Influence of Filler Loading on the Mechanical Properties of Flowable Resin Composites.

The aim of this study was to evaluate the correlation between the percent of inorganic filler by weight (wt. %) and by volume (vol. %) of 11 flowable resin composites (FRCs) and their mechanical properties. To establish the correlation, the quantity of inorganic filler was determined by combustion and shape/size analyzed by SEM images. The compressive strength (CS), flexural strength (FS), and flexural modulus (FM) were determined. The CS values were between 182.87-310.38 MPa, the FS values ranged between 59.59 and 96.95 MPa, and the FM values were between 2.34 and 6.23 GPa. The percentage of inorganic filler registered values situated between 52.25 and 69.64 wt. % and 35.35 and 53.50 vol. %. There was a very good correlation between CS, FS, and FM vs. the inorganic filler by wt. % and vol. %. (R2 = 0.8899-0.9483). The highest regression was obtained for the FM values vs. vol. %. SEM images of the tested FRCs showed hybrid inorganic filler for Filtek Supreme XT (A3) and StarFlow (A2) and a homogeneous type of inorganic filler for the other investigated materials. All of the FS values were above 50 MPa, the ISO 4049/2019 limit for FRCs.

Development of new radiopaque glass fiber posts.

The aim of this study was to analyze the radiopacity and filler content of three experimental glass fiber posts (EGFP) in comparison with other glass/carbon fibers and metal posts from the dental market. Three EGFP were obtained by pultrusion of glass fibers in a polymer matrix based on 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) monomers. Using intraoral sensor disks 27 posts, as well as mesiodistal sections of human molar and aluminum step wedges were radiographed for evaluation of radiopacity. The percentage compositions of fillers by weight and volume were investigated by combustion analysis. Two EGFP showed radiopacity higher than enamel. The commercial endodontic posts showed radiopacity as follows: higher than enamel, between enamel and dentin, and lower than dentin. The results showed statistically significant differences (p b 0.05)when evaluatedwith one-way ANOVA statistical analysis. According to combustion analyses, the filler content of the tested posts ranges between 58.84wt.% and 86.02wt.%. The filler content of the tested EGFP ranged between 68.91 wt.% and 79.04 wt.%. EGFP could be an alternative to commercial glass fiber posts. Futureglass fiber posts are recommended to present higher radiopacity than dentin and perhaps ideally similar to or higher than that of enamel, for improved clinical detection. The posts with a lower radiopacity than dentin should be considered insufficiently radiopaque. The radiopacity of some glass fiber posts is not greatly influenced by the amount of filler.

The influence of diabetes mellitus on survival of abdominal perforator flaps: an experimental study in rats with slowly induced diabetes mellitus.

BACKGROUND: Lower limb ulcers are a major source of morbidity and mortality in diabetic patients. Surgical coverage of these wounds is fraught with a high complication rate. Although clinically perforator flaps lead to good results in diabetic patients, there is little experimental data to support this finding. METHODS: A total of 60 Wistar rats were randomly assigned either to the diabetic (n = 30) or control (n = 30) group. Diabetes was induced by streptozotocin injection at 50 mg/kg body weight and was confirmed by blood glucose levels > 180 mg/dL preoperatively. In all rats, a cranial epigastric artery perforator flap was raised. At postoperative day 7, all flaps were raised, photographed by digital planimetry, and analyzed histologically. RESULTS: Mean glycemic levels preoperatively were 207.8 ± 16 in the diabetic group and 82.8 ± 5.1 in the control group (p < 0.05). Ninety percent of the flaps survived completely in the control group, compared with 66.7% in the diabetic group (p < 0.05). The mean flap survival area was lower in the diabetic group (83.3 ± 16.5%) than in the control group (96 ± 4%). There were significantly more perioperative complications in the diabetic group (46.7%) than in the control group (16.7%), but these did not affect flap survival. Superficial ulceration appeared only in the diabetic group as a complication. CONCLUSION: Perforator flaps can be successfully used for coverage of cutaneous defects in a rat diabetic model. These flaps show higher complication rates in diabetic versus nondiabetic animals; however, this complication rate has little influence on flap survival.

Influence of inorganic filler content on the radiopacity of dental resin cements.

Digital radiography was used to measure the radiopacity of 18 resin cements to determine the influence of inorganic filler content on radiopacity. Four disk specimens (n=4) of each light-curing cement were digitally radiographed alongside an aluminum step wedge using an intraoral sensor (XIOS Plus, Sirona, Germany), and their mean gray value measured. Percentage of filler by weight was determined using an analytical combustion furnace. Data were statistically analyzed using one-way ANOVA and Tukey's test (α=0.05). All materials were more radiopaque than dentin and 12 materials were more radiopaque than enamel. Filler percentage ranged between 17.36 to 53.56 vol% and radiopacity between 1.02 to 3.40 mm Al. There were no statistically significant differences in inorganic filler percentage and radiopacity among the different shades of the same material (p>0.05), but the highest radiopacity was measured for the material which contained a higher percentage of filler.