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1.
Int Orthod ; 20(3): 100665, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35851494

RESUMEN

OBJECTIVES: Information regarding the effects of orthodontic bracket debonding on zirconia restorations, and the preferred method for residual adhesive removal from the zirconia restoration surface is lacking. Thus, this study aimed to assess the effects of different methods of residual adhesive removal after orthodontic bracket debonding on flexural strength, surface roughness, and phase transformation of high-translucent (HT) zirconia. MATERIALS AND METHODS: This in vitro study evaluated 72 bar-shaped HT zirconia specimens; 18 specimens were assigned to the control group. Metal brackets were bonded to the remaining specimens by resin cement. After bracket debonding, the residual adhesive on the surface of specimens was removed by three methods (n=18): a 30-flute tungsten-carbide (TC) bur at low speed, an ultrafine diamond bur at high speed, and Er:YAG laser irradiation. The surface roughness (Ra and Rz) was measured. X-ray diffraction (XRD) analysis was carried out, and the flexural strength was measured as well. Data were statistically analyzed (α=0.05). RESULTS: Before polishing, all methods increased the Ra and Rz values (P<0.05) except for the diamond bur yielding a Rz value comparable to that of the control group. The Ra values of the test groups were comparable after polishing, and still higher than that of the control group (P<0.05). The flexural strength of all three test groups was comparable (P>0.05), and significantly lower than that of the control group (P<0.001). The monoclinic phase was not observed in any group. CONCLUSIONS: Orthodontic bracket debonding adversely affects the surface roughness and flexural strength of zirconia despite polishing.


Asunto(s)
Pulido Dental , Resistencia Flexional , Cementos Dentales , Pulido Dental/métodos , Diamante , Humanos , Rayos Láser , Ensayo de Materiales , Propiedades de Superficie , Tungsteno , Circonio
2.
Sci Rep ; 12(1): 12701, 2022 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-35882879

RESUMEN

Adsorption efficiency of Cefotaxime by novel nanocomposites beads composed of iota carrageenan (IC), sulfonated poly vinyl alcohol (SPVA) and nano sulfated zirconia (SZrO2) was evaluated in this study. SZrO2 was synthesized from solvent-free and easy calcination technique then embedded with 1-2.5 wt.% into the polymeric matrix. A batch adsorption experiment was carried out to investigate the effects of dosage, pH, beginning concentration, and time on Cefotaxime antibiotic adsorption. The ideal conditions to achieve complete removal are 88.97 mg L-1 initial cefotaxime concentration at time 3.58 h with 11.68 mg of beads composite with 2.5 wt.% of SZrO2. The pseudo second order kinetics model better illustrated the adsorption of cefotaxime on nanocomposite beads, and the maximum adsorption capacity are 659 mg g-1 for the composite with 2.5 wt.% of SZrO2. The mechanism of adsorption process depend mainly on the interactions between the different functional groups of SPVA, IC and SZrO2. The nanocomposites beads also exhibit excellent reproducibility after ten adsorption cycles. This type of nanocomposites beads can be easily separated from water without leaving any residue, verifying this novel nanocomposite beads has strong potential in water treatment for the antibiotic contaminant removal.


Asunto(s)
Quitosano , Nanocompuestos , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Antibacterianos , Cefotaxima , Quitosano/química , Concentración de Iones de Hidrógeno , Cinética , Nanocompuestos/química , Polímeros/química , Reproducibilidad de los Resultados , Sulfatos , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Circonio
3.
Comput Intell Neurosci ; 2022: 1589209, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35837209

RESUMEN

Objective: To explore the application effect of new material after surface modification of zirconia ceramics and patient evaluation. Methods: A total of 60 patients with tooth defect treated in our hospital from April 2020 to April 2021 were selected as the study subjects and randomly divided into the control group and experimental group, with 30 cases each. The patients in the control group were treated with glass-ceramics, and those in the experimental group received LiSi surface treatment, so as to compare the application effect and patients' evaluation between the two groups. Results: Between the two groups, no obvious differences in surface loss, adhesive strength, and transmittance at 3 months, 6 months, and 1 year were not observed (P > 0.05); and after intervention, the score on dental aesthetics, hardness value, and occlusal force were obviously higher in the experimental group than in the control group (P < 0.001). Conclusion: The new material enables forming an acid etchable coating on the zirconia surface, increases the adhesive strength, and achieves an aesthetic degree that is welcomed by the patients; meanwhile, after grinding, the edge is defect free and the tightness is higher. Further research will help to establish a better solution for patients.


