A comparison of the effects of incremental and snowplow techniques on the mechanical properties of composite restorations.

BACKGROUND: Glass fibre-reinforced composite (GFRC) has the potential to enhance the mechanical properties of resin-based restorations. Nevertheless, the application technique can influence the cervical margin porosity, potentially reducing the mechanical strength of restorations. METHODS: In an in vitro setup, mould specimens underwent six different treatments to assess the effects of snowplow and incremental curing techniques on the properties of GFRC (EverX) and universal resin composite (Filtek). Mechanical properties, namely flexural strength (FS), compressive strength (CS) and Vickers hardness (VH), were evaluated following ISO 4049 standards. Data interpretation utilized the Kruskal-Wallis tests. RESULTS: No significant difference emerged across groups for FS. CS in the snowplow method with lesser EverX thickness (SnPl_1) was comparable with only EverX and Filtek (P > 0.05). The CS was reduced in the snowplow technique with greater EverX thickness (SnPl_2) (P < 0.05) and further decreased with the incremental method (P < 0.001). VH results showed that EverX Posterior was consistently softer than Filtek, with specific patterns of hardness variations among different application methods. CONCLUSIONS: Applying EverX and Filtek using the snowplow technique delivers superior CS and VH for restorations in contrast to the incremental method. Utilizing the snowplow approach in high-stress areas can make restorations more fracture-resistant.

Evaluation of the cytotoxicity of contemporary glass-ionomer cements on mouse fibroblasts and human dental pulp cells.

PURPOSE: This study aimed to evaluate the cytotoxic effects of different types of contemporary GICs on human dental pulp cell (hDPCs) and mouse fibroblast (L929) cultures. METHODS: Three high-viscosity GICs (HVGIC; GC Equia Forte, Riva Self Cure, IonoStar Plus), three resin-modified GICs (RMGIC; Photac Fil, Riva Light Cure, Ionolux), and a metal-reinforced GIC (MRGIC; Riva Silver) were investigated. Twelve disc-shaped specimens of each material were prepared and stored in Dulbecco's modified Eagle medium (DMEM). L929 fibroblasts and DPCs were then cultured in 96-well plates. Uncultured DMEM was used as a negative control. Mitochondrial dehydrogenase activity (MTT) assays were performed to detect cell viability after 24, 48, and 72 h. Data were analysed using Mann-Whitney U and Friedman tests followed by a Bonferroni-corrected Wilcoxon signed rank test, with the statistical significance set at P < 0.05. RESULTS: Toxicity levels varied between the cell-culture systems. MTT assays of L929 cells showed significant differences in percentages of viable cells, as follows: Riva Self Cure = Riva Silver > GC Equia Forte > IonoStar Plus = Riva Light Cure = Photac Fil > Ionolux. MTT assays of DPCs showed the percentages of viable cells to be significantly lower for the Ionolux group when compared to the other GICs, which did not differ significantly from one another. With the exception of Ionolux, none of the other GICs tested showed any toxicity, and in fact, they all induced cell proliferation (> 100% cell viability). CONCLUSIONS: Although the degree of toxicity varied between the two cell-culture systems investigated, all the GICs tested, with the exception of Ionolux, performed favorably with regard to cytotoxicity (> 100% cell viability in both cell systems).

Association between C-reactive protein, neutrophil to lymphocyte ratio and the burden of apical periodontitis: a case-control study.

OBJECTIVE: Endodontic originated chronic apical periodontitis (AP) is an inflammatory disease of periapical tissue. High-sensitivity C-reactive protein (hsCRP) as an inflammatory marker and hemogram indexes provide valuable information to clinicians for diagnosis, screening and follow-up of various diseases. The aim of this study was to investigate AP in terms of its association with hemogram indices and hsCRP levels. MATERIAL AND METHODS: Study includes 104 patients with AP and 40 participants as the control group. 160 teeth were diagnosed as AP through digital radiographic images and scored with respect to Periapical Index (PAI) scoring. Afterwards, patients were categorized into 3 grades in accordance with both the number and the severity of AP. AP grade 0 was considered for the control group with regard to a new scoring system. Patients with only one tooth involved with AP with a PAI score of 3 or 4 were categorized as an AP Grade 1, when a patient had more than one tooth with a PAI score of 3 or 4 he was classified as an AP Grade 2 and a patient with at least one tooth scored as a PAI 5 was rated as an AP Grade 3. Hemograms and hsCRP levels were measured for each individual to establish a correlation with inflammatory markers. RESULTS: The neutrophil/lymphocyte ratio (NLR) levels of patients with AP Grade 3 were significantly higher than all other AP grades (p < .05). hsCRP levels in patients with an AP Grade 2 and 3 were higher than both AP Grade 0 and 1 (p < .05). CONCLUSIONS: hsCRP levels of patients were reliable predictive indicators for AP severity in correlation with the new proposed scoring system for AP.