QED
Fig 5
Silver point removed from the 12 with ultrasonic energy combined with R25 instrument
Continued »
an engine driven, Nickel Titanium (NiTi) instrument into a root canal without first investigating and negotiating it with a hand instrument. The Reciproc system was designed by Ghassan Yared to be safe and effective, regard- less of the experience of the operator. It uses a recipro- cating motor that mimics the ‘watch-winding’ or balanced- force movements we often use with small instruments. Rotary instruments tend to fracture when they bind and the motor keeps turning them until they break. The Reciproc instrument
works by binding, but then unwinding and cutting so the torsional stress limit is not exceeded. Once introduced into the canal the instru- ment will follow the line of least resistance – the empty canal – and its shape keeps it centred in the canal. Three light pecks at a time between cleaning the flutes of cut
72 Scottish Dental magazine
debris will allow the instru- ment to advance, usually, in time, to the apex. Where the canal is tight
or has an abrupt curvature and the Reciproc instrument does not advance then a small hand file can be used to create a glide path – occasionally the preparation needs to be finished by hand. After assessing the restor-
ability of a tooth to be re-treated the next step is to identify all the anatomy. Usually canals will be obtu- rated with gutta percha (GP) and this needs to be removed to enable thorough cleansing. I prefer to do this mechani- cally if possible (Figure 1). Dissolving GP with a suitable solvent is another method and sometimes this is neces- sary if the GP is age hardened. I find this often leaves a
residue of liquid GP which gets into the corners and is really tricky to remove. As GP is softer than the surrounding root dentine the Reciproc instrument will follow this
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