1 DDS, MS. Associate Professor, Department of Orthodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran

2 Assistant professor, Department of Orthodontics, School of Dentistry, Mazandaran University of Medical Sciences, Sari, Iran

3 Orthodontist



Background and aim: The aim of present study was to predict post treatment space available of mandibular arch and compare this method of measurement with the previous methods. 
Materials and methods: Pretreatment lower dental arch models of 33 patients attending to the department of orthodontics of Tehran University of medical sciences were randomly selected. Two conventional methods of brass wire and sectional way were done for estimating space available in traditional method. In predictive method two mathematical arch forms, β-function and the sixth degree polynomial function were selected as the based arches. Post treatment arch perimeter predicted according to these arch forms separately and finally the results were compared with traditional method of brass wire.
Results: According to this study, two traditional methods are so closed to each other and also two predictive methods, but differences between traditional method and predictive methods measurements were considerable. 
Conclusions: Using of post treatment arch parameters would be useful to predict post treatment space available in arches, and also detecting arch form, the position of the teeth, the retention requirements and so on.