FINISH LINE IN FPD FOR PARTICULAR TEETH

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INTRODUCTION OF THE SONIC HANDPIECE
To overcome these limitations, a sonic handpiece (KOMET SF1LM [KOMET USA]) was developed and introduced. It works with sonic vibrations (less frequent oscillations, approximately 6,000 Hz), but with an equal efficiency thanks to its adapted amplitude of vibrations (< 200 µm, depending on setting). Contrary to ultrasonic instruments, sonic instruments are not driven by an electrical power source. They are air-driven, allowing a sonic handpiece to be used like an ordinary handpiece. It simply attaches to the air tube of the dental turbine. The KOMET SF1LM has a MULTIflex connection. (MULTIflex is a registered trademark of KaVo Dental) The oscillation generated by this type of power source expands in all directions. Therefore, it is not linear; however, it traces an elliptical shape. This has led to the development of an instrument where, when vibrating, every part of its surface is active: the range sonic tips are available for different indications. This enables the sonic tip to be used in every possible angle of inclination. Unlike ultrasonic tips, sonic instruments do not need to be held at a strenuous fixed tilt angle during use. This makes the sonic tips easier to control, even by less experienced users. The vibrations’ lower frequency does not limit the action of the instrument (ie, excellent cutting through dentin at high settings and optimal finishing at low settings), but presents an advantage of creating a roughness of a few microns while smoothing the dentin’s surface. This promotes the retentive properties of the cement, which in these conditions flows perfectly, limiting the formation of undesirable and dangerous voids.
Two sonic tips with different diameters in the shape of a modified chamfer are now available: SF979.000.014 (0.14 mm) and SF979.000.016 (0.16 mm) with 0.64 µm for the positioning of the finishing line and the finer grit version SF8979.000.014 and 016 with 0.25 µm for perfect finishing of the finishing line. The KOMET SF1LM offers 3 settings (different amplitudes). For preparation and finishing of crown margins the KOMET SF1LM should be set to level1