The right answer to this open question is the following.
Ethics and etiquette affect your healthcare career in that they help you to project the confidence and the right public image that makes you a friendly and accessible professional.
Your patients need to trust the medical doctor or the dentist, or whatever healthcare profession you practice. Ir rapport and trust is not established, the relationship won't last. Since the very beginning, you need to be an educated doctor, introduce yourself properly using etiquette to create a great impact. Be open and amicable. Be discrete. Never talk about your patients in a social environment. They are trusting you. That is a big part of Ethics in the profession. Communicate with your patients openly and frankly, showing compassion and respect.