Influence of rotational speed, torque and operator proficiency on failure of Greater Taper files
Bibliographic record
Abstract
AIM: The purpose of this study was to evaluate the influence of rotational speed. torque, and operator experience on the incidence of locking, deformation, and separation of instruments when using a specific Ni-Ti rotary instrumentation technique in extracted human teeth. METHODOLOGY: Greater Taper Ni-Ti rotary instruments (GT) were used in a crown-down technique. In one group (rotational speed evaluation) of canals (n = 300) speeds of 150, 2 50 and 350 r.p.m. (subgroups 1, 2 and 3) were used. Each one of the subgroups included 100 canals. In a second group (evaluation of torque) (n = 300) torque was set at 20, 30 and 55 Ncm (subgroups 4, 5 and 6). In the third group (evaluation of operator proficiency) (n = 300 three operators with varying experience (subgroups 7, 8 and 9) were also compared. Each subgroup included the use of 10 sets of GT rotary instruments and 100 canals of extracted human molars. Each set of instruments was used in up to 10 canals and sterilized before each case. NaOCl 2.5% was used as an irrigant. The number of locked, deformed, and separated instruments was recorded for each group. Statistical analysis was carried out with pairwise comparisons using Fisher's exact tests for each of the failure type. RESULTS: When the influence of rotational speed was evaluated, instrument deformation and separation did not occur in subgroups 1 (150) r.p.m.), 2 (250 r.p.m.), and 3 (350) r.p.m.). Instrument locking occurred in subgroup 3 only. Statistical analysis demonstrated a significant difference between the 150 and 350 r.p.m. groups and between the 250 and 350 r.p.m. groups with respect to instrument locking. In torque evaluation, neither separation, deformation nor locking occurred during the use of the instruments, at 150 r.p.m., and at the different torque values. When the operators were compared, although two instruments were separated in canals prepared by the least experienced operator. Fisher's exact tests did not demonstrate a significant difference between the three subgroups. Instrument locking, deformation, and separation did not occur with the most experienced operator. None of the instruments separated with the trained operator. CONCLUSIONS: Preclinical training in the use of the GT rotary instruments when used with a crown-down technique at 150 r.p.m. was crucial in avoiding instrument separation and reducing the incidence of instrument locking and deformation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.023 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".