0.001) was observed following extraction. A significant increase in angulation measurements was observed (P = 0.001).
The study revealed a comparative reduction in mandibular arch width, a reduction in arch length in both the maxilla and the mandible, a reduced hemi-perimeter of dental arches, loss of dental extraction space, and a change in angulation of the erupted first permanent molars following premature loss of the primary molar.
当代影像学方法和快速发展的技术增加了医学和正畸学中可用的诊断工具的数量。本研究旨在确定混合牙列期上颌或下颌乳磨牙拔除后三维（3D）空间的变化。
本研究是一项纵向分口研究，包括研究组和对照组。样本由 20 名年龄在 6 至 9 岁之间的儿童组成。临床检查、放射学分析和石膏模型的 3D 数字图像依次用于收集所有数据。记录的牙弓宽度、牙弓长度、半周长、拔牙部位的牙间隙和第一恒磨牙的角度测量值。9 个月后，对儿童进行随访，并使用非破坏性的 3D 计算机断层扫描软件重复所有牙模测量值。对于重复测量，应用的检验是配对 t 检验，对于独立样本，应用的检验是学生 t 检验。
在拔牙后，观察到牙弓宽度（P = 0.001）、牙弓长度（P < 0.001）、半周长（P < 0.001）、D 空间（P < 0.001）和 E 空间（P = 0.001）显著减小。观察到角度测量值显著增加（P = 0.001）。
研究表明，下颌牙弓宽度相对减小，上颌和下颌牙弓长度减小，牙弓半周长减小，拔牙间隙丧失，以及第一恒磨牙萌出时的角度发生变化，这是由于乳磨牙过早丧失。
