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1.
Dent Mater J ; 2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34234048

RESUMO

This study evaluated the alterations of surface topography of the bovine enamel caused by different pH of in-office bleaching agents. 23% H2O2 with pH 5.5, 7.0 and 8.5 were applied on the bovine tooth specimens (n=10) and photo-irradiated for 10 min. The bleaching procedure was repeated three times and specimens were subjected to linear surface roughness (Ra) and Vickers microhardness test (VHN) at baseline and after three consecutive applications. The morphological alterations were observed before and after third bleaching application. Data were analyzed by two-way ANOVA followed by Tukey's HSD. The pH of the bleaching agent significantly affects the Ra and VHN (p<0.05). Low pH yielded a significant increase in Ra and decrease in VHN. All the groups showed morphological alterations and profound effect was found in pH 5.5 group. It was concluded that the pH of the bleaching agent can affect Ra, VHN and surface morphology.

2.
Dent Mater J ; 2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34305051

RESUMO

The effect of long-term water storage on the regional ultimate tensile strength (UTS), water sorption (Wsp) and water solubility (Wsl) of conventional and bulk-fill resin composites at various depths was investigated. Composite specimens light-cured from one side were sectioned into beams corresponding to different depths (1-5 mm) and stored in water for 24 h, 1 week, 1 month, 6 months or 1 year. UTS increased during the first week and then gradually decreased over time, especially in deeper regions. Bulk-fill composites initially exhibited similar UTS at all depths, whereas the UTS of conventional composites at 1 mm and 5 mm differed significantly at all time points. Wsp and Wsl increased with depth and storage time, markedly at 3-5 mm after 1 month for conventional composites and after 6 months for bulk-fill composites. The signs of degradation at depths beyond 3 mm suggested that even bulk-fill composites have suboptimal properties in layers more than 3 mm in thickness.

3.
Odontology ; 109(4): 828-835, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33991277

RESUMO

The purpose is to evaluate the effect of photo-thermal acceleration on in-office bleaching efficiency using a bleaching agent without photocatalysts in vitro. Artificially discolored bovine lower incisors were prepared, and the mixed in-office bleaching material contained hydrogen peroxide 23% was applied by following treatment for 10 min: high-(HI group) and low-intensity LED lights (LI group), oven at 38 °C (OV group), and room temperature at 23 °C (RT group). Color was measured before and after bleaching and color difference (∆E*) was calculated. The data were statistically analyzed using a two-way ANOVA and Tukey's post hoc test. The temperature change (∆T) of applied bleaching agent in HI and LI groups was measured using a thermography and was analyzed using a T test. The bleaching procedures were repeated 6 times. Irradiation in the HI group resulted in the highest ΔE, followed by the LI group whose ΔE was significantly lower. Both irradiated modes exhibited higher ΔE compared to non-irradiated OV and RT groups which were not significantly different from each other. The average temperature rise of bleaching agents in HI and LI groups after 10 min irradiation was 15.00 °C and 11.80 °C, respectively. The effect of photo-thermal acceleration was proved for an in-office bleaching agent without photocatalysts in vitro.


Assuntos
Clareadores Dentários , Clareamento Dental , Aceleração , Animais , Bovinos , Cor , Peróxido de Hidrogênio
4.
Dent Mater J ; 40(3): 566-572, 2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-33456029

RESUMO

This study investigated the effect of pH of bleaching agent, photo-irradiation time or application times on bleaching action using hematoporphyrin-stained papers (HSPs) and artificially stained bovine-teeth (BT). 23% H2O2 with pH 5.5, 6.0, 7.0, 8.0 and 9.0 were applied on the specimens. HSP was photo-irradiated for 1, 3 and 5 min. BT were photo-irradiated for 10 min and the bleaching was repeated ten times (n=10). CIE L*a*b* of the specimens were measured before and after the procedure. Data were analyzed by repeated-measures ANOVA followed by multiple comparisons with Bonferroni correction. For the HSP, longer irradiation time and higher pH yielded significantly higher color difference (ΔE). As for BT, increasing application times and higher pH resulted in higher ΔE. It was concluded that the pH of the bleaching agent significantly improved the bleaching effect with increased photo-irradiation time for HSP and with an increase of repeated application times for BT.


