Dark lines on the biting surfaces of teeth are usually due to pigmentation, caries, etc. and can be removed by scaling or filling treatments. 1. Cleaning: Eating colorful food or smoking may cause dark lines on the occlusal surfaces of the teeth, which can be removed by ultrasonic cleaning and polishing. 2. Filling treatment: The occlusal surfaces of teeth are susceptible to caries. It is important to note that due to the special structure of the occlusal surfaces of teeth, caries here usually appears as a triangular lesion with a small mouth and a large base, which looks like a black line on the surface, but the internal damage may already be very deep. It is recommended to receive early treatment to remove the decayed material and then fill and restore. There may be other reasons for black lines on the occlusal surfaces of the teeth, which should be treated in a timely manner.