Objective: To compare the efficacy of root canal cleanliness with and without Nd:YAP laser and to assess the effect of the laser on the mineral content of the dentin. Background Data: A high degree of cleanliness of the canal when using Nd:YAG laser has been shown while the laser had been in contact with the canal wall. A new Nd:YAP laser has been studied recently, which is considered to be superior to Nd:YAG with regard to antibactericidal ability due to its 1.34-μ wavelength, which is in the infra red range. This wavelength is absorbed better in water that of Nd:YAG. Materials and Methods: Fourteen extracted single rooted premplars were divided into two groups. In group 1, canals were cleaned, instrumented and shaped with K files. In group 2, initial preparation was done using K files and completed with a Nd:YAP laser. Teeth were then split longitudinally and submitted to SEM. Results: The cleanliness of the laser treated teeth was significantly greater than teeth treated with K files alone (p < 0.05). No difference in Ca and P content was detected when the use of K files was compared to the use of laser. Conclusions: It appears that Nd:YAP laser improves the cleanliness of the root canal. However, since Nd:YAP laser serves as an addition to K files, its clinical value for replacing conventional root canal instrumentation remains to be determined.