Assuntos
Clareadores , Clareadores Dentários , Clareamento Dental , Animais , Bovinos , Cor , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio
5.
Restor Dent Endod ; 45(4): e44, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33294409

RESUMO

Objectives: Phytic acid (IP6), a naturally occurring agent, has been previously reported as a potential alternative to ethylenediaminetetraacetic acid (EDTA). However, its effect on adhesion to sodium hypochlorite (NaOCl)-treated dentin and its interactions with NaOCl have not been previously reported. Thus, in this study, the effects of IP6 on resin adhesion to NaOCl-treated dentin and the failure mode were investigated and the interactions between the used agents were analyzed. Materials and Methods: Micro-tensile bond strength (µTBS) testing was performed until failure on dentin treated with either distilled water (control), 5% NaOCl, or 5% NaOCl followed with chelators: 17% EDTA for 1 minute or 1% IP6 for 30 seconds or 1 minute. The failed specimens were assessed under a scanning electron microscope. The reaction of NaOCl with EDTA or IP6 was analyzed in terms of temperature, pH, effervescence, and chlorine odor, and the effects of the resulting mixtures on the color of a stained paper were recorded. Results: The µTBS values of the control and NaOCl with chelator groups were not significantly different, but were all significantly higher than that of the group treated with NaOCl only. In the failure analysis, a distinctive feature was the presence of resin tags in samples conditioned with IP6 after treatment with NaOCl. The reaction of 1% IP6 with 5% NaOCl was less aggressive than the reaction of the latter with 17% EDTA. Conclusions: IP6 reversed the adverse effects of NaOCl on resin-dentin adhesion without the chlorine-depleting effect of EDTA.

6.
Lasers Med Sci ; 35(1): 213-219, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31342201

RESUMO

To investigate the prevalence of different patterns of cemento-enamel junction (CEJ) morphology under swept-source optical coherence tomography (SS-OCT). One hundred extracted human teeth were used consisting of incisors, premolars, and molars. Each sample was observed for every 500 µm circumferentially along CEJ and OCT images of the pattern were noted. Microscopic observations were done for the representative sample using confocal laser scanning microscope (CLSM) and transmission electron microscope (TEM). The OCT images exhibited four CEJ patterns: edge-to-edge (type I), exposed dentin (type II), cementum overlapping enamel (type III), and enamel overlapping cementum (type IV). The prevalence of CEJ patterns was further statistically considered for mesial, distal, buccal, and lingual surfaces. The real-time imaging by SS-OCT instantly determined CEJ morphology. CLSM and TEM observation revealed morphological features along CEJ, which corresponded to OCT images of CEJ anatomy. OCT results showed 56.8% of type I pattern predominantly found on proximal surfaces, followed by 36.5% of type II pattern on buccal and lingual surface, 6.4% of type III pattern, and 0.3% of type IV pattern. There was a significant difference in prevalence of CEJ patterns among different types of teeth, but there was no statistically significant difference among the four surfaces in each type of teeth. OCT is a non-invasive diagnostic tool to examine the CEJ patterns along the entire circumference. OCT observation revealed even minor dentin exposure that would need clinical and home procedures to prevent any symptoms.


Assuntos
Esmalte Dentário/anatomia & histologia , Esmalte Dentário/diagnóstico por imagem , Tomografia de Coerência Óptica , Colo do Dente/anatomia & histologia , Colo do Dente/diagnóstico por imagem , Dente Pré-Molar/anatomia & histologia , Dente Pré-Molar/diagnóstico por imagem , Humanos , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Dente Molar/anatomia & histologia , Dente Molar/diagnóstico por imagem
7.
Dent Mater J ; 38(5): 790-797, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31434830

RESUMO

The aim of this in vitro study was to evaluate the effects of desensitizer pre-treatment on in-office bleaching using an artificial discoloration tooth model. The stained specimens were divided into four groups (n=10); without application (Control group), Shield Force plus (SF group), UltraEz (UE group) and Teeth Mate AP paste (TM group) applied before bleaching. Each group was bleached by an in-office bleaching agent. The CIE L*a*b* values were measured by a colorimeter before and after ten consecutive bleaching treatments and the color difference (∆E) was calculated. There was no statistical difference among ∆E values of Control, UE, and TM groups (p>0.05). There was a significant difference between SF and Control groups (p<0.001). It was concluded that application of TM and UE did not affect the change of tooth shade while SF application impeded the bleaching effect.


