Ammoniacal Silver Research Articles

The Effect of Gravity on Marginal Integrity of Different Flowable Bulk-Fill Resin Composites.

Background and Objectives: The aim of this quantitative research was to investigate the effect of gravitational forces on the marginal integrity of different bulk-fill composites by micro-CT imaging. Materials and Methods: Fifty caries-free human third molars extracted for prophylactic purposes were used in this study. Each tooth was prepared with two proximal box cavities, with dimensions of 3 mm × 3 mm × 5 mm. Five distinct groups, each comprising 20 cavities, thus totaling 100 cavities for this study: (1, Group CON): Clearfil Majesty Flow + Clearfil Majesty Esthetic (as the control); (2, Group FBR): Filtek Bulk-fill Flowable Restorative + Clearfil Majesty Esthetic; (3, Group XTB): Voco Extrabase + Clearfil Majesty Esthetic; (4, Group SDR): SDR + Clearfil Majesty Esthetic; and (5, Group SNC): Sonicfill. When restoring the mesial cavities, the occlusal surfaces of the teeth in the mold were positioned upwards, counteracting the force of gravity. In contrast, for the restoration of the distal cavities, the occlusal surfaces were aligned downwards, to be parallel with the gravitational pull. After restorative procedures, each tooth was treated with 5000 thermal cycles. A solution of ammoniacal silver nitrate (AgNO3) was employed as a tracing agent. The micro-CT scans were conducted and the total volume of silver nitrate and the total volume of restorations within the relevant region of interest were calculated in "mm3" with software. Two-way ANOVA and Tukey tests were performed at a significance level of p = 0.05 with Graphpad Prism v 8.2.1 software. Results: Both gravity effect and interaction showed no statistical differences (p > 0.05). Statistically significant differences were observed in the restorative materials (p < 0.05). Conclusions: Gravitational forces do not emerge as a major factor affecting the marginal integrity of flowable bulk-fill composites in class II restorations. The chemical composition of the composites plays a more crucial role, with the XTB composite showing higher microleakage ratios compared to the others.

Tribuloside acts on the PDE/cAMP/PKA pathway to enhance melanogenesis, melanocyte dendricity and melanosome transport

Ethnopharmacological relevanceTribuloside, a natural flavonoid extracted from Chinese medicine Tribulus terrestris L., has shown potent efficacy in treating various diseases. In China, the fruits of Tribulus terrestris L. have long been utilized for relieving headache, dizziness, itchiness, and vitiligo. Water-based extract derived from Tribulus terrestris L. can enhance melanogenesis in mouse hair follicle melanocytes by elevating the expression of α-melanocyte stimulating hormone (α-MSH) and melanocortin-1 recepter (MC-1R). Nevertheless, there is a lack of information regarding the impact of tribuloside on pigmentation in both laboratory settings and living organisms. Aim of the studyThe present research aimed to examine the impact of tribuloside on pigmentation, and delve into the underlying mechanism. Materials and methodsFollowing the administration of tribuloside in human epidermal melanocytes (HEMCs), we utilized microplate reader, Masson-Fontana ammoniacal silver stain, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) to measure melanin contents, dendrite lengths, melanosome counts; L-DOPA oxidation assay to indicate tyrosinase activity, Western blotting to evaluate the expression of melanogenic and associated phosphodiesterase (PDE)/cyclic adenosine monophosphate (cAMP)/cyclic-AMP dependent protein kinase A (PKA) pathway proteins. A PDE-Glo assay to verify the inhibitory effect of tribuloside on PDE was also conducted. Additionally, we examined the impact of tribuloside on the pigmentation in both zebrafish model and human skin samples. ResultsTribuloside had a notable impact on the production of melanin in melanocytes, zebrafish, and human skin samples. These functions might be attributed to the inhibitory effect of tribuloside on PDE, which could increase the intracellular level of cAMP to stimulate the phosphorylation of cAMP-response element binding (CREB). Once activated, it induced microphthalmia-associated transcription factor (MITF) expression and increased the expression of tyrosinase, Rab27a and cell division cycle protein 42 (Cdc42), ultimately facilitating melanogenesis, melanocyte dendricity, and melanin transport. ConclusionTribuloside acts on the PDE/cAMP/PKA pathway to enhance melanogenesis, melanocyte dendricity, and melanosome transport; meanwhile, tribuloside does not have any toxic effects on cells and may be introduced into clinical prescriptions to promote pigmentation.