Asunto(s)
Cerámica , Circonio , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Propiedades de Superficie
4.
J Biomed Nanotechnol ; 18(4): 1164-1171, 2022 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35854466

RESUMEN

Gingival fibroblasts play an important role in the constitution of soft tissue attachment. This study aims to investigate whether porous zirconia coating has a positive effect on promoting human gingival fibroblast attachment. The porous zirconia coating was loaded on zirconia surface by the dip coating method, surface morphology and composition were confirmed by scanning electron microscope and energy dispersive spectrometer; Tested the tensile bond strength by universal testing machine; Tested the surface roughness by roughness analyzer; Human gingival fibroblast proliferation, integrin ß1 and F-actin immunofluorescence staining explored the influence of porous zirconia on the adhesion and proliferation of human gingival fibroblast. Zirconia0.2 group showed spherical zirconia particles with diameters of 3-8 µm are distributed on the surface; The bonding strength of zirconia particle coating group reached 16.1±0.1 MPa, and the surface roughness was 0.715±0.091 µm; In comparison with control group (P < 0.01), the percentage of human gingival fibroblasts adhering to zirconia was markedly higher. In zirconia group, integrin-ß1 and F-actin fluoresced more obvious than in control group. Porous zirconia coating can form a porous structure on the surface and the porous structure can promote the attachment and proliferation of human gingival fibroblast, it will be more beneficial for soft tissue early sealing.


Asunto(s)
Actinas , Circonio , Fibroblastos , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Porosidad , Propiedades de Superficie , Circonio/química
5.
Langmuir ; 38(28): 8677-8685, 2022 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-35786968

RESUMEN

A sorbent with a high enough capacity for NH4+ could serve as an oral binder to lower urea levels in end-stage kidney disease (ESKD) patients. A hydrogen-loaded cation exchanger such as zirconium phosphate Zr(HPO4)2·H2O (ZrP) is a promising candidate for this application. However, the NH4+ binding selectivity versus other ions must be improved. Here, we have developed a gas-permeable and hydrophobic surface coating on an amorphous form of ZrP using tetraethyl orthosilicate and methoxy-terminated polydimethylsiloxane. The hydrophobic coating serves as a barrier to ions in water solution from reaching the ion-exchanger's surface. Meanwhile, its gas-permeable nature allows for gaseous ammonia transfer to the cation exchanger. In vitro studies were designed to replicate the small intestine's expected ion concentrations and exposure time to the sorbent. The effectiveness of the coating was measured with NH4+ and Ca2+ solutions and uncoated ZrP as the negative control. X-ray photoelectron spectroscopy and scanning electron microscopy measurements show that the coating successfully modifies the surface of the cation exchanger─ZrP. Water contact angle studies indicate that coated ZrP is hydrophobic with an angle of (149.8 ± 2.5°). Simulated small intestine solution studies show that the coated ZrP will bind 94% (±11%) more NH4+ than uncoated ZrP in the presence of Ca2+. Meanwhile, Ca2+ binding decreases by 64% (±6%). The nearly fourfold increase in NH4+ selectivity can be attributed to the gas-permeable and hydrophobic coating applied on the ZrP surface. This work suggests a novel pathway to develop a selective cation exchanger for treating ESKD patients.


Asunto(s)
Compuestos de Amonio , Cationes , Humanos , Agua , Circonio/química
6.
Bone Joint J ; 104-B(7): 833-843, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35775177

RESUMEN

AIMS: This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). METHODS: Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years' follow-up. RESULTS: Patients in Group C were associated with increased mean liner wear rates compared to patients in Group A (0.133 mm/yr (SD 0.21) vs 0.031 mm/yr (SD 0.07), respectively; p < 0.001) and Group B (0.133 mm/yr (SD 0.21) vs 0.022 mm/yr (SD 0.05), respectively; p < 0.001) at ten years' follow-up. Patients in Group C were also associated with increased risk of osteolysis and aseptic loosening requiring revision surgery, compared with patients in Group A (7/133 vs 0/133, respectively; p = 0.007) and Group B (7/133 vs 0/135, respectively; p = 0.007). There was a non-statistically significant trend towards increased mean liner wear rates in Group A compared with Group B (0.031 mm/yr (SD 0.07) vs 0.022 mm/yr (SD 0.05), respectively; p = 0.128). All three groups were statistically comparable preoperatively and at ten years' follow-up when measuring normalized Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.410), 36-Item Short Form Health Survey (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p = 0.451). CONCLUSION: The use of UHMWPE was associated with progressively increased annual liner wear rates after THA compared to XLPE. At ten years' follow-up, the group receiving UHMWPE demonstrated an increased incidence of osteolysis and aseptic loosening requiring revision surgery compared to XLPE. Femoral heads composed of OxZr were associated with trend towards reduced wear rates compared to CoCr, but this did not reach statistical significance and did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two femoral head components. Cite this article: Bone Joint J 2022;104-B(7):833-843.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Prótesis de Cadera , Osteólisis , Artroplastia de Reemplazo de Cadera/efectos adversos , Aleaciones de Cromo , Cobalto , Cabeza Femoral/cirugía , Estudios de Seguimiento , Prótesis de Cadera/efectos adversos , Humanos , Osteólisis/cirugía , Polietileno , Estudios Prospectivos , Diseño de Prótesis , Falla de Prótesis , Circonio
7.
Acta Biomed ; 93(3): e2022160, 2022 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-35775764

