A conservative approach to localize loose implant screw through cemented crown: an in vitro experimental study.

BACKGROUND: Retrieval of cement-retained implant-supported restorations is intriguing in cases of screw loosening. Detecting the estimated size of the screw access hole (SAH) could decrease destruction to the prosthesis and preserve the crown. OBJECTIVES: To precisely localize loose implant screws through cemented crowns to reduce crown damage after screw loosening. MATERIALS AND METHODS: In this in vitro study, 60 cement-retained implants supported 30 zirconia-based, and 30 ceramics fused to metal (CFM) lower molar crowns were invented, and each was subdivided into three subgroups (10 each). In group I (AI/BI) (control), SAH was created with the aid of orthopantomography (OPG). In contrast, in group II (zirconia-crown), SAH was created with the aid of CBCT + 3D printed surgical guide with a 2 mm metal sleeve in subgroups IIA/IIIA and CBCT + MAR was used to develop SAH in subgroups IIB/IIIB. SEM and Micro-CT scanned the SAH openings to determine the diameter of the hole, cracking, chipping, and chipping volume. RESULTS: Regarding the effect of plane CBCT and CBCT + MAR on prepared crowns, a highly significant association between group I with group II (p = 0.001) and group III (p = 0.002) was detected. Regarding the cracking of SAH, significant differences between the zirconium crown and CFM restoration (p = 0.009) were found, while for the chipping, no significant association was seen between groups (p = 0.19). CONCLUSIONS: CBCT, either as a plane CBCT or with MAR, significantly improved the accuracy of drilling the screw channel and decreased injury to the existing restoration and abutment, aiding in better localization of SAH in loosened implant abutment screws.

SURVIVAL RATE OF IMPLANT-SUPPORTED, SINGLE-TOOTH RESTORATIONS BASED ON ZIRCONIA OR METAL ABUTMENT IN PATIENTS WITH TOOTH AGENESIS: A 5-YEARS PROSPECTIVE CLINICAL STUDY.

OBJECTIVES: The primary aim was to investigate survival rate of zirconia versus metal abutments, and the secondary aim was clinical outcomes of all-ceramic versus metal-ceramic crowns on single-tooth implants. METHODS: Patients with tooth-agenesis participated to previously published prospective clinical study with 3-year follow-up were recalled after 5 years. Biological variables included survival and success rate of implants, marginal bone level, modified Plaque and Sulcus Bleeding Index and biological complications. Technical variables included restoration survival rate, marginal adaptation and technical complications. The aesthetic outcome of crowns and peri-implant mucosa in addition to patient-reported outcome were recorded. Descriptive analysis, linear mixed model for quantitative data, or generalized linear mixed model for ordinal categorical data were applied; significance was set to 0.05. RESULTS: Fifty-three patients (mean age: 32.4 years), with 89 implants participated to the 5-years examination. The implants supported 50 zirconia abutments with 50 all-ceramic (AC) crown and 39 metal abutments with 29 metal-ceramic (MC) and 10 AC crowns. The Implant and restoration survival rate was 100% and 96%, respectively. No clinically relevant biological difference between implants supporting metal or zirconia abutments was registered. The technical complications were veneering fracture of AC-crowns (n = 3), crown loosening of MC-crowns (n = 4) and one abutment screw loosening (MC-crown on metal abutment). MC-crowns had significantly better marginal adaptation than AC-crowns (p = .01). AC-crowns had significantly better color and morphology than MC-crowns (p = .01). CONCLUSIONS: Zirconia-based single-tooth restorations are reliable alternative materials to metal-based restorations with favorable biological and aesthetic outcome, and few technical complications.

Dihydroxyl modified UiO-66 as dispersive solid-phase extraction sorbent coupled with ultra-high performance liquid chromatography tandem mass spectrometry for detection of neonicotinoid insecticides.

