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1.
Int J Comput Dent ; 23(3): 225-233, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32789310

RESUMEN

AIM: To evaluate the fracture resistance and failure pattern of 3D-printed and milled composite resin crowns as a function of different material thicknesses. MATERIALS AND METHODS: Three typodont tooth models were prepared to receive a full coverage composite resin crown with different thicknesses (0.5, 1.0, and 1.5 mm). The prepared master casts were digitally scanned using an intraoral scanner, and the STL files were used to fabricate 60 nanocomposite crowns divided into two groups according to the material thickness (n = 10) and fabrication method: a 3D-printed group (3D) using an SLA printer with nanocomposite, and a milled group (M) using a milling machine and composite blocks. All crowns were adhesively seated on stereolithography (SLA)-fabricated dies. All samples were subjected to thermomechanical loading and fracture testing. The load to fracture [N] was recorded and the failure pattern evaluated. Data were statistically analyzed using a two-way ANOVA followed by a Bonferroni post hoc test. The level of significance was set at α = 0.05. RESULTS: The 3D group showed the highest values for fracture resistance compared with the milled group within the three tested thicknesses (P < 0.001). The 3D and M groups presented significantly higher load to fracture for the 1.5-mm thickness (2383.5 ± 188.58 N and 1284.7 ± 77.62 N, respectively) compared with the 1.0-mm thickness (1945.9 ± 65.32 N and 932.1 ± 41.29 N, respectively) and the 0.5-mm thickness, which showed the lowest values in both groups (1345.0 ± 101.15 N and 519.3 ± 32.96 N, respectively). A higher incidence of irreparable fractures was observed for the 1.5-mm thickness. CONCLUSION: 3D-printed composite resin crowns showed high fracture resistance at different material thicknesses and can be suggested as a viable solution in conservative dentistry.


Asunto(s)
Porcelana Dental , Fracaso de la Restauración Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Impresión Tridimensional
2.
J Contemp Dent Pract ; 21(4): 367-371, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32584270

RESUMEN

AIM: The aim of this study was to compare the adaptation of complete denture base (CDB) manufactured by three different techniques: conventional, milling, and three-dimensional (3-D) printing. MATERIALS AND METHODS: A master cast was duplicated to create 60 gypsum casts. Twenty casts (n = 20) were attributed to each group. In the computer-aided design and computer-aided manufacturing (CAD/CAM) groups (milling and 3-D printing), the 40 gypsum casts reserved for these two groups were scanned. An STL file was obtained and a master CDB was designed and then fabricated according to each technique. In the conventional group, a polyvinyl siloxane putty mold was obtained from the milled CDB, and this mold was used to fabricate 20 conventional denture bases by compression molding using the silicon-gypsum technique in a bronze flask. The inner surfaces of the obtained 60 CDB were scanned and superimposed over their corresponding master cast. Deviation analyses were calculated using digital subtraction technique. Five functional areas (posterior palatal seal, anterior border seal, crest of the ridge, maxillary tuberosities, and palate) were selected to evaluate the variations in CBD adaptation. RESULTS: Based on the results and color maps of all selected regions, milling technique offers the best adaptation. The crest of ridge in the conventional technique showed the least adaptation and the posterior palatal seal in the 3-D printing technique showed the best adaptation. CONCLUSION: Within the limitations of this study, the CAD/CAM fabrication techniques seem to offer better adaptation of CDB compared to the conventional fabrication technique. Milled CDBs presented the most homogeneous distribution of adaptation, yet the 3-D printing process seems a promising techniques that needs to be addressed and perfected. CLINICAL SIGNIFICANCE: The CAD/CAM technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.


Asunto(s)
Bases para Dentadura , Diseño de Dentadura , Diseño Asistido por Computadora , Dentadura Completa , Humanos , Impresión Tridimensional , Calidad de Vida
3.
Saudi J Kidney Dis Transpl ; 31(6): 1388-1394, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33565451

