Flat-oval root canal preparation with Self-Adjusting File instrument: a micro-CT study
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The document discusses a study that evaluated root canal preparation in flattened root canals of mandibular incisors treated with either rotary instruments or the Self-Adjusting File (SAF) using micro-computed tomography analysis. Forty teeth were instrumented, half with rotary files and half with SAF. The SAF resulted in a more homogeneous preparation of the root canal walls compared to rotary instruments, particularly in the coronal third of the canal where it achieved significantly higher increases in volume and area as well as a higher percentage of prepared walls. The SAF was able to better prepare flattened root canals compared to rotary instrumentation.
Flat-oval root canal preparation with Self-Adjusting File instrument: a micro-CT study
- 1. Thank you very much. It is an honor to be here with you today. I would like to thank SkyScan for this invitation and to the University of São Paulo in the person of Prof. Manoel for the oportunity to be here. 1
- 2. A tooth is basically made up of two parts: the crown and the root. Different tissues make up each tooth. The enamel, the dentin, that supports the enamel, and the pulp that is a soft tissue located within a tooth, in a place called pulp cavity that is divided into root canal and pulp chamber. 2
- 3. Root canal treatment is a dental procedure which is undertaken to treat the infected pulp of a tooth. The ultimate goal of root canal preparation is to remove the inner layer of the dentin while allowing an irrigant solution to reach the entire length of the root canal. 3
- 4. To achieved this goal, different shaping techniques and instruments are available. 4
- 5. In the last 15 years, root canal preparation with rotary instruments has become popular. 5
- 6. Although many technical advances have been made in endodontics, canal preparation is still adversely influenced by the highly variable anatomy, especially in oval, flat, or curved root canals 6
- 7. In flattened canals, rotary files have failed to perform adequate cleaning and shaping leaving untouched fins or recesses on the buccal and/or lingual aspects of the bore created by the instrument. 7
- 8. Recently, The Self-Adjusting File has been devised with the purpose of sidestepping some of the limitations of rotary instruments. 8
- 9. The SAF is a hollow file designed as a compressible pointed cylinder composed of a thin nickel-titanium lattice. During its operation, the file is designed to adapt itself three-dimensionally to the shape of the root canal. 9
- 10. The purpose of this study was to evaluate the root canal preparation in flattened root canals of mandibular incisors treated with either rotary or SAF, using three- dimensional µCT analysis. 10
- 11. Forty single-rooted human mandibular incisor teeth were used. Before experimental procedure, each specimen was vertically positioned on a metal holder in the centre of the stage and scanned in a desktop X-ray microfocus CT scanner SkyScan 1174v2 11
- 12. Then, half of the sample was instrumented using rotary intruments and the other half using Self Adjusting File 12
- 13. Then, all sample was re-scanned using the same initial parameters. 13
- 14. Images were reconstructed from the apex to the level of the cementoenamel junction (NRecon v1.6.1.5; SkyScan) providing axial cross sections of the inner structure of the samples. For each tooth, evaluation was done for the full canal length in approximately 400 slices per specimen 14
- 15. CTAn v1.10.1.0 software (Skyscan) was used for three-dimensional analysis of volume and surface area. Increases of all analyzed parameters were calculated by subtracting the scores for the treated canals from those recorded for the untreated counterparts 15
- 16. OnDemand 3D software (Cybermed Inc., Irvine, CA, USA) was used for the analysis of the fifteen superimposed cross-sections images of each specimen (n=300 per group) regarding the percentage of instrumented and non-instrumented walls. The root canal preparation was classified into two categories: (a) cross-section in which the whole perimeter or almost all perimeter was treated (80% or more of the perimeter treated) and (b) cross-section in which most of the perimeter was untreated (20% or less of the perimeter treated). 16
- 17. OnDemand 3D software (Cybermed Inc., Irvine, CA, USA) was used for the analysis of the fifteen superimposed cross-sections images of each specimen (n=300 per group) regarding the percentage of instrumented and non-instrumented walls. The root canal preparation was classified into two categories: (a) cross-section in which the whole perimeter or almost all perimeter was treated (80% or more of the perimeter treated) and (b) cross-section in which most of the perimeter was untreated (20% or less of the perimeter treated). 17
- 18. OnDemand 3D software (Cybermed Inc., Irvine, CA, USA) was used for the analysis of the fifteen superimposed cross-sections images of each specimen (n=300 per group) regarding the percentage of instrumented and non-instrumented walls. The root canal preparation was classified into two categories: (a) cross-section in which the whole perimeter or almost all perimeter was treated (80% or more of the perimeter treated) and (b) cross-section in which most of the perimeter was untreated (20% or less of the perimeter treated). 18
- 19. CTVol software (Skyscan) was used for three-dimensional visualization and qualitative evaluation of the pre- and post-instrumented canals. Color-coded root canal models (green indicates preoperative, red postoperative canal surfaces) enabled qualitative comparison of the matched root canals before and after shaping. 19
- 20. Despite the mean increase of the canal volume was significantly higher with SAF (1.47 ± 0.67 mm3) than rotary instrumentation (2.32 ± 1.0 mm3) (P = .04), the same was not observed with the surface area (P > .05). Within group, volume and surface area showed significant statistical difference between pre- and postoperative results (P < .05). 20
- 21. The percentage of mechanically untreated canal walls at coronal, middle and apical third, calculated by using superimposed µCT data sets, were 8%, 35%, and 15% for SAF group and 38%, 56%, and 25% for rotary group. There was statistically significant difference between the instrumented and the non-instrumented walls between groups at coronal and middle thirds 21
- 22. Cross sections and tridimensional analysis showed that the use of SAF resulted in a more homogenous preparation of the root canal walls compared to rotary instruments. 22
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- 25. It can be concluded that in the coronal third of the canal, mean increases of area and volume of the root canal, as well as the percentage of prepared walls, were significantly higher with SAF than rotary instrumentation. By using SAF instrument, flat-oval-shaped canals of mandibular incisors were homogenously and circumferentially prepared. 25
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