Preparation Time and Hardness of 10 Core Composites and Dentine

Objectives: Composite is a well accepted core material due to its physical properties similar to dentine. This in-vitro study measured time for material preparation of 10 core build-up composites under standardized conditions and Vickers hardness compared to dentine.

Methods: 10 core build-up composites were investigated: Build-It (BI), Chroma Core (CC), Core Paste (CP), LuxaCore (LC), LuxaCore SmartMix (LS), Multicore Flow (MF), Rebilda D, LC and DC (RD, RLC, RDC), Ti-Core (TC). 5 disc specimens (5x10x50mm) of each material were fabricated. Human dentine (DE) slices were cutted using a band saw and glued together forming samples of the same size (control group). Vickers hardness (HV) was assessed (DIN 50133, 1N/sec). Preparation of the material was performed three times for each specimen with a cylindrical diamond bur (100µm) in a handpiece (150.000rpm, water cooling) under controlled pressure (50g). The preparation time of a distance of 10mm and a depth of 0.4mm was measured. Statistical analysis was carried out (Mann-Whitney U-test, a=0.05).

Results: Preparation time for DE amounted to 22.5±2.5sec and was on the same level as BI, CC, MF, RLC, RDC and TC (17.5-24.0sec). No statistically significant differences were found between these materials and DE (p>0.05). Values of CP, LN, LS and RD ranged on a lower level of 9.5-12.0sec and differed significantly compared to DE (p<0.001). Composites provided hardness values on a lower level of 35-46HV (CC, LS, MF, TC) and on a higher level of 53-60HV (BI, CP, LN, RLC, RDC). Best results were found for RD (66±1HV) and DE (77±2HV). Statistically significant differences were obtained beween all composites and DE (p<0.01) except of RD-DE (p<0.05).

Conclusion: Preparation times did not correlate with HV of the core composites. Six of ten tested materials offered preparation times comparable to dentine, but HV of all materials was lower than that of dentine.