Have you ever had a dental instrument break inside a tooth during a dental visit (commonly known as a “broken pin”)? Did you feel scared, fearful, or even sleepless, or even want to file a lawsuit because of it? Let’s talk about why instruments break in teeth and how to deal with them after they break, in the hope of dispelling your doubts and relieving your worries. First, let’s look at how broken pins happen. When a tooth needs to be killed because of endodontic disease, the tooth must be treated with a root canal, which is a more complex treatment in which the doctor uses a variety of dental instruments, either straight, curved, spiral, or barbed. These instruments are used to remove the nerve, enlarge and shape the root canal and fill the canal with medication. However, these instruments can fracture if they are subjected to high resistance or excessive torque. The root canal system of teeth is complex and variable, with some root canals being small and narrow, some having abnormal curvature, some being blocked by calcification or having uneven surfaces, which are often difficult to detect from the tooth surface or radiographs, thus increasing the complexity and risk of treatment. In recent years, mechanical root canal preparation instruments have been gradually used in clinical treatment, such as nickel-titanium root canal preparation systems, which are more efficient and effective than manual instruments, improving the quality of care and shortening the clinical treatment time, making them a new technology in root canal treatment. However, the fast speed and high cutting force of the instruments can also cause fracture when they encounter high resistance in the root canal. In addition, pain, fear, and tension during the treatment process cause the patient to dodge, which is more likely to cause the instrument to break in the root canal. Therefore, broken root canal instruments are one of the common complications during root canal treatment, and the presence of a broken needle is not considered “medical malpractice”. What should I do in case of a broken instrument in the tooth? When a broken instrument is found during treatment, an x-ray should be taken to determine the location of the broken pin, the length of the broken pin and its anatomical relationship to the surrounding tissue. If the broken pin is superficial, it can be removed and will not affect the next step of treatment or the prognosis of the affected tooth. Sometimes, if the broken needle is too deep or broken at the bend of the root canal, it is more time-consuming and difficult to remove, and may even destroy the original morphology of the root canal. Now, with the application of root canal microscope, doctors can observe the root canal more clearly and can even see where the broken needle is located, thus greatly improving the success rate of broken needle removal. Our endodontic department has done a lot of research work and accumulated rich clinical experience in the removal of broken instruments in root canals, and most of the broken instruments in root canals can be removed. However, the broken pin cannot be removed because it occurs in the part of the root canal that is too curved. Because the majority of broken instruments occur in the root canal and do not extend beyond the root, and are unlikely to enter the bloodstream (the root is surrounded by dense bone tissue, not vascular tissue) and flow to other parts of the body, it is not necessary to worry about the broken needle causing disease in other parts of the body. If the broken needle has been pushed out of the root, it can only be removed surgically. In addition, the instruments for root canal treatment are sterilized at high temperature, so the instruments themselves will not cause inflammation of the root tip. If there is inflammation in the root, or if the tooth still has inflammation that is difficult to eliminate after a period of treatment, then apical surgery can be considered to close the apical hole and eliminate the infection, and the inflammation of the root tip can be healed after these treatments. Clinically, it is rare to see a tooth extracted due to a broken pin, but this is often due to a combination of other diseases of the tooth itself, such as periodontal disease, root fracture, etc.