Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Prosthet Dent ; 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32037295

RESUMO

STATEMENT OF PROBLEM: Tooth preparations for ceramic crowns require precision and accuracy, which may be influenced by the choice of dental handpiece. However, comparisons of the accuracy of tooth preparations made with traditional air-turbine handpieces and electric handpieces are lacking. PURPOSE: The purpose of this in vitro study was to evaluate operator preferences and tooth preparation performance by using electric and air-turbine handpieces with self-reported preferences, sound levels, surface roughness, and the fit of the crown produced. MATERIAL AND METHODS: Twenty dentists were asked to use the air-turbine or the electric handpiece. Feedback on the noise, weight, feel of grip, flexibility, and tooth preparation in general was scored according to a visual analog scale (VAS). Additionally, the dentists were asked to complete a questionnaire on their handpiece preference. The noise of the 2 handpieces was measured by using a precision sound level meter. The surface roughness of 10 teeth was measured by using a profilometer. The other 18 teeth were prepared to measure the marginal and internal fit of ceramic crowns by the replica technique. The VAS scores of operator preferences were analyzed with the Wilcoxon signed ranks test. Decibel levels were analyzed with the Mann-Whitney U test. The McNemar test was used to compare the ratio of preferred handpiece. The surface roughness and marginal and internal fit were analyzed with the independent t test to determine significant differences (all α=.05). RESULTS: The electric handpiece was heavier, had a poorer grip feel, was less flexible (P<.001), produced lower noise and better feeling of the tooth preparation in general (P<.001), and was preferred in the finishing stage for its greater smoothness (P<.05). The noise produced by the electric handpiece was lower during both idling and tooth preparation at 15-cm, 30-cm, and 45-cm distances (P<.01). The electric handpiece produced surface roughness values (Sa) similar to those of the air-turbine handpiece (P>.05). No significant differences were noted for the marginal and internal crown fit between the air-turbine handpiece and electric handpiece groups (P>.05). CONCLUSIONS: Despite its heavier weight, poorer grip feel, and less flexibility, the electric handpiece emitted lower noise, produced better feeling of the tooth preparation in general, and was preferred in the finishing step of tooth preparation for its greater smoothness than the air-turbine handpiece. The surface roughness of the prepared teeth and the crown fit between the tooth and ceramic crown were not affected by the air-turbine or electric handpiece.

2.
Adv Sci (Weinh) ; 5(10): 1800873, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30356983

RESUMO

Biomineralization in vertebrates is initiated via amorphous calcium phosphate (ACP) precursors. These precursors infiltrate the extracellular collagen matrix where they undergo phase transformation into intrafibrillar carbonated apatite. Although it is well established that ACP precursors are released from intracellular vesicles through exocytosis, an unsolved enigma in this cell-mediated mineralization process is how ACP precursors, initially produced in the mitochondria, are translocated to the intracellular vesicles. The present study proposes that mitophagy provides the mechanism for transfer of ACP precursors from the dysfunctioned mitochondria to autophagosomes, which, upon fusion with lysosomes, become autolysosomes where the mitochondrial ACP precursors coalesce to form larger intravesicular granules, prior to their release into the extracellular matrix. Apart from endowing the mitochondria with the function of ACP delivery through mitophagy, the present results indicate that mitophagy, triggered upon intramitochondrial ACP accumulation in osteogenic lineage-committed mesenchymal stem cells, participates in the biomineralization process through the BMP/Smad signaling pathway.

3.
Int J Nanomedicine ; 12: 839-854, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28182119

RESUMO

Scaffold supplements such as nanoparticles, components of the extracellular matrix, or growth factors have been incorporated in conventional scaffold materials to produce smart scaffolds for tissue engineering of damaged hard tissues. Due to increasing concerns on the clinical side effects of using large doses of recombinant bone-morphogenetic protein-2 in bone surgery, it is desirable to develop an alternative nanoscale scaffold supplement that is not only osteoinductive, but is also multifunctional in that it can perform other significant bone regenerative roles apart from stimulation of osteogenic differentiation. Because both amorphous calcium phosphate (ACP) and silica are osteoinductive, a biodegradable, nonfunctionalized, expanded-pore mesoporous silica nanoparticle carrier was developed for loading, storage, and sustained release of a novel, biosilicification-inspired, polyamine-stabilized liquid precursor phase of ACP for collagen biomineralization and for release of orthosilicic acid, both of which are conducive to bone growth. Positively charged poly(allylamine)-stabilized ACP (PAH-ACP) could be effectively loaded and released from nonfunctionalized expanded-pore mesoporous silica nanoparticles (pMSN). The PAH-ACP released from loaded pMSN still retained its ability to infiltrate and mineralize collagen fibrils. Complete degradation of pMSN occurred following unloading of their PAH-ACP cargo. Because PAH-ACP loaded pMSN possesses relatively low cytotoxicity to human bone marrow-derived mesenchymal stem cells, these nanoparticles may be blended with any osteoconductive scaffold with macro- and microporosities as a versatile scaffold supplement to enhance bone regeneration.


