我知道的例子是成牙受伤，而且也是因为受伤后没有什么症状，过了一段时间才看的牙医，所以下面所说可能并不适用你现在的情况--- 当时牙医根据X-ray显示断面离牙髓很近，怀疑没有痛感也可能是因为牙神经已死。他用极冷的棉球碰触受伤的牙，说如果有感觉就说明牙神经没死。如果牙神经已死，就先要做根管治疗（防止因感染引发abscess），然后做牙冠；如果牙神经没事，门牙是可以补的，不过不是很牢固，不能咬很硬的东西，但是比较美观。你可以先打电话给牙医咨询一下，看是否有必要马上就医。 下面是网上关于牙齿受伤可能引起的问题（dead tooth）的相关信息（https://www.medicalnewstoday.com/articles/319062）： Tooth trauma If there is a physical trauma to the tooth, such as from a sports injury or a fall, then the blood vessels can burst, or the blood supply to the tooth may be cut off. Eventually, because there is no blood flowing to the tooth, the nerve and other living tissues inside the pulp will die. Treatment Early treatment to fix a dead tooth is vital. Even if a person is not feeling pain at first, if they suspect they have a dead tooth they should seek medical advice as it could become extremely painful. An X-ray will often help a dentist diagnose a dead tooth. There are two options for treatment for a dead tooth: extraction or removal root canal 非专业人士，一点个人经验，仅供参考。
It's just baby tooth which will fall off at age 6 or 7.
牙医那里有仪器可以做，好像是用电流，能测试出牙神经死没死
我知道的例子是成牙受伤，而且也是因为受伤后没有什么症状，过了一段时间才看的牙医，所以下面所说可能并不适用你现在的情况---
当时牙医根据X-ray显示断面离牙髓很近，怀疑没有痛感也可能是因为牙神经已死。他用极冷的棉球碰触受伤的牙，说如果有感觉就说明牙神经没死。如果牙神经已死，就先要做根管治疗（防止因感染引发abscess），然后做牙冠；如果牙神经没事，门牙是可以补的，不过不是很牢固，不能咬很硬的东西，但是比较美观。你可以先打电话给牙医咨询一下，看是否有必要马上就医。
下面是网上关于牙齿受伤可能引起的问题（dead tooth）的相关信息（https://www.medicalnewstoday.com/articles/319062）：
Tooth trauma If there is a physical trauma to the tooth, such as from a sports injury or a fall, then the blood vessels can burst, or the blood supply to the tooth may be cut off. Eventually, because there is no blood flowing to the tooth, the nerve and other living tissues inside the pulp will die.
Treatment Early treatment to fix a dead tooth is vital. Even if a person is not feeling pain at first, if they suspect they have a dead tooth they should seek medical advice as it could become extremely painful. An X-ray will often help a dentist diagnose a dead tooth. There are two options for treatment for a dead tooth: extraction or removal root canal
非专业人士，一点个人经验，仅供参考。