Comparison of the fracture toughness, flexural strength, and flexural modulus of nine restorative materials over five time intervals
Bibliographic record
Abstract
The aims of this study were: 1) to determine the effect of time on the fracture toughness (K[sub iC]), flexural strength (ϭf), and flexural modulus (E[sub f]) of six groups of direct restorative materials including amalgam; and 2) to compare the selected properties of the materials at each time. The null hypotheses tested were: 1) there is no difference between the 1-hour, 1-day, 7-day, 30-day, and 90-day values of each of the K[sub iC], cjf, and E[sub f] for each of the selected materials, and 2) there is no difference between the selected materials with respect to each of their mechanical properties tested at each time. The materials selected for this study were KetacFil (KF, ESPE) - a conventional glass-inomer cement (GIC); PhotacFil (PF; ESPE) - a resin-modified glass ionomer cement (RMGIC); Dyract (Dentsply) and F2000 (3M) - polyacid-modified composite resins (PAMCR) or "compomers"; Z100 (3M) -a hybrid composite resin; Heliomolar (H; Vivadent) - a microfil composite resin; SureFil (SF; Dentsply) and Prodigy Condensable (PC; Kerr) "packable" composite resins; and Valiant PHD XT (V; Ivoclar) - a phase dispersed unicompositional amalgam. Twelve notchless triangular prisms (NTP) (6x6x6x12 mm) and twelve rectangular bars (2x2x25 mm) were made for each test at each time following manufacturers' instructions, and stored in distilled water at 37° C for the duration of the five time intervals before testing. For the K[sub iC] test, the samples were placed in a specimen holder and loaded in tension at a crosshead speed of 0.1 mm/min. The maximum load recorded before crack arrest or complete failure was used to calculate K[sub iC] in MPa*ml/2. The bars were loaded in a three point bending mode and the maximum load recorded at failure was used to calculate df. The modulus was determined from the straight portion of the stress/strain curve. The results were analyzed using a one way ANOVA followed byy Scheffe multiple means comparisons (α=0.05). Based on the limitations of this study and representative materials the results indicate that GICs are the weakest materials and are inferior to RMGIC especially in the short term. RMGICs and PAMCRs are comparable, while both are inferior to CRs and PCRs. PCRs do not show any significant improvement over conventional CRs. Amalgam has the best intrinsic properties over time. The intrinsic properties, K[sub iC] and E[sub f], appear to correlate better with the clinical success of materials than their 07 does.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".