The Effect of Final Irrigation Protocols on the Apical Sealing Ability of Epoxy Resin-based and Bioceramic-based Root Canal Sealers

Aim: This study was designed to investigate the effect of different final irrigation protocols on the apical sealing ability of bioceramic and epoxy resin-based sealers.&#x0D; Materials and methods: Thirty human single-rooted mandibular premolars were instrumented using ProTaper Next rotary files. Teeth were randomly divided into three groups according to the final irrigation regimen; Group I: 5 ml 0.2% CNPs/3 min, Group II: 2.5 ml 0.2% CNPs/1.5 min followed by 2.5 ml 17% EDTA/1.5 min, and Group III: 5 ml 17% EDTA/3min. All groups were subdivided into two subgroups based on the obturation material; Subgroup A: gutta-percha/Sure-Seal Root BC Sealer and Subgroup B: gutta-percha/AH Plus. All canals were obturated using single cone obturation technique. The apical sealing ability was assessed using modified silver staining technique with ammoniacal silver nitrate tracer solution. Samples were sectioned longitudinally and examined using scanning electron microscope.&#x0D; Results: Sure-Seal Root BC sealer showed significantly lower nanoleakage compared to AH Plus (p &lt; 0.001). No significant difference was recorded in the nanoleakage of Sure-Seal Root BC sealer among the three groups (p = 0.284), while AH Plus showed a significantly higher nanoleakage in the EDTA group (p = 0.002). The depth of silver nitrate penetration into the dentinal tubules was significantly higher in AH Plus subgroup with the three different irrigation protocols (p &lt; 0.001). For both sealers, the highest penetration depth for silver nitrate tracer solution was recorded in the EDTA group (p &lt; 0.001).&#x0D; Conclusions: The apical sealing ability of bioceramic sealers is better than that of epoxy resin-based sealers. The type of the final irrigating solution seems to affect the post-obturation seal of both AH Plus and Sure-Seal Root BC sealer.&#x0D; Keywords: Bioceramic, AH Plus, Chitosan nanoparticles, EDTA, Sealing ability.

Four new species of Hysterocinetida (Protozoa: Ciliophora) from the digestive tract of earthworms collected to the lower Nyong estuary (South Coast, Cameroon)

Hysterocinetida are a large assemblage of ciliates characterized by sucker and buccal apparatus. They have a wide distribution in the digestive tract of oligochaete annelids of the genus Alma that inhabit hydromorphic parts of non-anthropic hydrosystems. On the basis of morphological, morphometric and infraciliature characteristics revealed by ammoniacal silver carbonate and 4',6-Diamidino-2-Phenyl Indole (DAPI) staining techniques, four forms were identified as new members belonging to three genera: Preptychostomum, Proptychostomum and Thurstonia. Preptychostomum donendaensis n. sp. is ovoid with a slightly narrowed anterior part and is commensal to the digestive tract of Alma emini and A. nilotica. There are 20-23 kineties on the lower side and 42-45 on the upper side. Proptychostomum gigas n. sp. is pear-shaped, with a narrowed anterior part and a wide posterior part (125-138 µm × 80-85 µm). There are 40 to 44 kineties, equally distributed on both sides of the ciliate. Its sucker is circular and measures 31-34 µm in diameter. The peristome follows the contour of the cell and the infundibulum has a turn of spire. Thurstonia emini n. sp. is identified in the digestive tract of A. emini. The cell is elongate, with the anterior pole narrower than the truncate posterior pole (90-115 µm × 40-55 µm). The kineties are equally distributed on both sides of the ciliate. The sucker is in the shape of an inverted U. Thurtonia nilotica n. sp. is commensal of the digestive tract of A. nilotica. The cell is pear-shaped, with the anterior part narrowed and the posterior part swollen (110-114 µm × 85-92 µm). 46 to 50 kineties are unevenly distributed on both sides of the ciliate. The sucker is shaped like an inverted lunar crescent.

Effect of Application Deviations on Dentin Sealing of a Universal Adhesive: Permeability and Nanoleakage.