RESUMEN

BACKGROUND: The present study aims to compare the rate of return to sports in patients who underwent surgery for mobile-bearing UKA with either hypoallergenic TiNbN or with oxidized zirconium alloy implants. METHODS: The records of two consecutive cohorts for a total of 90 hypoallergenic implants were prospectively analysed. The first cohort consisted of 41 consecutive series of medial mobile-bearing hypoallergenic TiNbN UKA, whereas the second cohort consisted of 49 consecutive medial fixed-bearing hypoallergenic Uni Oxinium.The clinical evaluation involved evaluating each patient's University of California, Los Angeles (UCLA) activity scoresand the High-Activity Arthroplasty Score(HAAS). Each patient was clinically evaluated on the day before surgery (T0), then after a minimum follow-up period of 12 months (T1), and finally after 24 months (T2).   Results:The only pre-operative difference between the two groups involved pre-operative BMI with significantly higher BMI in TiNbN Group (p<0.001). Both groups reported significant improvement at each follow-up compared with the previous and also at the final follow up with respect to UCLA and HAAS (p<0.05), except for UCLA in TiNbN between T1 and T2(p>0.05). Moreover, BMI improved significantly at the final follow up, but only in TiNbN group (p<0.05). CONCLUSIONS: Both TiNbN and Oxinium UKA procedures enabled patients to return to an acceptable level of sports activity with excellent radiographic outcomes after the final follow up regardless of the age, gender, BMI, and bearing type.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Osteoartritis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Humanos , Articulación de la Rodilla , Niobio , Osteoartritis de la Rodilla/cirugía , Volver al Deporte , Titanio , Circonio
8.
J Contemp Dent Pract ; 23(3): 343-350, 2022 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-35781441

RESUMEN

AIM: The aim of the in vitro study was to comparatively evaluate the bond strength of CAD/CAM monolithic zirconia copings using three luting agents and two different finish lines. MATERIALS AND METHODS: For the evaluation of bond strength, 60 extracted human maxillary first premolars were prepared to receive CAD/CAM monolithic zirconia copings. They were randomly divided into six groups of 10 samples each to receive CAD/CAM monolithic zirconia copings to bond with three different luting agents on two different finish lines. The luting agents used were RelyX U200, RMGIC, and Maxcem Elite with finish lines which were incorporated were 90° shoulder and radial shoulder finish lines. The tensile bond strength for all 60 samples was tested using the universal testing machine. RESULTS: Between and within the group differences in tensile bond strength were analyzed using one-way ANOVA test of significance with Tukey's post-hoc analysis. The statistical analysis revealed that the CAD/CAM zirconia copings used a combination of 90° shoulder and RelyX U200 as the luting agent (Group II) which offered the maximum bond strength. CONCLUSION: Within the constraints of this study, it could be concluded that CAD/CAM monolithic zirconia copings luted with RelyX U200 cement on a 90° shoulder finish line is the preferred method, taking the bond strength into consideration. CLINICAL SIGNIFICANCE: The results of this study can be extrapolated into a clinical scenario to help the clinician decide the most apt combination of finish line design and the luting agent to achieve superior bond strengths in CAD/CAM zirconia crowns and fixed dental prosthesis.


