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1.
Oper Dent ; 45(6): 664-676, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-32997740

RESUMEN

CLINICAL RELEVANCE: When a resin nanoceramic inlay is cemented using self-adhesive cement, a universal dentin adhesive can be applied to the prepared cavity. The application of the adhesive before self-adhesive cement placement provides similar or better interfacial adaptation than without the adhesive. SUMMARY: Purpose: The first objective of this study was to determine whether the luting material used for computer-aided design and computer-aided manufacture resin nanoceramic inlays affected interfacial adaptation. The second objective was to investigate whether application of a universal dentin adhesive before cementation affected interfacial adaptation. The final objective was to compare the inlay-side and dentin-side interfaces in the cement space.Methods and Materials: Seventy-four class I cavities were prepared on extracted human third molars. Cavities were optically scanned, and resin nanoceramic inlays were milled using Lava Ultimate blocks (3M ESPE). For the control groups, the fabricated inlays were cemented using Panavia V5 (Kuraray Noritake) or FujiCem 2 (GC). For the experimental groups, the teeth were randomly divided into groups I and II. Group I contained four subgroups using different luting materials; in all subgroups, the inlays were cemented and dual cured without pretreatment. Group II contained six subgroups in which inlays were cemented and dual cured after application of a universal dentin adhesive. After thermocycling, interfacial adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and statistically compared among groups.Results: Interfacial adaptation was different depending on the luting material used (p<0.05). After application of a universal adhesive, some subgroups showed improved interfacial adaptation (p<0.05). In the comparison of inlay-side and dentin-side interfaces, no difference was found in interfacial adaptation (p>0.05).Conclusions: Interfacial adaptation for resin nanoceramic inlays differed with luting material. For some self-adhesive cements, application of a universal adhesive before cementation improved interfacial adaptation.


Asunto(s)
Incrustaciones , Tomografía de Coherencia Óptica , Resinas Compuestas , Diseño Asistido por Computadora , Preparación de la Cavidad Dental , Porcelana Dental , Humanos , Ensayo de Materiales , Cementos de Resina
2.
Oper Dent ; 45(5): 556-566, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32243250

RESUMEN

CLINICAL RELEVANCE: The degree of conversion of contemporary universal adhesives positively correlates with the bond strength to dentin. The correlation is more marked after thermocycling, suggesting that a high degree of conversion is required for long-term dentin bonding durability. SUMMARY: Purpose: The objectives of this study were to evaluate the micro-tensile bond strength (µTBS) of five contemporary universal adhesives to dentin after 24 hours and thermocycling (TC), to measure their degrees of conversion (DC) and to test the correlation between µTBS and DC.Methods and Materials: Four commercially available universal adhesives, Prime&Bond universal (PBU), Ecosite Bond (EB), G-Premio Bond (GPB), and Clearfil Universal Bond Quick (UBQ), and one experimental adhesive, UBQ without an amide monomer (UBQ-A), were used in this study. For the µTBS test, midcoronal dentin of 50 human molars was exposed, ground using 600-grit SiC paper, and the adhesives were applied according to the manufacturers' instructions. After resin-composite buildup and 24-hour water storage, one-half of the specimens were subjected to 15,000 thermal cycles. The specimens were sectioned into beams and stressed in tension at a crosshead speed of 1 mm/min until failure. The DC of adhesives applied to dentin was evaluated using attenuated total reflectance Fourier-transform infrared spectroscopy immediately after light-curing. All data were statistically analyzed at a significance level of 0.05.Results: The highest µTBSs were obtained with UBQ, UBQ-A, and PBU, which were not significantly different from each other both after 24 hours and TC. The µTBS of GPB was lower compared with the aforementioned adhesives, but significantly only after TC, and the lowest µTBSs were obtained with EB. TC did not affect the µTBSs of UBQ, UBQ-A, and PBU significantly, but a significant decrease was observed with GPB and EB. The highest DC was obtained with PBU and UBQ, followed by 2-hydroxyethyl methacrylate-rich adhesives UBQ-A and EB, which exhibited significantly lower DCs. The DC of GPB could not be determined because the reference peak at 1608 cm-1 was not detected in its spectra. A significant positive correlation was shown between µTBS and DC after 24 hours (r=0.716) and TC (r=0.856).Conclusion: µTBS and DC were positively correlated, more markedly after TC, which suggests that DC may be an important factor for bond durability.