The objective of this study was to evaluate the effect that deviations from the recommended protocol of a universal adhesive system, applied to dentin according to the self-etch (SE) and the etch-and-rinse (ER) techniques, has on permeability and nanoleakage. Permeability: 60 extracted non-carious human third molars (N = 60) were sectioned to obtain 0.7-mm-thick dentin disks. The specimens were randomly assigned to three subgroups and treated with a universal adhesive system (Prime&Bond Active Universal) using the SE and ER techniques: (1) following the manufacturer's instructions with 5 seconds drying (MFR DRY 5S), (2) following the MFR DRY 10S, and (3) reduced application time of the adhesive to 5 seconds (APPL 5S). Nanoleakage: 12 additional 0.7-mm-thick dentin disks were prepared, treated and divided into six groups. They were immersed in 50 wt% ammoniacal silver nitrate and processed according to conventional methods for the analysis of nanoleakage under transmission electron microscopy. The results were statistically analyzed by two-way analysis of variance and post-hoc Bonferroni's test. Significant differences in permeability reduction were observed among the treatment groups (0.001). The results obtained for APPL 5S were significantly lower than the results obtained for both the MFR DRY 5S (p = 0.003) and MFR DRY 10S (p = 0.001). The reduced application time to 5 seconds creates imperfect dentin tubule sealing, which may explain clinical reports of postoperative sensitivity and early degradation of the resin-dentin interface.

Natural Citrus flavanone 5-demethylnobiletin stimulates melanogenesis through the activation of cAMP/CREB pathway in B16F10 cells

Background5-demethylnobiletin is a natural polymethoxyflavone which is isolated from the extract of citrus fruits peels. It exhibits a broad spectrum of biological activities such as anti-cancer, anti-inflammatory, cardiovascular protective and neuroprotective effects, however, its effect in melanogenesis remains uninvestigated. PurposeMelanin synthesis is a very important biological process in curing disease such as vitiligo with depigmentation on the skin. In the current work, we aim to confirm the bioactivity and mechanism of 5-demethylnobiletin in stimulating melanogenesis. Study DesignTo confirm the mechanistic role of 5-demethylnobiletin in enhancing melanogenesis, its effect on the activity of tyrosinase, together with the level of microphthalmia-associated transcription factor (MITF), Trp-1, Trp-2, melanocyte-specific marker protein PMEL17, Rab27a, Melanophilin and Myosin VA were studied in B16F10 melanoma cells. MethodsMultiple biological assays on melanogenesis-associated proteins such as melanin content detection, tyrosinase activity colorimetric assay, qPCR, western blot analysis, dual-luciferase reporter assay, cAMP activity assay and Fontana-Masson ammoniacal silver staining were used to confirm the role of 5-demethylnobiletin in stimulating melanin synthesis and the transportation of melanosomes. ResultsAs confirmed by multiple biological assays, 5-demethylnobiletin is found to stimulate dendrite structure formation in cells, melanin synthesis and the transportation of melanosomes, via inducing the phosphorylation of cAMP response element-binding protein (CREB) and increasing the intracellular levels of cAMP in vitro through the PKA-dependent pathway. ConclusionThe findings suggested that 5-demethylnobiletin may be considered as a potential natural product candidate for patients with pigment disorder.

Dentin Permeability and Nanoleakage of Universal Adhesives in Etch-and-rinse vs Self-etch Modes.

This study evaluates the reduction in dentin permeability (P) and the expression of nanoleakage in resin-dentin interfaces made with universal adhesives, comparing the self-etch mode of application with the etch-and-rinse mode of application. To measure dentin P at the baseline and after adhesive polymerization, 80 extracted noncarious human third molars (N=80) were sectioned to obtain 0.7-mm-thick midcoronal dentin disks. The specimens were randomly assigned to 8 groups according to the different adhesive systems and application modes used: Scotchbond Universal (SBU; etch-and-rinse [ER] mode vs self-etch [SE] mode), OptiBond XTR (OPT; etch-and-rinse mode vs self-etch mode), Clearfil Universal Bond Quick (CL; etch-and-rinse mode vs self-etch mode), and Adhese Universal (ADH; etch-and-rinse mode vs self-etch mode). A two-way analysis of variance with interaction was used to evaluate the P reduction differences among the groups (α=0.05). Sixteen additional 0.7-mm-thick dentin disks were similarly prepared and treated, immersed in 50 wt% ammoniacal silver nitrate, and then processed according to conventional methods for analysis under transmission electron microscopy. The differences in P reduction among the adhesives were significant (p=0.029). For OPT and ADH (p=0.0304 and p=0.0120, respectively), the P reduction was higher in the ER mode than in the SE mode. For CL and SBU, no differences in P reduction was observed between the two application modes (p>0.05). All the groups showed some pattern of nanoleakage. No adhesive system completely reduced dentin P. Dentin sealing was higher for OPT and ADH in the ER mode, while for SBU and CL, there was no difference between the two modes. All the adhesive systems showed nanoleakage.

