Influence of carbonated acid beverage on fracture resistance and marginal gap formation in different restorative approaches to non-carious cervical lesions

OBJECTIVE

This study is to evaluate fracture resistance, failure mode, and gap formation at the restorative interface of unrestored or restored non-carious cervical lesions (NCCLs) submitted to a short-term erosive environment.

MATERIALS AND METHODS

Artificial NCCLs were produced in vitro in bovine incisors, and were randomly divided into four restorative resins groups (n = 22): nanohybrid-NR; bulk-fill-BR; flow with a nanohybrid layer-FNR; bulk-fill with a nanohybrid layer-BNR; and a group unrestored-UR (n = 16). Half of the specimens were submitted to an erosive challenge (per 5 min, 3 × a day for 7 days, before and after restoration), and the other half, was immersed in artificial saliva. After, all teeth undergone thermal (5 ºC, 37 ºC, and 55 ºC, 3600 cycles) and mechanical (50 N, 2 Hz, 300,000 cycles) aging. Eighty teeth were subjected to compressive loading, and resistance and failures were analyzed, while 24 teeth were evaluated for gaps by microcomputed tomography. Statistical tests were performed (p < 0.05).

RESULTS

The restorative approaches affected fracture resistance (η2p = 0.14, p = 0.023), and gap formation (η2 = 0.18, p = 0.012) and so did the immersion medium (fracture η2p = 0.09, p = 0.008; gap η2 = 0.09, p = 0.017). BNR showed the highest resistance, while UR the lowest. FNR showed the highest gaps in both immersion media. Neither the resin groups nor the immersion media were associated with failure mode.

CONCLUSIONS

The erosive immersion medium based in acid beverages has been shown to affect NCCLs with or without restoration, but when Bulk-Fill resin is covered by nanohybrid resin, the performance is good.

CLINICAL RELEVANCE

Erosion negatively affects restorations, but unrestored NCCL shows worse biomechanical performance in stress-bearing situations.

Does the type of sagittal split ramus osteotomy influence fixation strength? Evaluation of the mechanical behavior of two types of fixation used in three types of sagittal split ramus osteotomy

PURPOSE

This study compared the mechanical behavior of two fixation techniques used in three sections representing the sagittal split ramus osteotomy (SSRO) in polyurethane replicas that were divided into groups, according to type of section, and sub-groups according to type of fixation, simulating 11-mm advancement and 6º clockwise mandibular rotation.

METHODS

Loads were applied in two regions, aiming at progressive application and consequent strength value, measured in kilogram-force in displacements of 1, 3, 5, and 7 mm, from the load application tip. Shapiro-Wilk test was performed, followed by two-way analysis of variance (ANOVA-2 way), and Bonferroni's multiple comparison.

RESULTS

The results showed no statistically significant difference in the type of section and type of fixation used when load was applied to the inter-incisor region. However, when load was applied to the first molar region, statistically significant difference was observed in 1-mm displacement, in which section described by Epker with two modifications showed greater strength, regardless of type of fixation used (p = 0.007).

CONCLUSION

In the application of load in the inter-incisor region, there was no statistical difference between the type of osteotomy and the type of fixation used. When applying loads to molars, there was a difference for the type of osteotomy, where the Epker osteotomy with 2 modifications presented greater resistance, regardless of the type of fixation used.

Box-Wilson Design for Optimization of in vitro Levan Production and Levan Application as Antioxidant and Antibacterial Agents

Background

Levan or fructan, a polysaccharide of fructose, is widely used in various commercial industries. Levan could be produced by many organisms, including plants and bacteria. The cloning of the gene from Bacillus licheniformis, which expressed levansucrase in Escherichia coli host, was carried out successfully. In the present study, we performed the in vitro production of levan and analyzed its potential application as antibacterial and antioxidant agents.

Methods

In vitro levan production catalyzed by heterologous-expressed levansucrase Lsbl-bk1 and Lsbl-bk2 was optimized with Box-Wilson design. The antibacterial activity of the produced levan was carried out using agar well diffusion method, while its antioxidant activity was tested by free radical scavenging assays.