The extensive usage of neonicotinoid insecticides (NIs) has raised many concerns about their potential harm to environment and human health. Thus, it is of great importance to develop an efficient and reliable method to determine NIs in food samples. In this work, three Zr4+-based metal-organic frameworks functionalized with various numbers of hydroxyl groups were fabricated with a facile one-pot solvothermal method. Among them, dihydroxy modified UiO-66 (UiO-66-(OH)2) exhibited best adsorption performance towards five target NIs. Then, a sensitive and efficient method for detection of NIs from vegetable and fruit samples was established based on dispersive solid phase extraction (dSPE) with UiO-66-(OH)2 as adsorbent coupled with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Key parameters affecting the dSPE procedure including amounts of adsorbent, adsorption time, eluent solvents and desorption time were investigated. Under the optimal conditions, rapid adsorption of NIs within five minutes was achieved due to the high affinity of UiO-66-(OH)2 towards NIs. The developed method exhibited high sensitivity with limits of detection (LODs) varied from 0.003 to 0.03 ng/mL and wide linearity range over 3-4 orders of magnitude from 0.01 to 500 ng/mL. Furthermore, the established method was applied for determining trace NIs from complex matrices with recoveries ranging from 74.6 to 99.6 % and 77.0-106.8 % for pear and tomato samples, respectively. The results indicate the potential of UiO-66-(OH)2 for efficient enrichment of trace NIs from complex matrices.

Effect of water glass treatment for zirconia and silane coupling on bond strength of resin cement.

OBJECTIVE: To evaluate the ability of the water glass treatment to penetrate zirconia and improve the bond strength of resin cement. MATERIAL AND METHODS: Water glass was applied to zirconia specimens, which were then sintered. The specimens were divided into water-glass-treated and untreated zirconia (control) groups. The surface properties of the water-glass-treated specimens were evaluated using surface roughness and electron probe micro-analyser (EPMA) analysis. A resin cement was used to evaluate the tensile bond strength, with2 and without a silane-containing primer. After 24 h in water storage at 37 °C and thermal cycling, the bond strengths were statistically evaluated with t-test, and the fracture surfaces were observed using SEM. RESULTS: The water glass treatment slightly increased the surface roughness of the zirconia specimens, and the EPMA analysis detected the water glass penetration to be 50 µm below the zirconia surface. The application of primer improved the tensile bond strength in all groups. After 24 h, the water-glass-treated zirconia exhibited a tensile strength of 24.8 ± 5.5 MPa, which was significantly higher than that of the control zirconia (17.6 ± 3.5 MPa) (p < 0.05). After thermal cycling, the water-glass-treated zirconia showed significantly higher tensile strength than the control zirconia. The fracture surface morphology was mainly an adhesive pattern, whereas resin cement residue was occasionally detected on the water-glass-treated zirconia surfaces. CONCLUSION: The water glass treatment resulted in the formation of a stable silica phase on the zirconia surface. This process enabled silane coupling to the zirconia and improved the adhesion of the resin cement.

Synthesis and characterization of TiNbZrMo medium-entropy bio-composites: Microstructure, mechanical properties, and in vitro degradation.

This study reports the synthesis and characterization of hydroxyapatite (HA)-based bio-composites reinforced with varying amounts (by weight, 1-15 wt.%) of bio-medium entropy alloy (BioMEA) for load-bearing implant applications. BioMEA powders consisting of Ti, Nb, Zr, and Mo were mechanically alloyed for 100 h and subsequently added to HA using powder metallurgy techniques. To show the effect of BioMEA, the microstructure, density, and mechanical tests have been conducted and the synthesized BioMEA was characterized by scanning electron microscope (SEM), x-ray diffractometer (XRD), and Fourier-transform infrared spectroscopy (FTIR) analysis. In addition, in vitro degradation behavior and bioactivity analyses of bio-composites have been conducted. XRD analysis revealed the formation of BioMEA after 20 h of mechanical alloying. The highest density value of 2.47 g/cm3 was found in 15 wt.% BioMEA-reinforced bio-composite. The addition of BioMEA reinforcement led to a significant increase in hardness and tensile strength values, with the highest values observed at 15 wt.% reinforcement. Compression tests demonstrated a significant increase in compressive strength and deformation capability of the bio-composites with the highest values observed at 15 wt.% BioMEA addition. The highest toughness of 7.68 kJ/m2 was measured in 10 wt.% MEA-reinforced bio-composites. The produced bio-composite materials have an elastic modulus between 3.5-5.5 GPa, which may provide a solution to the stress shielding problems caused by the high elastic modulus of metallic implant materials. The most severe degradation occurred in 15 wt.% MEA-reinforced bio-composites, and the effect of degradation caused a decrease in Ca and an increase in Ti-Ni-Zr-Mo in all bio-composites. These findings suggest that HA/BioMEA bio-composites have the potential to be developed as advanced biomaterials with moderate mechanical and biological properties for load-bearing implant applications.

