Objective: To study the difference in the cuspal incline angle of normal and cracked teeth by cone beam computer tomography (CBCT)

providing a theoretical basis for the rapid and non-invasive diagnosis of cracked teeth. Methods: According to the case inclusion criteria

22 patients were included in the cracked teeth group (11 maxillary first molars and 11 mandibular first molars) and 44 patients were included in the normal teeth group (22 maximum first molars and 22 mandibular first molars). After 3D reconstruction by CBCT scans

oblique angles of the mesial

buccal

lingual and mesial angles of the maxillary first molars were measured. Results: Oblique angles of the mesial and buccal tongue tips of the maxillary first molars in two groups were 106.70°±7.69°and 119.50°±7.97°

respectively

and of the distal and middle buccal and tongue tips were 109.30°±7.15°and 115.00°±7.48°. Oblique angles of the mesial and buccal tongue tips of the mandibular first molars were 104.40°±6.81°and 117.20°±9.25°

and of the distal and middle buccal and tongue tips were 105.60°±7.78°and 114.70°±8.35°. Oblique angle of the cusp in the cracked tooth group was smaller than that in the normal group (P<0.05). Conclusion: After detecting the oblique angle

it is found that the smaller the angle

the greater possibility of the occurrence of cracked teeth is

which provides a theoretical basis for the early detection of tooth cracks by CBCT.