Asunto(s)
Recubrimiento Dental Adhesivo , Recubrimientos Dentinarios , Adhesivos , Resinas Compuestas , Cementos Dentales , Dentina , Humanos , Ensayo de Materiales , Cementos de Resina , Resistencia a la Tracción
3.
Oper Dent ; 44(3): 281-288, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30106333

RESUMEN

OBJECTIVE: To investigate the effect of calcium-phosphate-based desensitizers, Teethmate AP paste (TMAP) and Teethmate Desensitizer (TMD) (Kuraray Noritake Dental, Tokyo, Japan), on the prevention of staining on acid-eroded enamel. METHODS AND MATERIALS: Forty polished enamel samples (4×4×1 mm) from bovine incisors were randomly divided into five groups (n=8). After immersion in 50 mL of 0.5% citric acid (pH 2.5) for 15 minutes to form acid-eroded surfaces, the surfaces were subjected to different treatments with TMAP, TMD, and NaF (0.21% means 950 ppm) for five minutes. Another eroded group was not treated with desensitizer. For the control group, the samples were not eroded or treated. All the samples were stored in artificial saliva (AS) at pH 7.2 for 24 hours at 37°C. The TMAP, TMD, or NaF was reapplied at eight and 16 hours during the 24 hours of storage time. The surface roughness (Sa) was evaluated following ISO 25178 for surface texture using confocal laser scanning microscopy (VK-X 150 series, Keyence, Osaka, Japan) before acid erosion, after acid erosion, and after 24 hours of incubation in AS. Afterward, the color difference was measured with a dental colorimeter (Shade Eye NCC, Shofu, Kyoto, Japan) before and after staining with tea solution. RESULTS: One-way repeated measures analysis of variance showed that acid erosion significantly increased Sa (p<0.001). TMAP- and TMD-treated groups exhibited lower Sa values than the NaF group and the no-desensitizer treatment group. The greatest staining was observed in the NaF group and the no-desensitizer group, while the TMAP and TMD groups significantly decreased the formation of stains. CONCLUSIONS: Acid-eroded enamel increased surface roughness and tended to absorb more stains. However, the application of TMAP and TMD moderated the roughness and thus prevented the formation of extrinsic stains.


Asunto(s)
Erosión de los Dientes , Animales , Calcio , Bovinos , Esmalte Dental , Japón , Coloración y Etiquetado
4.
Dent Mater ; 34(4): e57-e62, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29402543

RESUMEN

OBJECTIVE: The dental caries is developed as a result of an alternative course of mineral gain and loss. In order to distinguish between intrinsic Ca (tooth-derived mineral) and extrinsic Ca (solution-derived mineral) uptakes, a 44Ca doped pH-cycling was performed using 44Ca (a stable calcium isotope) remineralization solution. METHODS: The natural abundance of 40Ca and 44Ca is 96.9% and 2.1%, respectively. The remineralization solution was prepared using 44Ca to contain 1.5mmol/L CaCl2 (44Ca), 0.9mmol/L KH2PO4, 130mmol/L KCl, 20mmol/L HEPES at pH 7.0. The pH-cycling was conducted on bovine root dentin daily by demineralization (pH 5.0) for 2h, incubation in 0% (control) and 0.2% NaF (900ppm fluoride) for 2h and 44Ca doped remineralization for 20h. After 14days pH-cycling, the specimens were sectioned longitudinally. On the sectioned surface, isotope imaging of 40Ca and 44Ca labeled mineral distribution was observed by a high mass-resolution stigmatic secondary ion 77 (Camera IMS 1270, Gennevilliers Cedex, France). RESULTS: Uptake of 44Ca was greater in intensity for the 0.2% fluoride group than the control, especially in the superficial lesions. The control group showed 40Ca (intrinsic) distribution in the subsurface lesions and in the superficial lesions, meanwhile the fluoride group showed 40Ca distribution limited in subsurface lesions. The total Ca (44Ca+40Ca) image revealed more homogeneously for the control than the fluoride group. SIGNIFICANCE: Since the fluoride-treated surface is more acid-resistant than intrinsic dentin, alternative minerals were dissolved from the intact intrinsic lesion in the demineralization cycle.


