Aim: The aim of this research was to assess the reinforcing effect of silica nanoparticles on two provisional materials, by measuring the flexural strength and diametral tensile strength, as well as the influence on colour change
Methods: A total of sixty samples of two provisional materials were constructed and classified into two groups (n=30), group 1(Voco structure 2sc) and group 2 (Charm temp). Each group was classified into two subgroups (n=15) according to modification by silica nanoparticles, subgroup 1 (control) and subgroup II (modified by silica nanoparticles). Each subgroup was classified into three classes according to the type of the test (n=5) Flexural strength test, diametral tensile strength tests which were measured by using the universal testing machine, and colour change test was performed by spectrophotometer. Data were collected, tabulated and statically analyzed.
Results: Diametral tensile strength results showed a significant increase in modified samples (11.4±1.7, 14.2±3.7) in comparison to control samples (6.1±1.7, 8.3±2.2) in charm and voco, respectively. Regarding the flexural strength results, there was a non-significant decrease in modified samples (59.4±4.1, 33.5±4.9) in comparison to control samples (62.7±1.2, 42.1±11) in charm and voco , respectively. Colour change results showed a statistically significant increase in (ΔΕ) value in charm temp (5.1±1.7) in comparison to voco provisional material (2.4±0.8).

Conclusions: The addition of silica nanoparticles to both provisional materials significantly improves the diametral tensile strength, whereas decreases the flexural strength insignificantly. Colour change in voco structure 2sc was within the acceptable clinical range whereas in charm was above this range.