Hello, I can understand your concern and think of two possibilities for the greyish line you have described on the front teeth. Firstly, if you took iron supplements during pregnancy or after childbirth, it may have entered the child s bloodstream in uterus or through breast milk. The front teeth are developing in the uterus and matures in bone during initial months after birth, which may cause development of such lines. However, if this was the case, the line should have been present when the tooth erupted into oral cavity. As she has history of falling, it is quite a possibility that she may have damaged her front teeth. The teeth may not break or crack but the pulp inside the tooth may have died making the tooth appear dark. Invariably, this pulp would be infected and should be treated as the tooth is going to stay in oral cavity till your daughter ages 8-9 years. If this is the case, then she might need to go for pulpectomy procedure for the affected teeth. One more possibility is presence of plaque on the teeth due to inadequate oral hygiene and lack of proper toothbrushing. This can be removed by ultrasonic scaling procedure performed by the dentist In any case, I would recommend you to visit a dentist for examination of the line as confirmed diagnosis can be made only after physically looking at the teeth and the line you have described. If it is developmental, then no treatment is needed and it will be gone with the milk tooth shedding. In case of any other reason, treatment will be required as described. I hope this information helps you. Thank you for choosing HealthcareMagic. Take care. Best, Dr. Viraj Shah