Asunto(s)
Cementos Dentales , Circonio , Adaptación Psicológica , Humanos , Ensayo de Materiales , Circonio/química
9.
Am J Dent ; 35(2): 152-160, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35798711

RESUMEN

PURPOSE: To investigate the biomechanical and immunological reactions to coated and non-coated blasted PEEK implants in vivo after 12 weeks and review the associated literature. METHODS: Two osteotomy sites were performed in each proximal tibia of 10 lop-eared rabbits (n= 4 per rabbit). Each rabbit received a randomly placed (1) blasted zirconium phosphate nano-coated PEEK- (nano-ZrP), (2) blasted PEEK- (PEEK) and (3) titanium implant (Ti) and an empty sham site. At 12 weeks, removal torque of all implants and biological investigation with qPCR was performed. The implant surfaces were analyzed prior to insertion with interferometry, SEM and XPS. RESULTS: The interferometry analysis showed that there was no difference in roughness for the uncoated PEEK compared to the ZrP coated PEEK implants. The titanium implants were considerably smoother (Sa= 0.23 µm) than the uncoated Sa= 1.11 µm) and ZrP coated PEEK implants (Sa= 1.12 µm). SEM analysis on the PEEK implants corroborated the interferometry results; no difference in structure between the uncoated vs. the ZrP coated PEEK was visible on the micrometer level. At higher magnifications, the ZrP coating was visible in the SEM as a thin, porous network. All tested implants displayed osseointegration with the highest RTQ for nano-ZrP (18.4 Ncm) followed by PEEK (14.5 Ncm) and Ti (11.5 Ncm). All implants activated the immune system, with elevated macrophage and M2 macrophage qPCR markers at 12 weeks compared to the sham site. CLINICAL SIGNIFICANCE: Nano-ZrP coating improves osseointegration of blasted PEEK implants at 12 weeks of follow-up. Osseointegration of titanium, PEEK and nano-ZrP PEEK is not a normal bone healing process, but rather a shield-off mechanism that appears to be regulated by the innate immune system.


Asunto(s)
Implantes Dentales , Titanio , Animales , Benzofenonas , Materiales Biocompatibles Revestidos/química , Oseointegración/fisiología , Polímeros , Conejos , Propiedades de Superficie , Torque , Circonio
10.
J Clin Pediatr Dent ; 46(3): 199-203, 2022 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-35830632

RESUMEN

OBJECTIVE: The purpose of this study was to evaluate the effect of different crown materials on the interleukinone beta (IL-1ß) content of the gingival crevicular fluid and to study which crown material causes the highest inflammation on the marginal gingiva on a biochemical basis in pediatric patients. STUDY DESIGN: Twenty patients in the age group of 4-8 years with endodontically treated primary molars indicated for crown placement were selected for the study which was further divided into 3 groups for sample consideration: group 1-stainless steel crown, group 2-preformed zirconia crown, and group 3- control group (primary second molar). All assay procedures were carried out and the results of the collected samples were calculated using the ELISA-AID TM technique. RESULTS: On mean comparison among the groups using ANOVA oneway test, P-value turns out to be highly significant, on mean comparison using Tukey's HSD post-hoc test, The p-value was 0.000 ,0.000 ,0.193 on comparing group 1 with group 2, group 1 with group 3, group 2 with group 3 respectively. CONCLUSION: Preformed zirconia crown can be a relative replacement of SSC in primary molars as it causes comparatively less inflammation and with an advantage of esthetics.


Asunto(s)
Coronas , Diente Primario , Niño , Preescolar , Humanos , Inflamación , Diente Molar , Acero Inoxidable , Acero , Circonio
11.
PLoS Comput Biol ; 18(7): e1009715, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35839267

RESUMEN

Bispecific T cell engagers (TCEs) are an emerging anti-cancer modality that redirects cytotoxic T cells to tumor cells expressing tumor-associated antigens (TAAs), thereby forming immune synapses to exert anti-tumor effects. Designing pharmacokinetically acceptable TCEs and optimizing their size presents a considerable protein engineering challenge, particularly given the complexity of intercellular bridging between T cells and tumor cells. Therefore, a physiologically-relevant and clinically-verified computational modeling framework is of crucial importance to understand the protein engineering trade-offs. In this study, we developed a quantitative, physiologically-based computational framework to predict immune synapse formation for a variety of molecular formats of TCEs in tumor tissues. Our model incorporates a molecular size-dependent biodistribution using the two-pore theory, extravasation of T cells and hematologic cancer cells, mechanistic bispecific intercellular binding of TCEs, and competitive inhibitory interactions by shed targets. The biodistribution of TCEs was verified by positron emission tomography imaging of [89Zr]AMG211 (a carcinoembryonic antigen-targeting TCE) in patients. Parameter sensitivity analyses indicated that immune synapse formation was highly sensitive to TAA expression, degree of target shedding, and binding selectivity to tumor cell surface TAAs over shed targets. Notably, the model suggested a "sweet spot" for TCEs' CD3 binding affinity, which balanced the trapping of TCEs in T-cell-rich organs. The final model simulations indicated that the number of immune synapses is similar (~55/tumor cell) between two distinct clinical stage B cell maturation antigen (BCMA)-targeting TCEs, PF-06863135 in an IgG format and AMG420 in a BiTE format, at their respective efficacious doses in multiple myeloma patients. This result demonstrates the applicability of the developed computational modeling framework to molecular design optimization and clinical benchmarking for TCEs, thus suggesting that this framework can be applied to other targets to provide a quantitative means to facilitate model-informed best-in-class TCE discovery and development.


