Introduction: The main purpose of the present study was to describe the ultra structural changes which happened after treatment of the root surfaces with ultrasonic and hand devices followed by Er:YAG laser irradiation.

Methods: Sixty single-rooted maxillary and mandibular teeth which had been extracted due to periodontal problems were collected. Crown and apical parts of the root were cut off using a diamond bur. The specimens were mounted on an acrylic resin in order to make a plain surface of the root accessible. The samples were assigned as following: group1: samples were root planed using conventional hand curette, group2: were prepared by ultrasonic device, group3: roots after scaling by hand instrumentation were treated by Er:YAG laser with 50 mJ/pulse and frequency of 10 Hz, group4: roots were prepared by ultrasonic scaler and consequently were treated by laser. Furthermore, the teeth were dried, sputter-coated with gold, and monitored with scanning electron microscope (SEM).

Results: Photomicrographs from ten samples of root surfaces which were taken at magnifications up to 500X revealed that there were not any severe morphologic changes, such as melting and charring, in any group. However, the samples treated by laser irradiation showed more irregularities and distortions.

Conclusion: Er:YAG laser setting at 50mj/pulse, as an adjunctive to traditional scaling and root planning, did not induce severe damages to root surfaces, although root surface irregularities were more pronounced in laser treated groups compare to hand instruments.

Keywords: Er YAG lasers; root surface; scanning electron microscopy.