Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
J Mech Behav Biomed Mater ; 121: 104590, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34077907

RESUMO

Treatment the deeper and remineralizable carious zone (DRCZ) in dentin with various remineralizing methods, either with classic top-down or biomimetic bottom-up remineralization approaches, has remained a constant main issue to enhance dentin substrate bonding quality. The concern of remineralizing the remaining, partially demineralized and physiologically re-mineralizable collagen fibrils was the optimum target. However, applying already mineralized type I collage fibrils which have the ability to chemically cross-link with remaining collagen and minerals did not gain much interest. Synthesis of collagen/hydroxyapatite (Col/Hap) nanocomposite was done with self-assembling Hap in situ onto Col fibrils with different % (70/30, 50/50, 30/70% of Col/Hap, respectively). Micro-tensile bond strength (µTBS) was evaluated after pre-treatment of artificially demineralized dentin with these suggested protocols [nanocomposite together with grape seed extract (GSE; 6.5%) cross-linker for two periods, 10min and 1 h] then applying self-adhesive bonding system. Applied Col/Hap (30/70%) together with GSE (6.5%) gave the significantly highest µTBS (25.04 ± 5.47 and 25.53 ± 7.64 MPa, for 10min and 1 h application times, respectively). After thermocycling for 10,000 cycles at 5 and 55 °C, µTBS for all protocols and both application times substantially decreased especially for the two control groups. Using the suggested dentin pre-treatment protocols, in chair-side, may possibly enhance the bond strength to DRCZ and its durability.


Assuntos
Colagem Dentária , Nanocompostos , Colágeno , Dentina , Adesivos Dentinários , Durapatita , Teste de Materiais , Cimentos de Resina , Resistência à Tração
2.
Dent Mater ; 37(4): 711-730, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33581910

RESUMO

OBJECTIVE: Optimizing monolithic zirconia (ZrO2) aesthetically without affecting the unique mechanical properties remains a major ongoing interest. The purpose of this review is to evaluate the improvement of recent monolithic ZrO2 generations to meet aesthetic optimization qualities. Additionally, for how the extent of the former modifications negatively affected their mechanical properties and the impact on their clinical indications. METHODS: The current literature examines in-vitro studies evaluating both monolithic ZrO2 translucency and mechanical properties. The electronic search was done within these databases: Web of Science, ScienceDirect, Scopus, and PubMed within the period between 2009/10/01 and 2019/10/31. Search results that met eligibility criteria were classified into four groups; one for translucency parameter, two for uniaxial flexural strength and one for biaxial strength. RESULTS: Articles that remained for comprehensive analysis were fifty-three. They reported a significant impact of composition, microstructure and surface treatment on translucency and flexural strength assessment. Aging was found to be of no concern for zirconia structures with high yttria content. Smooth surface polish was found to significantly enhance strength while coarse grinding and mechanical fatigue was found to do the reverse. SIGNIFICANCE: Based on analyzing the previous in-vitro studies the following was found: Although significant improvement has occurred with recent monolithic zirconia types with higher yttria content having higher cubic/tetragonal ratio, they are still inferior to glass-ceramics' unique translucency. With improving zirconia aesthetically, some of mechanical performance was sacrificed. Care must be taken when dealing with thin sections of aesthetic zirconia structures especially when used in high bearing stress areas.


Assuntos
Materiais Dentários , Resistência à Flexão , Cerâmica , Estética , Teste de Materiais , Propriedades de Superfície , Zircônio
3.
Braz Dent J ; 31(1): 44-51, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32159705

RESUMO

This study evaluated the impact of using biomimetic analogs (poly-acrylic acid and sodium tri-meta-phosphate) on dentin remineralization using two cement materials, the first is calcium silicate based and the second is calcium hydroxide based materials. Two standardized occlusal cavities (mesial and distal) were prepared within dentin after removal of occlusal enamel. Artificial demineralized dentin was induced through pH cycling (8 h in demineralizing and 16 h in remineralizing solutions). Demineralized cavities were divided into four groups; two groups received cement materials. The other groups were first treated with biomimetic analogs then restored with pulp cement materials. Teeth were sectioned buccolingually into two halves. Treated cavities with analogs were stored in simulated body fluid containing poly-acrylic acid. Untreated cavities were stored in simulated body fluid only. Ground unstained sections of demineralized dentin were examined using light microscope. Specimens were examined after 1, 6 and 12 weeks of storage using energy dispersive X-ray Spectroscopy (EDX) and Vickers microhardness was evaluated. Two-way ANOVA was used to analyze data statistically. Calcium silicate-based cement group with biomimetic analogs showed the highest statistically significant calcium and phosphorous wt% in addition to highest surface hardness values after 12 weeks of storage. Demineralized dentin ground sections showed increase in light zones after total period of storage. Calcium silicate-based cement showed the best ability to enrich the artificial carious dentin with ions for remineralization. Using biomimetic analogs had a significant impact on demineralized dentin surface hardness improvement.


