The laser is utilized for the removal of the smear layer, cleaning and disinfecting the dental canal. Recently, diode laser has been offered with a wavelength of (635-980nm) for cleaning and disinfecting the dental root canal.
There is not adequate evidence for microcrack formation when using diode lasers with different powers. Therefore, the present study was conducted in order to analyze various powers of a diode laser in microcrack formation in dental root canals.
In this experimental study, 100 mandibular incisor teeth that were extracted because of periodontal disease were selected. Using stereo-microscope, the presence of crack and fracture of the root was evaluated before and after canal instrumentation. Then, samples were randomly divided into 10 groups (10 samples in any group) based on different powers of laser and canal to be humid or dry under laser radiation. The laser was utilized for 10s puls within three iterated times. The samples were cross-sectioned after disinfection with a diode laser at 3 and 6mm length from the dental apex. Sections were observed under a scanning electron microscope and images were taken.
The frequency of microcracks is increased at the distance of (3-6mm) from the dental apex by an increase in laser power level from 2 to 4w (P<0.05). Similarly, results showed that the probability of microcrack formation under dry condition than the humid condition at the distance of 3mm from the dental apex might increase to 6.606 times and at the distance of 6mm from the dental apex increase to 4.978 times more.
The optimal power of diode laser in the wavelength of (980nm) for cleaning and disinfecting of the root canal with the minimum damage on hard periodontium tissue is 1.5w.
Keywords: Dentin, Microcrack, Root canal treatment, Diode Laser, Scanning Electron Microscope, Dental apex.