Dental Applications Research Articles

Hydroxyapatite nano-pillars on TI-6Al-4V: Enhancements in cell spreading and proliferation during cell/surface integration.

Despite the attractive combinations of cell/surface interactions, biocompatibility, and good mechanical properties of Ti-6Al-4V, there is still a need to enhance the early stages of cell/surface integration that are associated with the implantation of biomedical devices into the human body. This paper presents a novel, easy and reproducible method of nanoscale and nanostructured hydroxyapatite (HA) coatings on Ti-6Al-4V. The resulting nanoscale coatings/nanostructures are characterized using a combination of Raman spectroscopy, scanning electron microscopy equipped with energy dispersive x-ray spectroscopy. The nanostructured/nanoscale coatings are shown to enhance the early stages of cell spreading and integration of bone cells (hFOB cells) on Ti-6Al-4V surfaces. The improvements include the acceleration of extra-cellular matrix, cell spreading and proliferation by nanoscale HA structures on the coated surfaces. The implications of the results are discussed for the development of HA nanostructures for the improved osseointegration of Ti-6Al-4V in orthopedic and dental applications.

Low Intensity Laser Therapy: A Review of Its Applications and Effectiveness in Health, General Dentistry and Endodontics

Aims: To evaluate the use of low-level laser therapy in endodontic treatment and its broader applicability in General Health and Dentistry. Study Design: Literature review. Place and Duration of Study: The study involved searching articles and book chapters in the Google Scholar and PubMed databases from 2018 to 2023, with the review concluding in 2024. Methodology: The review used descriptors from the Brazilian Health Sciences Descriptors database: Laser Therapy, Low-Level Light Therapy, Endodontic Treatment, Dentistry, and their Portuguese equivalents. A total of 34 articles were selected, focusing exclusively on low-level laser therapy and its applications. Articles not addressing this specific therapy were excluded. Results: Low-level laser therapy is frequently used as an adjunct in general health, dentistry and endodontic treatment. Clinical applications, such as postoperative pain control, root canal system disinfection, periapical surgery, and tissue repair, showed promising results. However, more theoretical and clinical evidence is still required to fully establish its efficacy. Further research is needed to strengthen the evidence base and optimize its clinical use. Conclusion: Low-level laser therapy offers a potential non-invasive treatment option in endodontics, with satisfactory outcomes in various clinical applications.

Ceramic Materials Based on a Complex Oxide Solid Solution of a Tetragonal Form of Zirconia: Application in Prosthetic Dentistry

Ceramic Materials Based on a Complex Oxide Solid Solution of a Tetragonal Form of Zirconia: Application in Prosthetic Dentistry

Impact of Polydeoxyribonucleotides on the Morphology, Viability, and Osteogenic Differentiation of Gingiva-Derived Stem Cell Spheroids