Assuntos
Biomimética , Remineralização Dentária , Cimentos Dentários , Dentina , Silicatos
4.
Braz. dent. j ; 31(1): 44-51, Jan.-Feb. 2020. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1089265

RESUMO

Abstract This study evaluated the impact of using biomimetic analogs (poly-acrylic acid and sodium tri-meta-phosphate) on dentin remineralization using two cement materials, the first is calcium silicate based and the second is calcium hydroxide based materials. Two standardized occlusal cavities (mesial and distal) were prepared within dentin after removal of occlusal enamel. Artificial demineralized dentin was induced through pH cycling (8 h in demineralizing and 16 h in remineralizing solutions). Demineralized cavities were divided into four groups; two groups received cement materials. The other groups were first treated with biomimetic analogs then restored with pulp cement materials. Teeth were sectioned buccolingually into two halves. Treated cavities with analogs were stored in simulated body fluid containing poly-acrylic acid. Untreated cavities were stored in simulated body fluid only. Ground unstained sections of demineralized dentin were examined using light microscope. Specimens were examined after 1, 6 and 12 weeks of storage using energy dispersive X-ray Spectroscopy (EDX) and Vickers microhardness was evaluated. Two-way ANOVA was used to analyze data statistically. Calcium silicate-based cement group with biomimetic analogs showed the highest statistically significant calcium and phosphorous wt% in addition to highest surface hardness values after 12 weeks of storage. Demineralized dentin ground sections showed increase in light zones after total period of storage. Calcium silicate-based cement showed the best ability to enrich the artificial carious dentin with ions for remineralization. Using biomimetic analogs had a significant impact on demineralized dentin surface hardness improvement.


Resumo Este estudo avaliou o impacto do uso de análogos biomiméticos (ácido poli-acrílico e tri-meta-fosfato de sódio) na remineralização da dentina usando dois materiais de cimento, o primeiro à base de silicato de cálcio e o segundo à base de hidróxido de cálcio. Duas cavidades oclusais padronizadas (mesial e distal) foram preparadas na dentina após a remoção do esmalte oclusal. A dentina desmineralizada artificial foi induzida por ciclagem de pH (8 h em soluções desmineralizantes e 16 h em soluções remineralizantes). Cavidades desmineralizadas foram divididas em quatro grupos; dois grupos receberam materiais de cimento. Os outros grupos foram tratados primeiro com análogos biomiméticos e depois restaurados com materiais de cimento de celulose. Os dentes foram seccionados bucolingualmente em duas metades. As cavidades tratadas com análogos foram armazenadas em fluido corporal simulado contendo ácido poli-acrílico. As cavidades não tratadas foram armazenadas apenas em fluido corporal simulado. Secções não coradas de dentina desmineralizada foram examinadas usando microscópio óptico. As amostras foram examinadas após 1, 6 e 12 semanas de armazenamento usando Espectroscopia de Raios-X dispersiva por energia (EDX) e microdureza Vickers. ANOVA a dois fatores foi usada para analisar os dados estatisticamente. O grupo de cimento à base de silicato de cálcio com análogos biomiméticos apresentou os maiores percentagens em peso estatisticamente significantes de cálcio e fósforo, além dos maiores valores de dureza superficial após 12 semanas de armazenamento. Seções desmineralizadas de dentina mostraram aumento nas zonas de luz após o período total de armazenamento. O cimento à base de silicato de cálcio mostrou a melhor capacidade de enriquecer a dentina cariada artificial com íons para remineralização. O uso de análogos biomiméticos teve um impacto significativo na melhoria da dureza superficial da dentina desmineralizada.

5.
J Clin Exp Dent ; 11(4): e360-e366, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31110616

RESUMO

Background: This study aimed to evaluate remineralizing ability of two hydraulic calcium-silicate cements (Biodentine and TheraCal LC). Material and Methods: Artificial carious lesions were introduced into the pulpal floors (1-1.5 mm) and axial walls of occlusal prepared cavity halves through pH cycling. Cycling was made through demineralizing solution (pH 3), for 8 hours and remineralizing solution (pH 7) for 16 hours. The total period of pH cycling was 14 days. Prepared cavities with the tested materials seated directly on the pulpal floor and in contact with the axial walls were stored in phosphate buffer solutions (PBS) (pH 7.2-7.4). The changes in the weight percentages (wt%) of calcium (Ca) and phosphorus (P) were detected using SEM and energy dispersive X-ray spectroscopy with reference to sound dentin after three intervals (one week, 3 and 6 months). Data were statistically analyzed using two-way ANOVA and Tukey's post hoc test. Results: Demineralized dentin, next to Biodentine, showed statistically higher intensities of Ca and P wt% after the three periods of incubation (p< 0.05). Surface mapping of both tested cements and their adjacent demineralized dentin showed increase in overall distribution of previous ions. SEM of subsurface layer under both materials showed filling of most intra-tubular areas with rod-like mineralized structure without significant difference. Conclusions: Biodentine has a higher ability to enrich the artificial carious dentin with significantly higher mineral contents available for remineralization. Both pulp-capping materials have significantly induced remineralization of demineralized dentin beneath them after total period of incubation. Key words:Artificial Caries, Hydraulic Cements, pH Cycling, Remineralization.

