Laser therapy has become one of the gold standards of treatment in routine dentistry. In the 1970s, CO2 lasers were the first lasers to be used in oral surgery on soft tissues. Subsequently, other lasers (Diode, Nd YAG, Er: YAG, Argon and Erbium) have also been used in periodontics, implantology, orthodontics and restorative dentistry, as well as for hard tissues, such as bone, enamel and dentin. The purpose of this systematic review is to analyze both the therapeutic properties and adverse effects of laser use in dentistry, related to a non-targeted choice of medical device based on clinical need as well as an inadequate learning curve. A systematic review was performed following the PRISMA guidelines using Pubmed, Scopus and Web of Science. The use of lasers requires a specific learning curve modifying the standard surgical approach. The use of lasers provides multiple therapeutic benefits but can lead to some failures in dental treatments. In restorative dentistry, it has been found that lasers can cause cracks that can lead to fractures and/or affect the composite restoration. In periodontal treatments, the use of lasers can produce thermal damage to pulp tissue. In surgical treatments, the use of a laser caused bleeding, post-operative pain and a burning sensation. The failure of tissue cooling during laser beam emission could produce the necrosis of hard and soft tissues.