Assuntos
Clareadores Dentários , Clareamento Dental , Descoloração de Dente , Dente , Cor , Humanos , Peróxido de Hidrogênio
8.
Clin Exp Dent Res ; 5(3): 212-218, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31249701

RESUMO

The purpose of this study was to evaluate the effect of pH conditioners on tooth bleaching using hematoporphirin-stained paper and artificially discolored bovine tooth model. Experimental bleaching gels containing 23% hydrogen peroxide, adjusting pH 7.0 by different pH conditioners (NaOH, NaHCO3, Na2CO3, KOH, KHCO3, and K2CO3), were prepared. Each bleaching gel was applied on a hematoporphirin-stained paper, and the light was exposed for 5 min. Before and after bleaching, color was measured and color difference was calculated. Artificially discolored bovine tooth samples were prepared and bleached by four experimental bleaching gels containing NaOH, NaHCO3, Na2CO3, or KHCO3. The bleaching time was 10 min with light exposure, and bleaching was repeated 10 times. The color of bleached surface was measured at each bleaching period, and color difference was calculated. In the experiment using hematoporphirin-stained paper, degrees of color difference were KHCO3 > NaHCO3 > KOH > NaOH > Na2CO3 ≥ K2CO3. In the experiment using bovine teeth, degrees of color difference were KHCO3 > NaHCO3 > NaOH > Na2CO3. It was concluded that the bleaching materials with same pH and different pH conditioners showed different bleaching effects and that both cation and anion in the pH conditioners affected bleaching effect.


Assuntos
Tampões (Química) , Peróxido de Hidrogênio/farmacologia , Clareadores Dentários/farmacologia , Clareamento Dental/métodos , Descoloração de Dente/terapia , Dente/efeitos dos fármacos , Animais , Bicarbonatos/farmacologia , Carbonatos/farmacologia , Bovinos , Hematoporfirinas , Concentração de Íons de Hidrogênio , Hidróxidos/farmacologia , Técnicas In Vitro , Papel , Potássio/farmacologia , Compostos de Potássio/farmacologia , Bicarbonato de Sódio/farmacologia , Hidróxido de Sódio/farmacologia
9.
Dent Mater J ; 38(3): 396-402, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30867346

RESUMO

The purpose of this study was to evaluate the effect of the repeated nonthermal atmospheric discharge (NADC) exposure without peroxide or water on bleaching effect of cycling stained tooth and to evaluate surface roughness and microhardness of the enamel surface exposed by NADC. Specimens with 5×5mm were prepared from extracted bovine teeth. Staining with tea and exposure by NADC were repeated for five times and color was measured at each step. Other specimens were prepared and surface roughness (Ra) and microhardness (Vickers hardness) were measured after exposure by NADC. The repeated NADC exposure without peroxide or water showed bleaching effect for stained bovine teeth. The surface roughness was not changed by NADC exposure. The less microhadness was shown by NADC exposere.


Assuntos
Clareamento Dental , Animais , Peróxido de Carbamida , Bovinos , Corantes , Dureza , Humanos , Peróxido de Hidrogênio , Alta do Paciente , Peróxidos , Ureia
10.
Lasers Med Sci ; 34(5): 901-906, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30421363

RESUMO

The objective of this study was to evaluate the bleaching effect of light sources with various wavelengths using 30% hydrogen peroxide (HP) in vitro. The hematoporphyrin-stained paper was bleached with HP and irradiated for 10 min using LED light sources with 265, 310, 365, 405, or 450 nm respectively. In control group, HP was applied for 10 min without light irradiation. The bleaching procedure was repeated two times. The L*a*b* values of the samples before bleaching and after each bleaching step were measured using a colorimeter. Color changes of specimens were then calculated and statistically analyzed. There was an interaction between light sources and time of irradiation in the color change (p < 0.05). Time and light sources significantly affected ΔE and ΔL (p < 0.05). The light source of 256 nm showed the highest bleaching effect over time followed by that of 310 nm, which were statistically different from other groups (p < 0.001). The 365 nm, 450 nm groups, and control group showed low bleaching effect visually with no significant differences in ΔE and ΔL (p > 0.05). It was concluded that the wavelengths of the light sources affected the bleaching by HP. The 310-nm light can be a potential source for bleaching.