RESUMEN

End-stage organ damage is the major cause of death worldwide. The number of donors is low, and one of the challenging phases in organ donation is the availability of organ donors. There are many studies that suggest a strong correlation between knowledge and beliefs toward organ donation. A study conducted among Health-Care Providers in the Intensive Care Units at a Tertiary Center at Riyadh reported that only 57% of the health-care providers in the Intensive Care Unit were willing to donate their organs. The objective of our study was to evaluate the knowledge, attitude, and awareness of organ donation and transplantation among health-care providers at different hospitals around the Kingdom of Saudi Arabia. The data of this cross-sectional descriptive study were collected between February and July 2018 in different hospitals all around the Kingdom of Saudi Arabia. The investigators formulated a questionnaire based on several published studies. Ethical approval was obtained from the Unit of Biomedical Ethics, Research Committee at King Abdul Aziz University. Of the 241 participants, 130 (53.9%) were female. In addition, 110 (45.6%) of them were medical residents. Moreover, 224 (92.9%) participants were aware of the concept of organ donation. The overall level of knowledge is good (55.2%).The study showed 62.2% have participated in the organ donation program for their close relatives only. In conclusion, the level of perception and knowledge about organ donation among health-care providers was inadequate, although they showed positive attitudes toward this issue.

4.
J Food Biochem ; 43(3): e12750, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-31353538

RESUMEN

Vitex agnus-castus (VAC, Verbenaceae) is widely used in Chinese traditional medicine as an antiinflammatory agent. This study aimed to explore the efficacy of the VAC extract to protect against lipopolysaccharide (LPS)-induced acute lung injury. The results have shown that VAC had a potent protective activity against LPS-induced acute lung damage. It significantly decreased pulmonary edema as there was a significant decrease in lung wet/dry ratio and in protein content. VAC also decreased the lactate dehydrogenase's activity in the bronchoalveolar fluid. VAC ameliorated LPS-induced inflammatory cells infiltration into the lung tissue and reversed the histopathological lesions of the lung. Furthermore, VAC counteracted LPS-induced oxidative stress as it attenuated the lipid peroxidation marker, malondialdehyde, in the lung. VAC increased the antioxidant activity as evident by elevated superoxide dismutase activity and increased reduced glutathione content in the lung tissue. Collectively, VAC has a protective activity against LPS-induced acute lung damage through its antioxidant potential. PRACTICAL APPLICATIONS: Vitex agnus-castus has been used in various traditional medicines for treating various ailments as digestive complains, acne, rheumatic pains, menstrual irregularities, premenstrual syndrome, infertility, and hyperprolactinemia. Its leaves are used as a spice and the fruits are used as a substitute for pepper. VAC food supplements are used by women against psychic and somatic premenstrual symptoms. The findings of this study can demonstrate the potent protective activity of the VAC extract against LPS-induced acute lung damage due to its antioxidative effects. Therefore, VAC could be developed as a health functional food to improve acute lung damage and many diseases caused by oxidative damage.


Asunto(s)
Antioxidantes/administración & dosificación , Medicamentos Herbarios Chinos/administración & dosificación , Lipopolisacáridos/efectos adversos , Lesión Pulmonar/tratamiento farmacológico , Vitex/química , Animales , Femenino , Glutatión/metabolismo , Humanos , Peroxidación de Lípido/efectos de los fármacos , Lesión Pulmonar/etiología , Lesión Pulmonar/metabolismo , Masculino , Malondialdehído/metabolismo , Ratones , Ratones Endogámicos BALB C , Hojas de la Planta/química , Superóxido Dismutasa/metabolismo
5.
J Prosthodont Res ; 62(2): 218-226, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29032176

RESUMEN

PurposeTo evaluate the influence of fabrication method and finish line design on marginal and internal fit of full-coverage interim restorations. MethodsFour typodont models of maxillary central-incisor were prepared for full-coverage restorations. Four groups were defined; knife-edge (KE), chamfer (C), rounded-shoulder (RS), rounded-shoulder with bevel (RSB). All preparations were digitally scanned. A total of 80 restorations were fabricated; 20 per group (SLA/3D-printed n=10, milled n=10). All restorations were positioned on the master die and scanned using micro-computed tomography. The mean gaps were measured digitally (ImageJ). The results were compared using MANOVA (α=.05). ResultsInternal and marginal gaps were significantly influenced by fabrication method (P=.000) and finish-line design (P=.000). 3D-Printed restorations showed statistically significant lower mean gap compared to milled restorations at all points (P=.000). The mean internal gap for 3D-printed restorations were 66, 149, 130, 95µm and for milled restorations were 89, 177, 185, 154µm for KE, C, RS, RSB respectively. The mean absolute marginal discrepancy in 3D-printed restorations were (30, 41, 30, 28µm) and in milled restorations were (56, 54, 52, 38µm) for KE, C, RS, RSB respectively. ConclusionsThe fabrication methods showed more of an influence on the fit compared to the effect of the finish-line design in both milled and printed restorations. SLA-printed interim restorations exhibit lower marginal and internal gap than milled restorations. Nonetheless, for both techniques, all values were within the reported values for CAD/CAM restorations. Significance3D-printing can offer an alternative fabrication method comparable to those of milled restorations.


