Design of Multi-Functional Bio-Safe Dental Resin Composites with Mineralization and Anti-Biofilm Properties.

This study aims to develop multi-functional bio-safe dental resin composites with capabilities for mineralization, high in vitro biocompatibility, and anti-biofilm properties. To address this issue, experimental resin composites consisting of UDMA/TEGDMA-based dental resins and low quantities (1.9, 3.8, and 7.7 vol%) of 45S5 bioactive glass (BAG) particles were developed. To evaluate cellular responses of resin composites, MC3T3-E1 cells were (1) exposed to the original composites extracts, (2) cultured directly on the freshly cured resin composites, or (3) cultured on preconditioned composites that have been soaked in deionized water (DI water), a cell culture medium (MEM), or a simple HEPES-containing artificial remineralization promotion (SHARP) solution for 14 days. Cell adhesion, cell viability, and cell differentiation were, respectively, assessed. In addition, the anti-biofilm properties of BAG-loaded resin composites regarding bacterial viability, biofilm thickness, and biofilm morphology, were assessed for the first time. In vitro biological results demonstrated that cell metabolic activity and ALP expression were significantly diminished when subjected to composite extracts or direct contact with the resin composites containing BAG fillers. However, after the preconditioning treatments in MEM and SHARP solutions, the biomimetic calcium phosphate minerals on 7.7 vol% BAG-loaded composites revealed unimpaired or even better cellular processes, including cell adhesion, cell proliferation, and early cell differentiation. Furthermore, resin composites with 1.9, 3.8, and 7.7 vol% BAG could not only reduce cell viability in S. mutans biofilm on the composite surface but also reduce the biofilm thickness and bacterial aggregations. This phenomenon was more evident in BAG7.7 due to the high ionic osmotic pressure and alkaline microenvironment caused by BAG dissolution. This study concludes that multi-functional bio-safe resin composites with mineralization and anti-biofilm properties can be achieved by adding low quantities of BAG into the resin system, which offers promising abilities to mineralize as well as prevent caries without sacrificing biological activity.

Corrosion Resistance of Titanium Dental Implant Abutments: Comparative Analysis and Surface Characterization.

Metals subjected to the oral environment are prone to corrosion over time and this can be harmful. Metallic restoration components such as dental subgingival implant abutments are exposed to pH changes and different ions while in contact with saliva. The aim of the study was to evaluate the corrosion resistance of titanium dental implant abutments and to compare and contrast the surface characteristics of these alloys before and after corrosion. The corrosion examination (Ecorr, jcorr, OCP, polarization curve) of two implant abutments (TiDesign EV, Astra Tech, Dentsply, York, PA, USA; Individual Titanium Abutment, Apollo Implants Components, Pabianice, Poland) was performed in 0.9% NaCl and 5% HCl. Moreover, specimens were investigated using SEM-EDS before and after the corrosion test. The value of jcorr in NaCl was higher for Astra (34.2 × 10-8 ± 2.5 × 10-8 A/cm2) than for Apollo (8.8 × 10-8 ± 2.5 × 10-8 A/cm2). Whereas, in HCl, the opposite relationship was observed (Astra 2.9 × 10-4 ± 0.8 × 10-4 A/cm2 and Apollo 62.7 × 10-4 ± 9.3 × 10-4 A/cm2). An average reactive anodic current density in NaCl for Astra amounted up to ~0.2 × 10-5-1.5 × 10-5 A/cm2, while for Apollo-up to ~3.3-9.7 × 10-7 A/cm2. The composition of both alloys after corrosion in NaCl demonstrated some changes: a decrease in the Ti, and Al and an increase in oxygen content. Hence, both alloys after corrosion in HCl demonstrated some minor changes in the elemental composition. Based on the results it can be concluded that: 1. Astra and Apollo abutments revealed good corrosion resistance and a passivation layer on the surface. 2. Apollo abutments exhibited better corrosion resistance in a neutral environment, suggesting that Astra abutments were found to be more resistant to corrosion in an acidic medium.

