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.

Mechanical properties, shrinkage stress, cuspal strain and fracture resistance of molars restored with bulk-fill composites and incremental filling technique.

OBJECTIVES: To compare bulk-fill with incremental filling techniques for restoring large mesio-occlusal-distal (MOD) restorations. METHODS: Seventy-five molars with MOD preparations were divided into five groups: Z350XT, incrementally filled with Filtek Z350XT and four bulk-fills-FBF/Z350XT, Filtek Bulk Fill/Filtek Z350XT; VBF/CHA, Venus Bulk Fill/Charisma Diamond; SDR/EST-X, SDR/Esthet-X HD; TEC, TetricEvoCeram Bulk Fill. Cuspal strains were measured using strain-gauges (n=10): CSt-Re, during restorative procedure; CSt-100N, during 100N occlusal loading; CSt-Fr, at fracture load. Before fracture load, teeth were load-cycled. Fracture resistance, fracture mode, and enamel cracks were recorded. The other five teeth were used for Elastic modulus (E) and Vickers hardness (VH). Post-gel shrinkage (Shr), diametral tensile strength (DTS) and compressive strength (CS) were determined (n=10). Shrinkage stresses were analyzed using finite element analysis. RESULTS: SDR had similar CS values as TEC, lower than all other composites. CHA had similar DTS values as Z350XT, higher than all other composites. Z350XT had the highest mean Shr and SDR the lowest Shr. New enamel cracks and propagation was observed after the restoration, regardless of filling technique. Z350XT had lower fracture resistance than bulk-fill composite techniques. No significant differences in failure modes were found. E and VH were constant through the depth for all techniques. Bulk-filling techniques had lower stresses compared to Z350XT. CONCLUSIONS: Flowable bulk-fill composites had lower mechanical properties than paste bulk-fill and conventional composites. All bulk-fill composites had lower post-gel shrinkage than conventional composite. Bulk-fill filling techniques resulted in lower cusp strain, shrinkage stress and higher fracture resistance. CLINICAL SIGNIFICANCE: Using bulk-fill composites cause lower CSt wich indicates lower stress in restored tooth. Furthermore, bulk-fill composites have a higher fracture resistance. Therefore, clinicians may choose the bulk-fill composite to decrease undesirable effects of restoration while simplifying filling procedure.