Improving reliability of permanent tooth staging for dental age estimation using the crown-root ratio method

Root staging for dental age estimation is subjective when no standard reference is available. This study developed a quantitative approach for Moorrees root stages (R1/4, R1/2, R3/4 and Rc) using crown-root ratio (CRR) measurements and stage-specific bounds.

The development phase included 269 Malaysian subjects (145 males, 124 females) aged 16-25 years. A total of 1,502 mature permanent mandibular left teeth (I1-M3) were measured on panoramic radiographs using ImageJ software to determine mean CRR values for mature roots (Rc), the fraction stages and stage-specific bounds, where [Formula: see text], [Formula: see text], and lower bound=succeeding stage CRR + 0.01. Sex differences were analysed using independent t-tests. Validation used 161 additional radiographs (78 males, 83 females) aged 3-24 years, with 774 developing and mature permanent mandibular left teeth measured and independently staged according to Moorrees' method. Measured CRR values were compared with stage-specific bounds and considered accurate when within the expected range. Accuracy was calculated as: [Formula: see text].

Mean CRR values ranged from 0.50 to 0.82, with M3 showing the greatest variability. Significant sex differences were observed for C, P1, M1 and M2 (p < 0.05). Overall staging accuracy was 89.9% (84.6%-95.7%) and declined progressively from R1/4 to Rc. M3 (95.7%) and C (91.3%) showed the highest accuracy, whereas I1 (85.7%) and M1 (88.0%) showed the lowest.

The CRR method provides an objective approach for defining Moorrees root stages and improving staging consistency.