The effect of in-office bleaching agents on the Vickers hardness and surface topography of polished and unpolished CAD/CAM composite materials.

In-office bleaching, using hydrogen peroxide, is effective to remove dental enamel stains. However, bleaching agents can deteriorate surface properties of CAD-CAM materials. This in vitro study aimed to investigate the effect of in-office bleaching agents on Vickers hardness and surface topography of polished and unpolished dental CAD-CAM composite materials (Grandio blocs, Lava Ultimate, BRILLIANT Crios, Cerasmart), and a polymer-infiltrated ceramic network block (Vita Enamic). The specimens were randomly divided into two groups: unpolished or polished. The micro-hardness and surface topography of each group were measured before bleaching, after a 60 min bleaching period, and 24-h and one-month post-bleaching. In-office bleaching significantly influenced the Vickers hardness of both the polished and unpolished CAD/CAM composite blocks, with Vita Enamic exhibiting the least hardness stability among all groups. Furthermore, in-office bleaching significantly influenced the surface roughness of unpolished CAD/CAM composite blocks. There was a significant difference in hardness reduction between the polished and unpolished specimens for most of the investigated materials at different time points. The bleaching did not influence the surface roughness of the investigated polished group, except for Vita Enamic and Lava Ultimate. However, it did influence the surface roughness of the investigated materials in the unpolished group.

Colour Parameters and Changes of Tea-Stained Resin Composite Exposed to Whitening Pen (In Vitro Study).

BACKGROUND: One of the crucial factors influencing the longevity of anterior aesthetic dental restorations is the colour stability of resin composites. Bleaching and whitening have become popular methods for enhancing dental aesthetics. Home whitening techniques, such as special pens, are widely available commercially. This in vitro study aimed to determine the efficiency of a whitening pen in removing tea stains from resin composite by measuring colour differences (ΔE00). Additionally, the study aimed to evaluate the variations in colour parameters measured by extra-oral and intra-oral spectrophotometers. METHODS: A total of 45 disc-shaped resin composite specimens were randomly divided into three groups; Group 1: stored in artificial saliva (control), Group 2: stored in artificial saliva followed by a whitening pen application, and Group 3: stored in tea followed by a whitening pen application. Colour measurements were taken three times for each specimen using two spectrophotometers (extra-oral and intra-oral devices); T1: before storage (baseline), T2: after storage in artificial saliva or tea for 6 days; and T3: after one week of whitening pen application in groups 2 and 3. The data were statistically analyzed using one-way ANOVA followed by the Tukey post hoc test (p ≤ 0.05). The independent sample t-test was also employed. The equation of CIEDE2000 (ΔE00) was used to calculate the colour difference between the dry, as-prepared specimens (baseline), and those after storage or bleaching. The colour changes exceeding the acceptability threshold (∆E00 = 1.8) were considered unacceptable. RESULTS: After whitening, the colour of the specimens stored in brewed tea (Group 3) remained unacceptable, as indicated by both the extra-oral and intra-oral spectrophotometers (ΔE00 = 4 and 2.9, respectively). Groups 1 and 2 exhibited lower ΔE00 values than Group 3 (p = 0.01 *). No significant difference was observed between Group 1 (stored in artificial saliva) and Group 2 (stored in artificial saliva and then bleached) (p = 0.3). Significant differences were consistently observed between the data obtained from the extra-oral spectrophotometer and the intra-oral one. CONCLUSIONS: The whitening pen proved ineffective in removing tea stains from resin composites. Although significant differences were found between the values obtained by the two spectrophotometers (extra-oral and intra-oral), both devices confirmed the unacceptable colour of the tea-stained resin composites after whitening.

Effect of Adding Silver-Doped Carbon Nanotube Fillers to Heat-Cured Acrylic Denture Base on Impact Strength, Microhardness, and Antimicrobial Activity: A Preliminary Study.

