University of São Paulo, Bauru School of Dentistry, Department of Prosthodontics and Periodontology; Hospital for Rehabilitation of Craniofacial Anomalies (HRAC/USP) (Bauru/SP, Brazil).
University of São Paulo, Bauru School of Dentistry, Department of Pediatric Dentistry, Orthodontics and Public Health (Bauru/SP, Brazil).
Dental Press J Orthod. 2024 Sep 2;29(4):e2423265. doi: 10.1590/2177-6709.29.4.e2423265.oar. eCollection 2024.
Symmetry is balance, some correspondence in the size, form, and arrangements of parts on opposite sides of a plane, line, or point. The opposite of this concept is asymmetry, or imbalance.
This retrospective study compared two methods for assessing arch symmetry with linear measurements based on triangles, to determine their applicability and efficiency.
Two groups were enrolled: children (n=20) and adults (n=20), and the arch symmetry was assessed from linear measurements. Method 1: the incisor-canine (INC), canine-molar (CM), and incisor-molar (INM) distances (paired t-test and Pearson correlation). Method 2: a mathematical equation between the cusps measurements of the canines and the distobuccal of the first molars leading to result 1 (t-test for one sample and bootstrapping analysis). Dental casts were digitized and analyzed using a software program. The Bland-Altman test compared the methods (α=0.05).
The Bland-Altman test revealed concordance between the methods; however, separately the results were different: In method 1, the mandibular arch did not demonstrate correlation (children, INC r=0.33; CM r=0.45; INM r=0.51; adults, CM r=0.46; INM r=0.35), however, the maxilla revealed a strong correlation in children and a strong/moderate correlation in adults. In method 2, both arches were symmetrical (p>0.05).
Method 1 may be appropriate during orthodontic treatment, and method 2 may be indicated for final treatment. These methods are useful; however, only method 1 identified the side of asymmetry. The methods can contribute to future studies in syndromic and non-syndromic patients, before and after orthognathic surgeries and orthodontic treatment, comparing results.
对称性是平衡，是平面、线或点两侧大小、形状和排列的某些对应。这个概念的对立面是不对称性或不平衡。
本回顾性研究比较了两种基于三角形的线性测量方法评估牙弓对称性的方法，以确定其适用性和效率。
共纳入两组：儿童（n=20）和成人（n=20），并通过线性测量评估牙弓对称性。方法 1：切牙-尖牙（INC）、尖牙-磨牙（CM）和切牙-磨牙（INM）距离（配对 t 检验和 Pearson 相关）。方法 2：一种通过尖牙的牙尖测量和第一磨牙的远颊侧建立的数学方程，结果为 1（单样本 t 检验和 bootstrap 分析）。牙模数字化后使用软件程序进行分析。Bland-Altman 检验比较了两种方法（α=0.05）。
Bland-Altman 检验显示两种方法之间存在一致性；然而，单独的结果有所不同：在方法 1 中，下颌弓没有相关性（儿童，INC r=0.33；CM r=0.45；INM r=0.51；成人，CM r=0.46；INM r=0.35），而上颌弓在儿童中表现出强相关性，在成人中表现出强/中度相关性。在方法 2 中，两个弓都是对称的（p>0.05）。
方法 1 可能适用于正畸治疗期间，方法 2 可能适用于最终治疗。这些方法是有用的；然而，只有方法 1 能够识别不对称的一侧。这些方法可用于未来的研究，包括综合征和非综合征患者，在正颌手术和正畸治疗前后，比较结果。