Paedodontic preformed crowns in primary teeth and relative degree of dental wear.

AIM: Prosthetic rehabilitation of deciduous teeth in paediatric age using pre-formed crowns has been considered one of the best methods of dental restoration since their introduction. Their main advantages are related to durability, longevity and a low rate of recurrent cavities. Since stainless steel crowns do not coincide with aesthetic needs of parents and patients, preformed paedodontic crowns made of zirconia and nano-hybrid composite was introduced. The aim of the study is to evaluate the degree of wear on the enamel and on themselves of the different paedodontic crowns. MATERIALS: Nine bovine teeth and nine paedodontic crowns for deciduous molars were selected for the study, three of which in zirconia, three in nano-hybrid composite and three in stainless steel. Wear test was carried out on the Rtech™ Instruments tribometer applying a force of 50 N. After that, both the bovine teeth and the paedodontic crowns were observed using a stereo microscope (Zeiss Stemi C-500) and a scanning electron microscope (SEM, Cambridge Stereoscan 440). The areas of wear were calculated with a software [ImageJ, version 1x, Wayne Rasband, Maryland, USA]. CONCLUSION: Pre-formed paediatric crowns in zirconia, nano-hybrid composite and stainless steel are a valid aid for the restoration of deciduous teeth and do not compromise the physiological wear characteristic of the phases of the dental exchange. The stainless steel crown is preferable for the restorations in the posterior sectors as its behaviour is the most similar to that of a natural tooth. Zirconia and nano-hybrid composite crowns showed an inversely proportional behaviour between their wear volume and that of the opposing tooth.

Bonding of Composite Cements Containing 10-MDP to Zirconia Ceramics Without Dedicated Ceramic Primer.

PURPOSE: To measure zirconia-to-zirconia microtensile bond strength (µTBS) using composite cements with and without primer. MATERIALS AND METHODS: Two Initial Zirconia UHT (GC) sticks (1.8x1.8x5.0 mm) were bonded using four cements with and without their respective manufacturer's primer/adhesive (G-CEM ONE [GOne] and G-Multi Primer, GC; Panavia V5 [Pv5]), and Panavia SA Cement Universal [PSAu], and Clearfil Ceramic Plus, Kuraray Noritake; RelyX Universal (RXu) and Scotchbond Universal Plus [SBUp], 3M Oral Care). Specimens were trimmed to an hour-glass shaped specimen whose isthmus is circular in cross-section. After 1-week water storage, the specimens were either tested immediately (1-week µTBS) or first subjected to 50,000 thermocycles (50kTC-aged µTBS). The fracture mode was categorized as either adhesive interfacial failure, cohesive failure in composite cement, or mixed failure, followed by SEM fracture analysis of selected specimens. Data were analyzed using linear mixed-effects statistics (α = 0.05; variables: composite cement, primer/adhesive application, aging). RESULTS: The statistical analysis revealed no significant differences with aging (p = 0.3662). No significant difference in µTBS with/without primer and aging was recorded for GOne and PSAu. A significantly higher µTBS was recorded for Pv5 and RXu when applied with their respective primer/adhesive. Comparing the four composite cements when they were applied in the manner that resulted in their best performance, a significant difference in 50kTC-aged µTBS was found for PSAu compared to Pv5 and RXu. A significant decrease in µTBS upon 50kTC aging was only recorded for RXu in combination with SBUp. CONCLUSION: Adequate bonding to zirconia requires the functional monomer 10-MDP either contained in the composite cement, in which case a separate 10-MDP primer is no longer needed, or in the separately applied primer/adhesive.