Electric current effects on bond strength, nanoleakage, degree of conversion and dentinal infiltration of adhesive systems

To evaluate the effect of three adhesive systems applied under electric current on microtensile bond strength (μTBS) and degree of conversion (DC). Molar teeth were restored with the aid of three adhesive systems (Adper Single Bond 2—SB2; Clearfil SE Bond—CSE; and Single Bond Universal—SBU) under different electric current intensities (0 μA; 25 μA; and 50 μA). Composite resin blocks were built up in increments (2 mm) and sectioned into 1 × 1 mm beams. The μTBS was tested after 24 h and 1 y distilled water storages. Samples (n = 10) from 24 h to 1 y storages were immersed in a 50% ammoniacal silver nitrate solution and submitted to scanning electron microscopy. The silver nitrate in the hybrid layer was quantified (ImageJ software). The adhesive systems' dentinal infiltration was analyzed using confocal laser scanning microscopy. Fourier transform near infrared spectroscopy was used to measure the DC. The μTBS data were submitted to two-way ANOVA (time vs. electric current) and Bonferroni's test (α = 0.05). Quantitative nanoleakage data were submitted to two-way ANOVA (electric current vs. adhesive) and Bonferroni's test (α = 0.05). DC data were submitted to one-way ANOVA and Tukey's test (α = 0.05) for each adhesive system. The electric current statistically increased the μTBS for SB2 and CSE in 24 h storage, as well as for SB2, CSE and SBU in 1 y storage. No significant difference was observed between storage time for CSE and SBU. When compared to the control, electric currents (25 μA and 50 μA) showed significantly higher DC mean values for SB2 and SBU, and had no effect on CSE. The electric currents (25 μA and 50 μA) reduced the adhesive system's nanoleakage after 1-year storage, and improved the infiltration of SB2 and CSE. Both electric current intensities improved dentinal interface stability.

Brief descriptions of the principles of prominent methods used to study the penetration of materials into human hair and a review of examples of their use.

Consumers are attracted to the latest fashion trends and different looks. This drives the search for novel hair treatments. Some chemicals present in hair treatment products can penetrate the hair shaft. These materials can either nourish or injure the hair cortex. Different techniques have been used to investigate the mechanism of molecule penetration and the conditions under which penetration occurs. This article reviews the techniques applied for this purpose. Various microscopy techniques are used to capture clear and colourful images to determine the diffusion pathways and the exact location of the molecules under study. However, the laborious sample preparation often leads to sample destruction since cross-sectioning is often required. While various other techniques have been successfully used for investigating the penetration methods, most of these require different amounts of work to be put in for sample preparation and instrumentation. Several spectroscopic techniques have been used to study the penetration of the molecules because of the high levels of accuracy and the quick response time of these techniques. Moreover, the samples are not damaged during the investigation.

Influence of selective etching on the enamel and dentin leakage of three low shrinkage composites in class V restoration

This study determined if prior selective enamel etching affected leakage of enamel/dentin margins in Class V low-shrinkage resin-based composite restorations. Round cavities, centered on the cemento/enamel junction, 2 mm in diameter and 2 mm in depth were prepared on the buccal, palatal or lingual surfaces of premolar teeth to have a total of 60 cavities. One side of the tooth received selective enamel etching and both sides were restored using one of 3 restorative materials (n = 10): Aelite LS posterior/All-bond SE, Estelite Sigma Quick/Bond Force, or Filtek P90/P90 System Adhesive. The teeth were fatigued for 5000 thermal cycles, and the marginal sealing was challenged with 50% ammoniacal silver nitrate. The interface was analyzed and the leakage score was calculated. Two-way ANOVA revealed that Filtek P90 (25.5±17.4) had lower leakage than Estelite Sigma Quick (63.1±34.5) and Aelite LS Posterior (64.2±41.8) with self-etching. With selective etching, the three materials showed reduced leakage in enamel. A significant difference (P &lt;0.05) was found between leakage in enamel and dentin for the Aelite LS Posterior selective etch group and for Estelite Sigma Quick. Selective etching reduced enamel leakage for all materials in one-step self-etch materials. Two-step self-etch adhesives bond better to enamel and dentin than one-step resin-based adhesives.