Assuntos
Peróxido de Hidrogênio/farmacologia , Luz , Clareadores Dentários/farmacologia , Clareamento Dental , Cor , Processamento de Imagem Assistida por Computador , Papel
11.
Clin Exp Dent Res ; 4(4): 113-118, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30181907

RESUMO

This in vitro study evaluated the effect of sodium fluoride (NaF) on the bleaching efficacy using an artificial discolored bovine tooth model. Twenty specimens were prepared from bovine teeth by staining with black tea extract and were divided into two groups (n = 10). In control group, specimens were immersed in distilled water for 30 min. In NaF group, specimens were applied with 0.2% NaF for 30 min. Then, the specimens in each group were bleached by an in-office bleaching material (Shofu Hi-Lite, Shofu, Kyoto, Japan). The CIE L*a*b* values were measured by a dental colorimeter before and after 10 consecutive bleaching treatments, and the color difference (ΔE) was calculated. Brightness and color difference (ΔE) increased in both groups per bleaching cycle. There were no statistical differences in ΔE values between both groups (p > 0.05). It was concluded that the application of NaF before bleaching did not interfere with the bleaching effect.

12.
Dent Mater J ; 37(3): 506-514, 2018 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-29491200

RESUMO

We evaluated the effect of different curing strategies for universal adhesives on micro-tensile bond strength (µTBS) between resin cement and dentin and/or between resin cement and indirect resin composite. Flat coronal dentin surfaces and composite resin disks were pretreated with silane-containing universal adhesives, with or without light-curing on the dentin-side and/or composite resin disk-side. Resin disks were luted onto the pretreated dentin surfaces with the corresponding dual-cure adhesive resin cements and light-cured, and cut into beams after 24-h water storage. After 0 or 10,000 thermocycles (5ºC/55ºC) in a water bath, the µTBS of the composite resin disk-dentin beam was tested. The µTBS was highest when universal adhesives were applied to both the dentin- and the indirect composite resin disk-side, followed by light-curing. Thermocycling decreased µTBS in all but the Scotchbond Universaltreated group, with light-curing on both sides. The effect of curing strategies is dependent upon the materials.


Assuntos
Resinas Acrílicas/química , Resinas Compostas/química , Colagem Dentária/métodos , Adesivos Dentinários/química , Poliuretanos/química , Restauração Dentária Permanente , Análise do Estresse Dentário , Humanos , Técnicas In Vitro , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Cimentos de Resina , Resistência à Tração
13.
J Mech Behav Biomed Mater ; 74: 274-282, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28646753

RESUMO

The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. MATERIALS AND METHODS: Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (µ-RS). The dentin 5-50µm depth beneath the lased surface was determined as testing area. Two-way analysis of variance (ANOVA) were used to compare the mechanical values between lased and untreated subsurface dentin (P = 0.05). RESULTS: A laser affected subsurface dentin layer after Er:YAG laser treatment is present. The laser irradiation is considered to decrease the mechanical properties in the superficial subsurface layer (<15µm deep). There was no significant difference in nanohardness and Young's modulus between lased subsurface dentin and untreated dentin (p > 0.05) under the depth of 15µm. However, the dentin at 5µm and 10µm depth beneath the lased surface exhibited significantly lower (~ 47.8% and ~ 33.6% respectively) hardness (p < 0.05). Er:YAG laser irradiation affected both mineral and organic components in subsurface dentin layer, a higher degree of crystallinity and reduced organic compounds occurred in the lased subsurface dentin. CONCLUSION: Under the tested laser parameters, Er:YAG laser irradiation causes lower mechanical values and reduction of organic components in subsurface dentin, which has deleterious effects on resin adhesion to this area.


