When you answer this question, be sure to remain positive, even if the experience wasn't. Avoid talking about any previous drama and do not speak poorly of your employer. Keep your answer short and respectful. The interviewer is asking you this question to learn more about your professional relationships. As a Dental Laboratory Technician, you work closely with the dentist to determine the need, requirements, and design of each item.
If you had a good relationship with your previous boss: "I have a great working relationship with my current dentist. He values my opinion and respects my work. We bounce ideas off of each other regularly to come up with the best prosthetic for the patient."
If you did not have a good relationship with your previous boss: "I have had healthier relationships in the past with previous employers, but we did the best that we could. Our communication styles were very different which made it challenging at times."