Asunto(s)
Antígeno de Maduración de Linfocitos B , Mieloma Múltiple , Linfocitos T , Anticuerpos Monoclonales/uso terapéutico , Antígeno de Maduración de Linfocitos B/metabolismo , Antígeno de Maduración de Linfocitos B/uso terapéutico , Humanos , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/patología , Radioisótopos/uso terapéutico , Distribución Tisular , Circonio/uso terapéutico
12.
Int J Oral Maxillofac Implants ; 37(4): 639-652, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35904820

RESUMEN

PURPOSE: This review aimed to summarize the current literature on the oral biofilm formation on alternative abutment materials compared with titanium (Ti) or Ti alloy in clinical and in situ conditions. MATERIALS AND METHODS: An electronic database search was conducted in PubMed, Cochrane Library, EMBASE, Scopus, Web of Science, LIVIVO, BVS, ProQuest, and OpenGrey up to November 2020. Clinical and in situ studies evaluating the biofilm formed on metallic, ceramic, or polymeric abutment materials compared with Ti or Ti alloy were included. Outcome measures were microbial counts/profile, cell viability, and biofilm coverage/thickness. Clinical parameters were deemed secondary outcomes. Risk of bias was assessed by RoB 2 and ROBINS-I tools. RESULTS: A total of 10 clinical and 9 in situ studies were included. Meta-analysis was not performed due to heterogeneity across studies. The abutment materials polytetrafluoroethylene, gold alloy, gold-platinum alloy, cobalt-chromium, alumina, and zirconia were reported. Six out of ten clinical studies (60%) and four out of nine in situ studies (44%) found no qualitative or quantitative microbiologic differences between tested materials. When significant differences were detected, conflicting results were reported. Clinical outcomes were consistent with healthy conditions for all investigated materials. CONCLUSION: There is not enough evidence to support the existence of relevant microbiologic differences in the biofilm formed on alternative abutment materials over Ti and its alloys in oral conditions. No evident relationship between microbiologic results and clinical outcomes were found. In situ studies and polymicrobial analyses showed a higher tendency to find significant differences between materials.


Asunto(s)
Pilares Dentales , Implantes Dentales , Aleaciones , Biopelículas , Materiales Dentales , Titanio , Circonio
13.
Int J Oral Maxillofac Implants ; 37(4): 677-684, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35904823

RESUMEN

PURPOSE: To compare the fracture resistance of a press-on ceramic custom implant restoration with pressed and cemented restorations. MATERIALS AND METHODS: Thirty-two (32) lithium disilicate (IPS e.max Press) custom hybrid abutment restorations were fabricated. The restorations were divided into two groups (n = 16) according to the construction technique: the commercial control group (C) and the press-on group (P). For the control group, lithium disilicate restorations were pressed and cemented on titanium bases. For the press-on group, lithium disilicate pressable ceramic (IPS e.max Press) was pressed on the titanium bases with injection molding. Each group was further divided according to the restoration design, either screw- or cement-retained, into two subgroups of eight specimens each. Specimens of C group were divided into screw-retained (cemented hybrid abutment crown, CHAC) or cement-retained (cemented hybrid abutment, CHA). Specimens of the P group were also divided into screw-retained (pressed hybrid abutment crown, PHAC) and cement-retained (pressed hybrid abutment, PHA). The specimens were subjected to static loading until failure with a universal testing machine. Two-way analysis of variance (ANOVA) was used to assess the effect of different techniques and designs on the fracture resistance of the samples (P < .05), followed by one-way ANOVA and Tukey honest significant difference (HSD) test (α = .05). RESULTS: C group showed higher mean fracture resistance (812.443 ± 129.14 N) than P group (596.71 ± 108.83 N), and the difference was statistically significant (P < .05). Regarding restoration design, HA groups showed higher mean fracture resistance (742.621 ± 153.82 N) than HAC (666.53 ± 163.07 N) groups with no statistically significant difference. CHA showed the highest mean fracture resistance (817.65 ± 161.76 N), while PHAC showed the lowest mean fracture resistance values (525.83 ± 47.29 N). CONCLUSION: The commercial cemented lithium disilicate restorations showed higher fracture resistance than the press-on restorations, although both showed a maximum load capacity that was greater than physiologic incisal force in the anterior region, and both hybrid abutments and hybrid abutment crowns were equally efficient in withstanding occlusal loading forces.