The influence of Zircos-E® etchant, silica coating, and alumina air-particle abrasion on the debonding resistance of endocrowns with three different preparation designs.

OBJECTIVES: The study aimed to evaluate the debonding resistance of three different endocrown designs on molar teeth, using three different zirconia surface pretreatments. MATERIAL AND METHOD: Ninety human mandibular first molars were divided into three main groups: endocrowns without ferrule, with 1 mm ferrule, and with 2 mm ferrule. The subgroups were defined by their surface pretreatment method used (n = 15): 50 µm alumina air-particle abrasion, silica coating using 30 µm Cojet™ particles, and Zircos-E® etching. The endocrowns were fabricated using multilayer zirconia ceramic, cemented with self-adhesive resin cement, and subjected to 5000 thermocycles (5-55°C) before debonding. The data obtained were analyzed using a two-way ANOVA. RESULTS: All test specimens survived the thermocyclic aging. The results indicated that both the preparation design and the surface treatment had a significant impact on the resistance to debonding of the endocrowns (p < .001). The 2 mm ferrule followed by the 1 mm ferrule designs exhibited the highest debonding resistance, both were superior to the endocrown without ferrule. Zircos-E® etching and silica coating yielded comparable debonding resistance, which were significantly higher than alumina air-particle abrasion. All endocrowns demonstrated a favorable failure mode. CONCLUSIONS: All designs and surface treatments showed high debonding resistance for a single restoration. However, ferrule designs with Zircos-E® etching or silica coating may represent better clinical options compared to the nonferrule design or alumina airborne-particle abrasion. Nonetheless, further research, including fatigue testing and evaluations with different luting agents is recommended.

Effect of toothbrushing with conventional and whitening dentifrices on monolithic zirconia after finishing procedures.

PURPOSE: To evaluate the effect of toothbrushing with conventional and whitening dentifrices on the color difference (ΔE00), gloss (Δgloss), and surface roughness (SR) of stained stabilized zirconia with 5 mol% of yttrium oxide (5Y-TZP) after polishing or glazing. METHODS: Specimens were divided into four groups (n=20): C (control), S (staining), SG (staining and glazing) and SP (staining and polishing). 50,000 toothbrushing cycles were performed with conventional (n=10) and whitening (n= 10) dentifrice slurries. The ΔE00 and Δgloss were measured using a spectrophotometer and CIEDE2000 system while SR was measured by laser confocal microscope. The ΔE00 and Δgloss data were analyzed using 2-way ANOVA, and SR data were analyzed using the linear repeated measures model, with Bonferroni's complementary test (α= 0.05). RESULTS: The ΔE00 values were beyond the acceptability threshold and no differences were found among the groups. There was no difference among groups to Δgloss after toothbrushing with conventional dentifrice while SP presented the highest values of Δgloss after toothbrushing with whitening dentifrice. Conventional dentifrice decreased the SR of stained groups and whitening dentifrice decreased SR of S and SG. The toothbrushing with conventional and whitening dentifrices promoted color difference, but did not impair gloss and surface roughness of stained 5Y-TZP. CLINICAL SIGNIFICANCE: Monolithic zirconia has been routinely used for esthetic restorations, however the type of finishing procedures that is carried out on it must be taken into consideration, in addition to the fact that brushing can influence the color difference of the material as well as interfere with surface roughness and gloss.

Full-ceramic resin-bonded fixed dental prostheses: A systematic review.