Effect of shelf-life of a universal adhesive to dentin

The microtensile bond strength (μTBS), nanoleakage expression (NL), and endogenous enzymatic activity of a simplified universal adhesive system used in combination with a dual-cure resin cement for luting indirect restorations were evaluated considering its shelf-life (as-received vs expired). The universal adhesive was used as-received (AS-R) by manufacturer or after three months after being expired (EXP). Resin composite overlays (n = 10) were luted to flat deep coronal dentin surfaces with a universal bonding system (iBond universal, used in the self-etch mode) in combination with a dual-cure resin cement (RelyX Ultimate; 20s of light-cure followed by 15 min of self-cure at 37 °C). After 24 h, the specimens were cut into microtensile sticks (1 mm2) and stressed to failure under tension, in accordance with ISO/TS 11.405. The fracture pattern was evaluated with optical microscopy. The significance level of p = 0.05 was used for the statistical analysis. Additional specimens (n = 4) were processed for quantitative interfacial nanoleakage expression using ammoniacal silver nitrate. To investigate the endogenous enzymatic activity within the hybrid layer in situ zymography was performed. The EXP group obtained significantly lower μTBS values than those recorded in the AS-R group (p < 0.05). NL resulted in higher deposition of AgNO3 granules when the adhesive was used in the EXP group compared to the AS-R bonding system. In situ zymography assay revealed increased level of fluorescence when the universal bonding system was used at the end of shelf-life compared to the AS-R group. The use of the universal adhesive system beyond the expiry limit resulted in decreased bonding performances. Furthermore, the higher endogenous enzymatic activity recorded after the end of the shelf life of the universal adhesive would portend for a shortened durability of the restorations.

A comparison of different nanoscopic silver species with respect to their capacity to bind mercury from the gas-phase using total reflection X-ray fluorescence

Mercury compounds like mercury chloride (HgCl2) were often used to protect cultural heritage specimens, e.g., herbaria and paintings from damage. Over time, Hg0 is formed by bacterial activity and released into the air.Here we present our study on the performance of different nanoscopic Ag species to collect airborne Hg, which is subsequently analyzed by total reflection X-ray fluorescence (TXRF). We studied silver nanoparticles (AgNPs) of different size, i.e., 10 nm and 100 nm AgNPs(Citrate) and particles with presumably weaker stabilizers, i.e., 10 nm AgNPs(borohydride(BH4−)) as well as species from light-exposed (LE) pure aqueous (LE-AgNO3(H2O)) and ammoniacal silver nitrate solutions (LE-AgNO3(NH3)). Hg capture was highest for the LE-AgNO3(NH3) species with a ratio of Hg/Ag of 0.78 in the amalgam. The performance to capture Hg decreased from LE-AgNO3(NH3) to AgNPs(Citrate) in the following order LE-AgNO3(NH3) > LE-AgNO3(H2O) > 10 nm AgNPs(BH4−) > 10 nm AgNPs(Citrate) > 100 nm AgNPs(Citrate), the latter collected airborne Hg with a ratio of Hg/Ag of 0.0006. The relative standard deviation of the TXRF measurements of Hg collected from a saturated atmosphere (n = 3 and n = 5) was lowest with 9% for LE-AgNO3(H2O) and highest for the AgNPs(Citrate) with 38%. The AgNPs(BH4−) and AgNPs(Citrate) species were also used to study Hg capture from the gas-phase in concentrations between 0.0012 mg/m3 and 0.024 mg/m3 (European Union regulated threshold: 0.02 mg/m3; saturated Hg atmosphere: 13.6 mg/m3 at 20 °C). Detection limits were found to be 0.018 μg/m3 for AgNPs(BH4−) and AgNPs(Citrate).

The effects of cavity disinfection on the nanoleakage of compomer restorations: an in vitro study.

