If there is a black line in the fossa, but no hole, an oral radiograph should be taken before treatment. If the area of the black line is hard and does not produce a roughness when the probe is outlined, you can continue to observe it by paying attention to your oral hygiene. If the X-ray shows low-density shadows in the fossa, it can be grinded along the black line, and when a flask-shaped cavity is found to occur at the bottom, the decayed tooth tissue should be completely removed, the cavity should be filled with glass ionomer cementum and composite resin, and resin or all-ceramic inlay restoration can be fabricated as well. At the same time, attention should be paid to strengthening the cleaning of the maxillofacial fossa and fissure to avoid the retention of food debris and soft scale.