Comparative Study of Hardness and Setting-Time of Temporary Cementing Agents

TempBond® (Kerr, Romulus, MI) is a popular and well-accepted temporary cement which often shows undesirable effectiveness in retaining a restoration. Life® (Kerr, Romulus, MI) is used as a calcium-hydroxide base. However, clinicians and researchers have found better results with this material as a temporary cement in terms of retention capacity compared to TempBond®. However, there is a lack of studies testing the hardness and setting time of temporary cements. Objective: The purpose of this project was to compare hardness and setting time of temporary cements: TempBond®, TempBond NE® (Non Eugenol), and Life®, Method: 30 Specimens were prepared in a metal mold of 10 mm in diameter by 2 mm in depth for each study group. Knoop microhardness was measured for each group at three different locations on each sample, using a Micro Indentation Hardness Tester Clark CM 700® (Sun-Tec Corp. Novi, MI) at 100 grams load. Setting time of 10 samples for each study group were tested using 400g Vicat apparatus in a 37°C incubator. Data was recorded and analyzed by oneway ANOVA. Results: Repeated measures ANOVA indicated significant differences in microhardness (p<0.0001). Life had the higher microhardness value (mean 12.7/SD 1.88), followed by Temp Bond (mean 3.67/SD 0.99) and TempBond NE (mean 1.29/SD 0.28). ANOVA also found significant differences in setting time (p<0.0001), TempBond (mean 3.73/SD 0.28) and TempBond NE (mean 3.82/SD 0.47) had a significant longer setting time than Life (mean 2.86/SD 0.29), with no difference between TempBond and TempBond NE. Conclusions: Within the limits of this in vitro testing, results showed that Life® has higher microhardness and shorter setting time than TempBond®, and TempBond NE®. Dentist may consider Life® as a temporary cement not only because it has better properties but also because presents the benefit of being calcium-hydroxide base.