Despite the development of implant-supported prostheses, there are still patients for whom conservative treatments such as resin-bonded fixed dental prostheses (RBFDPs) are more appropriate. This study's objective was to analyze the available research on full-ceramic RBFDPs. In this study, Web of Science, MEDLINE/PubMed, Scopus, Embase, Cochrane Library, and Google Scholar databases were searched for articles published in English between 2010 and 2020. A total of 14 studies were reviewed based on the eligibility criteria. The results showed that using a cantilever design with one abutment had an advantage over two abutments. Additionally, it was proposed that preparations designed with retentive aids, such as a proximal box, groove, and pinhole, could improve RBFDP survival rates. IPS e.max ZirCAD, In-Ceram alumina, and zirconia CAD/CAM were the most commonly used framework materials. Most studies used air abrasion, salinization, or hydrofluoric acid for surface treatment. Adhesive resin cements were the most frequently used type of cement. The survival rate of In-Ceram ceramics (85.3%-94.8%) was lower than that of In-Ceram zirconia and IPS e.max ZirCAD. Debonding, followed by framework fracture, was the leading cause of failure. Following 3-10 years follow-up, the survival percentage of all-ceramic RBFDPs ranged from 76% to 100%. Although RBFDPs have demonstrated satisfactory success as a conservative treatment, long-term follow-ups and higher sample sizes in clinical research are required to gain more reliable outcomes on the clinical success rate of various RBFDP designs.

Effect of Various Surface Treatments of Zirconia on its Adhesive Properties to Dentin: An In Vitro Study.

AIM: To assess the effectiveness of various surface treatments and adhesives on the bond strength of zirconia-based ceramic to dentin. MATERIALS AND METHODS: Eighty samples of zirconia were subjected to the four-surface treatment protocols (sandblasting, 48% hydrofluoric acid (HF), 48% hydrofluoric acid + 70% nitric acid (HNO3) and no treatment (control) following which the samples from each group were subdivided into two subgroups (n = 10) based on the resin cement employed for cementation (RelyX U200 and G-Cem Linkforce). The bonded specimens were subjected to shear stress to measure the bond strength using Universal testing machine. To test the difference in bond strength among the eight study groups, the Kruskal-Wallis ANOVA test was applied and for comparison between cements in each group, Mann-Whitney U test was applied. RESULTS: The highest bond strength values were observed for 48% HF group cemented with G-Cem Linkforce resin cement (16.220 ± 1.574) and lowest for control group-RelyX (4.954 ± 0.972). G-Cem cement showed higher bond strength than RelyX for all surface treatments except 48% HF + 70% nitric acid. CONCLUSION: It can be inferred that 48% HF can etch zirconia and generate a porous structure that proves to be beneficial for bonding. CLINICAL SIGNIFICANCE: The increasing demand for esthetics has led to the replacement of metal-ceramic materials with zirconia-based ceramics. However, the chemical inertness of zirconia to various conventional surface treating agents has continuously challenged researchers to discover a new surface treatment protocol that could enhance the bond strength of zirconia. How to cite this article: Yenamandra MS, Joseph A, Singh P, et al. Effect of Various Surface Treatments of Zirconia on its Adhesive Properties to Dentin: An In Vitro Study. J Contemp Dent Pract 2024;25(3):226-230.

Impact of the sintering parameters on the grain size, crystal phases, translucency, biaxial flexural strength, and fracture load of zirconia materials.

OBJECTIVES: To investigate the influence of the zirconia and sintering parameters on the optical and mechanical properties. METHODS: Three zirconia materials (3/4Y-TZP, 4Y-TZP, 3Y-TZP) were high-speed (HSS), speed (SS) or conventionally (CS) sintered. Disc-shaped specimens nested in 4 vertical layers of the blank were examined for grain size (GS), crystal phases (c/t'/t/m-phase), translucency (T), and biaxial flexural strength. Fracture load (FL) of three-unit fixed dental prostheses was determined initially and after thermomechanical aging. Fracture types were classified, and data statistically analyzed. RESULTS: 4Y-TZP showed a higher amount of c + t'-phase and lower amount of t-phase, and higher optical and lower mechanical properties than 3Y-TZP. In all materials, T declined from Layer 1 to 4. 3/4Y-TZP showed the highest FL, followed by 3Y-TZP, while 4Y-TZP showed the lowest. In 4Y-TZP, the sintering parameters exercised a direct impact on GS and T, while mechanical properties were largely unaffected. The sintering parameters showed a varying influence on 3Y-TZP. Thermomechanical aging resulted in comparable or higher FL. CONCLUSION: 3/4Y-TZP presenting the highest FL underscores the principle of using strength-gradient multi-layer blanks to profit from high optical properties in the incisal area, while ensuring high mechanical properties in the lower areas subject to tensile forces. With all groups exceeding maximum bite forces, the examined three-unit FDPs showed promising long-term mechanical properties.

