1 Assistant Professor of Orthodontics Department, Qazvin University of Medical Sciences, School of Dentistry

2 Associate Professor of Orthodontics Department, Shahid Beheshti University of Medical Sciences, School of Dentistry

3 Assistant Professor operative Dentistry, Zanjan University of Medical Sciences



Aim: One of the core parts of clinical orthodontics is the analysis of dentofacial growth. Changes that occur in the shape, form and size of dentoalveolar arch may result in various problems during diagnosis and treatment planning. The aim of this study was to investigate the late changes of alignment in the anterior teeth of mandible during 4-years follow up in young adults with normal occlusion in Qazvin
Materials and Methods: This was a longitudinal descriptive survey with 23 samples (13 girls and 10 boys). Subjects with an age range of 13±1 were selected for dentoalveolar change assessment. Two dental models were prepared from each subject one at the start of the investigation and one at the 4 years follow up; photographs of each model were taken at the time. Inter-canine distance, anterior arch depth, arch shape index, anterior teeth width (6 anterior teeth), anterior arch circumference (ATSALD) were measured using AutoCAD 2004 software and digital caliper. Means and standard deviations were measured using Npar test analysis. Data were compared at 0 and 4 years and between two genders using Wilcoxon test (P<0.05).
Results: The most prevalent changes in samples belonged to ATSALD (2.2mm increase) over the four years. The least changes were detected in arch shape index. Anterior arch circumference and ATSALD were the dominant changes in boys and girls, respectively.
Conclusion: During this critical growth period, anterior crowding of mandibular teeth increases in both boys and girls, while the inter-canine distance and arch shape index decrease.