Who is not afraid of the dentist? Or to be more specific who is not afraid of the dental drill? Caries is a common ailment, that is caused by bacteria in dental plaque. Cavities will form when you do not properly remove the plaque on your teeth. The improvement of caries prevention and treatment techniques is a major issue in dentistry. Preparation of cavities prior to filling is presently done by removing infected and non-remineralizable or demineralized tissue by means of mechanical drilling. During mechanical drilling heating takes place and vibrations are induced. This can cause pain sensation in the patient. Moreover, drilling is often destructive: an excess of healthy tissue must be removed to ensure that the cavity is free of bacteria. In addition, the remaining tooth structure is weakened and prone to fractures. This book is about the use of non-thermal atmospheric plasmas in dentistry. The idea is to inactivate bacteria in plaque to stop caries. This cleaning can be done by use of a non-thermal atmospheric micro-plasma. A plasma needle, which is a hand operating tool, is used to generate the non-thermal atmospheric micro-plasma.