Effect of Sodium Fluoride Varnish and Potassium Iodide on Remineralization Efficacy of Silver Diamine Fluoride

The purpose of this study was to compare the effect of sodium fluoride(NaF) varnish and potassium iodide(KI) on remineralization efficacy of silver diamine fluoride(SDF) by measuring microhardness and evaluating surface morphology by scanning electron microscope(SEM). Artificial caries lesions were induced on extracted primary molars and vickers microhardness was measured. Specimens were randomly separated into 4 groups for treatment. The specimens in group I were treated with SDF, group II with NaF varnish after SDF, group III with KI after SDF and group IV with distilled water. After 8 days of pH cycling, vickers microhardness was measured and difference before and after treatment was calculated. For SEM, 2 samples were evaluated respectively after enamel polishing, lesion formation and after pH cycling. Group III showed highest increase in microhardness. Group I showed higher increase in microhardness than Group II but without statistical difference. Group IV showed lowest increase in microhardness value among 4 groups. On SEM image, group I, II and III showed smoother and less irregular surface compared to group IV. Amorphous crystal pellicles were observed in group III. In conclusion, SDF, SDF and NaF, SDF and KI groups showed smoother surface and increase in microhardness suggesting the possibility that remineralization effect might take place in oral conditions. In addition, in limited conditions of this study, applying NaF varnish after SDF did not increase the remineralization efficacy of SDF while KI significantly increased the remineralization efficacy of SDF. However, additional study considering various conditions that might affect demineralization and remineralization in clinical situations need to be conducted.

PEMBUATAN GEL HIDROKSIAPATIT CANGKANG KERANG-SIMPING (Amusium pleuronectes) DAN PENGARUHNYA SETELAH APLIKASI DI LESI WHITE-SPOT EMAIL GIGI

Masalah kesehatan gigi tertinggi di Indonesia adalah karies yaitu rusaknya jaringan keras gigi. Pencegahan karies dapat dilakukan dengan meningkatkan remineralisasi. Cangkang kerang-simping merupakan limbah industri kaya kalsium yang dapat menjadi prekursor hidroksiapatit yaitu kristal penyusun gigi. Penelitian ini bertujuan untuk mensintesis gel hidroksiapatit dari cangkang kerang- simping dan mengetahui pengaruh gel hidroksiapatit terhadap remineralisasi email gigi. Metode penelitian merupakan eksperimental laboratoris 2 tahap. Pertama adalah sintesis hidroksiapatit dan evaluasi fisikokimia menggunakan SEM-EDX dan XRD. Hidroksiapatit kemudian dibuat menjadi sediaan gel dan diuji secara organoleptik. Tahap kedua adalah penelitian pre dan post-test control group design menggunakan 16 sampel gigi premolar satu rahang atas post ekstraksi yang terbagi menjadi 2 kelompok yaitu kelompok gel hidroksiapatit 20%, dan kelompok kontrol. Uji kekerasan email gigi menggunakan Vickers microhardness tester sebanyak 2 kali, yaitu sebelum dan setelah aplikasi gel. Hasil menunjukkan bahwa hidroksiapatit cangkang kerang simping berukuran nano, berbentuk granular dengan rasio molar Ca:P 3,22. Konsistensi gel hidroksiapatit homogen, sedikit berbau dan berwarna putih krem. Pada hasil uji kekerasan email terdapat perbedaan signifikan sebelum dan sesudah aplikasi (p0,05) dan terdapat signifikansi perbedaan peningkatan kekerasan antar kelompok (p0,05). Peningkatan kekerasan email kelompok gel hidroksiapatit lebih tinggi daripada kelompok kontrol. Kesimpulannya adalah gel hidroksiapatit cangkang kerang-simping berpotensi sebagai agen remineralisasi email gigi

Influence of Carbon Nanowalls Interlayer on Copper Deposition

This research deals with the deposition of copper on a steel substrate. Two different methods were investigated: electrochemical and magnetron sputtering. The deposition parameters were optimized to obtain a coating layer with uniform granular structure and good adhesion to the substrate. As a novelty, carbon nanowalls (CNW) were used as reinforcement in copper coatings on the steel surface. The morphology of the coatings, adhesion and Vickers microhardness were performed to emphasize the CNW influence on the coating properties. Open circuit potential and Tafel analysis were used for electrochemical characterization. These kinds of CNW-copper composite with improved hardness and adhesion and surface electrical resistance around 1 Ω·cm could have miscellaneous applications in different domains such as aerospace, electronics, automotive and power-generation.