Assuntos
Dentina/efeitos da radiação , Lasers de Estado Sólido , Érbio , Humanos , Microscopia Eletrônica de Varredura , Estrutura Molecular
14.
J Prosthodont Res ; 61(3): 251-258, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27777071

RESUMO

PURPOSE: Phytic acid (IP6) works well as an etchant in dentin bonding to remove the smear layer due to its acidity and chelating effect. This study compared the etching effect of IP6 with phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA) on resin-dentin bond strength, micromorphology of the etched dentin surface and nanoleakage formation along resin-dentin interfaces and compared the protecting effect against collagen degradation. METHODS: Dentin disks and flat dentin surfaces were obtained from extracted human teeth. Specimens were etched with 35% PA (15s), 0.5M EDTA (30s) or 1% IP6 (30s). The surfaces and longitudinal sections of the etched dentin disks were observed using field emission scanning electron microscope (FE-SEM). An etch-and-rinse adhesive was used to create composite build up-specimens for microtensile bond strength (µTBS) testing and nanoleakage observation. To evaluate the effect on collagen degradation, demineralized bovine root dentin blocks were challenged with bacterial collagenase and then observed under light microscope. RESULTS: PA- and EDTA- treated groups showed significantly lower µTBS when compared to IP6-treated group. PA showed distinct nanoleakage and severe collagen degradation. Only slight nanoleakage was detected in IP6 group. IP6 showed better effect than EDTA in preventing collagen degradation induced by bacterial collagenase. CONCLUSIONS: IP6 effectively removed the smear layer and etched dentin, providing high bond strength values and causing minimal nanoleakage and slight collagen degradation.


Assuntos
Condicionamento Ácido do Dente , Colágeno , Colagem Dentária , Corrosão Dentária , Dentina , Ácido Fítico , Resinas Sintéticas , Ácido Edético , Humanos , Ácidos Fosfóricos , Proteólise , Resistência à Tração
15.
Dent Mater ; 33(1): 33-42, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27771138

RESUMO

OBJECTIVE: Dentin collagen can be modified by some plant-derived flavonoids to improve properties of dentin organic matrix. Hesperidin (HPN), a hesperetin-7-O-rutinoside flavonoid, has a potential of dentin modification for being based on evidence that a treatment with HPN may resist collagenase degradation and arrest demineralization of human dentin. In this study, biophysical and molecular-level information on the interaction of HPN and collagen was investigated. METHODS: HPN is extracted from citrus fruits. Sample collagenous solution was prepared using atelocollagen (ATCL) as a triple-helical peptide model. We have performed circular dichroism spectroscopic analysis, sedimentation velocity measurement by ultracentrifuge and saturation transfer difference measurement (STD) by NMR on HPN-collagen in solution state. RESULTS: The circular dichroism and sedimentation velocity measurement showed the evidence for the molecular interaction between ATCL and HPN, while HPN did not induce any conformational change of ATCL. The STD-NMR study further confirmed this interaction and suggested that HPN interacted with ATCL through its aromatic part, not through its disaccharide moiety. SIGNIFICANCE: These findings indicated that HPN is weakly bound to ATCL not causing structural modification of collagen. This interaction may contribute to the preservation of collagen by protecting from collagenase degradation.


Assuntos
Colágeno/metabolismo , Dentina/metabolismo , Hesperidina/farmacologia , Colagenases/metabolismo , Humanos , Espectroscopia de Ressonância Magnética
16.
J Med Imaging (Bellingham) ; 2(1): 014001, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26158079

RESUMO

A technology to characterize early enamel lesions is needed in dentistry. Optical coherence tomography (OCT) is a noninvasive method that provides high-resolution cross-sectional images. The aim of this study is to compare OCT with microfocus x-ray computed tomography ([Formula: see text]) for assessment of natural enamel lesions in vitro. Ten human teeth with visible white spot-like changes on the enamel smooth surface and no cavitation (ICDAS code 2) were subjected to imaging by µCT (SMX-100CT, Shimadzu) and 1300-nm swept-source OCT (Dental SS-OCT, Panasonic Health Care). In [Formula: see text], the lesions appeared as radiolucent dark areas, while in SS-OCT, they appeared as areas of increased signal intensity beneath the surface. An SS-OCT attenuation coefficient based on Beer-Lambert law could discriminate lesions from sound enamel. Lesion depth ranged from 175 to [Formula: see text] in SS-OCT. A correlation between [Formula: see text] and SS-OCT was found regarding lesion depth ([Formula: see text], [Formula: see text]) and also surface layer thickness ([Formula: see text], [Formula: see text]). The images obtained clinically in real time using the dental SS-OCT system are suitable for the assessment of natural subsurface lesions and their surface layer, providing comparable images to a laboratory high-resolution [Formula: see text] without the use of x-ray.