Asunto(s)
Implantes Dentales , Fracaso de la Restauración Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Materiales Dentales , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Titanio , Circonio
14.
Int J Oral Maxillofac Implants ; 37(4): 748-755, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35904831

RESUMEN

PURPOSE: To evaluate the mechanical stability of highly translucent zirconia (Zr) cantilevered fixed dental prostheses (cFDPs) and to investigate the influence of the number of implants (one versus two) supporting cFDPs with different restorative materials on their mechanical stability and load-bearing capacity. MATERIALS AND METHODS: Thirty-two specimens consisting of implant-supported prostheses embedded in resin blocks were fabricated. Sixteen specimens received one implant (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) to support two-unit cement-retained cFDPs with one extension unit and the other 16 received two implants (bone-level implant, 4.1-mm diameter, 13-mm length; Straumann) positioned corresponding to the missing maxillary central incisors to support three-unit cement-retained cFDPs with one extension unit. Two different prosthetic materials, chromium-cobalt (Cr-Co; Wirobond C+, Bego) and highly translucent Zr (Lava Plus, 3M ESPE) were selected to fabricate the two- and three-unit cFDPs. Standardized twoand three-unit Cr-Co frameworks (CC-I, n = 8; CC-II, n = 8) and highly translucent Zr frameworks (Zr-I, n = 8; Zr-II, n = 8) with a 6-mm cantilever extension were fabricated using CAD/CAM (EOS M 290). Following thermomechanical fatigue loading, the specimens were tested for fracture resistance under static loading. The influence of restoration material and number of supporting implants on fracture resistance were tested using two-way analysis of variance (ANOVA). The level of statistical significance was set below 5% (α < .05). RESULTS: All specimens survived aging. The mean (± standard deviation) fracture resistance values were 416.25 (± 42.71) N for Zr-I, 548.75 (± 75.41) N for Zr-II, 601.0 (± 41.51) N for CC-I, and 664.5 (± 37.59) N for CC-II. CC and Zr group specimens showed significantly different fracture resistance results (P < .001). The number of implants significantly influenced the fracture resistance of Zr groups (P = .001), whereas the influence was not significant for CC groups (P = .089). CONCLUSION: Within the limitations of this in vitro study, highly translucent zirconia cFDP frameworks demonstrated the potential to withstand reported physiologic occlusal forces applied in the anterior region. The increase in the number of implants supporting zirconia cFDPs significantly contributed to achieving higher fracture resistance values.


Asunto(s)
Implantes Dentales , Prótesis Dental de Soporte Implantado , Diseño Asistido por Computadora , Pilares Dentales , Materiales Dentales/química , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Ensayo de Materiales , Circonio/química
15.
Int J Oral Maxillofac Implants ; 37(4): 804-811, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35904838

RESUMEN

PURPOSE: In recent years, ceramic implants made of zirconia have secured a niche position next to established titanium implants, due partly to new scientific findings and positive clinical experience with the handling of ceramic implants. The aim of this study was to assess the clinical and radiographic data for monotype ceramic implants that have remained in place for 60 months under masticatory loading. MATERIALS AND METHODS: In 2011, this prospective clinical study included patients with a single-tooth gap in the maxilla and mandible. Monotype ceramic implants (Straumann) were used according to a standard protocol. Provisional prostheses were placed after 3 months, followed by final prostheses 3 months later. Patients were invited for a 60-month follow-up. Implant survival was analyzed from lifetime data. Success rates and crestal bone levels were evaluated from implant placement to 6, 12, 36, and 60 months after surgery. RESULTS: From the initial 44 patients recruited, 36 were analyzable for the 60-month follow-up. With one implant lost before the 6-month followup, the survival rate after 60 months was 97.7%, and the mean survival time was 58.7 months. Sixty months after implant placement, the success rate was 97.2% (95% confidence interval = 84.6% to > 99.9%). Mean bone loss after 60 months was 0.99 (± 0.59) mm. CONCLUSION: After 60 months, monotype ceramic implants made of zirconia achieved success and survival rates comparable with those reported for titanium implants in selected patient populations. Ceramic implants can be used as an alternative to titanium implants at the request of patients and if specifically indicated, for example, due to titanium intolerance.