Poly (methyl methacrylate) (PMMA), is an acrylic polymer substance that is mostly used for denture base applications. The purpose of this laboratory study was to investigate the effect of adding 0.05 wt.% Ag-doped carbon nanotubes (CNT) to PMMA-based (PMMA and MMA) denture base material on the impact strength, microhardness, and antimicrobial activity. A total of 60 heat-cured acrylic resin specimens were prepared. The specimens were randomly divided into two main groups (n = 30/group), according to the powder used: (a) control group, using heat-cured PMMA; (b) treatment group, using a powder prepared by blending 0.05 wt.% silver-doped CNT nanoparticles with heat-cured PMMA. The impact strength, microhardness and anticandidal activity for each group were assessed via the Charpy, Vickers and agar diffusion tests, respectively (n = 10/test for each subgroup). Data were analyzed using independent-sample t-tests (p ≤ 0.05). The results of the impact strength test revealed that the treated heat-cured PMMA-MMA with Ag-doped CNT (2.2 kJ/mm2) was significantly higher than that of the control heat-cured PMMA (1.6 kJ/mm2). Similarly, the Vickers microhardness of the treatment group (52.7 VHN) was significantly higher than that of the control group (19.4 VHN). Regarding the agar diffusion test, after 24 h of incubation, the treated heat-cured PMMA with the Ag-doped CNT exhibited significantly higher anticandidal activity than that of the control group. Therefore, Ag-doped carbon nanotubes could be considered as promising fillers for the dental heat-cured acrylic resin to improve the resistance of the resultant denture against sudden fractures, scratching, and candida invasion.

Diagnostic Accuracy of CBCT for the Detection of Accessory Mental Foramina Using Different Devices and Imaging Modalities

This study investigated the diagnostic accuracy of CBCT for detection of accessory mental foramina (AMFs) in dry mandibles using two different devices and three different CBCT imaging modalities. A total of 40 dry mandibles (20 per group) were selected to generate corresponding CBCT images, each with three different CBCT imaging modalities (high, standard, and low doses), using ProMax 3D Mid (Planmeca) and Veraview X800 (J. Morita). The presence, count (n), location, and diameter of the AMFs were measured on both dry mandibles and CBCT scans. The Veraview X800 with different imaging modalities showed the highest accuracy (97.5%), while the ProMax 3D Mid in low-dose imaging modality exhibited the lowest accuracy (93.8%). The most common AMF sites on dry mandibles were anterior-cranial and posterior-cranial, while anterior-cranial was the most frequent on CBCT scans. As for AMF diameter, the mean mesiodistal and vertical diameters on dry mandibles were 1.89 mm and 1.47 mm, respectively, which were greater or equal to the values obtained from CBCT scans. The overall diagnostic accuracy for assessing AMFs exhibited good results, but some caution is warranted when using a low-dose imaging modality with a large voxel size (400 µm).

One-Pot Preparation of Cetylpyridinium Chloride-Containing Nanoparticles for Biofilm Eradication.

Quaternary ammonium compounds (QACs) have been widely used due to their excellent antimicrobial activity. However, using the technology where nanomaterials are employed as drug carriers to deliver QAC drugs has not been fully explored. In this study, mesoporous silica nanoparticles (MSNs) with short rod morphology were synthesized in a one-pot reaction using an antiseptic drug cetylpyridinium chloride (CPC). CPC-MSN were characterized via various methods and tested against three bacterial species (Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis), which are associated with oral infections, caries, and endodontic pathology. The nanoparticle delivery system used in this study prolonged the release of CPC. The manufactured CPC-MSN effectively killed the tested bacteria within the biofilm, and their size allowed them to penetrate into dentinal tubules. This CPC-MSN nanoparticle delivery system demonstrates potential for applications in dental materials.

Biocompatibility and mechanical properties of an experimental E-glass fiber-reinforced composite for dentistry.