Assuntos
Regeneração Óssea/efeitos dos fármacos , Fosfatos de Cálcio/farmacologia , Nanopartículas/química , Osteogênese/efeitos dos fármacos , Polímeros/química , Dióxido de Silício/química , Alilamina/química , Animais , Materiais Biocompatíveis/química , Bovinos , Diferenciação Celular/efeitos dos fármacos , Colágeno/química , Humanos , Nanopartículas/administração & dosagem , Ácido Silícico/análise , Engenharia Tecidual , Tecidos Suporte
4.
Dent Mater ; 32(10): 1235-1247, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27497745

RESUMO

OBJECTIVES: An experimental discoloration-free calcium aluminosilicate cement has been developed with the intention of maximizing the beneficial attributes of tricalcium silicate cements and calcium aluminate cements. The present study examined the effects of this experimental cement (Quick-Set2) on the mineralogenic characteristics of osteogenic lineage-committed human dental pulp stem cells (hDPSCs), by comparing the cellular responses with a commercially available tricalcium silicate cement (white mineral trioxide aggregate (ProRoot(®) MTA); WMTA). METHODS: The osteogenic potential of hDPSCs exposed to the cements was examined using qRT-PCR for osteogenic gene expressions, Western blot for osteogenic-related protein expressions, alkaline phosphatase enzyme activity, Alizarin red S staining, Fourier transform infrared spectroscopy and transmission electron microscopy of extracellular calcium deposits. RESULTS: Results of the six assays indicated that osteogenic differentiation of hDPSCs was significantly enhanced after exposure to the tricalcium silicate cement or the experimental calcium aluminosilicate cement, with the former demonstrating better mineralogenic stimulation capacity. SIGNIFICANCE: The better osteogenic stimulating effect of the tricalcium silicate cement on hDPSCs may be due to its relatively higher silicate content, or higher OH(-) and Ca(2+) release. Further investigations with the use of in vivo animal models are required to validate the potential augmenting osteogenic effects of the experimental discoloration-free calcium aluminosilicate cement.


Assuntos
Silicatos de Alumínio/farmacologia , Cimentos Dentários/farmacologia , Polpa Dentária/citologia , Osteogênese/efeitos dos fármacos , Animais , Compostos de Cálcio , Argila , Humanos , Silicatos , Células-Tronco
5.
Acta Biomater ; 31: 312-325, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26678828

RESUMO

UNLABELLED: Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious skeletal complication associated with the long-term oral or intravenous use of nitrogen-containing bisphosphonates (N-BPs). Here, we investigated the effects of an ionic cocktail prepared from water-soluble microfibrous borate glass on neutralizing the inhibitory effects of two heterocyclic N-BPs, risedronate or zoledronic acid, on osteoclastogenesis, apoptosis of differentiated osteoclasts and osteoclast function. Cell growth and proliferation assays were first performed on RAW 264.7 cells to optimize the concentrations of the ionic cocktail and N-BPs to be used for static cell culture. The pre-osteoclasts were then stimulated with RANKL to differentiate into osteoclasts. The effects of the ionic cocktail and N-BPs on osteoclast differentiation, apoptosis and function were subsequently examined using 3 series of experiments conducted at the gene, protein, morphological and functional levels. After concentration optimization, the ionic cocktail was found to partially reverse N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclast resorptive activity. Ultrastructural examination of osteoclasts that had been exposed to either N-BP identified classical features of late apoptosis and secondary necrosis, while osteoclasts exposed simultaneously to the concentration-optimized ionic cocktail and N-BPs exhibited only signs of early apoptosis that were possibly reversible. Taken together, the results of the 4 series of experiments indicate that the ionic cocktail produced from dissolution of borate glass dressings has the potential to rescue the adverse effects of heterocyclic N-BPs on osteoclast differentiation and function. These results warrant further confirmation using dynamic cell culture and small animal BRONJ models. STATEMENT OF SIGNIFICANCE: Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) may result in bisphosphonate-related osteonecrosis of the jaw (BRONJ) due to the suppression of normal bone turnover. There is no effective treatment for such a complication to date. This work reported the use of an ionic cocktail derived from water-soluble microfibrous borate glass to revert heterocyclic N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclasts resorption in static cell culture condition. This ionic cocktail may have the potential to be further developed into a new adjunctive treatment for BRONJ.