Asunto(s)
Implantes Dentales , Diseño de Prótesis Dental , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración Dental , Humanos , Estudios Prospectivos , Titanio , Resultado del Tratamiento , Circonio
16.
Org Biomol Chem ; 20(29): 5803-5811, 2022 07 27.
Artículo en Inglés | MEDLINE | ID: mdl-35833893

RESUMEN

Access to 5-bromopentanal and 6-bromohexanal derivatives from Weinreb amides is described. The method relies on the sequential C-bromination/zircona-aminal hydrolysis of bis-C,O-zirconocenes, which are generated in situ from unsaturated Weinreb amides using Schwartz's reagent. Synthetic illustrations of such bromo-aldehydes, which can act as carbocycle and heterocycle precursors, are also presented.


Asunto(s)
Amidas , Halogenación , Aldehídos , Hidrólisis , Compuestos Organometálicos , Circonio
17.
Int J Oral Maxillofac Implants ; 37(4): 740-747, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35904830

RESUMEN

PURPOSE: Titanium-zirconium (Ti-Zr) alloy has been developed to strengthen the implant body, but clinically relevant information is still limited. The aim of this in vitro study was to compare the rotational load fatigue performance of implant-abutment connections in narrow-diameter (3.3-mm) and regular-diameter (4.1-mm) implants made with commercially pure grade 4 titanium alloy (CPTi-G4) and Ti-Zr. MATERIALS AND METHODS: Narrow-diameter (N) and regular-diameter (R) implants with CPTi-G4 (Ti) or Ti-Zr (Tz) materials were tested. This resulted in four test groups: NTi, NTz, RTi and RTz. Five specimens were made for each group (n = 5). Abutments used were milled from titanium-aluminum-niobium alloy abutment blanks. A rotational load fatigue machine applied a sinusoidally varying load at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz in air at 20°C. The number of cycles to failure was recorded. The upper limit was set as 5 million cycles. Results were evaluated using analysis of variance (ANOVA) and Tukey post hoc tests. Failure locations and patterns were evaluated with scanning electron microscope (SEM). RESULTS: All regular-diameter test groups reached the upper limit of 5 million cycles without failure. All narrow-diameter test groups failed within the range of 402,530 cycles to 3,374,353 cycles. It could be observed that NTz showed a higher mean cycle count as compared to NTi. NTi test group recorded two implants damaged, one implant fracture, five abutment fractures, and four screw fractures. NTz test group showed only abutment fractures at the level of implant platform, with no damage to the implant bodies. Significant difference was found between implants of different diameters. There was no significant difference between implants of different materials. CONCLUSION: Regular-diameter implants performed significantly better than narrow-diameter implants, regardless of material, while no significant difference in cyclic load to failure was found between groups of different alloys. All NTz failures were at the abutment only, without damage to the implant. This failure pattern can potentially be clinically advantageous in terms of retrieval and subsequent replacement of a failed prosthesis.


Asunto(s)
Implantes Dentales de Diente Único , Implantes Dentales , Aleaciones , Pilares Dentales , Diseño de Implante Dental-Pilar , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Titanio , Circonio
18.
J Appl Biomater Funct Mater ; 20: 22808000221114218, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35876066

RESUMEN

OBJECTIVE: In order to optimize the properties of dental zirconia, the sintering process involves firing zirconia to elevated temperatures for an extended time that can take several hours. The aim of this study is to investigate the effect of firing temperature and firing duration on the hardness of dental zirconia to indicate the optimum sintering conditions. METHODS: Thirty-six zirconia specimens in shape of bars were randomly assigned to nine groups. The zirconia specimen groups were sintered using a sintering furnace with different firing temperatures (900°C, 1200°C, and 1800°C) and firing durations (6, 9, and 12 h). A total of 108 hardness measurements were conducted for all specimens (12 hardness readings per group). For each of the specimen groups, micro Vickers hardness test was performed using a load of 1 Kgf (9.807 N) and the Vickers hardness number was computed. Statistical analysis using Kruskal-Wallis test was conducted to examine the significant differences on Vickers hardness number HV among the specimen groups according to the firing parameters with 0.005 p-value used as an indicator. RESULTS: Results suggest that there is an association between the increase in the hardness number and the increase in firing duration at a given firing temperature. The results also indicate that there is an association between the increase in the hardness number and increase in firing temperature at a given firing duration. CONCLUSIONS: The greatest rate of hardness increase with time is associated with groups of firing temperature 1200°C. The highest rate of hardness increase with temperature happened during the first 6 h of sintering process. On the other hand, there is no significant increase in the hardness number when increasing the firing temperature beyond 1200°C.


