New regression equations for predicting human teeth sizes
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HEAD & FACE MEDICINE
RESEARCH
Open Access
New regression equations for predicting human teeth sizes Vanessa Paredes1, Beatriz Tarazona1*, Natalia Zamora1, Rosa Cibrian2 and Jose Luis Gandia1
Abstract Introduction: The aims of the study were; to evaluate the applicability of the Moyers and Tanaka-Johnston Methods to individuals with a Spanish ancestry, to propose new regression equations using the lower four permanents incisors as predictors for the sum of the widths of the lower permanent canine and premolars, and to compare the new data to those from other populations. Methods: A total of 359 Spanish ancestry adolescents were selected. Their dental casts were measured using a 2D computerized system. Real teeth measurements were compared with those predicted using Moyers probability tables and Tanaka and Johnston equations, and standard regression equations were then developed. Results: Results showed that Upper and Lower Canine and Premolar (UCPM, LCPM) predictions are quite different depending on the used method. Moyers tables can only be validly applied to a 75% percentile for the mandible in both, males and females, 85% in males and 90-92% in females. Conclusions: Moyers predictions tend to underestimate UCPM and LCPM whereas Tanaka-Johnston predictions tend to overestimate them. Equations for estimating the combined width of the unerupted canine and premolars were; Male: UCPM = 12.68 + 0.42 LI and LCPM = 11.71 + 0.44 LI. Female: UCPM = 12.06 + 0.43LI and LCPM = 10.71 + 0.46 LI. Keywords: Moyers, Prediction, Regression equations, Tanaka-Johnston
Introduction Predicting unerupted tooth size of Upper and Lower Canine and Premolars (UCPM, LCPM) in mixed dentition is important for a good diagnosis and for choosing a therapy [1]. To date, three basic groups have been used to determine the mesiodistal widths of unerupted canines and premolars. 1- Analyses based on correlation and regression equations, expressed as prediction tables. Both Moyers’ regression scheme [2] and Tanaka and Johnston’s equations [3] have achieved widespread clinical acceptance because of their simplicity and ease of application. 2- Analyses based on measurements taken from radiographs [4,5] of unerupted teeth. 3- Analyses based on a combination of correlations and regression equations and measurements on radiographs [6-8]. * Correspondence: [email protected] 1 Orthodontics Department, Faculty of Dentistry and Medicine, University of Valencia, Gasco Oliag nº1, 46010 Valencia, Spain Full list of author information is available at the end of the article
However, bearing in mind that these prediction methods are based on individuals of North American ancestry, it is not appropriate to use them on different populations of different biological origin. For this reason, several linear regression equations have been proposed for different populations [9-23]. Odontometric data from Spanish ancestry children are not so widely available and, to date, there is no study in the literature examining the accuracy of Moyers probability tables a
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