Relationship between dental crowding, skeletal base lengths, and dentofacial measurements

Objectives: The objectives of this study were to study the correlation between dental crowding, skeletal base lengths, and dentofacial measurements.

Materials and methods: Pretreatment dental casts and lateral cephalograms of randomly selected 45 Class I orthodontic cases divided into two groups according to the severity of mandibular crowding were evaluated. Group 1 comprised 15 patients with mandibular crowding less than 3mm while group 2 comprised 30 patients with mandibular crowding of 3mm or more. Maxillary and mandibular dental crowding and dentofacial measurements were compared between the two groups. For correlations the whole sample was combined to a single group where crowding was used as a continuous variable.

Results: The only significant difference (p=0.000) between the two groups was in the amount of dental crowding in the lower arch. Direct moderate correlation (r=0.45; p=0.002) between maxillary crowding and mandibular crowding, direct high correlation (r=0.68; p=0.000) between maxillary base length (Co-A) and mandibular base length (Co-Gn) and also direct high correlation (r=0.74; p=0.000) between maxillary base position (SNA angle) and mandibular base position (SNB angle) were detected. Correlation between maxillary incisor position and facial vertical dimension measured by the MP to SN angle showed inverse moderate correlation. Correlation between mandibular incisor position and the anteroposterior jaw relationship measured by the ANB angle showed direct moderate correlation.

Conclusions: Results showed the presence of correlation between the skeletal dimensions and the absence of correlation between dental crowding and the same measurements. Results suggest that dental crowding is independent of the skeletal measurements.