Dental implant and abutment in PEEK: stress assessment in single crown retainers on anterior region.

OBJECTIVE: Stress distribution assessment by finite elements analysis in poly(etheretherketone) (PEEK) implant and abutment as retainers of single crowns in the anterior region. MATERIALS AND METHODS: Five 3D models were created, varying implant/abutment manufacturing materials: titanium (Ti), zirconia (Zr), pure PEEK (PEEKp), carbon fiber-reinforced PEEK (PEEKc), glass fiber-reinforced PEEK (PEEKg). A 50 N load was applied 30o off-axis at the incisal edge of the upper central incisor. The Von Mises stress (σvM) was evaluated on abutment, implant/screw, and minimum principal stress (σmin) and maximum shear stress (τmax) for cortical and cancellous bone. RESULTS: The abutment σvM lowest stress was observed in PEEKp group, being 70% lower than Ti and 74% than Zr. On the implant, PEEKp reduced 68% compared to Ti and a 71% to Zr. In the abutment screws, an increase of at least 33% was found in PEEKc compared to Ti, and of at least 81% to Zr. For cortical bone, the highest τmax values were in the PEEKp group, and a slight increase in stress was observed compared to all PEEK groups with Ti and Zr. For σmin, the highest stress was found in the PEEKc. Stress increased at least 7% in cancellous bone for all PEEK groups. CONCLUSION: Abutments and implants made by PEEKc concentrate less σvM stress, transmitting greater stress to the cortical and medullary bone. CLINICAL RELEVANCE: The best stress distribution in PEEKc components may contribute to decreased stress shielding; in vitro and in vivo research is recommended to investigate this.

Effect of cement spacer on fit accuracy and fracture strength of 3-unit and 4-unit zirconia frameworks.

BACKGROUND: Cement spacer is essential for compensating deformation of zirconia restoration after sintering shrinkage, allowing proper seating and better fracture resistance of the restoration. Studies assessing the effect of cement spacer on fit accuracy and fracture strength of zirconia frameworks are missing in the literature. Therefore, the aim of this study was to evaluate the effect of different cement spacer settings on fit accuracy and fracture strength of 3-unit and 4-unit zirconia frameworks. METHODS: Sixty standardized stainless-steel master dies were manufactured with 2 prepared abutments for fabricating 3-unit and 4-unit zirconia frameworks. The frameworks were assigned into 6 groups (n = 10) according to cement spacer setting (30 µm, 50 µm, and 80 µm) as follows: 3-unit frameworks; 3u-30, 3u-50, 3u-80, and 4-unit frameworks; 4u-30, 4u-50, and 4u-80. The frameworks were assessed for fit accuracy with the replica method. The specimens were cemented to their corresponding dies, and the fracture strength was measured in a universal testing machine. The Weibull parameters were calculated for the study groups and fractured specimens were inspected for failure mode. Two-Way ANOVA followed by Tukey test for pairwise comparison between study groups (α = 0.05). RESULTS: The cement spacer had a significant effect on both fit accuracy and fracture strength for 3-unit and 4-unit frameworks. The 50 µm spacer had significantly better fit accuracy followed by 80 µm, and 30 µm spacers. Both 50 µm and 80 µm spacers had similar fracture strength, and both had significantly better strength than 30 µm spacer. CONCLUSIONS: For both 3-unit and 4-unit zirconia frameworks, 50 µm cement spacer can be recommended over 30 µm and 80 µm spacers for significantly better fit accuracy and adequate fracture strength.

Multiarmed DNA jumper and metal-organic frameworks-functionalized paper-based bioplatform for small extracellular vesicle-derived miRNAs assay.