Objectives: To evaluate the biocompatibility and mechanical properties of experimental bis-phenol-A and bis-GMA free E-glass fiber-reinforced composites (FRCs) prepared with hexanediol dimethacrylate (HDDMA) based resin. Methods: Two ratios of HDDMA/TEGDMA resin were evaluated: exp-1 (70/30 wt.%) and exp-2 (50/50 wt.%) with two bis-GMA resin control groups (bis-GMA/MMA and bis-GMA/TEGDMA resins, both 70/30 wt.%). E-glass fibers were embedded into the resins to prepare FRCs specimens. Biocompatibility was assessed for cytoviability and biofilm formation with Streptococcus mutans, Streptococcus sanguinis, Enterococcus faecalis, and Candida albicans. Mechanical properties were evaluated for flexural strength and hardness (24 h, water storage 1 and 28 days), water sorption (1, 7, 14, and 28 days), contact angle, and surface roughness. The data were analyzed statistically by one-way and two-way ANOVA (p < 0.05). Results: Cytoviability of the experimental groups was significantly higher than the control groups (p < 0.05). The exp-1 cytoviability (98.2 ± 1.3%) met the ISO 10993-5 standard requirement for noncytotoxic materials. The adherence of bacteria to the experimental FRCs was visibly less than the controls, while Candida albicans adhered visibly more to the experimental groups than the controls (p < 0.05). Flexural strength showed slightly higher values for controls than for the experimental groups. The exp-1 hardness value was significantly higher in the control groups for all storage conditions (p < 0.05). The water sorption of the experimental groups was significantly higher than the controls. The surface roughness indicated no significant difference (p = 0.87). The exp-1 showed a higher contact angle with the control groups. Conclusion: The experimental HDDMA/TEGDMA-based FRCs might be potential alternatives for bis-GMA-based FRCs. Clinical significance: The HDDMA/TEGDMA E-glass FRCs might provide biocompatible restorations.

A biomimetic approach to evaluate mineralization of bioactive glass-loaded resin composites.

PURPOSE: This study explores novel solutions other than standard SBF for biomimetic evaluations of mineralization particularly for resin composites containing bioactive glass (BAG). METHODS: Experimental UDMA/TEGDMA resin composites with 0.0, 1.9, 3.8 or 7.7 vol% of 45S5 BAG fillers were prepared. Besides simulated body fluid (SBF) as control, the specimens were immersed in three other solutions either with bicarbonate which are Hank's balanced salt solution (HBSS) and cell culture medium (MEM), or without bicarbonate which is a novel Simple HEPES-containing Artificial Remineralization Promotion (SHARP) solution, for 3, 7 and 14 days. These solutions were then analyzed by ICP-OES and pH meter, and the surfaces of the BAG composites were analyzed by SEM, XRD and FTIR. RESULTS: ICP-OES revealed Ca and P concentration continuously decrease, while Si concentration increases with time in the solutions other than SBF, which showed almost unchanged elemental concentration. Only SHARP solution is able to maintain a constant pH over the immersion time. SEM, together with XRD and FTIR, showed nano-sized octacalcium phosphate (OCP) nanospheres formation on 3.8 and 7.7 vol% BAG composites after 14 days immersion in HBSS (500-600 nm) and MEM (300-400 nm). SHARP solution enabled OCP formation after 3 days and then self-assembled into urchin-like carbonated hydroxyapatite (CHA) microspheres encompassed with nanorods of 100 nm width and 8 µm length after 14 days of immersion for 7.7 vol% BAG composites. CONCLUSION: This study suggests SHARP solution can evaluate mineralization biomimetically whereas CHA microspheres can be formed on BAG-containing resin composites.

Accuracy of CBCT in the Identification of Mental, Lingual, and Retromolar Foramina: A Comparison with Visual Inspection of Human Dry Mandibles.

