Thimmegowda Umapathy, Niwlikar Kumar B, Khare Vaibhav, Prabhakar Ashwini Chikkanayakanahalli
Senior Reader, Department of Pedodontics and Preventive Dentistry, Rajarajeswari Dental College and Hospital, Bengaluru, Karnataka, India.
Senior Lecturer, Department of Orthodontics and Dentofacial Orthopedics, Dayanandsagar College of Dental Sciences, Bengaluru, Karnataka, India.
J Clin Diagn Res. 2017 Jun;11(6):ZC16-ZC19. doi: 10.7860/JCDR/2017/25962.9995. Epub 2017 Jun 1.
Essential part of diagnostic procedures in mixed dentition analysis is to determine adequate space available for the erupting permanent teeth. Various methods of analysis for mixed dentition are available; among them Tanaka Johnston method of space analysis for children was developed for North American children and is widely used. Its reliability among different racial and ethnic groups is yet to be determined.
To check the applicability of Tanaka Jhonston method and to derive the mesiodistal width of unerupted canines and premolars and also derive new regression equations for Bangalore population.
Considering the selection criteria, 400 subjects of Bangalore aged 13-16 years were randomly selected and study models were prepared. Mesiodistal widths of permanent lower incisors, canines and premolars were measured. Estimated width of upper, lower canines and premolars were also derived using Tanaka Jhonston method. Data was utilized to predict mesiodistal widths of erupting permanent canines and premolars. Descriptive analysis, independent student t-test, correlation and regression analysis were carried out.
Measured and estimated widths of upper and lower canines and premolars were compared and the results showed that estimated widths of upper and lower canines and premolars over estimated as to the actual measurements. A new regression equation was developed by using the formula Y=a+b(X) where Y= predicted width of canine and premolars, "a" and "b" are the constants and X= lower incisal width. Regression equations for males and females were derived separately.
The original Tanaka Jhonston method over estimated for local Bangalore population. New regression equations and prediction tables were derived for males and females separately, which should be more conveniently used chairside by the clinician.
混合牙列分析诊断程序的重要部分是确定恒牙萌出时可用的足够间隙。有多种混合牙列分析方法；其中，针对北美儿童开发的田中-约翰斯顿儿童间隙分析方法被广泛使用。其在不同种族和族裔群体中的可靠性尚待确定。
检验田中-约翰斯顿方法的适用性，得出未萌出尖牙和前磨牙的近远中宽度，并为班加罗尔人群推导新的回归方程。
根据选择标准，随机选取400名年龄在13 - 16岁的班加罗尔受试者，并制作研究模型。测量恒牙下切牙、尖牙和前磨牙的近远中宽度。还使用田中-约翰斯顿方法得出上下尖牙和前磨牙的估计宽度。利用数据预测恒牙尖牙和前磨牙萌出时的近远中宽度。进行描述性分析、独立样本t检验、相关性和回归分析。
比较了上下尖牙和前磨牙的测量宽度与估计宽度，结果表明上下尖牙和前磨牙的估计宽度高于实际测量值。通过公式Y = a + b(X)（其中Y = 尖牙和前磨牙的预测宽度，“a”和“b”为常数，X = 下切牙宽度）推导了新的回归方程。分别得出了男性和女性的回归方程。
原始的田中-约翰斯顿方法对班加罗尔当地人群的估计过高。分别为男性和女性推导了新的回归方程和预测表，临床医生在椅旁使用会更方便。
