A dentist is bound to make mistakes at one time or another. Dentists are human, just as all doctors are. However, a mistake can place a patient in pain or mean that they are required to return for additional treatments.
As a dentist, it is your responsibility to take care of your patients and do what is best for them. If you have a patient who is upset about the work you've done, it is important to review that work and make sure that there are no errors on your part. Serious errors could result in pain or the loss of bone in a patient's mouth among other issues.
There are a few times when a dentist could face charges. These include when they perform unwarranted treatment, make errors or breach the standard of care accepted by the dental community.
Here's an example. If a dentist tells a patient that they have 10 cavities but the reality is that there are only eight that require treatment, then the patient will feel frustrated if they find at a later time that the dentist performed work that did not need to be done. It is not just money that is a factor in these situations. Even though something like filling a cavity is standard procedure, it is still a surgery and something to be taken seriously.
If you make an error when working on a patient, your best bet to avoid a lawsuit is to do whatever you can to resolve the problem or reverse the damage that has been done. Something like placing a crown incorrectly may be fixable, and your honesty about the mistake may make the patient feel like they're respected and that you are truly apologetic. This simple act could help you prevent a lawsuit and an unhappy patient.