17.
J Mech Behav Biomed Mater ; 48: 145-152, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25933170

RESUMO

OBJECTIVE: This study examined the effect of phytic acid (IP6) in stabilizing the morphology of dentine collagen network and resin-dentine bonding. METHODS: Dentine beams were fully demineralized with 10% phosphoric acid (PA) or 1% IP6 (pH 1.2). PA-demineralized beams were divided into three groups: (a) no further treatment (control), (b) treatment with 5% glutaraldehyde (GA) for 1 h and (c) treatment with 1% IP6 (pH 7) for 1 h. IP6-demineralized beams received no further treatment. The beams were then subjected to ultimate tensile strength (UTS) testing. Dentine micromorphology evaluation was performed using a field-emission scanning electron microscope (FE-SEM). Dentine disks were etched with 35% PA for 15 s or 1% IP6 for 30s. PA-etched dentine disks were divided into three groups as (a), (b) and (c) as for UTS testing, but the treatment with GA or IP6 was done in 1min. For microtensile bond strength (µTBS) testing, flat dentine surfaces etched with PA or IP6 were blot-dried (wet dentine) or air-dried for 10s (dry dentine) and bonded with an etch-and-rinse adhesive followed by composite build-up. RESULTS: IP6-demineralized dentine showed significantly higher UTS, when compared to PA-demineralized dentine. GA and IP6 significantly improved UTS of PA-demineralized dentine. FE-SEM observation revealed that dentine collagen network was preserved by GA and IP6. No significant difference in µTBS was found between the wet and dry IP6-etched dentine groups. CONCLUSION: IP6 etching showed a structural stabilizing effect on demineralized dentine matrix and produced good resin-dentine bonding, regardless of dentine moistness or dryness.


Assuntos
Colagem Dentária , Dentina/efeitos dos fármacos , Ácido Fítico/farmacologia , Resistência à Tração , Dente/efeitos dos fármacos , Análise do Estresse Dentário , Dentina/fisiologia , Humanos , Cimentos de Resina , Propriedades de Superfície , Dente/fisiologia
18.
J Investig Clin Dent ; 6(1): 59-62, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23857900

RESUMO

AIM: Mussel-mimetic, bioadhesive polymers are synthesized from plant-derived sources. The strong adhesive action is caused by interactions between the catechol groups at the end of the polymer terminal chains and the substrate surface. Here, we present a preliminary study of the adhesion properties and a discussion of the adhesion mechanism. METHODS: Two bioadhesive polymers were synthesized from natural plant-derived monomers by the transesterification of: (a) caffeic acid (3,4-dihydroxycinnamic acid; DHCA) and p-coumaric acid (4-hydroxycinnamic acid; 4HCA) to produce poly(DHCA-co-4HCA); and (b) 4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(3-hydroxyphenyl) propionic acid (3HPPA) to produce poly(DHHCA-co-3HPPA). Thermoplastic poly(DHCA-co-4HCA) or poly(DHHCA-co-3HPPA) was placed between glass, carbon, steel, or bovine dentin substrates, and a lap shear adhesion test was conducted to compare them using conventional cyanoacrylate glue and epoxy resin. RESULTS: The greatest adhesion for all tested substrates was exhibited by poly(DHHCA-co-3HPPA), followed by epoxy resin adhesive, poly(DHCA-co-4HCA), and cyanoacrylate adhesive. The adhesive strength of poly(DHHCA-co-3HPPA) was greater than 25.6 MPa for glass, 29.6 MPa for carbon, 15.7 MPa for steel, and 16.3 MPA for bovine dentin. CONCLUSION: The adhesion of poly(DHHCA-co-3HPPA) might be the strongest reported for a mussel-mimic adhesive system, and could be a feasible alternative to petroleum adhesives.


