First, porcelain teeth, due to the unstable chemical properties of metals, their metal ions are released and deposited in the hard tissues of gums or roots adjacent to porcelain teeth, which makes the gums in contact with porcelain teeth black and affects the appearance.

Second, the medical technicians are not skilled, the edge of porcelain teeth is not suitable, they are located above the gums or do not fit the real teeth, and there is a gap between them after being worn on the real teeth. At this time, there will be a series of problems with porcelain teeth, including the black line on the gums. This is the main cause of gingival black line. It's not the material, but the doctor's skill and attitude.

Thirdly, the metal layer inside the porcelain tooth is opaque, and when the light is refracted inside the porcelain tooth, it can't reach the neck of the porcelain tooth well, so the part of the porcelain tooth in contact with the gum is darker than other parts. This situation is a common problem of all metal porcelain teeth. All-ceramic teeth do not have this problem because there is no opaque metal layer.

5. If unqualified porcelain teeth are prepared, and the porcelain teeth are not close to the real teeth, no matter what kind of metal is used, gingival black lines may appear, including precious metal porcelain teeth (gold porcelain teeth).

6. If the producer of porcelain teeth has high technical level and standardized technology, the probability of gingival edge blackening of base metal porcelain teeth can be greatly reduced. If the quality of the porcelain teeth is poor, no matter what the porcelain teeth are, gum problems such as blackening, inflammation, redness and pain may occur.

The main causes of gingival blackening caused by porcelain teeth are as follows:

First, porcelain teeth, due to the unstable chemical properties of metals, their metal ions are released and deposited in the hard tissues of gums or roots adjacent to porcelain teeth, which makes the gums in contact with porcelain teeth black and affects the appearance.

Second, the medical technicians are not skilled, the edge of porcelain teeth is not suitable, they are located above the gums or do not fit the real teeth, and there is a gap between them after being worn on the real teeth. At this time, there will be a series of problems with porcelain teeth, including the black line on the gums. This is the main cause of gingival black line. It's not the material, but the doctor's skill and attitude.

Thirdly, the metal layer inside the porcelain tooth is opaque, and when the light is refracted inside the porcelain tooth, it can't reach the neck of the porcelain tooth well, so the part of the porcelain tooth in contact with the gum is darker than other parts. This situation is a common problem of all metal porcelain teeth. All-ceramic teeth do not have this problem because there is no opaque metal layer.

5. If unqualified porcelain teeth are prepared, and the porcelain teeth are not close to the real teeth, no matter what kind of metal is used, gingival black lines may appear, including precious metal porcelain teeth (gold porcelain teeth).

6. If the producer of porcelain teeth has high technical level and standardized technology, the probability of gingival edge blackening of base metal porcelain teeth can be greatly reduced. If the quality of the porcelain teeth is poor, no matter what the porcelain teeth are, gum problems such as blackening, inflammation, redness and pain may occur.