The present dry-mandible study evaluated the presence of the mental (MF), lingual (LF), and retromolar (RMF) foramina to assess the accuracy of CBCT in detecting these anatomical structures. In total, 38 human dry mandibles were analyzed (30 men, 8 women; mean age: 61.9 ± 13.7 years). CBCT scans were taken using low-dose parameters, and LF, MF, and RMF were assessed visually and radiographically. Both the presence (yes/no) and the count (n) of each foramen were compared between CBCTs and visual assessment. For the presence assessment, only RMF exhibited a significant difference between CBCT and visual inspection (P = .035). For count, the RMF (P = .049) and paramedian LF (P = .003) exhibited differences between the two methods. The agreement between CBCT and visual inspection was excellent for the MF, moderate-excellent for the LF, and low-moderate for the RMF. Intra- and interassessor agreement varied from excellent (MF), to moderate-excellent (LF), and low-moderate (RMF). The LF and RMF represent challenging structures to identify on CBCT images due to their limited dimension. False negative findings in CBCTs in the assessment of foramina, especially LF, might lead to surgical complications during implant surgery.

Trans-Cinnamaldehyde Attenuates Enterococcus faecalis Virulence and Inhibits Biofilm Formation.

Enterococcus faecalis as an important nosocomial pathogen is critically implicated in the pathogenesis of endocarditis, urinary tract, and persistent root canal infections. Its major virulence attributes (biofilm formation, production of proteases, and hemolytic toxins) enable it to cause extensive host tissue damage. With the alarming increase in enterococcal resistance to antibiotics, novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Trans-cinnamaldehyde (TC), the main phytochemical in cinnamon essential oils, has demonstrated promising activity against a wide range of pathogens. Here, we comprehensively investigated the effect of TC on planktonic growth, biofilm formation, proteolytic and hemolytic activities, as well as gene regulation in E. faecalis. Our findings revealed that sub-inhibitory concentrations of TC reduced biofilm formation, biofilm exopolysaccharides, as well as its proteolytic and hemolytic activities. Mechanistic studies revealed significant downregulation of the quorum sensing fsr locus and downstream gelE, which are major virulence regulators in E. faecalis. Taken together, our study highlights the potential of TC to inhibit E. faecalis biofilm formation and its virulence.

TRPM7 kinase-mediated immunomodulation in macrophage plays a central role in magnesium ion-induced bone regeneration.

Despite the widespread observations on the osteogenic effects of magnesium ion (Mg2+), the diverse roles of Mg2+ during bone healing have not been systematically dissected. Here, we reveal a previously unknown, biphasic mode of action of Mg2+ in bone repair. During the early inflammation phase, Mg2+ contributes to an upregulated expression of transient receptor potential cation channel member 7 (TRPM7), and a TRPM7-dependent influx of Mg2+ in the monocyte-macrophage lineage, resulting in the cleavage and nuclear accumulation of TRPM7-cleaved kinase fragments (M7CKs). This then triggers the phosphorylation of Histone H3 at serine 10, in a TRPM7-dependent manner at the promoters of inflammatory cytokines, leading to the formation of a pro-osteogenic immune microenvironment. In the later remodeling phase, however, the continued exposure of Mg2+ not only lead to the over-activation of NF-κB signaling in macrophages and increased number of osteoclastic-like cells but also decelerates bone maturation through the suppression of hydroxyapatite precipitation. Thus, the negative effects of Mg2+ on osteogenesis can override the initial pro-osteogenic benefits of Mg2+. Taken together, this study establishes a paradigm shift in the understanding of the diverse and multifaceted roles of Mg2+ in bone healing.

A Multi-Element-Doped Porous Bioactive Glass Coating for Implant Applications.