Is the Er:YAG laser affect the surface characteristics and bond strength of Y-TZP?

This study evaluated the surface characteristics and bond strength of Y-TZP treated with Er:YAG laser at different focal distances. 120 Y-TZP blocks were divided into five groups (n=24), according to the surface treatment: no treatment (C-); sandblasting with silica-coated aluminum oxide particles (C+); and Er:YAG laser application at focal distances of 1mm (Er:YAG-1), 4mm (Er:YAG-4), and 7mm (Er:YAG-7). Surface characteristics were analyzed using Vickers microhardness, confocal laser microscope, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). For the bond strength test, 100 Y-TZP blocks were subdivided into two subgroups (n=10), according to the resin cement used: with (MDP+) or without 10-methacryloyloxydecyl dihydrogen phosphate (MDP-). The Vickers microhardness and surface roughness were analyzed by one-way ANOVA and bond strength by two-way ANOVA and Tukey's test for both (α=0.05). Vickers microhardness differences were not observed between the groups (p>0.05); C+ showed higher surface roughness values. SEM images showed micromorphological differences between the groups. The XRD data detected tetragonal crystals for C- and, for the other groups, tetragonal and monoclinic peaks. For bond strength, no statistically difference significance were observed among the cements with or without MDP (p>0.05) but showed significant difference between the surface treatments (C+ > C- = Er:YAG1 > Er:YAG4 = Er:YAG7) (p<0.05). Suggested that the Er:YAG laser cannot replace conventional treatment with aluminum oxide particles and the presence of MDP in the resin cement had no influence on the bond strength.

Evaluation of surface roughness and Vickers microhardness of various nano-herbal extracts on demineralized dentin and their bactericidal efficacy with 970-nm wavelength diode laser irradiation

Objective Was to evaluate effect of clove, turmeric and garlic nano-herbal extracts on surface roughness and microhardness of demineralized dentin, and their bactericidal effect on Streptococcus mutans and Streptococcus sobrinus with or without diode laser irradiation. Methods Three 5% nano-formulas were prepared and characterized using transmission electron microscope. MI paste Plus™ was used as control. A total of 100 specimens of demineralized dentin were prepared and treated with 3 W-power diode laser; then, the different tested materials for 10-min before the surface roughness and Vickers microhardness tests were conducted. Eighty coronal cavities were prepared (1-mm diameter × 2-mm depth). Cavities were inoculated with the tested materials with S. mutans or S. sobrinus bacteria, with or without diode laser irradiation for 20-s. Colony-forming unit method was used for counting the viable bacteria. Data were explored for normality using Kolmogorov–Smirnov and Shapiro–Wilk tests and showed parametric distribution for the surface roughness and microhardness tests, and non-parametric distribution for the bactericidal activity test. Results The herbal formulas had a significant surface roughness and microhardness mean values. It showed a significant antimicrobial effect on the tested bacteria. When they were combined with diode laser, they showed a significantly higher antimicrobial effect. Conclusions The tested herbal formulas represent potent topical remineralizing and antibacterial agents especially when they are used in conjunction with diode laser irradiation.

Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins

Aim: The aim of this study was to investigate the effect of different application techniques on microhardness in one universal resin material and three different bulk-fill composite resin materials. Materials and Methods: In this study, one universal composite resin (Universal Restorative 200 [U], 3M-ESPE, USA) and three different bulk-fill composite resins (Filtek-One Bulk-Fill Restorative [F]; 3M-ESPE, USA: Tetric Evo-Ceram Bulk-Fill [E]; and Ivoclar-Vivadent, Liechtenstein; Tetric N-Ceram Bulk-Fill [N], Ivoclar-Vivadent, Liechtenstein) materials were used. A total of 60 disk-shaped samples, including 20 samples from each bulk-fill composite resin group, were prepared. The polymerization of the bulk-fill composite resins in one group was completed using a 2 mm (40 sec) + 2 mm (40 sec) incremental technique, and in the other group, it was completed using a 4 mm bulk technique (40 sec). The U composite resin (control group) polymerization was completed using a 2 mm + 2 mm (40 sec) incremental technique (n = 10). The Vickers microhardness (VHN) values ​​of the samples were calculated. The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests (p < 0.05). Results: Higher VHN values ​​were found in the U composite resin compared to those in the bulk-fill composite resins (p < 0.05). In the bulk technique, a lower VHN value ​​was observed in the N bulk-fill composite resin than in the control group (p < 0.05), while there was no difference between the N and E composite resin groups (p > 0.05). A lower N bulk-fill composite resin was observed in the groups in which the incremental technique was applied than in the control group (p < 0.05). When the techniques applied to the bulk-fill composite resins were evaluated within themselves, higher VHN values ​​were observed in the E composite resin in the group in which the incremental technique was applied but not in the group in which the bulk was applied. Conclusion: It was observed that the content differences of composite resins were effective at different VHN values. The U composite resin (control) group showed higher VHN values than all the bulk-fill composite groups. How to cite this article: Fidan M, Gönder HY. Investigation of the effect of different application techniques on microhardness in bulk-fill composite resins. Int Dent Res 2021;11(Suppl.1):32-7. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.6 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Study of Lithium Disilicate Based Nano Glass Ceramics Containing P2O5.

