Core dimensional stability is important to overlying all-ceramic crown stability. Objectives: This study evaluated the influence of distilled water on the volumetric dimensional change of six direct placement core build-up materials by using Archimedes' principle over 6 months. The materials tested were CoreStore 2 (CR), Build-It FR (BI), CorePaste (CP), Ti-Core (TC), CompCore AF (CC) and Fuji II LC Core (FU). Methods: Cylindrical specimens were prepared (7 + 0.1 mm diameter and 2 + 0.1 mm height) in a controlled environment of 23 + 1^oC and 55-60% RH. Each material was tested in silicone oil at 23^oC and 37^oC and distilled water at 23^oC and 37^oC (n=5). The temperature of the liquid was recorded to a resolution of 0.1^oC to determine liquid density. A 0.01 mg resolution balance was used to determine % volumetric dimensional change using an Archimedian equation. This was accomplished within two minutes after removal from the storage fluid and the cycle repeated five times for each specimen. Measurements were made 30 minutes after mixing (baseline), and at 1-day, 14-days, 3-months and 6-months. Data were compared using repeated measures analysis of variance. Comparisons between materials were made using Student-Newman-Keuls All-Pairwise Multiple Comparisons procedures. Results: All materials showed significant increases in expansion (p<0.05). The increase was greatest for FU at all times with values ranging from 3.49% to 5.48%. CC was greater than CR, BI, CP, and TC at all times longer than 1-day with values ranging from 1.08% to 3.20%. All other materials showed 1.02% or less expansion at both temperatures and all time periods. Conclusions: Distilled water causes current resin-containing core materials to exhibit a significant free-volumetric expansion over time but the amount varies significantly between materials.

Back to the Dental Materials: VI - Polymer Materials-Mechanical Properties and Degradation Program
Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

Top Level Search