1 Professor, Department of Orthodontics, Tehran University of Medical Sciences

2 Post graduate Student, Department of Endodontics, Shahid Beheshti University of Medical Sciences



Aim: To extract or not to extract?! This fundamental decision has spawned some intense debate in orthodontics. Crowding, as a common problem in permanent dentition, is usually handled by extraction and non extraction treatment. It is well established that increase in dental arch length and width during orthodontic treatment tend to return toward pretreatment values after retention. An undocumented criticism of extraction treatment is that it results in narrower dental arches and therefore less attractive smile esthetics.
Purpose: The main purpose of this study was to examine the dental arch width changes of extraction and non extraction treatment in patients treated in dental faculty of Tehran University of medical science.
Materials and Methods: This study was performed on pretreatment and post treatment dental casts of 75 patients (36 extraction and 39 non extraction). Arch widths were measured from the cusp tips of the canines and first molars, using a digital caliper.
Results: Multiple regression analysis was used to evaluate the treatment changes in the arch width dimensions. The results show that intercanine arch width in both arches at the end of treatment was not significantly changed neither in extraction nor non extraction treatment. However; intermolar arch width in both arches shows differences between two groups. It increased significant) in non extraction treatment, and decreased in extraction samples.
Conclusion: The results of this study indicate that intercanine arch width has no significant relationship with the type of treatment, but intermolar arch width shows statistically significant difference between two groups. We can conclude that constricted arch widths are not a usual outcome of extraction treatment, as there is no significant difference between post treatment intercanine arch width in two types x of treatment (DO 2006;1:187-93).