The effect of time on two physical properties of four tissue conditioners applied to an acrylic base – in vitro comparative study

Abstract

Introduction: Tissue conditioners are frequently used to aid in the healing of denture-bearing areas that are compromised and act as functional impression materials for relining dentures. They exhibit different clinical behaviours, especially noticeable in their viscosity properties. When choosing the right tissue conditioner for clinical situations, it is essential to take this variability into account. Aim and objectives: This research examines the physical characteristics of four distinct tissue conditioners after being submerged in phosphate buffered saline (PBS) for periods of 1 and 7 days. The study offers a quantitative comparative in vitro analysis focusing on the hardness and surface tension of the four tissue conditioner categories. The categories include Visco-Gel, GC Coe-Comfort, GC Soft-Liner, and Functional Impression Tissue Toner (FITT). Each category comprised 25 samples, and assessments were conducted on days 0, 1, and 7 of immersion in the PBS solution, leading to a total of 100 samples for this research. Additionally, four separate specimens (one from each tissue conditioner) were used to measure hardness using a digital Shore hardness tester, another way to test hardness. Result: The shore hardness of all four tissue conditioners increased significantly over time (p < 0.001). Visco-Gel exhibited the most significant increase from a mean of 0.1809 MPa on Day 0 to 0.3664 MPa on Day 7, indicating substantial hardening. The GC Soft-Liner exhibited an increase from 0.1721 MPa to 0.3311 MPa. FITT and GC Coe-Comfort exhibited the lowest hardness values at all measured time points, indicating enhanced softness retention. Particularly, FITT increased from 0.1208 MPa to 0.2294 MPa, while Coe Comfort increased from 0.1556 MPa to 0.2958 MPa. Wettability analysis revealed a statistically significant difference in contact angles among the materials (p < 0.05). On Day 0, Visco-Gel exhibited the lowest mean contact angle of 67.8°, indicating a higher level of hydrophilicity. On Day 7, the angle increased to 77.7°, signifying a decrease in wettability. In contrast, GC Soft-Liner exhibited a gradual decrease in contact angle (from 75.8° to 73.4°), while FITT and GC Coe-Comfort maintained relative hydrophobic characteristics with contact angles exceeding 80° during the observation period. The findings indicate changes in mechanical and surface properties that tend to be specific to the material and dependent on time. Conclusion: Comparing the effect of time on two physical properties of the four different commercially available tissues applied to the acrylic base, it was observed that after Day 1 and Day 7 day of immersion in phosphate buffered saline, Visco-Gel increased in hardness and steps, followed by GC Soft-Liner, while FITT and GC Coe-Comfort showed a lower hardness than recommended for cases requiring softness and mucosal preservation. Comparing the effect of time on the surface tension of four different commercially available conditioners applied to the acrylic base on Day 1 and Day 7 of immersion in phosphate-buffered saline, it was observed that the contact angle showed significant variations across materials. Visco-Gel demonstrated the lowest contact angle on Days 0, 1 and 7, indicating enhanced hydrophilicity and initial wettability. FITT and GC-Coe Comfort had higher contact angles, meaning they repel water, while the GC Soft-liner had a middle value. The results of this study highlight the need for evaluating material choices. The clinical finding supports that material selection should be based on specific clinical requirements