Cavity disinfection, in addition to routine caries removal methods, is recommended to eliminate the microorganisms. The aim of this study was to compare the effect of various systems Er,Cr:YSGG lasers, diode lasers and FotoSan and agents Corsodyl; Cervitec and Cervitec Plus and Fluor Protector-on the nanoleakage of compomer restorations when used for cavity disinfection. A total of 40 intact human deciduous molar teeth containing Black V cavities (3×2×1.5 mm) on the buccal and lingual surfaces parallel to the cementoenamel junction were randomly divided into 8 groups according to the cavity disinfection methods. The antibacterial agents and systems were applied according to the manufacturer's instructions. Restorations were completed using a compomer. The restored teeth were then subjected to thermocycling for 500 cycles in a water bath at 5°C and 55°C with a dwell time of 30 seconds. After the thermocycling procedures, 1-mm sticks were obtained from the center of each cavity to prepare for the nanoleakage test. After the teeth were sectioned, they were immersed in 50 wt % ammoniacal silver nitrate solution for 24 hours and dipped in photo-developing solutions for 8 hours with fluorescent light irradiation. The samples were examined under a scanning electron microscope (SEM). The non-parametric Kruskal-Wallis and Mann-Whitney U test (p<0.05) were applied. The Er,Cr:YSGG laser group showed significantly less nanoleakage than all of the tested groups (p<0.01). The diode laser, Fluor protector and FotoSan groups showed similar nanoleakage to that of the control group (p>0.05). The Corsodyl (p<0.01) and Cervitec (p<0.001) groups showed significantly higher nanoleakage than the control group. Er,Cr:YSGG laser irradiation which showed lower nanoleakage scores from either control or tested groups can be recommended for cavity disinfection Additionally, a diode laser and FotoSan, which have antibacterial effects and no negative effect on leakage, can be used for cavity disinfection.

Superficial and internal adaptations of a new self-curing composite resin restored class Ⅴ cavity

Objective: To investigate the superficial and internal adaptations of a new self-curing composite resin in Class Ⅴ cavities. Methods: Class Ⅴ cavities were prepared in 56 caries-free human maxillary premolars (collected from Department of Oral and Maxillofacial Surgery, Capital Medical University School of Stomatology) extracted for orthodontic reasons, and these premolars were assigned into two groups (28 specimens each group). Experimental group were restored with a pretreating agent (Tooth primer) and a new self-curing composite resin (Bondfill SB). Control group were restored with a self-etching adhesive (Scotchbond Universal) and a light-curing composite resin (Z100). The restored teeth were subjected to a fatigue test to simulate temperature change and occlusal load in oral environment: mechanical cycles (1 200 000 cycles at 49 N with a frequency of 1 Hz) and thermocycles (3 000 cycles from 5 ℃ to 55 ℃ with a dwelling time of 1 min each). Before and after fatigue test, restored teeth were immersed in an 50% ammoniacal silver nitrate solution and reduced. Superficial perfect margin percentage value and length of silver deposit along the internal interface were quantified by scanning electron microscopy (SEM). Ultrastructure of dentin bonding interface was analyzed by transmission electron microscope (TEM). Results: Before fatigue test, superficial gaps at dentin side in the specimens in experimental group were narrower than those in control group, and length of silver deposit at enamel side [(0.67±0.15) μm] in specimens in the control group was significantly lower than that in the experimental group [(33.54± 10.27) μm] (P<0.05). After the fatigue test, control group showed higher perfect margin percentage value to enamel [(55.08±15.20)%] than experimental group [(25.15±12.47)%] did (P<0.05). After the fatigue test, cohesive failures could be more easily found in experimental group than in control group at surficial and internal interfaces. In TEM results, more silver deposits were found at dentin bonding interface in control group than in experimental group before the fatigue test. After the fatigue test, the deterioration at dentin bonding interface mostly happened at the bottom of the hybrid layer in control group, while in experimental group it could be found at the bottom of the hybrid layer and in the restorative material. Conclusions: When restored in Class Ⅴ cavity, the studied light-curing composite shows better superficial and internal adaptations for enamel than the new self-curing composite resin and the new self-curing composite resin shows good superficial and internal adaptations for dentin.

Bonding Performance of Simplified Dental Adhesives with Three Application Protocols: An 18-month In Vitro Study.

To evaluate the influence of application protocol on the shear bond strength (SBS) and nanoleakage of simplified adhesives over 18 months. 810 dentin slices were obtained from 405 caries-free human molars. They were randomly assigned to 54 experimental groups resulting from the combination of "adhesive" (Adper Scotchbond 1XT [S1XT], Solobond M [SM], Scotchbond Universal Adhesive in etch-and-rinse mode [SUER] and self-etch mode [SUSE], Adper Easy Bond [EB], Clearfil S3 Bond Plus [CS3]), "application protocol" (manufacturer's instructions [MI], two extra layers of adhesive [EL], hydrophobic resin layer [HL]), and "aging time" (24 h [24H], 6 months [6M], and 18 months [18M] in water). SBS tests were carried out using a Watanabe device followed by failure mode analysis. For the nanoleakage study, specimens from 54 additional molars were prepared as previously described, immersed in ammoniacal silver nitrate, and evaluated with SEM. SBS data were analyzed with ANOVA followed by Tukey's post-hoc tests; failure mode data were analyzed using chi-squared tests (α = 0.05). Nanoleakage data were analyzed with the Kruskal-Wallis test followed by LSD tests (α = 0.05). After 18M, S1XT and SUSE achieved the highest mean SBS (p < 0.05). Regarding the application protocols, EL and HL provided higher mean SBS than those obtained with MI (p < 0.05). HL resulted in the highest mean SBS and the lowest mean nanoleakage after 18M. Simplified adhesives may need an extra hydrophobic resin layer to achieve a stable and durable adhesive interface. The self-etch approach should be recommended for the universal adhesive.