Asunto(s)
Coronas , Diseño de Prótesis Dental/métodos , Restauración Dental Permanente/métodos , Impresión Tridimensional , Diseño Asistido por Computadora , Adaptación Marginal Dental , Incisivo , Microtomografía por Rayos X
6.
J Mech Behav Biomed Mater ; 75: 521-528, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28846981

RESUMEN

PURPOSE: The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. MATERIALS AND METHODS: A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°(Vertical), 45° (Oblique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. RESULTS: The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2MPa) and 90° (866.7MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196nm to 3.3µm. The mean Ra (arithmetic mean roughness) value of 1.59µm (±0.41) and Rq (root mean squared roughness) value of 1.94µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. CONCLUSIONS: DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects.


Asunto(s)
Materiales Dentales , Ensayo de Materiales , Impresión Tridimensional , Circonio , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Itrio
7.
Int J Prosthodont ; 30(5): 474­484, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28750105

RESUMEN

PURPOSE: The aim of this article was to critically review the current application of additive manufacturing (AM)/3D-printing techniques in prosthodontics and to highlight the influence of various technical factors involved in different AM technologies. MATERIALS AND METHODS: A standard approach of searching MEDLINE, EMBASE, and Google Scholar databases was followed. The following search terms were used: (Prosth* OR Restoration) AND (Prototype OR Additive Manufacture* OR Compute* OR 3D-print* OR CAD/CAM) AND (Dentistry OR Dental). Hand searching the reference lists of the included articles and personal connections revealed additional relevant articles. Selection criteria were any article written in English and reporting on the application of AM in prosthodontics from 1990 to February 2016. RESULTS: From a total of 4,290 articles identified, 33 were seen as relevant. Of these, 3 were narrative reviews, 18 were in vitro studies, and 12 were clinical in vivo studies. Different AM technologies are applied in prosthodontics, directly and indirectly for the fabrication of fixed metal copings, metal frameworks for removable partial dentures, and plastic mock-ups and resin patterns for further conventional metal castings. Technical factors involved in different AM techniques influence the overall quality, the mechanical properties of the printed parts, and the total cost and manufacturing time. CONCLUSION: AM is promising and offers new possibilities in the field of prosthodontics, though its application is still limited. An understanding of these limitations and of developments in material science is crucial prior to considering AM as an acceptable method for the fabrication of dental prostheses.


Asunto(s)
Diseño Asistido por Computadora , Diseño de Prótesis Dental/métodos , Prótesis Dental , Impresión Tridimensional
8.
Int J Prosthodont ; 30(2): 182-188, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28267830

RESUMEN

PURPOSE: The aim of this study was to evaluate the effect of the build orientation/build angle on the dimensional accuracy of full-coverage dental restorations manufactured using digital light-processing technology (DLP-AM). MATERIALS AND METHODS: A full dental crown was digitally designed and 3D-printed using DLP-AM. Nine build angles were used: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. The specimens were digitally scanned using a high-resolution optical surface scanner (IScan D104i, Imetric). Dimensional accuracy was evaluated using the digital subtraction technique. The 3D digital files of the scanned printed crowns (test model) were exported in standard tessellation language (STL) format and superimposed on the STL file of the designed crown [reference model] using Geomagic Studio 2014 (3D Systems). The root mean square estimate (RMSE) values were evaluated, and the deviation patterns on the color maps were further assessed. RESULTS: The build angle influenced the dimensional accuracy of 3D-printed restorations. The lowest RMSE was recorded for the 135-degree and 210-degree build angles. However, the overall deviation pattern on the color map was more favorable with the 135-degree build angle in contrast with the 210-degree build angle where the deviation was observed around the critical marginal area. CONCLUSIONS: Within the limitations of this study, the recommended build angle using the current DLP system was 135 degrees. Among the selected build angles, it offers the highest dimensional accuracy and the most favorable deviation pattern. It also offers a self-supporting crown geometry throughout the building process.


