Comparative evaluation of gingival fibroblast growth on 3D-printed and milled zirconia: An in vitro study.

PURPOSE: The purpose of this study was to analyze the fibroblast growth and proliferation on 3D-printed zirconia in presence and absence of porosities. MATERIAL AND METHODS: A total of 40 bars (8 × 4 × 3) were included in this study. Thirty 3D-printed and 10 milled zirconia samples were prepared. The 3D-printed samples had different porosities, 0% (PZ0), 20% (PZ20), and 40% (PZ40) with 10 specimens in each group. Milled zirconia samples were used as the control (MZ). Rat gingival fibroblasts were cultured for 48 h, and the proliferation of fibroblasts on each sample in each group (n = 10) was determined by MTT assays. The differences among the four groups were compared by one-way ANOVA. To test the significance of the observed differences between two groups, an unpaired Student's t-test was applied. The significance level was set at p < 0.05. Qualitative analysis for the cell culture was performed using scanning electron microscopy. RESULTS: One-way ANOVA showed that the numbers of the fibroblasts among the four groups had a statistical difference. Post hoc Bonferroni test revealed that there was no significant difference between PZ0 and MZ; however, all other groups and among groups were significantly different. CONCLUSIONS: Fibroblasts had a better affinity toward the MZ and PZ0 in a short period of cell culture time.

Surface Nanohardness of Normal and Fluorosed Enamel Adjacent to Restorative Materials: An In Vitro Study and Polarized Light Microscopy Analysis.

AIM AND OBJECTIVE: To evaluate nanohardness of normal and fluorosed enamel in teeth restored with Cention N (CN), Equia forte (EF), glass ionomer cement (GIC), and resin composite using the nanoindentation test. MATERIALS AND METHODS: Eighty freshly extracted human premolars were selected. Standardized cavities were prepared on the buccal surface of normal (40) and fluorosed (40) teeth. Based on the type of the restorative material, the teeth were subgrouped into (n = 10): CN, EF, Type VIII GIC, and Tetric N-Ceram (TNC). The teeth were subjected to pH cycle (progressive caries test), which consisted of alternative demineralization (18 hours) and remineralization with artificial saliva (6 hours) for 3 consecutive days. Surface nanohardness was determined using a nanoindenter at distances of 100, 200, and 300 µm from the restoration-tooth margin. A polarized light Microscope was used to correlate the effect of remineralization on the enamel. Data were analyzed by one-way ANOVA with the Scheffe's post hoc and independent t-test. RESULTS: Nanohardness values of the fluorosed/normal enamel adjacent to various materials in descending order were as follows: EF 3.67/2.95 GPa, GIC 3.33/3.15 GPa, CN 3.13/3.23 GPa, and TNC 1.17/1.82 GPa, respectively. Statistically significant differences were found among various materials in both types of the enamel (p < 0.05). CONCLUSION: Based on the nanohardness test, EF can be a better choice for restoration in fluorosed teeth, followed by CN and GIC; GIC was better in normal enamel; however, this was not significant compared to CN and EF. Tetric N-Ceram composite resin had least influence on increasing the nanohardness of the adjacent enamel. CLINICAL SIGNIFICANCE: The surface nanohardness of normal and fluorosed enamel can be influenced by the type of restorative material used. The results of present study deserve clinician's attention while selecting restorative materials especially in dental fluorosis.