Life Science Journal 2013;10(1) http://www.lifesciencesite.com 989 Evaluation of Different Resharpening Techniques on the Working Edges of Periodontal Scalers: A Scanning Electron Microscopic Study Hani EL Nahass and Gihane Gharib Madkour Department of Oral Medicine, Diagnosis and Periodontology, Faculty of Oral and Dental Medicine, Cairo University, Egypt Nahass77@gmail.com ; GihaneMadkour@gmail.com Abstract: Scaling and root planning contribute to the recovery of periodontal health. All periodontal instruments lose their fine cutting angle after use. To maintain this angle, correct sharpening is required using specifically designed stones. The characteristics of sharpening stones and the sharpening technique will be reflected upon the blade of the instruments. Therefore, the purpose of this study was to evaluate three different sharpening stones and two different sharpening techniques by scanning electron microscope (SEM). Material and Methods: Twenty hygienist scaler (Healthco ® ) H6/7 were randomly selected and divided into five groups. Each group consisted of four double-ended scalers with eight working edges. Scalers were examined as received from the factory (group Ι), after dulling (group ΙΙ) and then after resharpening with either one of three sharpening stones; Arkansas (Hu Friedy ® ) (group ΙΙΙ), India (Hu Friedy ® ) (group ΙV) and ceramic stone on power driven sharpener (Hu Friedy Side Kicks ® ) (group V). The scalers were separated from their stems and photomicrographs of experimental areas were obtained with a SEM (Jeol JXA- 840A, JEOL, Ltd®, Tokyo, Japan). The photomicrographs were then evaluated to obtain the data. Results and Conclusions: The instruments sharpened by the manufacturer showed bevels and wire edges indicating the need for every new instrument to be sharpened. Moreover, hand sharpening performed using Arkansas stone (fine grit) produced the best cutting edge followed by India stone (medium grit). Furthermore, power driven device showed the worst results with irregular cutting edges and bevels. We concluded that Arkansas and India stones may be indicated for the routine sharpening of the instruments that are partly dull. [Hani EL Nahass and Gihane Gharib Madkour. Evaluation of Different Resharpening Techniques on the Working Edges of Periodontal Scalers: A Scanning Electron Microscopic Study. Life Sci J 2013;10(1):989-993] (ISSN:1097-8135). http://www.lifesciencesite.com .153 Key Words: Scanning electron microscopy, scaling, dental instruments, power driven sharpening device, sharpening stones. 1. Introduction: Treatment of periodontal disease has been traditionally directed toward removal of deposits which are the principal cause of the disease (1). Scaling and root planning (SRP) is considered the most important phase of periodontal therapy (2), thus it has been postulated that high quality cutting edges of periodontal instruments are essential for effective scaling (3-5).Sharp scalers become dull after a few strokes and require frequent resharpening. The edge quality of a scaler is determined by the angle between the two edge forming contiguous surfaces by edges smoothness, by edges sharpness or dullness, and by the presence or absence of metallic projections (wire edges).Wire edges can be classified as functional or non-functional. Functional wire edges extend in the same direction of the cutting stroke while the non- functional wire edges are perpendicular to the cutting stroke (6, 7). Various types of resharpening stones are available. The fine abrasiveness or grit of a natural stone, such as an Arkansas stone, allows a smooth surface and a linear cutting edge. Arkansas stone is usually recommended for sharpening as it is reputed to produce a better working edge, a smoother surface with a more linear cutting edge (8).On the other hand, Synthetic stones are reported to cause unnecessary metal removal, rough surfaces and wire edges (9).Therefore, it is important to know sharpening techniques, as well as the type of stone that offers more advantages in terms of cutting angle fineness. The development of a more objective description of a good cutting edge was achieved with the aid of scanning electron microscopy (SEM) (10). The purpose of the present study was to evaluate, by SEM, and compare the quality of the cutting edge of periodontal scalers resharpened by different methods. 2. Material and Methods: Twenty new double-ended hygienist scalers (Healthco ®) H6/7 containing forty stainless steel working edges were randomly selected. Four scalers with eight working edges were examined as received from the factory and were taken as control group (group Ι). The remaining sixteen scalers with thirty- two working edges were subjected to dulling. Dullness was obtained by scaling a rod containing aluminum oxide (200 μm) for 5 strokes to ensure consistency; the rod was marked to ensure a consistent dulling stroke