OBJECTIVES: The objectives of the study were (1) to develop a novel multi-element-doped porous 58S bioactive glass coating for titanium implants and (2) to investigate the physiochemical, cell cytotoxic and antibacterial properties of this novel coating for titanium implants. METHODS: This study employed the sol-gel method to develop a silver-, cobalt (II) oxide- and titanium dioxide-doped 58S bioactive glass coating. The surface topography and in vitro bioactivity of the new bioactive glass-coated implants were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The surface nanohardness and coating degradation were evaluated using atomic force microscopy (AFM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. The cell cytotoxicity was assessed using cell viability of osteoblast-like mouse cells. The antibacterial property was examined using colony-forming units (CFUs) of the implant coating against Porphyromonas gingivalis. RESULTS: The multi-element-doped porous 58S bioactive glass-coated titanium implant was synthesized. SEM showed that calcium phosphate was formed on the novel coating but not on the 58S bioactive glass coating. The mean surface nanohardness of the novel coating and the 58S coating were 124 ± 24 and 50 ± 17 MPa, respectively (p < 0.001). ICP-AES showed that the releases of Si, Ca and P ions of the novel coating were significantly higher than that of a 58S bioactive glass-coated implant. No significant difference in cell cytotoxicity was found between the novel coating and the 58S coating (p > 0.1). The mean CFUs of the novel coating and the conventional coating were 120 × 106 and 49 × 106 /mL. CONCLUSION: A novel multielement-doped porous bioactive glass coating for titanium implants was developed. The coating displays promising biocompatibility and antibacterial activity. CLINICAL SIGNIFICANCE: the coating can be used to improve the clinical success of dental implants for patient care if it shows success in clinical trials.

Anteroposterior length of the maxillary complex and its relationship with the anterior cranial base.

OBJECTIVES: To use both absolute anteroposterior maxillary complex length (APMCL) and relative APMCL to investigate the relationship between the maxillary complex, its individual bony segments, and their association to the anterior cranial base. In addition, the relationship between length and position of the maxillary complex was analyzed. MATERIALS AND METHODS: Sixty human skulls were analyzed using cone beam computed tomography. The maxillary complex length was measured between anterior and posterior nasal spine (ans-pns), and the average was used as the cut-off to identify a high- and a low-length group based on absolute APMCL. The length ratio between the maxillary complex and the anterior cranial base (ans-pns/SN) was used to identify the two groups based on relative APMCL. The anterior cranial base length and the lengths of the maxillary complex bones were compared between the high- and low-length groups. RESULTS: Based on absolute APMCL, individuals with shorter maxillary complex had shorter anterior cranial base (P = .003), representing normal proportions. Based on relative APMCL, individuals with shorter maxillary complex had longer anterior cranial base and vice versa (P = .014), indicating disproportions. Individuals with shorter maxillary complex exhibited shorter maxilla (Δ = -1.5 mm, P = .014). CONCLUSIONS: When skeletal deformity of the midface is suspected, individual disproportions in the anteroposterior length of the maxillary complex in relation to the anterior cranial base (relative measurements) should be assessed through radiological imaging. A shorter maxillary complex may be associated with a shorter maxilla, and not with a shorter premaxilla or palatine bone.

A simple solution to recycle and reuse dental CAD/CAM zirconia block from its waste residuals.

Purpose To seek a simple solution that can recycle and regenerate dental CAD/CAM zirconia green blanks from its waste residuals.Methods Waste residuals (3M® Lava™ Plus HT) were pulverized after dry milling and cutting, and subsequently sieved before pickling in a 0.5 M nitric acid. These powders were then dry-pressed and pre-sintered into blocks at seven different temperatures in the range 800-1100 °C. New zirconia blocks flagged with the same batch numbers were used as control. These blocks were cut into bars before subjected them to manufacturer-recommended sintering at 1450 °C. Crystalline phases (by XRD), elemental compositions (by EDX), surface morphologies (by SEM), machinability, linear shrinkage rate, relative density, and Knoop microhardness were evaluated before and after sintering, and four-point flexural strengths were also evaluated for the sintered zirconia bars.Results Only tetragonal phases were found in both pre- and fully-sintered recycled zirconia blocks. SEM results showed that pre-sintered samples at 950 °C had smooth and flat surfaces with evenly distributed particles. Recycled and control zirconia blocks had similar elemental compositions. Results from machined surface, linear shrinkage rate, relative density, and Knoop microhardness established that 950 °C and 1000 °C were suitable pre-sintering temperatures for recycling zirconia. Pre-sintered recycled zirconia had no significant differences in flexural strengths, however, samples pre-sintered at 1000 °C exhibited the closest value (897 MPa) compared to that of the control (904 MPa).Conclusions Dental CAD/CAM zirconia can be recycled and reused from its waste residuals by adopting a simple method that requires a pre-sintering at 950 or 1000 °C.