Assuntos
Boratos/química , Difosfonatos/química , Vidro/química , Nitrogênio/química , Osteoclastos/citologia , Osteonecrose/prevenção & controle , Animais , Apoptose , Reabsorção Óssea , Diferenciação Celular , Difosfonatos/efeitos adversos , Imidazóis/efeitos adversos , Macrófagos/citologia , Camundongos , Microscopia Eletrônica de Transmissão , Osteoclastos/efeitos dos fármacos , Osteoclastos/metabolismo , Estresse Oxidativo , Ligante RANK/metabolismo , Células RAW 264.7 , Espécies Reativas de Oxigênio/metabolismo , Ácido Risedrônico/efeitos adversos , Água/química , Ácido Zoledrônico
6.
Dent Mater ; 31(12): 1510-22, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26494267

RESUMO

OBJECTIVES: In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchymal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus. METHODS: Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogenic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05. RESULTS: The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracellular mineralization better than the positive control (zinc oxide-eugenol-based cement). SIGNIFICANCE: A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularization. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs.


Assuntos
Compostos de Alumínio/química , Bismuto/química , Compostos de Cálcio/química , Cimentos Dentários/química , Polpa Dentária/irrigação sanguínea , Polpa Dentária/citologia , Osteogênese/efeitos dos fármacos , Óxidos/química , Materiais Restauradores do Canal Radicular/química , Silicatos/química , Células-Tronco/efeitos dos fármacos , Adolescente , Adulto , Compostos de Alumínio/toxicidade , Bismuto/toxicidade , Compostos de Cálcio/toxicidade , Sobrevivência Celular , Cimentos Dentários/toxicidade , Combinação de Medicamentos , Citometria de Fluxo , Humanos , Teste de Materiais , Óxidos/toxicidade , Materiais Restauradores do Canal Radicular/toxicidade , Silicatos/toxicidade , Cimento de Óxido de Zinco e Eugenol/química , Cimento de Óxido de Zinco e Eugenol/toxicidade
7.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 48(3): 165-9, 2013 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-23751532

RESUMO

OBJECTIVE: To evaluate the effect of an 8% arginine-CaCO3 containing desensitizing polishing paste on bonding strength of two self-etching adhesives to dentin. METHODS: Thirty-six intact human premolars extracted for orthodontic reasons were collected within 1 month after extraction and randomly assigned into three groups using a table of random numbers (n = 12): specimens without any treatment served as control. In the polishing powder group specimens were polished with a slurry of pumice, and in the desensitizing polishing paste group dentin surfaces of the sample teeth were treated with 8% arginine-CaCO3 containing desensitizing polishing paste. Then each group was divided into two sub-groups using a table of random numbers in order to evaluate the bonding strength of two self-etching adhesive agents (G-Bond, GC; Fl-Bond II, Shofu). Microtensile bond strength test was conducted immediately and after 5000 thermocycling (n = 15). Scanning electron microscope (SEM) was used to evaluate the occluding effect of the desensitizing polishing paste. RESULTS: In the pre-thermocycling stage, there were no significant differences in Fl-Bond II bonding strength among the three groups [control: (30.34 ± 5.42) MPa, polishing powder group: (29.72 ± 5.16) MPa, desensitizing polishing paste group: (31.53 ± 4.86) MPa] (P > 0.05). However there were significant differences among the three groups in G-Bond bonding strength [control: (38.19 ± 4.42) MPa, polishing powder group: (36.47 ± 4.72) MPa, desensitizing polishing paste group: (46.88 ± 7.83) MPa] (P < 0.05). After thermocycling process, there were no significant differences in bonding strength among the three groups in both G-Bond groups and Fl-Bond II groups. SEM observation showed that the desensitizing polishing paste could occlude open dentinal tubules effectively, and the application of self-etching adhesives could re-open the dentinal tubular orifices. An even layer can be seen on the dentin surface treated with self-etching adhesive containing functional monomers. CONCLUSIONS: The 8% arginine-CaCO3 containing desensitizing polishing paste could effectively occlude dentinal tubules, thus may have potential benefits in preventing post-operative sensitivity. Additionally, it had no adverse effect on bonding strength of self-etching adhesives to dentin.