Background and Objectives: Polydeoxyribonucleotides (PDRN), composed of DNA fragments derived from salmon DNA, is widely recognized for its regenerative properties. It has been extensively used in medical applications, such as dermatology and wound healing, due to its ability to enhance cellular metabolic activity, stimulate angiogenesis, and promote tissue regeneration. In the field of dentistry, PDRN has shown potential in promoting periodontal healing and bone regeneration. This study aims to investigate the effects of PDRN on the morphology, survival, and osteogenic differentiation of gingiva-derived stem cell spheroids, with a focus on its potential applications in tissue engineering and regenerative dentistry. Materials and Methods: Gingiva-derived mesenchymal stem cells were cultured and formed into spheroids using microwells. The cells were treated with varying concentrations of PDRN (0, 25, 50, 75, and 100 μg/mL) and cultivated in osteogenic media. Cell morphology was observed over seven days using an inverted microscope, and viability was assessed with Live/Dead Kit assays and Cell Counting Kit-8. Osteogenic differentiation was evaluated by measuring alkaline phosphatase activity and calcium deposition. The expression levels of osteogenic markers RUNX2 and COL1A1 were quantified using real-time polymerase chain reaction. RNA sequencing was performed to assess the gene expression profiles related to osteogenesis. Results: The results demonstrated that PDRN treatment had no significant effect on spheroid diameter or cellular viability during the observation period. However, a PDRN concentration of 75 μg/mL significantly enhanced calcium deposition by Day 14, suggesting increased mineralization. RUNX2 and COL1A1 mRNA expression levels varied with PDRN concentration, with the highest RUNX2 expression observed at 25 μg/mL and the highest COL1A1 expression at 75 μg/mL. RNA sequencing further confirmed the upregulation of genes involved in osteogenic differentiation, with enhanced expression of RUNX2 and COL1A1 in PDRN-treated gingiva-derived stem cell spheroids. Conclusions: In summary, PDRN did not significantly affect the viability or morphology of gingiva-derived stem cell spheroids but influenced their osteogenic differentiation and mineralization in a concentration-dependent manner. These findings suggest that PDRN may play a role in promoting osteogenic processes in tissue engineering and regenerative dentistry applications, with specific effects observed at different concentrations.

Mechanical property, corrosion behavior and cytocompatibility of CoCrMo for dental application: A comparative study of cast and laser powder bed fusion

In this work, by employing powders sourced directly from the original ingot for additive manufacturing, we enabled a comparative overview of the performance between CoCrMo manufactured via laser powder bed fusion (LPBF) and those in their original cast condition. Microstructural analysis revealed that the cast (CT) alloy predominantly consisted of coarse grains with distribution of sigma phase, while the LPBF process resulted in a refined grain structure devoid of the sigma phase. The tensile strength tests demonstrated that the LPBF-derived CoCrMo alloy had substantially greater tensile strength, and ductility compared to CT alloy. Corrosion tests indicated superior corrosion resistance in the LPBF alloy, albeit with a lower metal ion release. In vitro assays confirmed that LPBF CoCrMo alloys displayed favorable cytocompatibility. Consequently, it is concluded that the CoCrMo alloy processed through laser powder bed fusion exhibited enhanced mechanical performance and corrosion resistance. These improvements are primarily attributed to the transformation of the original coarse columnar grain structure through the LPBF technique.

Design of new β-type Ti alloys with outstanding corrosion and wear resistance for dental application

β-type Ti alloys have drawn extensive attention as potential metallic implants. In this work, the microstructure, corrosion behavior, and wear performance of Ti−17.3Nb−1.8Fe (TNF) and Ti−22Nb−30Zr−4Cr (TNZC) biomedical alloys were experimentally investigated, and CP−Ti and Ti6Al4V alloy were also used for comparisons. TNF and TNZC alloys after solution treatment at 1273K showed a single β phase. It was found that TNF and TNZC alloys revealed better corrosion resistance than CP−Ti and Ti6Al4V alloy in different artificial saliva containing 0.15wt.% NaF with the pH values of 3.9 and 5.7, which could be ascribed to the formation of a double-layer passive film composed of multiple species oxides. Moreover, TNF and TNZC alloys exhibited higher wear resistance compared with CP−Ti and Ti6Al4V alloy, whose wear mechanism was adhesive wear and abrasive wear. The present results shows that TNF and TNZC alloys are nice candidates for dental application.

Optimizing the microstructure, mechanical, and optical properties of recycled zirconia for dental applications

Efficient recycling of dental zirconia residues from computer-aided design/manufacturing processes is crucial for sustainable development in dentistry. This study employed ball milling to modify recycled zirconia powder (RZP). Initial RZP and ball-milled RZP (RZP-BM) were pre-sintered at 1000–1150 °C and then final sintered at 1500 °C. Initial RZP had irregular shapes, while RZP-BM showed finer and more uniform morphology, higher packing density, and improved de-agglomeration after 6 h of ball milling. For pre-sintered zirconia, RZP-BM samples achieved properties comparable with commercial zirconia at 1100 °C, whereas initial RZP required 1150 °C. For final sintered zirconia, initial RZP samples exhibited lower Vickers microhardness, density, strength, and transmittance, with numerous defects in its microstructure. RZP-BM samples showed significant improvement in mechanical and optical properties, comparable with commercial zirconia. This study establishes a viable approach for recycling dental zirconia residues, enhancing its properties for potential reuse as dental materials.