Multi component Lithium disilicate based glasses containing P2O5 have been synthesized by conventional melt quenching technique. The replacement of (Li2O+SiO2) by P2O5 and its nucleating effect has been discussed. Structural features of glasses were evaluated by DTA, FTIR and Raman spectroscopy. The glass samples have been converted into glass ceramics by following three stage heat treatment schedule. XRD, FESEM, HAADF imaging and EDX analysis has been carried out for glass ceramics. Vickers microhardness and Vickers indentation fracture toughness of all the glass ceramics have been measured. UV–Visible spectroscopy study has been carried out for glass ceramics to investigate the optical properties. The glass ceramic with 1.5 mol % P2O5 has highest transmittance. Glass ceramics with P2O5 ≥1 mol % having Li2Si2O5 as main phase exhibit high Vickers microhardness (Hv) about 6.71-6.82 GPa which is suitable for dental and armor applications.

Propriedades mecânicas das fases ferrita e austenita de aço inoxidável duplex

Aços inoxidáveis duplex apresentam elevada resistência mecânica e resistência à corrosão, propriedades requeridas pelas indústrias petroquímicas. Esta combinação tem ampliado a utilização destes aços, e motivado diversas pesquisas. Os aços inoxidáveis duplex recebem este nome, devido à microestrutura ser formada por aproximadamente 50% de austenita e 50% de ferrita. Sabe-se que a dureza está diretamente relacionada à resistência mecânica, e que esta propriedade pode variar de acordo com a microestrutura do material. O objetivo do presente trabalho é avaliar e comparar a dureza das fases austenita e ferrita presentes nos aços duplex. Uma amostra foi preparada metalográficamente, sendo posteriormente atacada com a solução Behara pela técnica de “color etching”. Após o ataque químico as amostras foram submetidas a ensaios de microdureza Vickers, apresentando 247,8±35,1 HV0,1 e 263,22±11,6 HV0,1 para a ferrita e austenita, respectivamente. Após analise estatística dos resultados, concluiu-se que as fases ferrita e austenita possuem durezas similares. Duplex stainless steels have high mechanical strength and corrosion resistance properties required by the petrochemical industry. This combination has expanded the use of these steels, and motivated many studies. The duplex stainless steels are named because of the microstructure is formed by about 50% to 50% austenite and ferrite. It is known that the hardness is directly related to mechanical strength, and that this property can vary depending on the microstructure of the material. The objective of this study is to evaluate and compare the hardness of austenite and ferrite phases present in the duplex stainless steels. A sample was prepared by metallographic preparation techniques, and was then attacked with the solution BEHARA with technique of color etching. After etching the samples were tested for Vickers microhardness, with 247.8 ± 35.1 HV0, 1 and 263.22 ± 11.6 HV0, 1 for ferrite and austenite, respectively. After statistical analysis of results showed that the ferrite and austenite phases have similar hardness.

Microstructures and Mechanical Properties of Solid-State Welded Steels

This study aimed to evaluate the soundness of solid-state welded steels. STS 430F alloy with a rod type was selected as experimental material, and the friction welding was conducted at a rotation speed of 2,000 RPM and upset length of 3 mm. The application of friction welding on STS 430F rods led to significant grain refinement in the welded zone (1.3 µm) compared to that observed in the base material (16.8 µm). The refined grains in the welds contributed to the development of the mechanical properties. In particular, the Vickers microhardness was increased by approximately 25% compared to the base material, and the fracture at the tensile specimen of the welds occurred at the base material zone and not in the welded zone, which suggests a soundly welded state on the STS 430F rods.