1 Dept. of Orthodontics, Islamic Azad University, Isfahan (khorasgan branch)

2 DDS. Dentist



Background and aim: The objective of this study is determining the correlation among the dental crowding and mesiodistal tooth width and dental arch dimensions.
Materials and methods: In this case-control study dental casts of two groups of 40 subjects was investigated. Each group included 20 male and 20 female subjects with the age range of 17 to 25 years old.
The first group had class I malocclusion with nominal or no crowding. (space deficiency ≤ 4).
The second group had class I malocclusion with significant crowding. (space deficiency ≥ 4).
The following parameters were measured and compared in both groups:
The sum of mesiodistal tooth width, arch length in canine and molar spaces and arch perimeter. In order to compare the two group independent t-test with 95% confidence was applied.
Results: In lower arch a significant difference was detected in both tooth size (P=0/02) and arch dimensions. The group with the significant crowding has smaller arch dimension and larger tooth size in comparison to the group with no crowding. In the upper arch a significant difference in intercanine width (P=0/01), arch perimeter (P=0/023), arch length (P=0/012), and intermolar width (P=0/03) was detected.
Conclusion: The results of this study indicated that in upper arch the arch dimensions plays a significant role in crowding, and in the lower one both tooth size and arch dimensions have important role in crowding.