The demand for an acceptable appearance, including a natural and attractive smile, has nowadays a great effect on clinical practice. More patients than ever are requesting various types of cosmetic dentistry in order to improve their smile. The clinical practitioner has to deal with discolorations, particularly in the anterior region of the mouth. The most severe of these problems are caused by administration of tetracycline or other medicine during the period of mineralization. The usual treatment of these cases includes full crown restorations and more recently, direct or indirect veneers (porcelain or composite-resin veneers). As an alternative, the various techniques of bleaching consist the most conservative of all above treatments. For many year, their application gives effective solutions in many cases. This article describes both clinical and laboratory procedures of a new technique for bleaching discolored vital teeth. This technique uses a warming device to apply controlled heat to the bleaching solution which is placed on both labial and lingual surfaces of the teeth to be bleached. Special thermotrays are used for the placement of the solution according to the specifications of the manufacturer. This paper presents a preliminary study of the advantages and disadvantages of this bleaching method and gives an evaluation of the results from several clinical cases.