Results

The optimum conditions for levan production were observed at 36 °C and pH 7 in 12% (w/v) sucrose for levansucrase Lsbl-bk1, while the optimum catalysis of levansucrase Lsbl-bk2 was obtained at 32 oC and pH 8 in the same sucrose concentration. The in vitro synthesized levan showed an antibacterial activity within a concentration range of 10-20% (w/v) against Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa. The same levan was also able to inhibit the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with the antioxidant strength of 75% compared to ascorbic acid inhibition.

Conclusion

Our study, therefore, shows that the optimized heterologous expression of levansucrases encoded by Lsbl-bk1 and Lsbl-bk2 could open the way for industrial levan production as an antibacterial and antioxidant agent.

Establishment of an in vitro model using the rat alveolar macrophage cell line NR8383

OBJECTIVE

To establish an in vitro model of radiation-induced lung injury using rat lung alveolar macrophages (NR8383).

METHODS

Using a medical electronic linear accelerator, cells were irradiated with either 0 Gy or 6 Gy X-rays. At 6, 12, 24, 30 and 48 h, the DNA damage index (8-OHdG) and lipid damage index (MDA) were measured in the two groups. We also determined the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and transforming growth factor-β (TGF-β).

RESULTS

The levels of 8-OHdG and MDA in the 6 Gy irradiation group were higher than those in the 0 Gy group at 6, 12, 24, 30 and 48 h after irradiation. The levels reached the highest value -6 h after irradiation, and then gradually decreased. The levels of the inflammatory factors TNF-α, TGF-β and IL-6 were higher in the 6 Gy irradiation group than those in the 0 Gy group at 6, 12, 24, 30 and 48 h after irradiation.

CONCLUSION

Six Gy X-ray irradiated NR8383 cells can be used to establish an in-vitro model of radiation-induced lung injury. The levels of 8-OHdG, MDA, TNF-α, TGF-β and IL-6 can be used as effective evaluation indicators.

3D Neural Culture in Dual Hydrogel Systems

3D in vitro culture systems may yield physiological outcomes that more closely approximate in vivo behavior. A number of fabrication techniques and hydrogel scaffold materials are available to researchers, but often their implementation is complex and seemingly prohibitive. Herein, we describe a simplistic and adaptable dual hydrogel photolithography method utilized to engineer advanced in vitro systems for studies of neuronal development and characterization.

Effects of alkaloid extracts of mesquite pod on the products of in vitro rumen fermentation

The objective of this study was to evaluate the effects of alkaloid extracts of Prosopis juliflora (Sw.) D.C. pods obtained by two extraction methods as compared with sodium monensin on the gas production kinetic, mitigation of methane, and rumen fermentation products using wheat bran or Tifton 85 hay as substrates, by the semi-automatic in vitro gas production technique. A completely randomized design was adopted, and two natural additives were tested made from mesquite pod (alkaloid extract I and alkaloid extract II) at three levels (3.9, 7.9, and 12 μg), sodium monensin 5 μM (positive control), and no inclusion of additives (negative control). The volume of gases produced by the degradation of the fibrous fraction of wheat bran was influenced by the concentration of the extract I added to the medium, and the amounts of 7.9 and 12 μg were equal to monensin at the lowest value. The degradation rate of the fibrous carbohydrates with additive extract I at 12 μg was lower in relation to monensin. When Tifton 85 hay was utilized, alkaloid extract I provided a shorter colonization time as compared with monensin at the added amounts of 7.9 and 12 μg and higher production of gases from the fibrous fraction but without interfering with the total volume of gases produced during 96 h of fermentation of carbohydrates. In the periods of 12 and 24 h of incubation, utilizing alkaloid extract I, the mean values of methane production with wheat bran and Tifton 85 hay were lower than monensin (p < 0.05) when the respective amounts of 7.9 and 12 μg were added. Alkaloid extract I has similar potential to sodium in reducing production of total gases, methane, and the acetate/propionate ratio.