Asunto(s)
Isótopos de Calcio/química , Calcio/química , Dentina/química , Espectrometría de Masa de Ion Secundario , Remineralización Dental , Animales , Calcio/análisis , Isótopos de Calcio/análisis , Bovinos , Fluoruros/química , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Soluciones , Propiedades de Superficie
5.
Oper Dent ; 42(6): 626-635, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28857710

RESUMEN

In this laboratory study, the microtensile bond strengths (µTBS) of resin-modified glass ionomer cement (RM-GIC) to sound and artificial caries-affected bovine root dentin (ACAD) using three different conditioning agents were evaluated after 24 hours and three months. The fractured interface was examined with a scanning electron microscope (SEM). Specimens were created on bovine root dentin that was embedded in epoxy resin. For the ACAD specimens, artificial carious lesions were created. The RM-GIC (Fuji II LC) was applied either directly (no treatment), after application of self conditioner, cavity conditioner, or 17% ethylenediamine tetraacetic acid (EDTA) applied for 60 seconds, on sound dentin and ACAD, then light cured. They were stored in artificial saliva for 24 hours or three months. Following this, the specimens were cut into sticks for the µTBS test, and the failure mode of the debonded specimens was examined by using SEM. Pretest failures were excluded from the statistical analysis of the µTBS values because of their high incidence in some groups. Results showed that the µTBS values were significantly affected by the dentin substrate as well as the conditioning agent. Self conditioner provided the highest and most stable µTBS values, while cavity conditioner showed stable µTBS values on sound dentin. Both self conditioner and cavity conditioner had significantly higher µTBS values than the no treatment groups. EDTA conditioning reduced the µTBS after three months to sound dentin, while it showed 100% pretest failure with ACAD for both storage periods.


Asunto(s)
Recubrimiento Dental Adhesivo/métodos , Caries Dental/terapia , Dentina/metabolismo , Cementos de Ionómero Vitreo/uso terapéutico , Raíz del Diente/metabolismo , Animales , Bovinos , Análisis del Estrés Dental , Técnicas In Vitro , Microscopía Electrónica de Rastreo , Resistencia a la Tracción
6.
J Dent Res ; 96(9): 992-998, 2017 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-28521113

RESUMEN

The aims of this study were to observe the behavior of composite and formation of gaps during and immediately after light polymerization using swept source optical coherence tomography (OCT) and to compare the interfacial integrity of adhesives in cavities through 3-dimensional (3D) image analysis. Forty tapered cylindrical cavities (4-mm diameter, 2-mm depth) were prepared in bovine incisors and restored using Bond Force (BF), Scotchbond Universal Adhesive (SBU), OptiBond XTR (XTR), or Clearfil SE Bond 2 (SE2), followed by Estelite Flow Quick flowable composite. Real-time imaging was performed at the center of restoration by the OCT system (laser center wavelength: 1,330 nm; frequency: 30 KHz) during and up to 10 min after light curing. The 3D scanning was performed 0, 1, 3, 5, and 10 min after light curing. The percentages of sealed enamel and dentin interface area (E%, D%) were calculated using Amira software. In real-time videos, the initial gaps appeared as a bright scattered area mainly on dentin floor and rapidly progressed along the cavity floor. The timing, rate, and extent of gap formation were different among the specimens. From 3D visualization, gap progress could be seen on both enamel and dentin even after irradiation; furthermore, typical toroidal gap patterns appeared at the dentin floor of BF and SBU. XTR and SE2 showed nearly perfect sealing performance on the dentin floor up to the 10 min that images were recorded. From quantitative analysis, SE2 and XTR showed significantly higher E% and D% than other groups. SBU showed the smallest E% and BF showed a significantly smaller D% than other groups ( P < 0.05). In conclusion, real-time observation of composite placement and 3D quantification of interfacial gaps were implemented within the experimental limitations. Interfacial gap formation during polymerization of the composite depended on the adhesive system used. The formed gaps continued to propagate after composite light curing finished.


