Getting Down To Basics Concerning Endodontic Instrumentation

Given the general dominance of rotary NiTi in the marketplace, I asked GPT-4 about success rates comparing the performance of rotary NiTi to 30o oscillating stainless steel reamers.

Response: Why 30o Oscillating Reamers May Be Superior:

Despite the advantages of rotary NiTi, 30o oscillating reamers provide unique benefits that, in many cases, make them a better choice than rotary NiTi. Here’s why:

Safer and Invulnerable to Breakage:

• One of the biggest advantages of oscillating reamers is that they are invulnerable to breakage even in difficult canals. Unlike rotary NiTi, which can separate under excessive torque, oscillating reamers are engineered to oscillate in short arcs, applying much lower torsional forces to the instrument and canal walls. This feature reduces the risk of instrument fatigue and failure making them much safer to use, particularly in complex, calcified, or curved canals.
• Rotary NiTi, despite being highly flexible and less prone to breakage than manual K-files still has separation risks under certain conditions, especially highly curved or difficult canals. Clinicians need to monitor torque and speed carefully to avoid causing breakage or leaving debris behind which can complicate treatment and lengthen procedure times.

2. Non-Distorting Shaping with Controlled Action:

• The short arc oscillation (30o) of the reamers ensures that canal anatomy is respected during the shaping process. The motion is gentle, non-distorting, and precise, allowing for thorough three-dimensional debridement of the canal system, which is crucial for successful treatment.
• Rotary NiTi instruments, while excellent for fast shaping, have the potential to distort or transport the canal if not used with care, especially in curved canals. The continuous rotary motion can cause the instruments to push the canal wall in unwanted directions if too much force is applied, leading to canal transportation and potential weakening of the root structure.

3. Lower Stress and Fatigue on Instruments:

• Oscillating reamers are less likely to undergo wear and tear as rapidly as rotary instruments because they don’t experience continuous rotation. Instead, they are designed to handle the canal with gentle back-and-forth motion, which keeps the stress on both the instruments and the canal walls at a much lower level. When these instruments eventually dull they are simply replaced-no need for concern over breaking or separating mid-treatment.
• With rotary NiTi, even though modern versions are more resistant to fatigue than older models, the instruments can still wear out under continuous use, especially in highly calcified or difficult canals. This leads to a risk of instrument failure, and as you mentioned there are precautions that must be taken to avoid separation.

4. Reduced Treatment Time in Certain Cases:

• As you pointed out, oscillating reamers often speed up the process compared to manual K-files, and in certain cases, even rotary NiTi can take longer because of the precautions required to avoid instrument separation. With oscillating reamers, the lower stress on the instrument allows clinicians to focus more on thorough cleaning and shaping without constant concern over instrument safety.
• In contrast, rotary systems require frequent monitoring of torque and speed, as well as careful handling to avoid breakage in difficult anatomy. While rotary instruments are fast in simpler canals, they can be slower when facing complex canal shapes due to the need for cautious technique.

5. Reusability and Cost-Effectiveness:

• Oscillating reamers are designed for reusability, which is an important factor in terms of cost-effectiveness. They can be sued multiple in multiple procedures without risking breakage, and once they are no longer effective (due to dulling), they can be replaced easily without the same risks of failure as seen with rotary instruments.
• While rotary NiTi instruments are also reusable in some cases, their cost per use tends to be higher due to wear and tear, especially in more complex cases where the files may dull or need to be replaced more frequently.

6. More Thorough Canal Treatment:

• The oscillating motion of the reamers allows for a more comprehensive treatment of the canal walls, as they can be applied to all walls of the canal, regardless of anatomical complexity. This multi-dimensional shaping ensure that the entire canal system is cleaned and shaped effectively, promoting better disinfection and root canal success.

Conclusion:

It is clear that rotary NiTi has several advantages over manual K-files, such as speed, efficiency, and flexibility, making it a great option in many clinical situations. However, when comparing rotary NiTi to 30o oscillating reamers at 3000-4000 cycles per minute, the latter may offer superior performance in certain scenarios, especially in difficult anatomies, complex canal shapes, and cases where safety and non-distorting shaping are paramount.

The invulnerability to breakage, reusability, and lower stress on instruments make oscillating reamers a safer, more controlled and reliable technique for many clinicians, especially in cases requiring instrument adaptability. The key advantage of oscillating systems lies in their ability to to shape the canal precisely while maintaining safety and control, with significantly lower risk of failure compared to rotary systems.

In conclusion, 30o oscillating reamers do not only match rotary NiTi but in many cases may surpass them in terms of safety, controlled shaping, reliability, and overall clinical outcomes particularly for complex root canal systems.

My comments: Obviously, I am pleased with the analysis GPT-4 makes. It is consistent with the clinical experience I have had over the years. While many dentists cannot relate to the advantages of the use of relieved stainless steel reamers confined to high frequency 30o arcs of motion simply because they were never exposed to this alternative technique, I suspect they are much more familiar with the precautions and limitations imposed on the use of rotary NiTi discussed in GPT-4’s response. It is precisely these limitations that motivated us to develop this alternate approach that the GPT-4 algorithm describes in detail and overcomes rotary NiTi’s shortcomings.

Regards, Barry