A laboratory evaluation of cell viability, radiopacity and tooth discoloration induced by regenerative endodontic materials.

AIM: To analyse the cytotoxicity, colour change and radiopacity of MTA Flow (MTA), UltraCal XS (UC) and Bio-C Temp (BT). METHODOLOGY: Human dental pulp cells (hDPCs) stimulated with lipopolysaccharide (LPS) were placed in contact with several dilutions of culture media previously exposed to the experimental materials and tested for cell viability using MTT. Bovine teeth were prepared to simulate an open apex and to mimic extensive crown fracture. The roots were filled with a mixture of agar and blood, and the materials placed over this mixture. The control group consisted of teeth filled only with agar and blood. Colour assessment analyses were performed before and immediately after material insertion and repeated at 30, 45 and 60 days using a spectrophotometer. The total colour change (ΔEab , ΔE00 and whiteness index (WI)) was calculated based on the CIELAB colour space. Digital radiographs were acquired for radiopacity analysis. Cell viability was analysed by one-way anova, whilst differences in colour parameters (ΔEab , ΔE00 and WI) were assessed by two-way repeated measures anova (α = 0.05). Tukey's test was used to compare the experimental groups, and Dunnett's test was used to compare the experimental groups with the control group. RESULTS: MTA, UC and BT had similar cell viability to that of the control group (DMEM) (P > 0.05), except for the BT group at the 1 : 1 and 1 : 2 dilutions, which had significantly lower viability (P < 0.001). All materials were associated with discoloration values greater than what is considered to be the acceptable threshold, and BT resulted in less or similar tooth colour change than MTA and UC, respectively. Decreasing radiopacity over time was observed only in the MTA group (P = 0.007). Lower values of radiopacity were found in the BT group compared with the UC and MTA groups (P < 0.001). CONCLUSIONS: The new bioceramic material (BT) had acceptable cell viability, similar to that of MTA and UC at the highest dilutions, and BT resulted in less tooth colour change than MTA and UC. Despite its lower radiopacity, BT was identified radiographically.

Evaluation of apoptosis/necrosis and cytokine release provoked by three root canal sealers in human polymorphonuclears and monocytes.

AIM: To evaluate the in vitro cytotoxicity and cytokine release of three fresh root canal sealers and to determine the type of cell death they induce. METHODOLOGY: The sealers tested were Sealer 26 (S26), AH Plus (AHP), and Endosequence BC Sealer (END). Fresh sealers were cultivated in contact with monocytes and polymorphonuclears (PMNs) obtained from the peripheral blood of humans. Cell viability, apoptosis and necrosis were analysed at 4 h (PMNs) or 24 h (monocytes) using Annexin-V and propidium iodide in a cytometer. The supernatants were used to quantify Interleukin (IL)-4, IL-6, IL-10, IL-12 and tumour necrosis factor-α (TNF-α) in monocytes and IL-8 in PMNs by ELISA. One-way ANOVA and the Tukey post-test were used to compare data for cytotoxicity, and the multiple T-test was used to determine the differences between sealers in the release of cytokines that were statistically significant. RESULTS: After 4 h of treatment, S26 was associated with greater cell viability than the other sealers (P < 0.05) in the PMN culture and had similar values of necrosis as END (P > 0.05). After 24 h of treatment, AHP and END had greater monocyte cell viability than S26 (P < 0.05), which had more necrosis (P < 0.05). END had the lowest levels of IL-12 compared to the other sealers (P < 0.05) and higher levels of IL-6 compared to S26 (P < 0.05). The tested sealers did not differ in the release of IL-8, IL-10, TNF-α and IL-4 (P > 0.05). CONCLUSIONS: The effect of toxic agents released varied depending on the cell type studied. The composition of the sealers appeared to alter the form of self-regulation in the production of these cytokines by cells.

Effect of different storage media on root dentine composition and viability of fibroblasts evaluated by several assay methods.

AIM: To perform multiparametric analysis of the effects of soya milk (SM), whole milk (WM) and Hank's balanced salt solution (HBSS) on the viability of fibroblasts (HGF). The study also aimed to evaluate the influence of these solutions on bovine root dentine according to OH- and PO43- on the surface. METHODOLOGY: The HGF cytotoxicity was determined according to XTT, NR and SRB assays at 1, 3 and 6 h. Root dentine fragments were assessed by Fourier infrared (FTIR) spectrophotometer before and after immersion in the solutions for the same periods. The positive control group included cells and tooth fragments maintained in Dulbecco's modified Eagle's medium (DMEM), and the negative control included tooth fragments that were kept dry. Data were analysed using anova and Tukey's test. RESULTS: No significant difference was found in cell viability evaluated by XTT (P > 0.05). Using the NR assay, WM and HBSS had significantly lower cell viability compared to the positive control group at 6 h (P < 0.05). SM had similar cell viability to the positive control group at all periods evaluated when assessed using all three tests (P > 0.05). A significant difference was found in values of OH- for the negative control group at 1 h (P = 0.002). CONCLUSIONS: Soya milk promoted better cell viability, whereas on dentine composition, the solutions behaved similarly. The association of different assay methods is promising for improving cell viability analysis. The 1-h time-point is a crucial factor in the prognosis of dental replantation because the teeth remain more hydrated and help maintain cell viability.

Powdered coconut water as a storage medium to preserve the viability of periodontal ligament cells: a laboratory study.

AIM: To investigate the ability of newly developed powdered coconut water formulas (ACP) with different osmolarities to maintain the viability of periodontal ligament (PDL) cells over time compared with other solutions. METHODOLOGY: Dogs teeth were extracted and stored for two periods, 3 h or 24 h, in the following media: long-shelf life CW (CW), pH-adjusted long-shelf life CW (pH-CW) and powdered CW that was pH and osmolality adjusted (ACP-404-I, 250 mOsm kg-1 H2 O; pH 7.0; ACP-404-II, 372 mOsm kg-1 H2 O; pH 7.0; ACP-404-III, 300 mOsm kg-1 H2 O; pH 7.4). The positive control group (Pc) corresponded to immediate measurement after tooth extraction, and two negative controls (Nc) corresponded to 3 h and 24 h of dry time. PDL cells were extracted, and cell viability analysed by Trypan blue exclusion. Data were analysed statistically using two-way anova followed by the Tukey test and one-way anova followed by the Dunnett test (P < 0.05). RESULTS: At 3 h and 24 h, ACP-404-I had a performance similar to those of ACP-404-II and pH-CW, with significantly higher (P = 0.004) percentages of viable cells than ACP-404-III and CW. The positive control group had a significantly higher (P = 0.002) percentage of viable cells than the negative control groups, CW and ACP-404-III, irrespective of the period evaluated. CONCLUSION: Powdered coconut water formulas, ACP-404-I and ACP-404-II, preserved viability for up to 24 h.