Small extracellular vesicle-derived microRNAs (sEV-miRNAs) have emerged as promising noninvasive biomarkers for early cancer diagnosis. Herein, we developed a molecular probe based on three-dimensional (3D) multiarmed DNA tetrahedral jumpers (mDNA-Js)-assisted DNAzyme activated by Na+, combined with a disposable paper-based electrode modified with a Zr-MOF-rGO-Au NP nanocomplex (ZrGA) to fabricate a novel biosensor for sEV-miRNAs Assay. Zr-MOF tightly wrapped by rGO was prepared via a one-step method, and it effectively aids electron transfer and maximizes the effective reaction area. In addition, the mechanically rigid, and nanoscale-addressable mDNA-Js assembled from the bottom up ensure the distance and orientation between fixed biological probes as well as avoid probe entanglement, considerably improving the efficiency of molecular hybridization. The fabricated bioplatform achieved the sensitive detection of sEV-miR-21 with a detection limit of 34.6 aM and a dynamic range from100 aM to 0.2 µM. In clinical blood sample tests, the proposed bioplatform showed results highly consistent with those of qRT-PCRs and the signal increased proportionally with the NSCLC staging. The proposed biosensor with a portable wireless USB-type analyzer is promising for the fast, easy, low-cost, and highly sensitive detection of various nucleic acids and their mutation derivatives, making it ideal for POC biosensing.

Bioactivity and antibacterial effects of zinc-containing bioactive glass on the surface of zirconia abutments.

OBJECTIVES: This study aimed to enhance gingival fibroblast function and to achieve antibacterial activity around the implant abutment by using a zinc (Zn)-containing bioactive glass (BG) coating. METHODS: 45S5 BG containing 0, 5, and 10 wt.% Zn were coated on zirconia disks. The release of silica and Zn ions in physiological saline and their antibacterial effects were measured. The effects of BG coatings on human gingival fibroblasts (hGFs) were assessed using cytotoxicity assays and by analyzing the gene expression of various genes related to antioxidant enzymes, wound healing, and fibrosis. RESULTS: BG coatings are capable of continuous degradation and simultaneous ion release. The antibacterial effect of BG coatings increased with the addition of Zn, while the cytotoxicity remained unchanged compared to the group without coatings. BG coating enhances the expression of angiogenesis genes, while the Zn-containing BG enhances the expression of antioxidant genes at an early time point. BG coating enhances the expression of collagen genes at later time points. CONCLUSIONS: The antibacterial effect of BG improved with the increase in Zn concentration, without inducing cytotoxicity. BG coating enhances the expression of angiogenesis genes, and Zn-containing BG enhances the expression of antioxidant genes at an early time point. BG coating enhances the expression of collagen genes at later time points. CLINICAL SIGNIFICANCE: Adding 10 wt% Zn to BG could enhance the environment around implant abutments by providing antibacterial, antioxidant, and anti-fibrotic effects, having potential for clinical use.

A bimetallic peroxidase-mimicking nanozyme with antifouling property for construction of sensor array to identify phosphoproteins and diagnose cancers.

Protein phosphorylation is a significant post-translational modification that plays a decisive role in the occurrence and development of diseases. However, the rapid and accurate identification of phosphoproteins remains challenging. Herein, a high-throughput sensor array has been constructed based on a magnetic bimetallic nanozyme (Fe3O4@ZNP@UiO-66) for the identification and discrimination of phosphoproteins. Attributing to the formation of Fe-Zr bimetallic dual active centers, the as-prepared Fe3O4@ZNP@UiO-66 exhibits enhanced peroxidase-mimicking catalytic activity, which promotes the electron transfer from Zr center to Fe(II)/Fe(III). The catalytic activity of Fe3O4@ZNP@UiO-66 can be selectively inhibited by phosphoproteins due to the strong interaction between phosphate groups and Zr centers, as well as the ultra-robust antifouling capability of zwitterionic dopamine nanoparticle (ZNP). Considering the diverse binding affinities between various proteins with the nanozyme, the catalytic activity of Fe3O4@ZNP@UiO-66 can be changed to various degree, leading to the different absorption responses at 420 nm in the hydrogen peroxide (H2O2) - 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) system. By simply extracting different absorbance intensities at various time points, a sensor array based on reaction kinetics for the discrimination of phosphoproteins from other proteins is constructed through linear discriminant analysis (LDA). Besides, the quantitative determination of phosphoproteins and identification of protein mixtures have been realized. Further, based on the differential level of phosphoproteins in cells, the differentiation of cancer cells from normal cells can also be implemented by utilizing the proposed sensor array, showing great potential in disease diagnosis.

