The Relationship Between Maxillary and Mandibular Base Lengths and Dental Crowding in Patients with True Class II Malocclusions

INTRODUCTION: Orthodontists, for a long time have considered that occlusion and facial beauty are so interdependent that they must be equal goals of treatment.
AIM: To validate the relationship between maxillary and mandibular effective lengths and dental crowding in patients with Class II malocclusions.
MATERIALS AND METHOD: A sample of 40 orthodontic patients with complete bilateral Class II malocclusions in the permanent dentition (25 males, 15 females) who were divided into two groups based on severity of pre-treatment mandibular anterior dental crowding. The maxillary and mandibular effective lengths and tooth-arch size discrepancies were measured on the pre-treatment Lateral cephalograms and initial casts, respectively. Intergroup comparisons of apical base lengths were assessed with independent t-tests. Correlation between effective length and dental crowding was assessed by Pearson's correlation coefficient (P <.05).
RESULTS: Subjects with Class II malocclusion and moderate to severe crowding had significantly smaller maxillary and mandibular effective lengths compared with subjects without crowding and with minimal dental crowding. A weak inverse correlation was also found between maxillary and mandibular effective lengths and the severity of dental crowding.
CONCLUSION: In patients with complete Class II malocclusion, decreased maxillary and mandibular effective lengths constitute a significant factor associated with dental crowding.