6.
J Conserv Dent ; 22(1): 17-22, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30820077

RESUMO

Background: This study investigated cytotoxic probability, osteogenic potential, and antibacterial efficacy of two pulp-capping hydraulic calcium-silicate cements. Materials and Methods: For osteogenic potential and cytotoxicity evaluation, mesenchymal stem cells (MSCs) and materials disc-shaped specimens were used. Increase or decrease in a number of proliferating MSCs was calculated after three intervals. Alkaline phosphatase (ALP) levels in osteogenic media were normalized to the total protein content of cells and measured spectrophotometrically. Antibacterial efficiency through growth curves of Streptococcus mutans in direct contact with tested materials. Results: Biodentine showed the highest number of proliferating MSCs (278000.41 ± 4000.06, after 72 h) and the highest concentration of ALP after 12 days (209.26 ± 7.17 µU/µg protein). It showed the lowest slope (0.003 ± 0.0005) of S. mutans strains growth curves after 18 h. Conclusion: Biodentine proved a highly significant osteogenic ability and gave a significant reduction of S. mutans growth.

7.
Dent Mater ; 34(3): 551-559, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29361309

RESUMO

OBJECTIVE: To evaluate the effect of different pH media on zirconia-reinforced lithium silicate glass ceramic and how they interact with opposing dentition after being aged in different pH cycling and high temperature conditions. METHODS: Twenty-five rectangular shaped specimens were prepared from lithium silicate reinforced with zirconia blanks (Suprinity, Vita Zahnfabrick) and stored in different pH media (3 & 7.2) for different periods (24h & 7 days) at temperature (55°C). After their surface roughness (Ra) evaluation, aged ceramic specimens were subjected to cyclic abrasive wear with opposing natural teeth enamel for 150,000 cycles using a chewing simulator. Weight loss and Scanning Electron Microscope (SEM) images were used to evaluate the cyclic wear results. RESULTS: After different pH storage, ceramic group stored at 3 pH for 1-W (1 week) gave significantly higher mean Ra value (0.618µm±0.117) than control lowest mean value (0.357µm±0.054) before cyclic wear. On the other hand, it caused the least significant weight loss value (0.004gm±0.001) to opposing tooth enamel. There was significant tooth enamel weight loss (0.043gm±0.004) when opposed with ceramic group stored in 3 pH media for 24h (24-H). Their SEM images showed a prominent wear scar on enamel cusp tip. There was a significant increase in surface roughness Ra of ceramic material after abrasive cyclic wear. SIGNIFICANCE: Great attention should be paid to Ra of this type of glass ceramic even if it is considered as minimal values. It can induce a significant amount of enamel tooth wear after a period equivalent to one year of intra-oral function rather than the significantly higher surface Ra of such ceramic type can do.


Assuntos
Cerâmica/química , Lítio/química , Silicatos/química , Desgaste dos Dentes , Zircônio/química , Materiais Dentários/química , Dureza , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Teste de Materiais , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície
8.
Acta Biomater Odontol Scand ; 1(2-4): 86-92, 2015 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-27335897

RESUMO

Objective: To evaluate the hydrothermal aging effect on the translucency of partially stabilized tetragonal zirconia with yttria (Y-TZP) used as monolithic or fully milled zirconia and of core type. Methods: Twenty disc-shaped specimens (1 and 10 mm) for each type of monolithic and core Y-TZP materials were milled and sintered according to the manufacturer's instruction. The final specimens were divided into two groups according to the type of Y-TZP used. Translucency parameter (TP) was measured over white and black backgrounds with the diffuse reflectance method; X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the microstructure of both Y-TZP types before and after aging. Data for TP values was statistically analyzed using Student's t-test. Results: Monolithic Y-TZP showed the highest TP mean value (16.4 ± 0.316) before aging while core Y-TZP showed the lowest TP mean value (7.05 ± 0.261) after aging. There was a significant difference between the two Y-TZP types before and after hydrothermal aging. XRD analysis showed increases in monoclinic content in both Y-TZP surfaces after aging. Conclusion: Monolithic Y-TZP has a higher chance to low-temperature degradation than core type, which may significantly affect the esthetic appearance and translucency hence durability of translucent Y-TZP.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...