Incorporating an artificially synthesized fluoride complex into urethane-acrylate-based 3D printing resin: Effects on mechanical properties, cytotoxicity, antimicrobial actions, and its long-term fluoride-releasing properties

ObjectivesTo synthesize a 3D printing resin with antibacterial and long-term fluoride-releasing properties. Methods(4,4-Bis-4-[2‑hydroxy-3-(2-methacryloyloxy)propoxy]-phenyl-pentanol-amine)-N,N-diacetic acid zirconium (IV) fluoride complex was synthesized from 4,4-bis-(4-hydroxyphenyl)-pentanoic acid and monitored using proton nuclear magnetic resonance spectroscopy. The synthesized complex was incorporated into a urethane-acrylate-based (UA) resin at 5 wt% and 10 wt% (5F-UA and 10F-UA groups, respectively). The UA resin without the synthesized complex was considered as the control group. All groups were 3D printed using a DLP printer, followed by 10 min of washing and 20 min of curing. Surface characteristics were observed using scanning electron microscopy. The mechanical properties were assessed by measuring its flexural strength and Vickers hardness. The antibacterial property was investigated with direct and indirect contact tests and a WST-8 metabolic activity assay. The suspension was fully mixed and diluted for counting the number of colony-forming units. The cell viability test was performed using a cell proliferation assay. The amount of fluoride released was measured daily for 28 days using ion chromatography. One-way analysis of variance was performed for statistical analyses using SPSS software. ResultsThe amount of fluoride released increased with the concentration of fluoride complex in the resin. The fluoride ions were constantly released at a low concentration from the 3D printed specimens (5F-UA: around 0.13 ppm daily; 10F-UA: around 0.22 ppm daily). The antibacterial efficacy was acceptable in both the 5F-UA and 10F-UA groups, and higher in the latter. No cytotoxicity of the resin was detected. The mechanical properties were significantly influenced by the addition of the fluoride-releasing complex. ConclusionsThe present 3D printing UA resin incorporating a fluoride complex effectively inhibited the growth of S. mutans and demonstrated the ability to slowly release fluoride over an extended period of time. Clinical significanceThis study provided informative composition of a fluoride-releasing UA-based 3D printing resin, ideal for dental applications such as crowns, bridges, removable partial dentures, and orthodontic appliances, which can benefit from sustained fluoride release and antimicrobial properties. Further modifications to the resin composition can be easily achieved to enhance the resin qualities.

Biocompatibility and Enamel Remineralization Potential of Titanium-Doped Phosphate Glasses With/Without Diode Laser Irradiation

This study investigates the biocompatibility and enamel remineralization potential of titanium-doped phosphate glasses (TDPG), third-generation materials with promising applications in dentistry. The biocompatibility of TDPG paste and its components (TDPG powder and polyacrylic acid liquid) was assessed using human gingival fibroblast cells (hGF) and human dental pulp stem cells (hDPSC). Cell attachment and viability were examined at 1, 3, and 7 days, comparing results with Nupro® Prophy paste and Teethmate, commonly used desensitizers, and positive control cells in normal tissue culture medium. Furthermore, the remineralization potential of these glasses with or without the use of diode laser irradiation on white spot lesions in enamel was explored at 12- and 21-days using Raman Spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). The remineralization potential of TDPG was compared with Nupro® Prophy paste and Teethmate. Furthermore, both sound and demineralized enamel were also used as other controls.Results indicated that cells exposed to TDPG extracts displayed similar morphology and viability to positive control cells. While all tested pastes did not show remineralizing action after 12 days, Nupro® Prophy and Teethmate exhibited such action after 21 days. However, laser application enhanced remineralization potential for all pastes at both time points, with TDPG showing comparable results to Nupro® Prophy paste and significantly higher potential than Teethmate when used with laser at 21 days.In summary, this study reveals the biocompatibility and enhanced remineralization potential of TDPG when combined with diode laser irradiation. These findings signify innovative strides in dental materials and treatment modalities, offering new possibilities for advanced dental applications.

