Ways of improving endodontics are often being tumbled on the shoulders of dentists. Though, the plane of safety supposes the intactness of
instruments and maintaining the root strength. The plane of convenience concerns the time of cleaning and shaping before canal obturating. The number of the instruments used determines the time that is needed to perform the task. The frequency of their usage influences the cost of the service. In such a way, one plane influences the other plane. In any case, changes in the technique of the procedure increase the quantity of emerging problems during resolving of the initial ones.
GREATER TAPERED ROTATING Ni-Ti ALLOY INSTRUMENTS’ PARADIGM CHALLENGING
The rotation around the curve causes squeezing and straining stresses that lead to tool separation indivisible from rotating Ni-Ti. New Ni-Ti alloys and heat-treated materials are more tolerant to the failure of material caused by the stress from repetitive loads. Torsional stress also matters when the tips of the tool bind apically.
The issue of separation has been challenged by:
- non-linear reciprocation
- crown-down preparations
- newer Ni-Ti alloys
- straight-line access
- single usage files.
Both interrupted and continuous rotations influence the tool and lead to its separation. The practitioner knows about the tool’s separation immediately thankfully to radiograph. Microcracks in the dentine caused by greater tapered rotating Ni-Ti tools cannot be seen clinically. The dentist will be able to find them only years after, when they enlarge and grow in to a vertical fracture.
The greater taper instrumentation and the rotation that drives it bear responsibility for the defects increasing the incident count of vertical root fracture. Complete elimination or reduction of this problem was noticed when hand tools were used. Though, professionals who have increased their skills and reduced hand failure will not be very glad to turn back to K-files from the rotating Ni-Ti.
However, the engine-driven tool does not lead to dentinal defects if the motion amplitude is small. A SAF with motion amplitude of 0.4 mm oscillating at 5,000 cycles per 1 minute does not cause microcracks. A 30/02 relieved stainless steel reamer in a 30° reciprocating hand piece balancing between 3,000 and 4,000 cycles per minute creates a 0.104 mm arc of motion. As you see, 30° reciprocation is safe for both canals and the tools.
Short manual arcs of motion will not lead to tool separation. The rotating Ni-Ti tools cannot be used vigorously the buccolingual plane while the tools with low amplitude of motion allow it. 30° to 45° reciprocation secures the tools and teeth from cyclic fatigue and torsional stresses.
IT’S INSTRUMENT DESIGN AND TECHNIQUE THAT MATTER
The relieved reamer used manually and in a clockwise manner will overpass the full apical length with less resistance than a K-file. The first clockwise move of it takes dentin away from the canal walls and eases the resistance and engagement. 02-tapered modified stainless steel reamers are very flexible and are able to adapt to various curves without distortion. Each instrument creates a well-partitioned way for the next larger tool.
Modified reamers are efficient for creating the glide path without hand fatigue. Using a reciprocating hand piece with 2 more tools can make the system work more vigorously in the buccolingual plane. The new system can extend the buccolingual preparation and embrace the whole tissue area after the apical opening of the canals.