The evolution and growth of the use of lasers in medicine during the last two decades occurs initially within the disciplines of ophthalmology, dermatology, and general surgery. The advantages of lasers, such as accuracy, reduction of anesthesia, minimized scars, haemostatic effect and bactericidal effect, soon evoke the acceptance of lasers as alternatives to traditional methods in medicine. It also became one of the events that created a great interest in the last decade in the role of lasers in dentistry. The application of lasers on different therapies demands a fully understanding of the characteristics of each specific laser. This paper reviews the development of lasers in dentistry and current literatures regarding hard tissue lasers in non-surgical periodontal therapy. An encouragement of further animal or clinical longitudinal studies is awaken to achieve the requirement of sufficient evidences as the base of scientific dentistry.