Impact of zirconia-based oxide on endothelial cell dynamics and extracellular matrix remodeling

IntroductionZirconia (ZrO2) is highly regarded in dental restoration due to its aesthetic compatibility and mechanical properties that align with biological tissues. This study explores the effects of stabilized ZrO2 on endothelial cell function and extracellular matrix (ECM) remodeling, processes critical to successful osseointegration in dental implants. MethodologyHuman Umbilical Vein Endothelial Cells (HUVECs) were cultured in ZrO2 -enriched medium under both static and shear stress conditions. Newly implemented techniques, including detailed zirconia surface characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD), were used to verify material properties. Gene and protein expression related to cell adhesion, proliferation, and ECM remodeling were assessed through RT-qPCR and Western blotting. Zymography was used to evaluate the activity of matrix metalloproteinases (MMP2 and MMP9) involved in ECM remodeling. ResultsCharacterization data confirmed the stability and structural properties of ZrO2, revealing a tetragonal crystalline structure and rough surface morphology conducive to cell adhesion. ZrO2 exposure led to the downregulation of Src, a key regulator of cell adhesion, while upregulating cell cycle regulators p15, CDK2, and CDK4, indicating enhanced cell proliferation. Under shear stress, ZrO2 modulated TGF-β and MAPK signaling, affecting cell proliferation and angiogenesis. MMP2 and MMP9 activity increased in static conditions but decreased under shear stress, suggesting ZrO2 dynamic role in ECM remodeling. ConclusionThis study shows that stabilized zirconia (ZrO2) modulates endothelial cell dynamics and ECM remodeling, key for osseointegration. ZrO2 downregulated Src expression and upregulated cell cycle regulators, enhancing endothelial proliferation. It also affected TGF-β and MAPK pathways, influencing angiogenesis, and differentially modulated MMP2 and MMP9 activity depending on mechanical conditions. These findings highlight ZrO2 has potential ability to enhance vascular and tissue integration in dental applications.

Synergistic Action of Vanillic Acid-Coated Titanium Oxide Nanoparticles: Targeting Biofilm Formation Receptors of Dental Pathogens and Modulating Apoptosis Genes for Enhanced Oral Anticancer Activity.

The prevalence of bacterial and fungal infections is caused byS. aureus, S. mutans, E. faecalis, and Candida albicans are often associated with dental illnesses. In the present study, a unique strategy was used to combat these diseases by fabricatingtitanium dioxide nanoparticles (TiO2 NPs) conjugated with the plant-based molecule vanillic acid (VA).Molecular modeling investigations were performed to better understand the interactions among vanillic acid and dental pathogen receptors using the Autodock program. The findings indicated that VA-TiO2 NPs exhibited strong free radical scavenging activity. Additionally, they showed excellent antibacterial action towards dental pathogens, with a minimum inhibition level of 60 μg/mL. Furthermore, at doses of 15 μg/mL, 30 μg/mL, 60 μg/mL, and 120 μg/mL, VA-TiO2 NPs demonstrated concentration-dependent apoptotic impacts on human oral carcinoma cells. Apoptotic gene over-expression was identified by the molecular perspectives that revealed the anticancer mechanism of VA-TiO2 NPs on KB cells. This study highlights the promising suitability of VA-TiO2 NPs for dental applications due to their robust antioxidant, anticancer, and antimicrobial characteristics. These nanoparticles present an evident prospect for addressing oral pathogen challenges and improving overall oral health.