Asunto(s)
Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Impresión Tridimensional , Humanos , Luz , Ensayo de Materiales , Reproducibilidad de los Resultados
9.
Int J Prosthodont ; 29(5): 503-10, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27611757

RESUMEN

PURPOSE: The aim of the present study was to evaluate the effect of the build angle and the support configuration (thick versus thin support) on the dimensional accuracy of 3D-printed full-coverage dental restorations. MATERIALS AND METHODS: A full-coverage dental crown was digitally designed and 3D-printed using stereolithography-additive manufacturing (SLA-AM) technology. Nine different angles were used during the build process: 90, 120, 135, 150, 180, 210, 225, 240, and 270 degrees. In each angle, the crown was printed using a thin and a thick support type, resulting in 18 specimens. The specimens were digitally scanned using a high resolution optical surface scanner (IScan D104i; Imetric 3D). The dimensional accuracy was evaluated by digital subtraction technique. The 3D digital files of the scanned printed crowns (test model), exported in standard tessellation language (STL) format, were superimposed with the STL file of the designed crown (reference model) using Geomagic Studio 2014 (3D Systems). RESULTS: The root mean square estimate value and color map results suggest that the build angle and support structure configuration have an influence on the dimensional accuracy of 3D-printed crown restorations. Among the tested angles, the 120-degree build angle showed a minimal deviation of 0.029 mm for thin support and 0.031 mm for thick support, indicating an accurate fit between the test and reference models. Furthermore, the deviation pattern observed in the color map was homogenously distributed and located further away from the critical marginal area. CONCLUSIONS: Within the limitations of this study, the selection of build angle should offer the crown the highest dimensional accuracy and self-supported geometry. This allows for the smallest necessary support surface area and decreases the time needed for finishing and polishing. These properties were mostly observed with a build angle of 120 degrees combined with a thin support type.


Asunto(s)
Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Impresión Tridimensional , Resinas Compuestas/química , Adaptación Marginal Dental , Materiales Dentales/química , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Rayos Láser , Imagen Óptica/métodos , Técnica de Sustracción , Propiedades de Superficie , Tecnología Odontológica/métodos , Factores de Tiempo , Interfaz Usuario-Computador
10.
J Prosthet Dent ; 115(6): 760-7, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26803175

RESUMEN

STATEMENT OF PROBLEM: The application of 3-dimensional printing technology is emerging in dentistry and is being increasingly used to fabricate dental restorations. To date, scientific evidence is lacking regarding the effect of different factors on the mechanical properties of the printed restorations with the additive manufacturing technique. PURPOSE: The purpose of this in vitro study was to evaluate the effect of build direction (layer orientation) on the mechanical properties of a novel 3-dimensionally (3D)-printed dental restorative material. MATERIAL AND METHODS: Based on the printing direction, 2 groups were tested. In the first group (n=20), the specimens were vertically printed with the layers oriented perpendicular to the load direction. In the second group (n=20), the specimens were horizontally printed with the layers oriented parallel to the load direction. All specimens were fabricated using the DW028D 3D-printer. The specimens were loaded with a universal testing machine at a crosshead speed of 1 mm/min with a 10-kN load cell. The test was performed at room temperature (22°C) under dry testing conditions. The compressive strength was calculated for both groups, and the results were compared using the unpaired t test (α=.05). RESULTS: The mean ±SD compressive strength for the vertically printed specimens was 297 MPa (±34) compared with 257 MPa (±41) for the horizontally printed specimens (P=.002). CONCLUSIONS: Within the limitations of this study, the layer orientation was found to influence the compressive strength of the material. Vertically printed specimens with the layers oriented perpendicular to load direction have improved mechanical properties more than horizontally printed specimens with the layers oriented parallel to load direction.


Asunto(s)
Restauración Dental Provisional/métodos , Impresión Tridimensional , Resinas Compuestas/uso terapéutico , Fuerza Compresiva , Técnica de Impresión Dental , Materiales Dentales , Análisis del Estrés Dental , Humanos
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