Evaluation of the effect of different core substrates on the accuracy of intraoral scanners.

BACKGROUND: The aim of this study was to determine if different types of core substrates have any effect on the trueness and precision of digital intraoral impressions. MATERIAL AND METHODS: A customized typodont with four similar cores of natural dentine, composite, metal (Ni-Cr), and zirconia in the position of premolars was fabricated. The study model was scanned five times with two types of intraoral scanners (Carestream 3600 and 3Shape Trios 3), and a reference standard scan was obtained using a laboratory scanner (3shape D1000). A metrology software (Geomagic X) was used to align the data of experimental scans and the reference scan to determine deviation values (trueness). Precision values were calculated with random superimposition in each intraoral scanner group. The Kruskal-Wallis test was used to compare differences between different substrates, and the Mann-Whitney test was used to compare the average values between the two scanners. RESULTS: Trios 3 was found to be significantly truer and more precise than Carestream 3600 (p value = .005, <0.001). There were no significant differences in the trueness of different substrates when they were scanned by Trios 3, while different materials showed significantly different trueness values in the Carestream 3600 group (p value = .003). Dentin showed the best trueness, and zirconia performed worse than other substrates. Regarding the precision of the scanners, neither of the scanners was affected by the type of scanning substrate. CONCLUSION: For Carestream 3600, substrate type did impact the trueness of intraoral scans, with dentin and zirconia showing the highest and lowest accuracy, respectively, while Trios 3 was similarly accurate across all substrates. Trios 3 had both higher trueness and precision than Carestream 3600.

Laser debonding of ultrathin occlusal veneers fabricated from different CAD/CAM ceramic materials.

BACKGROUND: Erbium lasers safely offer the possibility of reuse for debonded restorations. Since these lasers have a high affinity for water molecules, they are absorbed by resin cement causing explosive ablation of the cement and thus, the restoration debonds. The efficiency of this process depends on many factors, including the ceramic type, its chemical composition and thickness. Therefore, this study was designed to test the time taken to debond ultrathin occlusal veneers made of three types of milled ceramic materials and evaluate the integrity of these restorations after debonding. METHODS: Three ceramic types were evaluated in this study: lithium disilicate (IPS Emax CAD), highly condensed lithium disilicate (GC initial®LiSi), and translucent zirconia (Katana zirconia STML). Each group consisted of 8 occlusal veneers of 0.5 mm thickness. The samples were cemented to the occlusal surfaces of the upper molar teeth. An Er; Cr: YSGG laser was applied to the occlusal veneers using the scanning method, and time until debonding was calculated. The debonded samples were then inspected under a stereomicroscope for possible damage. Numerical data are presented as the mean with 95% confidence interval (CI), standard deviation (SD), minimum (min.) and maximum (max.) values. Normality and variance homogeneity assumptions were confirmed using Shapiro-Wilk's and Levene's tests, respectively. Data were normally distributed and were analyzed using one-way ANOVA followed by Tukey's post hoc test. The significance level was set at p < 0.05 for all tests. Statistical analysis was performed with R statistical analysis software version 4.3.2 for Windows (R Core Team (2023). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/). RESULTS: There was no significant difference in debonding time between the different materials (p = 0.995). The longest debonding time was found for Katana STML (87.52 ± 20.45) (seconds), followed by Emax (86.94 ± 20.63) (seconds), while the lowest value was found for LiSi initial (86.14 ± 25.16) (seconds). In terms of damage to the debonded veneers, The Emax and zirconia samples showed no damage. However, 40% of the LiSi samples fractured during debonding, and 20% exhibited cracks. Only 40% of the LiSi samples were sound after debonding. CONCLUSION: Er; Cr: YSGG laser can be used efficiently to remove ceramic occlusal veneers. However, its effect on LiSi restorations needs further research.