Effect of Hybrid Nanofillers on the Mechanical Characteristics of Polymethyl Methacrylate Denture Base Composite

The research study focused on enhancing the mechanical characteristics of polymethyl methacrylate (PMMA) denture bases. PMMA is commonly used in dentistry due to its easy fabrication, cost-effectiveness, and favourable physical properties. However, its limitations include low wear resistance, hardness, and mechanical strength, making it less suitable for long-term dental applications. To address these limitations, the study employed a combination of hybrid nano-fillers, specifically HNTs (halloysite nanotubes) and MWCNTs (multi-walled carbon nanotubes), at varying loading levels to improve the mechanical characteristics of the PMMA composite. These nano-fillers underwent treatment by using a coupling agent to enhance their compatibility with PMMA. Key findings of the research include that introducing HNTs/MWCNTs into the PMMA matrix led to a substantial increase in flexural strength, with a significant improvement of 109.1 MPa compared to unfilled PMMA. This indicates that the composite material became more resistant to bending or deformation. There was a substantial rise in flexural modulus values, suggesting improved stiffness in the nanocomposite compared to unfilled PMMA. In addition, the tensile strength of the PMMA composite increased by 64.4 MPa with the addition of the hybrid nano-fillers, indicating enhanced resistance to stretching or pulling forces. The study found that the improvement in flexural and tensile strength was dependent on the concentration of MWCNTs. Increasing the MWCNT concentration up to 0.75 wt.% led to improved mechanical properties, but further increases resulted in a reduction in PMMA properties. Although there was a modest improvement in Vickers hardness (approximately 18.93 kg/mm<sup>2</sup>), the addition of HNTs/MWCNTs as hybrid nano-fillers effectively enhanced the properties of the PMMA nanocomposite. The study concludes that incorporating hybrid nano-fillers into PMMA could contribute to the longevity and durability of dental composites, addressing some of the material's inherent limitations. The specific combination and concentration of nano-fillers played a crucial role in determining the mechanical properties of the resulting nanocomposite.

Dental Applications of Ion-Substituted Hydroxyapatite: A Review of the Literature.

Hydroxyapatite (HA) forms an essential constituent of human teeth and bone. Its distinctive characteristic features, such as bioactivity and osteoconductivity, make it an ideal candidate to be used as an implant coating in restorative dentistry and maxillofacial surgery for bone regeneration. However, low fracture toughness and brittleness are a few of the inherent features of HA, which limit its application in load-bearing areas. The potential of HA to engage its lattice structure with either partial or complete substitution with external ions has become an increasing area of research as this phenomenon has the potential to enhance the biological and functional properties of the material. Consequently, this review aimed to highlight the role of various substituted ions in dental applications. Data indicate that the newly formed HA-substituted biomaterials demonstrate enhanced remineralization and antimicrobial activity along with improved hardness. Ion-substituted HA offers a promising strategy for future clinical research as these materials may be incorporated into various dental products for therapeutic treatments.

Can deep learning-designed anterior tooth-borne crown fulfill morphologic, aesthetic, and functional criteria in clinical practice?