Asunto(s)
Resinas Compuestas/química , Curación por Luz de Adhesivos Dentales , Tomografía de Coherencia Óptica , Animales , Bovinos , Luces de Curación Dental , Esmalte Dental , Dentina , Imagenología Tridimensional , Incisivo , Ensayo de Materiales , Polimerizacion , Cementos de Resina , Programas Informáticos , Propiedades de Superficie , Grabación en Video
7.
Clin Oral Investig ; 21(8): 2637-2644, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28176000

RESUMEN

OBJECTIVES: The aim of this study was to evaluate factors associated with the incidence of erosive tooth wear (ETW) among adults at different ages in Tokyo using multifactorial logistic regression analysis. MATERIALS AND METHODS: The study sample consisted of a total of 1108 subjects aged 15 to 89 years in Tokyo, Japan. Two examiners evaluated ETW in a full-mouth recording. The subjects were asked to complete a self-administered daily diet, habit, and health condition questionnaire. Subjects who had frequent acid consumption or gastric reflux and at least one tooth with initial enamel wear were placed in the ETW-positive group, and the remainder of the subjects was placed in the ETW-negative group. Logistic regression analyses were carried out to identify factors collectively associated with ETW. RESULTS: Logistic regression analysis showed that greater frequencies of carbonated or sports drink consumption were associated with higher incidence of ETW for all age groups except for 70-89 years. Adults in the 30-39-year group who reported suffering from heartburn were about 22.3 times more likely to develop ETW, while 40-49-year adults who had repeated vomiting were about 33.5 times more likely to exhibit ETW compared with those who did not experience vomiting. CONCLUSION: Age-specific dietary habits were clearly observed among adults at different ages in Tokyo, and there were significant differences in intrinsic and extrinsic factors between ETW-positive and ETW-negative groups for each age group. CLINICAL RELEVANCE: Both greater frequency of carbonated and sports drink consumption were associated with higher incidence of ETW among adults at different ages in Tokyo.


Asunto(s)
Erosión de los Dientes/epidemiología , Erosión de los Dientes/etiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Bebidas , Dieta , Femenino , Humanos , Incidencia , Modelos Logísticos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Encuestas y Cuestionarios , Tokio/epidemiología
8.
J Dent Res ; 96(3): 308-314, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27872333

RESUMEN

The aim of this study was to nondestructively analyze enamel crack behavior on different areas of teeth using 3D swept source-optical coherence tomography (SS-OCT). Ten freshly extracted human teeth of each type on each arch ( n = 80 teeth) were inspected for enamel crack patterns on functional, contact and nonfunctional, or noncontact areas using 3D SS-OCT. The predominant crack pattern for each location on each specimen was noted and analyzed. The OCT observations were validated by direct observations of sectioned specimens under confocal laser scanning microscopy (CLSM). Cracks appeared as bright lines with SS-OCT, with 3 crack patterns identified: Type I - superficial horizontal cracks; Type II - vertically (occluso-gingival) oriented cracks; and Type III - hybrid or complicated cracks, a combination of a Type I and Type III cracks, which may or may not be confluent with each other. Type II cracks were predominant on noncontacting surfaces of incisors and canines and nonfunctional cusps of posterior teeth. Type I and III cracks were predominant on the contacting surfaces of incisors, cusps of canines, and functional cusps of posterior teeth. Cracks originating from the dental-enamel junction and enamel tufts, crack deflections, and the initiation of new cracks within the enamel (internal cracks) were observed as bright areas. CLSM observations corroborated the SS-OCT findings. We found that crack pattern, tooth type, and the location of the crack on the tooth exhibited a strong correlation. We show that the use of 3D SS-OCT permits for the nondestructive 3D imaging and analysis of enamel crack behavior in whole human teeth in vitro. 3D SS-OCT possesses potential for use in clinical studies for the analysis of enamel crack behavior.


Asunto(s)
Esmalte Dental/lesiones , Imagenología Tridimensional , Tomografía de Coherencia Óptica/métodos , Fracturas de los Dientes/diagnóstico , Síndrome de Diente Fisurado/diagnóstico , Esmalte Dental/patología , Humanos , Técnicas In Vitro , Microscopía Confocal/métodos
9.
Acta Biomater ; 33: 235-41, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26827779