Asunto(s)
Cerámica , Materiales Dentales , Circonio , Dureza , Ensayo de Materiales , Propiedades de Superficie , Temperatura
19.
Evid Based Dent ; 23(2): 72-73, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35750734

RESUMEN

Data sources Electronic database searches were carried out using predefined search terms using Embase, Google Scholar, Medline, The Cochrane Library, The Cochrane Central Register of Controlled Trials and Latin American and Caribbean Health Sciences Literature. The Trip medical database was also used to identify randomised control trials investigating stainless steel and zirconia crowns. Studies published from 1 January 2000 until 6 June 2021 were included, and reference lists of included studies analysed to ensure data saturation along with grey literature searches.Study selection Inclusion criteria included research published in English only, randomised control trials investigating the clinical and radiographic effectiveness of zirconia crowns compared to stainless steel crowns, the rehabilitation of pulp-treated posterior primary teeth and randomised control trials with children in good health. Expert opinion, case reports and reviews were excluded. Studies with a follow-up period of less than 12 months, studies including children with special care requirements or non-compliant children were also excluded.Data extraction and synthesis Two reviewers (AKP, VKC) were involved with the primary search of abstracts and titles independently; both reviewers were involved in full text assessment. Disagreements were resolved by a third reviewer (NRV). The study characteristics, number of teeth evaluated, follow-up duration, type of zirconia and stainless steel crowns, outcome assessed and outcome results were extracted. Extracted data was analysed using Review Manager, Version 5.3 and dichotomous data was summarised as risk ratios with 95% confidence intervals. Continuous data was summarised as mean difference. Heterogeneity was summarised by I2 scores and a random-effects model and Mantel-Haenszel statistical test was used.Results From the initial 641 studies screened, six studies met the inclusion criteria for the systematic review and were included for analysis. Risk of bias assessment for the included studies was graded as 'low' for three of the six included studies and 'some concern' for the remaining three studies. This was based upon allocation concealment in the randomised control trials. Clinical failures were observed in 63 of 497 events. Rehabilitation with zirconia crowns may result in less clinical failures than stainless steel crowns: risk ratio 0.48; 95% CI (0.15-1.52) p = 0.021. Gingival health was better with zirconia rather than stainless steel crowns: risk ratio 0.32; 95% CI (-0.42-0.23) p <0.001.Conclusions Primary posterior teeth restored with zirconia crowns may have 52% less risk of experiencing clinical failures than teeth with stainless steel crowns and better gingival health than stainless steel crowns, observed after 12 months. However, due to the low quality of included studies and 'very low' grade rating of the evidence provided, further clinical trials are required to provide further evidence on the clinical and radiographic effectiveness of zirconia and stainless steel crowns.


Asunto(s)
Coronas , Acero Inoxidable , Niño , Humanos , Diente Molar , Ensayos Clínicos Controlados Aleatorios como Asunto , Circonio/uso terapéutico
20.
Bioorg Med Chem Lett ; 72: 128847, 2022 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-35700955

RESUMEN

Zirconium-89 (89Zr) has been explored for molecularly targeted positron emission tomography (PET) imaging of various diseases. We synthesized and evaluated a novel chelator (DA-18C6-BHA) for 89Zr. The new chelator is structured on a macrocyclic backbone (1,10-diaza-18-crown-6) and contains hydroxamates as acyclic donor groups. The new chelator ((DA-18C6-BHA) was rapidly labeled with 89Zr under mild conditions. The 89Zr-labeled DA-18C6-BHA complex remained stable in human serum and apotransferrin for 7 days. When challenged with excess EDTA solution, 89Zr-labeled DA-18C6-BHA was shown to hold 89Zr without losing considerable radioactivity to EDTA. The 89Zr-labeled DA-18C6-BHA complex displayed high complex stability in normal mice as evidenced by low bone uptake.


Asunto(s)
Quelantes , Éteres Corona , Animales , Hidroxianisol Butilado , Ácido Edético , Humanos , Ácidos Hidroxámicos , Ratones , Tomografía de Emisión de Positrones/métodos , Radioisótopos , Circonio
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