All of his printed material has this saying and pictures of hot air balloons. Hot air ballooning is also his hobby. A logo can also take the graphic form of your last name or practice name. For instance, a Dr. Hart, may have a heart logo or a practice named Applewood Family Dental Center may have an apple logo. Use your imagination.
Some dentists also like to use caricatures of themselves on the business card.
This is fine. As long as you are comfortable with your design and it fits the image of your practice, then it will be right for you. Make sure your logo is easy to read and understand. Far too many logos are filled with lines, pictures and words and no one is quite sure exactly what the picture is supposed to represent. Remember that you logo has to be both increased and decreased in size depending upon where it is being printed.