Why are white lines appearing between the resin and the tooth structure?

Issues with white lines:

1.The inclined surface after preparation was not polished with a silicone point.

2.Blind areas exist in edge etching and bonding.

3.Poor fit between resin and tooth structure.

4.Excessive shrinkage leading to edge bonding edge tearing.

5.Immediate polishing after filling and incorrect polishing direction.

6.Sharp edges. Insufficient rounding of internal line angles (posterior teeth).

Essentially, it is due to adhesive failure between the resin and the tooth structure at the boundary!”