Assuntos
Dessensibilizantes Dentinários , Adesivos Dentinários , Condicionamento Ácido do Dente , Humanos , Técnicas In Vitro , Distribuição Aleatória , Resistência à Tração
9.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 46(12): 755-8, 2011 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-22333359

RESUMO

OBJECTIVE: To evaluate the micropermeability on bonding hydrophobic adhesive to dentin with ethanol-wet bonding under simulated pulp pressure. METHODS: Twenty-four intact human third molars were used in the study. After the enamel of occlusal surfaces was removed, the molars were randomly divided into six groups. Adper Scotchbond Multi-Purpose was used in the control group; in the experimental groups, the dentin surfaces were saturated with ethanol for 20 s (group 1), 1 min (group 2), 2 min (group 3), 3 min (group 4) or with a series of increasing ethanol concentrations before application of hydrophobic adhesive (group 5). All the bonding procedures were done under simulated pulp pressure. After 24 hours, micro-tensile bond strength test were performed on the specimens. Bonding interfaces were observed under laser scanning confocal microscope (LSCM) after the pulp chamber were filled with a water-soluble fluoroprobe rhodamine B for 3 hours. RESULTS: Compared with the control group [(38.14 ± 4.97) MPa], bond strengths in group 1 [(21.02 ± 7.23) MPa] and group 2 [(29.64 ± 3.81) MPa] were statistically lower (P > 0.05), while bond strength in group 3 [(38.40 ± 5.03) MPa], group 4 [(37.26 ± 4.68) MPa] and group 5 [(40.12 ± 5.95) MPa] were similar to the control group (P < 0.05). The images taken by LSCM showed that with extension of ethanol-wet time, the deposition of fluorescent dye in hybrid layer and along the dentinal tubules decreased gradually. Especially in group 5, only spare fluorescent dye deposition could be detected in the hybrid layer. CONCLUSIONS: Dentin saturated with ethanol for more than 2 min before bonding hydrophobic adhesive to dentin could provide favorable bond strength and decreased the micropermeability of bonding interfaces under simulated pulp pressure.


Assuntos
Cimentos Dentários , Adesivos Dentinários , Dentina , Etanol , Condicionamento Ácido do Dente , Resinas Compostas , Colagem Dentária , Esmalte Dentário , Cavidade Pulpar , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Cimentos de Resina , Resistência à Tração , Água
10.
Chin J Dent Res ; 14(2): 105-11, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22319751

RESUMO

OBJECTIVE: To investigate the effects of ethanol-wet bonding on the adhesion of experimental hydrophobic and commercial hydrophilic adhesives to root dentine. METHODS: A total of 43 single-rooted integrated human premolars were selected and sectioned. Of the 86 initially obtained specimens, 66 were randomly and equally divided into water-wet bonding and ethanol-wet bonding groups (n = 33). The specimens of each group were subdivided into three subgroups (n = 11) based on different adhesives: two experimental hydrophobic adhesives (Bis-GMA/TEGDMA, BT; and UDMA/TEGDMA, UT) and one commercial hydrophilic adhesive (Adper™ Single Bond 2, SB). The root surfaces were ground, acid-etched and rinsed and resin composite applied. After storing in distilled water for 24 h at 37°C, the shear bond strength (SBS) of each specimen was measured. A sample from each subgroup was randomly selected and prepared for scanning electron microscopy (SEM) analysis. The remaining 20 specimens were used in the contact angle (CA) experiment, and the values of CA were measured. SBS was analysed with two-way ANOVA/Tukey's multiple comparison test and CA with independent sample t test. RESULTS: A significant increase in SBS to root dentine was observed in the ethanol-wet bonding group compared with the traditional water-wet bonding group. The experimental hydrophobic adhesives (UT group) with ethanol-wet bonding presented the highest SBS (22.44 ± 3.32 MPa). CA increased significantly after the dentine surfaces were dried, especially for the water-saturated group. CONCLUSION: The adhesion to root dentine surfaces with ethanol-wet bonding may be superior to water-wet bonding.


Assuntos
Colagem Dentária/métodos , Adesivos Dentinários/química , Dentina/ultraestrutura , Etanol/química , Solventes/química , Raiz Dentária/ultraestrutura , Condicionamento Ácido do Dente/métodos , Bis-Fenol A-Glicidil Metacrilato/química , Cimentos Dentários/química , Materiais Dentários/química , Dessecação , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Microscopia Eletrônica de Varredura , Organofosfonatos/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Resistência ao Cisalhamento , Estresse Mecânico , Propriedades de Superfície , Temperatura , Fatores de Tempo , Água/química , Molhabilidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA