Fabrication of Highly Oriented Cylindrical Polyacrylonitrile, Poly(lactide-co-glycolide), Polycaprolactone and Poly(vinyl acetate) Nanofibers for Vascular Graft Applications

Small-diameter vascular grafts fabricated from synthetic polymers have found limited applications so far in vascular surgeries, owing to their poor mechanical properties. In this study, cylindrical nanofibrous structures of highly oriented nanofibers made from polyacrylonitrile, poly (lactide-co-glycolide) (PLGA), polycaprolactone (PCL) and poly(vinyl acetate) (PVAc) were investigated. Cylindrical collectors with alternate conductive and non-conductive segments were used to obtain highly oriented nanofibrous structures at the same time with better mechanical properties. The surface morphology (orientation), mechanical properties and suture retention of the nanofibrous structures were characterized using SEM, mechanical tester and universal testing machine, respectively. The PLGA nanofibrous cylindrical structure exhibited excellent properties (tensile strength of 9.1 ± 0.6 MPa, suture retention strength of 27N and burst pressure of 350 ± 50 mmHg) when compared to other polymers. Moreover, the PLGA grafts showed good porosity and elongation values, that could be potentially used for vascular graft applications. The combination of PLGA nanofibers with extracellular vesicles (EVs) will be explored as a potential vascular graft in future.

Modifications of the mechanical properties of in vivo tissue-engineered vascular grafts by chemical treatments for a short duration

In vivo tissue-engineered vascular grafts constructed in the subcutaneous spaces of graft recipients have functioned well clinically. Because the formation of vascular graft tissues depends on several recipient conditions, chemical pretreatments, such as dehydration by ethanol (ET) or crosslinking by glutaraldehyde (GA), have been attempted to improve the initial mechanical durability of the tissues. Here, we compared the effects of short-duration (10 min) chemical treatments on the mechanical properties of tissues. Tubular tissues (internal diameter, 5 mm) constructed in the subcutaneous tissues of beagle dogs (4 weeks, n = 3), were classified into three groups: raw tissue without any treatment (RAW), tissue dehydrated with 70% ET (ET), and tissue crosslinked with 0.6% GA (GA). Five mechanical parameters were measured: burst pressure, suture retention strength, ultimate tensile strength (UTS), ultimate strain (%), and Young’s modulus. The tissues were also autologously re-embedded into the subcutaneous spaces of the same dogs for 4 weeks (n = 2) for the evaluation of histological responses. The burst pressure of the RAW group (1275.9 ± 254.0 mm Hg) was significantly lower than those of ET (2115.1 ± 262.2 mm Hg, p = 0.0298) and GA (2570.5 ± 282.6 mm Hg, p = 0.0017) groups. Suture retention strength, UTS or the ultimate strain did not differ significantly among the groups. Young’s modulus of the ET group was the highest (RAW: 5.41 ± 1.16 MPa, ET: 12.28 ± 2.55 MPa, GA: 7.65 ± 1.18 MPa, p = 0.0185). No significant inflammatory tissue response or evidence of residual chemical toxicity was observed in samples implanted subcutaneously for four weeks. Therefore, short-duration ET and GA treatment might improve surgical handling and the mechanical properties of in vivo tissue-engineered vascular tissues to produce ideal grafts in terms of mechanical properties without interfering with histological responses.

Influence of Hydrofluoric and Nitric Acid Pre-Treatment and Type of Adhesive Cement on Retention of Zirconia Crowns

Background: The aim of this study was to test the impact of hot acids etching and two types of adhesive cement on the retention of zirconia crowns. Methods: Forty maxillary premolars were prepared, and zirconia crowns were designed and fabricated with proximal extensions, then divided into 4 groups (n = 10). Group AP; the crowns were air-abraded and cemented using Panavia SA Cement. Group AL; the crowns were air- abraded and cemented using GC LinkForce. Group AHP; the crowns were air-abraded, etched with the hot acids (48% hydrofluoric acid and 69% nitric acid), and cemented using Panavia SA Cement. Group AHL; the crowns were air-abraded, etched with the hot acids, and cemented using GC LinkForce. Each zirconia crown was pre-treated and bonded to its corresponding tooth. After thermocycling (5–55 °C/10,000), the retention test was performed and the load required to dislodge the crown was reported in Newton (N), and mode of failure was recorded. The retention strength (MPa) was calculated for each tested variable and statistically analyzed. Results: Group AHP showed the highest mean value of the retention strength, followed by group AP then group AHL. Group AL showed the lowest value. A statistically significant effect (p = 0.001) of the hot acids etching on the retention of zirconia crown was found. Also, there was a significant effect (p = 0.000) of the cement type. The interaction between surface treatment and the cement type has no significant impact (p = 0.882). The main mode of failure for Panavia SA Cement is mixed mode of failure, while for G-CEM LinkForce is adhesive failure. Conclusions: Hot acid etching pre-treatment improved the retention of zirconia crown. Usage of Panavia SA Cement with hot acids etching is effective can be used for adhesive cementation of zirconia crown.