Universal adhesives and dual-cured core buildup composite material: adhesive properties.

Dual-cured buildup composites and simplified light-cured adhesive systems are mixed with a chemical activator to prevent the incompatibility between them.Objective:To evaluate microshear bond strength (μSBS) and nanoleakage (NL) of three universal adhesives used under buildup composites using different curing modes, at baseline and after 6-months (6m).Methodology:Dentin specimens of 55 molars were assigned to: Clearfil Universal Bond[CFU], Prime&Bond Elect[PBE] and One Coat 7 Universal[OCU]. All-Bond Universal[ABU] and Adper Scotchbond Multi-Purpose[SMP] were used as controls. CFU, PBE, and OCU were: light-cured [LC], dual-cured using a self-curing activator [DC], and self-cured, using a self-curing activator and waiting for 20 min [SC]. Upon the application of the adhesive, transparent matrices were filled with a dual-cured buildup composite and light cured, then tested in mSBS. For NL, the specimens were submersed in ammoniacal silver nitrate and sectioned to observe under the SEM. Three-way ANOVA and Tukey's test were applied (α=0.05).Results:OCU/LC-PBE/LC resulted in higher mean μSBS than ABU/LC. For SMP/DC higher mean μSBS were obtained than for both CFU/DC and OCU/DC (baseline). No universal adhesive was significantly affected by curing mode or storage time. CFU, PBE, and OCU did not undergo significant changes in any curing mode (p>0.05). NL (baseline) PBE/LC resulted in higher %NL compared to ABU/LC. SMP/DC resulted in higher %NL than CFU/DC-OCU/DC. CFU/LC/DC resulted in lower %NL than CFU/SC. PBE/SC resulted in lower %NL than PBE/DC. OCU/LC/SC showed lower %NL than OCU/DC. OCU showed significant lower %NL than CFU and PBE. All CFU groups, as well as OCU/SC, resulted in increased %NL at 6m when compared with baseline.Conclusion:For universal adhesives used in etch-and-rinse mode, self-cured activator and different curing modes did not influence μSBS. However, some interactions were observed for NL, but this influence was material-specific.

Pío del Río-Hortega: The Revolution of Glia.

Pío del Río-Hortega (Portillo, 1882-Buenos Aires 1945) was a Spanish pioneer scientist. Here, we highlight his professional merits and scientific qualities, facets that permitted him to open the eyes of the scientific community to the existence of microglia and oligodendroglia. Indeed, after Cajal formulated the "neuron doctrine" (1888), Río-Hortega was perhaps whose contributions represent the most important advances in our understanding of the microscopic anatomy of the nervous system. Río-Hortega achieved his discoveries thanks to a histological staining method developed by himself, the ammoniacal silver carbonate staining, absolutely fundamental for his histological studies. His early education in Histology was due to Professor Leopoldo López-García, at the Faculty of Medicine of Valladolid. Later in Madrid (1912), Santiago Ramón y Cajal and Nicolás Achúcarro became his definitive tutors. Achúcarro was an exceptional neurohistopathologist and authentic mentor for Río-Hortega until his death in 1918. The scientific career of Río-Hortega oscillated between the international recognition of his scientific discoveries (nominated for the Nobel Prize in 1928 and 1937), and the personal/social misfortunes he suffered in Spain, such as his expulsion from Cajal's Laboratory in 1920, the hostile envy of some conservative Spanish academics for his scientific merit (1934), and his sad political exile (Paris, Oxford, and Buenos Aires) due to the Spanish Civil War (1936-1939). Perhaps, Pío del Río-Hortega is the paradigm of a Spanish scientist of the beginning of XXth century, living between the heaven and the hell, he revolutionized the scientific concept of glia. Anat Rec, 303:1232-1241, 2020. © 2019 American Association for Anatomy.

