OBJECTIVETo explore a method for classifying root abnormality and to investigate the status of root abnormality in patients with aggressive periodontitis (AgP).

METHODSA total of 108 patients (2841 teeth) with AgP, 41 patients (1135 teeth) with chronic periodontitis (CP) and 30 periodontal healthy subjects (840 teeth) were included in the study. The abnormality of roots was evaluated on a full set of periapical radiographs. A reference parameter of "root width" in the middle of root was introduced in this study for classifying various types of root abnormality. The root abnormality was categorized into five types: cone-root (incisor, premolar), slender-root, curved-root, maladjusted proportion of crown and root, and synergetic root.

RESULTSTo compare with normal incisor root, the parameter of root width in cone-root incisor is much lower [up incisor: (0.04 +/- 0.01) and (0.10 +/- 0.03) cm; low incisor: (0.02 +/- 0.02) and (0.07 +/- 0.02) cm, P < 0.001], and root is shorter with maladjusted proportion of crown. To compare with normal root, the slender-root in low incisor and premolar cone-root, the parameters of root width are also lower [low incisors: (0.02 +/- 0.02) and (0.07 +/- 0.02) cm; up premolar: (0.03 +/- 0.03) and (0.07 +/- 0.01); low premolar: (0.02 +/- 0.01) cm and (0.18 +/- 0.26) cm, P < 0.001]. The number (or percentage) of teeth with root abnormality in AgP group, CP group, and control group was 407 (14.3%), 57 (5.0%), and 31 (3.7%), respectively. Significant differences of percentage of teeth with root abnormality were found among the three groups. AgP group had the highest percentages of teeth with root abnormality, while the control group had the lowest percentage.

CONCLUSIONSThe patients with aggressive periodontitis had more teeth with root abnormality than the patients with chronic periodontitis or healthy subjects. The root abnormality could be a local contributing factor for AgP patients.