Age Group Subjects (30) Mean Chronologic Age ± SD Mean Estimated Age by Indian Formula ± SD Mean Estimated Age by Demirjian Formula ± SD Difference in Estimated Age and Chronological Age by Indian Formula Difference in Estimated Age and Chronological Age by Demirjian Formula
10.1–15 10 13.20±0.815 14.31±1.25 12.66±0.692 1.10±1.106 –0.55±0.672
15.1–20 18 17.12±0.527 17.56±1.41 14.54±0.836 0.44±0.987 –2.58±0.987
20.1–25 1 20.25 19.07 15.26 –1.18 –4.99
25.1–30 1 26.17 19.44 16.33 –6.73 –9.84
P value   <0.0001 <0.0001 <0.0001 <0.0001
Table 2: Comparison between chronological age and estimated age derived by Indian formula and Demirjian's formula in the orthodontic group.