Validation of a method of quantifying 3D leakage in dental restorations

Statement of problemA reliable and validated protocol for nondestructive analysis of the entire restorative interface that could be applicable in studies assessing the adaptation of direct and indirect restorations is lacking. PurposeThe purpose of this in vitro study was to validate a 3D protocol for microleakage assessment in class II mesio-occluso-distal (MOD) cavities restored with composite resin. Material and methodsSixteen human third molars received standardized class II MOD preparations with cervical margins located 1 mm apical to the cemento-enamel junction. The specimens were restored with Filtek Bulk Fill Posterior (FBP) or Filtek Bulk Fill Flowable (FBF) and submitted to 10 000 thermocycles (5 °C and 55 °C with a 30-second dwell time at each temperature and 5-second transfer time). The specimens were scanned with microcomputed tomography (μCT) before and after immersion in 50% ammoniacal silver nitrate solution for 12 hours. Scanned data were processed, and the 3D amount of infiltrated silver nitrate was analyzed through the entire adhesive interface. In addition, the linear distance of silver nitrate infiltration was assessed using 3 axial images obtained from each specimen proximal box (2D analysis). Data were tested for homogeneity by using the Shapiro-Wilk test and evaluated by using 1-way ANOVA, followed by the post hoc Tukey HSD test (α=.05). ResultsFBP showed significantly lower leakage than FBF for both 2D and 3D analyses. A low correlation was observed between the assessment methods. ConclusionsThree-dimensional analysis of microleakage using μCT is a predictable and more reliable method for nondestructive and comprehensive analysis of the entire specimen.

Diazepam enhances melanogenesis, melanocyte dendricity and melanosome transport via the PBR/cAMP/PKA pathway

Diazepam is a medicament of the benzodiazepine family and it typically produces a sedative effect. Researchers have revealed that diazepam can induce melanogenesis and produce dendrite-like structures in B16 melanoma cells. However, the associated mechanisms of melanogenesis and phenotypic alterations have mostly remained unknown. In this study, we determined the effects of diazepam on melanogenesis, cellular phenotypic alterations, the location of melanosomes and the expression of relevant proteins in melanocytes using Masson–Fontana ammoniacal silver staining, scanning electron microscopy, immunocytochemistry and western blot analysis. Our results collectively indicated that diazepam had a pivotal role in melanocytes by enhancing melanin synthesis, melanocyte dendricity, melanosome trafficking, and capture at the dendrite tips. These functions might be attributed to the fact that diazepam activated the peripheral benzodiazepine receptor (PBR). This increased intracellular levels of cAMP, which stimulated the phosphorylation of cAMP response element-binding (CREB). As a result, this increased the tyrosinase, microphthalmia-associated transcription factor (MITF), Rab27a, Myosin Va, Rab17 and Cdc42 expression. This caused melanogenesis and melanosome transport. Therefore, our findings may provide a potential strategy for treating anti-hypopigmentation disorders.

Impact of shelf-life simulation on bonding performance of universal adhesive systems

ObjectivesTo evaluate the micro-tensile bond strength to dentin (μTBS), the degree of conversion (DC) and nanoleakage expression (NL) of eight dental adhesives considering their expiry date (as-received, half-life and or end of shelf-life) after shelf-life simulation. MethodsFive universal adhesives (Single Bond Universal, SBU; Tetric Bond Universal, TBU; OneCoat Universal, OCU; OptiBond Universal, OBU; and Prime&Bond Elect, P&B), two two-step self-etch adhesives (Clearfil SE, CSE; and AdheSE, ASE) and one two-step etch-and-rinse adhesive (Adper Singlebond 2, ASB) were evaluated. Shelf-life was simulated by storing the materials in an acclimatization chamber for different periods of time. The μTBS was tested in accordance with ISO/TS 11,405. DC was evaluated by means of FTIR spectroscopy. NL was evaluated after ammoniacal silver challenge. The significance level of α=0.05 was used for all statistical analyses. ResultsThe μTBS to dentin of TBU, P&B, ASE, and ASB adhesive systems remained stable throughout the shelf-life periods evaluated, while for SBU, OCU, OBU, and CSE, decreased significantly after evaluation in the ‘half-life’ or ‘end of shelf-life’ condition (p<0.05). Except for P&B, ASE and OBU, the degree of conversion significantly decreased after the shelf-life simulation (p<0.05). OCU, ASE, and CSE showed significantly increased percentage of silver deposition within the adhesive layer (p<0.05). SignificanceStoring conditions and progressively longer storage time affect the performance of universal adhesives systems.