The effects of sequential and continuous chelation on dentin.

OBJECTIVE: Proteolytic and demineralizing agents have a profound influence on the dentin ultrastructure, which plays a key role in the mechanical integrity of the tooth and integrity of dentin-biomaterial interfaces. In-depth characterization of dentin treated with a novel root canal irrigation protocol comprising sodium hypochlorite (NaOCl) and etidronate (HEDP) is lacking. This study comprehensively characterized and compared the effects of the continuous chelation (NaOCl/HEDP) and sequential chelation (NaOCl/EDTA) protocols on dentin. METHODS: Dentin blocks, dentin powder and root canals of mandibular premolars were distributed into Group 1, Saline (control); Group 2, NaOCl/EDTA; and Group 3, NaOCl/HEDP. Ultrastructural characteristics of the treated dentin were investigated using electron microscopy and light microscopy, while the surface roughness was analyzed using atomic force microscopy. Chemical compositional changes were characterized using Fourier transform infrared spectroscopy (FTIR) and energy-dispersive-X-ray spectroscopy (EDS), while collagen degradation was determined using ninhydrin assay. Data were statistically analyzed using multiple-factor one-way ANOVA and Tukey HSD tests (P = 0.05). RESULTS: NaOCl/HEDP resulted in partially degraded, yet mineralized collagen fibers, with minimal alteration to the subsurface matrix. Conversely, NaOCl/EDTA dissolved the hydroxyapaptite encapsulation, exposing collagen fibre bundles. There was no significant difference in the surface roughness between the two protocols (P > 0.05). NaOCl/HEDP resulted in homogenous distribution of organic and inorganic components on the treated surface. SIGNIFICANCE: This study highlighted that continuous chelation (NaOCl/HEDP) resulted in a frail surface collagen layer while sequential chelation (NaOCl/EDTA) exposed bare collagen fibres. These surface and sub-surface effects potentially contribute to structural failures of dentin and/or dentin-biomaterial interfacial failures.

Biomechanical and biological evaluations of novel BPA-free fibre-reinforced composites for biomedical applications.

This aim was to assess the biomechanical and biocompatibility properties of novel glass fibre-reinforced composites (FRCs) with a fluorinated urethane dimethacrylate (FUDMA) resin. Three ratios of FUDMA/TEGDMA (30/70 wt%, 50/50 wt%, 70/30 wt%) and two ratios of control FRCs with bis-GMA/TEGDMA (50/50 wt% and 70/30 wt%) containing long silanized E-glass fibres were prepared. Despite 70 wt% bis-GMA-FRC showed a significantly higher flexural strength (p < 0.05), 50 wt% FUDMA- and bis-GMA-FRCs were not differ from each other. The greatest surface hardness and weight increase after water storage were found in 70 wt% and 30 wt% FUDMA-FRCs, respectively. No significant difference was found in water sorption and solubility among all groups. Average surface roughness was 1.80 ±â€¯0.05 µm, while 70 wt% FUDMA-FRC exhibited the greatest contact angle (p > 0.05). Viabilities and ALP activities of MC3TC-E1 cells in all FUDMA-FRCs were higher than bis-GMA-FRCs after 5 days. To conclude, the novel FUDMA-FRCs are potential substitutes that exhibited superior cytocompatibility properties but comparable biomechanical properties to bis-GMA-FRCs.

Nano-CT as tool for characterization of dental resin composites.

Technological advances have made it possible to examine dental resin composites using 3D nanometer resolution. This investigation aims to characterize existing dental nano-hybrid and micro-hybrid resin composites through comparing and contrasting nano-computed tomography (nano-CT) with micro-CT and high-resolution SEM images. Eight commercially available and widely used dental resin composites, 2 micro-hybrid and 6 nano-hybrid were researched. Cured samples were examined and characterized using nano-CT (resolution 450 nm) and compared with micro-CT images (resolution 2 µm). Acquired images were reconstructed and image analysis was carried out to determine porosity and pore morphology. A comprehensive comparison of scanning micrograph images unsurprisingly revealed that the nano-CT images displayed greater detail of the ultrastructure of cured dental resin composites. Filler particle diameters and its volumes were lower when measured using nano-CT, porosity being higher where analysed at higher resolution. There were large variations between the examined materials. Fewer voids were found in Tetric EvoCeram and IPS Empress Direct, the smallest pores being found in Universal XTE and Tetric EvoCeram. Nano-CT was successfully used to investigate the morphology of dental resin composites and showed that micro-CT gives a lower porosity and pore size but overestimates filler particle size. There were large discrepancies between the tested composites. Evidence of porosities and pores within a specimen is a critical finding and it might have a detrimental effect on a material's clinical performance.

A quaternary ammonium silane antimicrobial triggers bacterial membrane and biofilm destruction.

To study the antimicrobial effects of quaternary ammonium silane (QAS) exposure on Streptococcus mutans and Lactobacillus acidophilus bacterial biofilms at different concentrations. Streptococcus mutans and Lactobacillus acidophilus biofilms were cultured on dentine disks, and incubated for bacterial adhesion for 3-days. Disks were treated with disinfectant (experimental QAS or control) and returned to culture for four days. Small-molecule drug discovery-suite was used to analyze QAS/Sortase-A active site. Cleavage of a synthetic fluorescent peptide substrate, was used to analyze inhibition of Sortase-A. Raman spectroscopy was performed and biofilms stained for confocal laser scanning microscopy (CLSM). Dentine disks that contained treated dual-species biofilms were examined using scanning electron microscopy (SEM). Analysis of DAPI within biofilms was performed using CLSM. Fatty acids in bacterial membranes were assessed with succinic-dehydrogenase assay along with time-kill assay. Sortase-A protein underwent conformational change due to QAS molecule during simulation, showing fluctuating alpha and beta strands. Spectroscopy revealed low carbohydrate intensities in 1% and 2% QAS. SEM images demonstrated absence of bacterial colonies after treatment. DAPI staining decreased with 1% QAS (p < 0.05). Fatty acid compositions of dual specie biofilm increased in both 1% and 2% QAS specimens (p < 0.05). Quaternary ammonium silane demonstrated to be a potent antibacterial cavity disinfectant and a plaque inhibitor and can be of potential significance in eliminating caries-forming bacteria.

An introduction of biological performance of zirconia with different surface characteristics: A review.

Zirconia (ZrO2) ceramic is widely used in dentistry as a clinical dental biomaterial. In this review, we are focusing on and summarizing the biological performance of zirconia under different surface characteristics. We have included an initial tissue cell attachment study on zirconia and bacterial adhesion on zirconia. Our results suggest that surface modifications applied on zirconia may change the interfacial surface characteristics e.g. surface roughness, surface free energy, and chemistry of zirconia. The modifications also result in advanced biological performance of zirconia, including enhanced tissue cell attachment and reduction of bacterial adhesion. The recent laboratory research has provided many interesting modification methods and showed clinically interesting and promising outcomes. A few of the outcomes are validated and have been applied in clinical dentistry.