[en] Photo-activated decontamination (PAD) has been reported in caries treatment as an aid in dentine decontamination. The aim of this study is to verify the harmlessness for pulp vitality of photo-activated decontamination (PAD) in caries treatment. Twenty freshly extracted single-rooted teeth were used. Deep class I cavities with a </= 0.5 mm dentine thickness between the floor of the cavity and the roof of cameral pulp were prepared. Following the manufacturer's instructions, cavities were filled with a photo-sensitizer (Phenothiazinechloride: 10 mg /ml), irradiated during 30 s with a 660-nm diode laser (output power: 40 mW in continuous wave; total delivered energy density: 4.87 J/cm(2)). Pulp temperature raises were recorded using a thermocouple (ALCr). Measurements were recorded every second during the irradiation and 150 s afterwards. Six records were repeated for each tooth. After 30 s of irradiation, the mean of temperature rise was 0.83 degrees C +/- 0.22 degrees C. All records showed temperature increases lower than the 3 degrees C (safety level for pulp injury). Based on our in vitro study, we can conclude that the dental pulp temperature rise following the use of PAD technique for the decontamination of dentine can be considered as save procedure for pulp vitality.