One horror story is when a patient felt an extreme pain during a root canal because the dental instrument slipped and hit a nerve. It was excruciating and the pain lasted for days after the procedure.
I've heard of a situation where a dental instrument broke off inside a patient's mouth during a filling. The dentist had to struggle to remove it, causing a lot of panic for the patient. The patient was left with a feeling of dread about future dental procedures and had to constantly worry about any potential complications from the incident.
There was a case where a dentist used a rusty dental instrument. The patient got an infection in their gum that spread and caused a lot of swelling and discomfort. They had to take strong antibiotics for weeks to clear it up. This was really a horror story as it could have been much worse and affected the overall dental health permanently.