Assuntos
Adesivos/química , Materiais Biomiméticos/química , Biopolímeros/química , Preparações de Plantas/química , Adesividade , Animais , Ácidos Cafeicos/química , Carbono/química , Catecóis/química , Bovinos , Cinamatos/química , Ácidos Cumáricos/química , Cianoacrilatos/química , Dentina/química , Resinas Epóxi/química , Esterificação , Vidro/química , Polimerização , Propionatos , Proteínas/química , Aço/química , Estresse Mecânico
19.
Dent Mater ; 31(2): 88-92, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25499247

RESUMO

OBJECTIVE: 2-Hydroxyethylmethacrylate (HEMA) diffuses in wet dentin and promotes adhesion during dentin priming and bonding. We have investigated the molecular level interaction between HEMA and a collagen model by using saturation transfer difference (STD) NMR. METHODS: The binding of HEMA to collagen was preliminarily investigated by suspending demineralized human dentin powders in a 4mM HEMA solution for 1h and measuring the decrease in the HEMA concentration on a spectrophotometer. The molecular level interaction of HEMA with atelocollagen, which was used as a collagen model, was investigated by STD-NMR spectroscopy. RESULTS: The HEMA concentration in the suspension did not change, indicating that HEMA did not bind to dentin collagen. This was confirmed by STD-NMR; when the atelocollagen resonance was saturated, no saturation was propagated to HEMA and no STD signals were detected. SIGNIFICANCE: The HEMA protons were not near the atelocollagen surface, indicating HEMA did not interact with atelocollagen. The collagen fibrils may be surrounded by water molecules in dentin/bond interfaces, which prevent the direct HEMA binding interaction.


Assuntos
Colágeno/química , Adesivos Dentinários/química , Dentina/química , Espectroscopia de Ressonância Magnética/métodos , Metacrilatos/química , Humanos , Técnicas In Vitro , Dente Molar
20.
J Endod ; 41(2): 242-7, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25453568

RESUMO

INTRODUCTION: The objectives of this study were to investigate the effect of phytic acid, inositol hexakisphosphate (IP6), as a final rinse on the surface of instrumented root canals and smear-layered flat dentin surfaces treated with sodium hypochlorite (NaOCl) and to evaluate its effect on the viability and alkaline phosphatase activity of osteoblast-like cells (MC3T3-E1). METHODS: The universally accepted chelating agent EDTA was used as the control in all conducted experiments. Root canals of human canines were instrumented with rotary files and irrigated with 5% NaOCl, followed by a final rinse of 17% EDTA (1 minute), 1% IP6 (1 minute or 30 seconds), or distilled water. NaOCl-treated flat coronal dentin surfaces were also treated with 17% EDTA (1 minute), 1% IP6 (1 minute or 30 seconds), or distilled water. The presence or absence of smear layer was evaluated with scanning electron microscopy. Cell viability and alkaline phosphatase assays were performed to evaluate the effect of IP6 and EDTA on cultured MC3T3-E1 cells. RESULTS: The results demonstrated the ability of IP6 to remove the smear layer from instrumented root canals and flat coronal dentin surfaces. When compared with EDTA, IP6 was less cytotoxic and did not affect the differentiation of MC3T3-E1 cells. CONCLUSIONS: IP6 shows the potential to be an effective and biocompatible chelating agent.


Assuntos
Quelantes/administração & dosagem , Dente Canino/efeitos dos fármacos , Ácido Fítico/administração & dosagem , Tratamento do Canal Radicular , Fosfatase Alcalina/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas/efeitos dos fármacos , Dente Canino/patologia , Cavidade Pulpar/diagnóstico por imagem , Cavidade Pulpar/efeitos dos fármacos , Cavidade Pulpar/patologia , Dentina/efeitos dos fármacos , Dentina/patologia , Ácido Edético/administração & dosagem , Humanos , Microscopia Eletrônica de Varredura , Irrigantes do Canal Radicular/administração & dosagem , Irrigantes do Canal Radicular/uso terapêutico , Preparo de Canal Radicular/métodos , Camada de Esfregaço/diagnóstico por imagem , Camada de Esfregaço/tratamento farmacológico , Camada de Esfregaço/patologia
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