ObjectivesThis study aimed to compare the design outcomes of anterior crowns generated using deep learning (DL)-based software with those fabricated by a technician using conventional dental computer-assisted design (CAD) software without DL support, with a focus on the evaluation of crown morphology, function, and aesthetics. MethodsTwenty-five in vivo datasets comprising maxillary and mandibular arch scans of prepared maxillary central incisors were utilized to design anterior crowns by using three methods: 1) a DL-based method resulting in as-generated outcome (DB), 2) a DL-based method further optimized by a technician (DM), and 3) a conventional CAD-based method (NC, control). Evaluations were conducted for crown morphology (total discrepancy volume (TDV), root mean square (RMS), positive average (PA) and negative average (NA) deviations), functional aspects (incisal path: deviations, length, and mean inclination), and aesthetics (crown width, height, width-to-height ratio, angular radius of mesioincisal line angle, proximal contact length, and tooth axis angle). ResultsSignificant differences in TDV ratio were noted between the DB–NC (32.3 ± 8.5 %) and DM–NC (26.5 ± 5.4 %) pairs (P = 0.006). No significant differences were observed in TDV between the DB–NC (65.3 ± 24.4 mm3) and DM–NC (54.3 ± 21.0 mm3) pairs (P = 0.095). For the entire palatal surface, significant differences in RMS and PA values were observed between the DB–NC and DM–NC pairs (P < 0.037). Significant differences in RMS values for the incisal half (P = 0.021) and in PA values for the cervical half (P = 0.047) of the palatal surface were also noted between these pairs. Significant differences in the deviation of the incisal path were observed between the DB–NC (290.4 ± 212.4 μm) and DM–NC (132.0 ± 122.3 μm) pairs (P < 0.001). However, no significant differences were found among the groups (DB, DM, and NC) in terms of the length and mean inclination of incisal paths or in aesthetic outcomes. ConclusionsA DL-based method can result in promising outcomes with clinically acceptable morphology and aesthetics for anterior crowns. Minor deviations in incisal path of the crowns may lead to anterior guidance discrepancies, which can be corrected by the dental technician at the design stage. Clinical significanceWith the potential of DL-based design methods in dental applications, integrating AI technology into dental CAD workflow can enhance the clinical efficiency and consistency of anterior crown design, although human intervention may be required to refine functional aspect.

Assessing the Impact of IOS Scanning Accuracy on Additively Manufactured Occlusal Splints.

Introduction: Digital workflow and intraoral scanners (IOSs) are used to clinically obtain data for a wide range of applications in restorative dentistry. The study aimed to compare two different IOSs with inexperienced users in the digital workflow of oral split manufacturing. Material and Methods: Anonymous stone models of upper and lower dentate patients were used. Both models were scanned with a desktop 3D scanner 3Shape D2000 to obtain the reference models (STLR). Ten inexperienced operators scanned each model three times with each IOS system (3Shape TRIOS 3 and Carestream CS 3800). Finally, 20 intraoral scanners were randomly chosen from the obtained dataset (10 per IOS system) to design and manufacture 20 nightguards. All the nightguards were scanned. Trueness and precision were calculated and compared between the two IOS systems. Results: All the mean errors both for trueness and precision were below 40 µm, more than acceptable for the design and manufacturing of intraoral devices such as nightguards. All the mean errors (except one) for trueness between the inner part of the nightguards and the upper control model were below 100 µm, less than a printed layer height. For inexperienced operators, both IOSs are suitable for a digital workflow of manufacturing occlusal splints.

Synthesis and Characterization of a Chemico-structurally Modified Bis-GMA Analog for Dental Applications.

This study aimed to synthesize and characterize a novel Bis-GMA analog, termed P-Bis-GMA, through structural modification by replacing hydroxyl (-OH) groups with phosphonooxy [-O-P(=O)(OH)2] groups and to evaluate and compare its viscosity with Bis-GMA. Bis-GMA, triethylamine, dichloromethane, and phosphoryl chloride were utilized for the synthesis of P-Bis-GMA through phosphorylation. Fourier discerned the chemical structure of the synthesized P-Bis-GMA transform infrared spectroscopy (FTIR), and its viscosity was assessed by rheometry in oscillatory shear mode over a frequency sweep range of 0.1-100 (ω, rad/s) at 25°C with a 25 mm parallel plate design and a 0.5 mm gap. The data was recorded and statistically analyzed. The FTIR analysis confirmed the successful synthesis of P-Bis-GMA, evidenced by the disappearance of hydroxyl (-OH) peaks and the emergence of phosphonooxy [-O-P(=O)(OH)2] peaks in the P-Bis-GMA. Rheological testing demonstrated a notable reduction in viscosity for P-Bis-GMA (436.62 Pa.s) when compared to conventional Bis-GMA (1089.02 Pa.s), indicating improved handling characteristics. P-Bis-GMA was successfully synthesized by phosphorylation reaction where the -OH groups responsible for the high viscosity in the Bis-GMA were replaced with the [-O-P(=O)(OH)2] groups with significantly reduced viscosity. The development of P-Bis-GMA holds promise for simplifying dental procedures by reducing chairside time with uncooperative children. The P-Bis-GMA-based composites possess self-adhering properties thereby eschewing the etching and bonding procedures with reduced moisture contamination of the restoration during bonding. This ultimately leads to better clinical outcomes and improved patient experiences by reducing technical vulnerabilities. How to cite this article: Ajay R, Selvabalaji A, Muthamilselvi M, et al. Synthesis and Characterization of a Chemico-structurally Modified Bis-GMA Analog for Dental Applications. J Contemp Dent Pract 2024;25(6):588-592.

Antibacterial Properties of Grape Seed Extract-Enriched Cellulose Hydrogels for Potential Dental Application: In Vitro Assay, Cytocompatibility, and Biocompatibility.

Hydrogels elaborated from Dasylirion spp. and enriched with grape seed extract (GSE) were investigated for tentative use in dental treatment. Cellulose-GSE hydrogels were elaborated with varying GSE contents from 10 to 50 wt%. The mechanical and physical properties, antimicrobial effect, biocompatibility, and in vitro cytotoxicity were studied. In all the cases, the presence of GSE affects the hydrogel's mechanical properties. The elongation decreased from 12.67 mm for the hydrogel without GSE to 6.33 mm for the hydrogel with the highest GSE content. The tensile strength decrease was from 52.33 N/mm2 (for the samples without GSE) and went to 40 N/mm2 for the highest GSE content. Despite the adverse effects, hydrogels possess suitable properties for manipulation. In addition, all hydrogels exhibited excellent biocompatibility and no cytotoxicity, and the antibacterial performance was demonstrated against S. mutans, E. Faecalis, S. aureus, and P. aureginosa. Furthermore, the hydrogels with 30 wt% GSE inhibited more than 90% of the bacterial growth.

In Vitro Evaluation of Speed Sintering and Glazing Effects on the Flexural Strength and Microstructure of Highly Translucent Multilayered 5 mol% Yttria-Stabilized Zirconia.

This study aimed to investigate the impact of speed sintering and glazing on the flexural strength and microstructure of multilayered 5 mol% yttria-stabilized (5Y-) zirconia, which remains unknown. Bar-shaped specimens (N = 600) were fabricated from 5Y-zirconia (FX; Ceramill Zolid FX ML, ST; Katana STML) by cutting, polishing, sintering (conventional and speed sintering), and then glazing. A flexural strength test (n = 30/group), field emission scanning electron microscopy (FE-SEM) observation (n = 2/group), and an X-ray diffraction (XRD) study with Rietveld refinement (n = 1/group) were performed. The flexural strength was analyzed using three-way ANOVA and a post hoc Scheffé test. The grain size was analyzed using the Kruskal-Wallis H test and Bonferroni-Dunn post hoc test. Flexural strength slightly decreased in the nonglazed FX after speed sintering (p < 0.05). Glazing with and without glazing paste did not affect flexural strength at both sintering speeds (p > 0.05). Speed sintering and glazing minimally changed the Weibull modulus and phase fraction, and did not affect grain size (p > 0.05). ST had a larger grain size and lower tetragonal phase content than FX and had a lower flexural strength than FX in most groups (p < 0.05). Overall, the multilayered 5Y-zirconia is considered suitable for dental application using speed sintering and glazing.

