Strains in the implant collars supporting a cantilevered cross‐arch bar prosthesis. An in vitro study
Bibliographic record
Abstract
PURPOSE: To examine the strains in the collar area of implants supporting a cantilevered cross-arch bar prosthesis during vertical load application. MATERIALS AND METHODS: A milled cross-arch metal framework supported by four implants in a trapezoidal design was supported in polymethylmethacrylate. T-strain gage rosettes were attached to the crestal areas of the implants with two grids, one recording circumference strain of the crestal area of the implant and the second recording vertical strain, torquing strains of the implant. The framework was subject to vertical loading from an MTS 810 mechanical system. Loading sites were directly on anterior and posterior implants, and on a cantilever at 7.5, 15, 22.5, and 30 mm (0.5, 1.0, 1.5, and 2.0 of the anterior-posterior spread) distal from the posterior implant on the right side. The anterior-posterior (A-P) spread from anterior to posterior implants was 15 mm. Sites were loaded individually with 50 and 100 N. The data from the rosettes were transferred to a desktop computer and processed using StrainSmart 5000 software. RESULTS: Means and standard deviations were calculated for the 10 trials at each of the loading sites. Two-way ANOVAs were done separately for each dependent variable, the vertical grid, and the circumferential grid. The independent variables were the load magnitude and the load site. Tukey's test was used to compare groups post hoc. When directly loading the implants, loading the anterior implant resulted initially in compression followed by increasing tensile strain with 100 N loads. Loading the implant adjacent to cantilever (the posterior implant) resulted in greater strain at the collar than that observed with anterior implant with minimal bending strains. When loading the cantilever, anterior implant showed increasing bending strain at greater cantilever length, whereas the circumferential strains were greater for the supporting implant adjacent to the cantilever, particularly at 100 N loads, p ≤ 0.001. CONCLUSIONS: Limiting cantilever lengths to A-P spread ratios of 0.5 are preferred. Ratios greater than 1.0 should be avoided as flexing of the collar may occur. The dimensions of the implant, particularly wall thickness, adjacent to the cantilever should be carefully considered when planning the cantilevered implant-supported prosthesis.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".