Relationship of maxillary and mandibular effective base length, arch length and dental crowding in different vertical growth pattern

The objectives of the study were to assess, measure, and correlate the maxillary and mandibular effective base length, arch length to the amount of dental crowding in different vertical growth pattern patients. Sample comprising 100 pre-treatment lateral cephalograms and study models (age group – 16–25 years) was randomly selected. The sample was divided into two groups, that is, clockwise (50) and anticlockwise (50) rotation based on the measurement of the gonial angle. The gonial angle and maxillary and mandibular effective lengths were measured on pre-treatment lateral cephalograms. Dental crowding and arch length were measured on the pre-treatment dental casts. Intergroup comparisons of effective base length, arch length, and crowding were performed with unpaired t-tests. Correlations between effective base length, arch length, and dental crowding were examined by means of Pearson’s correlation coefficient (P < 0.05). Subjects with clockwise rotation significantly had more mandibular dental crowding and significantly decreased mandibular arch length compared to the anticlockwise group. An inverse correlation was found between maxillary and mandibular effective base length, arch length, and dental crowding while a positive correlation was found between maxillary and mandibular base length and arch length in both the groups. Clockwise rotation of the mandible along with skeletal and dental factors such as decreased effective base lengths and arch length, respectively, constitutes an important factor leading to dental crowding.