Insights into the metal retention role in the antibacterial behavior of montmorillonite and cellulose tissue-supported copper and silver nanoparticles

The role of the retention strength of Cu0 and Ag0 nanoparticles on the induced antibacterial properties of montmorillonite and cellulose-supported polyol dendrimer against Escherichia coli DH5α and Bacillus subtilis 168 was comparatively investigated.

Pengaruh penggunaan denture adhesive sediaan powder dan denture adhesive sediaan cream terhadap kekuatan retensi pada pemakai gigi tiruan lengkapThe effect of denture adhesive powder preparations and denture adhesive cream preparations usage on the retention strength in complete denture wearers

Pendahuluan: Pemakaian gigi tiruan lengkap prevalensinya lebih tinggi pada usia lanjut daripada usia muda. Perubahan fisik yang terjadi pada usia lanjut yang memakai gigi tiruan lengkap akan berpengaruh pada kualitas dan kuantitas saliva serta resorpsi tulang alveolar sehingga berkurang kekuatan retensi gigi tiruan lengkap. Denture adhesive digunakan untuk meningkatkan kekuatan retensi gigi tiruan lengkap. Tujuan penelitian ini adalah untuk menganalisis pengaruh penggunaan denture adhesive sediaan powder dan cream terhadap kekuatan retensi pada gigi tiruan lengkap. Metode: Jenis penelitian ini adalah eksperimental dengan rancangan penelitian uji klinis. Penelitian ini dilakukan pada gigi tiruan lengkap rahang atas yang telah diberikan hook dengan menggunakan alat push and pull gauge pada 10 sampel setiap kelompok dan dibagi tiga kelompok (kelompok tanpa denture adhesive, denture adhesive powder dan denture adhesive cream). Data dianalisis dengan uji ANOVA dan dilanjutkan uji LSD. Hasil: Hasil uji statistik ANOVA menunjukkan adanya pengaruh penggunaan denture adhesive powder dan denture adhesive cream terhadap kekuatan retensi (p = 0,0001, <0,05). Hasil uji LSD menunjukkan adanya perbedaan pengaruh penggunaan denture adhesive sediaan powder dan cream terhadap kekuatan retensi, terlihat perbedaan yang signifikan antara kelompok Tanpa Denture Adhesive dengan Denture Adhesive Powder dan Denture Adhesive Cream, tetapi tidak signifikan antara denture adhesive powder dan denture adhesive cream. Simpulan: Kekuatan retensi pada denture adhesive sediaan cream lebih tinggi dibandingkan denture adhesive sediaan powder sehingga penggunaan denture adhesive sediaan cream lebih direkomendasikan pada pasien yang membutuhkan denture adhesive.Kata kunci: Retensi, gigi tiruan lengkap, denture adhesive. ABSTRACTIntroduction: The use of complete denture is more commonly found in elderly than the younger age. Physical changes that occur in elderly complete denture wearers will affect the quality and quantity of saliva and alveolar bone resorption so that retention strength of complete dentures will be reduced. Denture adhesive is used to increase the retention strength of complete dentures. The purpose of this study was to analyse the effect of using denture adhesives with the various form of powder and cream on the retention strength in complete dentures. Methods: This research was experimental research with a clinical trial research design. This study was measured on the maxillary complete denture that had been hooked using the push and pulls gauges towards 10 samples of each group, then divided into three groups (no denture adhesive; denture adhesive powder; and denture adhesive cream). Data were analysed by ANOVA test then continued by LSD test. Results: Based on the ANOVA test results, the influence of the use of denture adhesive powder and denture adhesive cream on the retention strength (p = 0.0001; p < 0.05). The LSD test results showed a difference in the effect of using denture adhesive powder and cream form on the retention strength of complete denture, also, a significant difference between the group with no denture adhesive with denture adhesive powder and cream form groups. However, there was no significant difference between denture adhesive powder and cream form groups. Conclusion: The retention strength of denture adhesive cream form is higher than powder form; thus, the use of denture adhesive cream form is more recommended in patients who need a denture adhesive.Keywords: Retention, complete denture, denture adhesive.