Cutting ability of a KiS 2D tip with varying powers and loads

Aim To correlate the vibrations of a retro tip under a range of loads and generator powers with its cutting ability. Methodology A scanning laser vibrometer was used to measure the maximum vibration displacement amplitude of a KiS 2D tip (Obtura Spartan, USA) under loads of 10–50 g (10 g increments). Loads were applied by contacting the tip against a polished root dentine surface (1200 grit) and were measured using a load cell (RDP Electronics, UK). A calibrated scale was placed over the power dial of the generator (Piezon Master 400; EMS, Switzerland) which enabled incremental power settings (1–5) to be selected between minimum and quarter power of the total generator output. Ten repeat scans were made for each load and generator power combination. The retro tip was then used to create cavities in polished dentine surfaces. The tip was operated using the same experimental conditions as described above (five power settings, 10–50 g loads). For each condition, the tip was contacted against surfaces for 5 s and used to make 10 repeat cavities. Cavities were scanned with a 3D laser profilometer (TaiCaan, UK), enabling the maximum width and length of the cavity to be measured. The same generator and handpiece were used throughout the experiment. Results Load significantly reduced tip vibration displacement amplitude at 30–50 g (P