Comparison of Faster R-CNN, YOLO, and SSD for Third Molar Angle Detection in Dental Panoramic X-rays.

The use of artificial intelligence algorithms (AI) has gained importance for dental applications in recent years. Analyzing AI information from different sensor data such as images or panoramic radiographs (panoramic X-rays) can help to improve medical decisions and achieve early diagnosis of different dental pathologies. In particular, the use of deep learning (DL) techniques based on convolutional neural networks (CNNs) has obtained promising results in dental applications based on images, in which approaches based on classification, detection, and segmentation are being studied with growing interest. However, there are still several challenges to be tackled, such as the data quality and quantity, the variability among categories, and the analysis of the possible bias and variance associated with each dataset distribution. This study aims to compare the performance of three deep learning object detection models-Faster R-CNN, YOLO V2, and SSD-using different ResNet architectures (ResNet-18, ResNet-50, and ResNet-101) as feature extractors for detecting and classifying third molar angles in panoramic X-rays according to Winter's classification criterion. Each object detection architecture was trained, calibrated, validated, and tested with three different feature extraction CNNs which are ResNet-18, ResNet-50, and ResNet-101, which were the networks that best fit our dataset distribution. Based on such detection networks, we detect four different categories of angles in third molars using panoramic X-rays by using Winter's classification criterion. This criterion characterizes the third molar's position relative to the second molar's longitudinal axis. The detected categories for the third molars are distoangular, vertical, mesioangular, and horizontal. For training, we used a total of 644 panoramic X-rays. The results obtained in the testing dataset reached up to 99% mean average accuracy performance, demonstrating the YOLOV2 obtained higher effectiveness in solving the third molar angle detection problem. These results demonstrate that the use of CNNs for object detection in panoramic radiographs represents a promising solution in dental applications.

Role of the novel aloe vera-based titanium dioxide bleaching gel on the strength and mineral content of the human tooth enamel with respect to age.

There has been an increased demand for dental bleaching globally irrespective of age and gender. Main drawbacks associated with conventional tooth bleaching agents have been compromised strength and mineral-content of tooth enamel which results in sensitivity, discomfort, roughness, and structure loss of human teeth. Currently, nanoparticles synthesized by green synthesis have gained popularity especially in medical and dental applications because of their versatile and beneficial nano-scaled features. Titanium dioxide nanoparticles (TiO2Nps) in this study were prepared from green ecofriendly source using the aloe vera plant extract and were then characterized via dynamic light scattering (DLS), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), and energy dispersive X-ray (EDX), for size, shape, composition and true-phase. These TiO2 Nps were incorporated in commercial bleaching gel containing hydrogen peroxide to form a novel TiO2-bleaching gel which was used to bleach extracted anterior teeth belonging to four different age groups: 20-29 years, 30-39 years, 40-49 years and ≥50 years. These teeth were investigated for micro-hardness (Vickers microhardness tester) and mineral-content (EDX spectroscopy) including sodium, magnesium, phosphorus, calcium in an in-vitro environment both before and after bleaching. Results revealed that TiO2 Nps prepared by aloe vera plant were nanos-sized of about 37.91-49 nm, spherical shape, true anatase phase with pure titanium and oxygen in their composition. The values of Vickers micro-hardness and mineral-content (Na, Mg, P, Ca) of enamel specimens belonging to different age groups enhanced in a linear pattern before bleaching with the increase in age (p value < 0.05). There was negligible reduction observed in Vickers micro-hardness and mineral-content elements (Na, Mg, P, Ca) of all enamel specimens belonging to different ages after the bleaching (p value > 0.05). The novel TiO2-bleaching gel prepared was effective enough in preventing the declination in Vickers micro-hardness strength and mineral-content of all the enamel specimens belonging to different age groups even after the bleaching procedure which makes it a promising biomaterial.