Association of ABO blood group with crowding among patients with different malocclusions

Introduction: This study correlated ABO blood groups and crowding in the lower anterior region and also to find an interrelationship between ABO blood grouping system and sagittal relation of the jaws. Materials and Methods: The sample size consisted of 138 Maharashtrian patients (60 males and 78 females) age range from 12 to 30 years which were randomly selected. Each patient's records comprised: a lateral cephalometric head film, photographs, and dental casts as standard pretreatment records. Based on ANB angles, patients were divided into Group-1: ANB 1–3° (51 individuals with 27 males and 24 females), Group-2: ANB >3° (60 individuals with 24 males and 36 females), and Group-3: ANB Results: The mean ± standard deviation of age in Group 1, Group 2, and Group 3 was 16.53 ± 2.43 years, 17.60 ± 3.73 years, and 18.67 ± 3.28 years, respectively. The gender distribution of cases studied did not differ significantly across three study groups. The distribution of median ANB did not differ significantly across various blood groups in the study group. The blood group distribution of cases studied did not differ significantly across three study groups. The distribution of Little's index differs significantly across perfect alignment and minimal irregularity as well as between minimal irregularity and moderate irregularity. The distribution of Little's index did not differ significantly between perfect alignment and moderate irregularity. Conclusions: The occurrence of blood group B+ was more in Class I and II skeletal patterns whereas in Class III skeletal pattern individuals have more prevalence of blood group A+. ABO blood groups and Little's Irregularity Index for crowding is found to be correlated between perfect alignment and minimal irregularity individuals as well as between minimal and moderate irregularity subjects.