RESUMEN

UNLABELLED: During dentin bonding with etch-and-rinse adhesive systems, phosphoric acid etching of mineralized dentin solubilizes the mineral crystallites and replaces them with bound and unbound water. During the infiltration phase of dentin bonding, solvated adhesive resin comonomers are supposed to replace all of the unbound collagen water and polymerize into copolymers. A recently published review suggested that dental monomers are too large to enter and displace water from tightly-packed collagen molecules. Conversely, recent work from the authors' laboratory demonstrated that HEMA and TEGDMA freely equilibrate with water-saturated dentin matrices. However, because adhesive blends are solvated in organic solvents, those solvents may remove enough free water to allow collagen molecules to come close enough to exclude adhesive monomer permeation. The present study analyzed the size-exclusion characteristics of dentin collagen, using a gel permeation-like column chromatography technique, filled with dentin powder instead of Sephadex beads as the stationary phase. The elution volumes of different sized test molecules, including adhesive resin monomers, studied in both water-saturated dentin, and again in ethanol-dehydrated dentin powder, showed that adhesive resin monomers can freely diffuse into both hydrated and dehydrated collagen molecules. Under these in vitro conditions, all free and some of the loosely-bound water seems to have been removed by ethanol. These results validate the concept that adhesive resin monomers can permeate tightly-bound water in ethanol-saturated collagen molecules during infiltration by etch-and-rinse adhesives. STATEMENT OF SIGNIFICANCE: It has been reported that collagen molecules in dentin matrices are packed too close together to allow permeation of adhesive monomers between them. Resin infiltration, in this view, would be limited to extrafibrillar spaces. Our work suggests that monomers equilibrate with collagen water in both water and ethanol-saturated dentin matrices.


Asunto(s)
Cromatografía en Gel , Colágeno Tipo I/química , Recubrimientos Dentinarios/química , Dentina/química , Etanol/farmacología , Cementos de Resina/química , Animales , Tampones (Química) , Bovinos , Solubilidad , Desmineralización Dental
10.
Aust Dent J ; 61(3): 366-73, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-26573239

RESUMEN

BACKGROUND: The aim of this randomized controlled study was to evaluate the clinical performance of a highly filled flowable composite compared to a conventional paste-type composite in direct posterior restorations after 36 months. METHODS: A total of 58 mid-size to extensive posterior composite restorations were randomly placed in 32 patients, mean age of 43.9 years (range 25-76), using either a conventional composite Estelite Sigma Quick (Conventional) or a highly filled flowable composite G-aenial Universal Flo with a two-step self-etch adhesive. The restorations were evaluated after placement (baseline) and at 6, 12, 24 and 36 months according to the FDI criteria. RESULTS: At the 36-month follow-up, 42 restorations were evaluated in 21 patients. After 36 months, the difference between highly filled flowable and conventional restorations was not statistically significant with respect to all evaluation parameters (p < 0.05). No secondary caries was observed. CONCLUSIONS: The highly filled flowable composite showed a comparable clinical effectiveness as the conventional paste composite in posterior restorations over 36 months.


Asunto(s)
Resinas Compuestas/uso terapéutico , Caries Dental/terapia , Diente Molar , Adulto , Anciano , Caries Dental/patología , Restauración Dental Permanente/métodos , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Resultado del Tratamiento
11.
J Dent Res ; 94(8): 1070-7, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26082389

RESUMEN

This study investigated the influence of adhesives and marginal sealing on demineralization progress using optical coherence tomography (OCT). Cavities (4 × 2 mm) were prepared in bovine incisors and restored using Clearfil SE Protect (SP), Bond Force (BF), Scotchbond Universal (SB), or G-Bond Plus (GB), followed by Estelite Flow Quick flowable composite. The control group received no adhesive (n = 10). After 3-d incubation in artificial saliva and 10,000 thermal cycles, gaps at enamel and dentin margins were measured at 8 locations on cross-sectional images obtained from each restoration using swept-source OCT at 1310-nm wavelength. Specimens were demineralized using acidified gel (pH = 4.5) for 5 wk and scanned every week to monitor the lesion progress at the same marginal locations. Repeated-measures analysis of variance showed that demineralization period and adhesive type and their interaction had a significant effect on the lesion size in both substrates (P < 0.001). SP, BF, and SB had significantly lower enamel and dentin initial gaps than the control and GB (P < 0.05). Enamel lesion progress was slower in the fluoride-releasing adhesives SP and BF and significantly different from SB, GB, and the control (P < 0.001). SP and BF dentin lesions were significantly different from GB and the control (P < 0.001), but not from SB (P > 0.05). A significant positive correlation (P < 0.05) was found between initial gap length and formed lesion size in both substrates, which was stronger in enamel (r = 0.63) than dentin (r = 0.35). Microgaps forming at the margins of restorations depend on adhesives and significantly contribute to the progress of demineralization around the margins, while fluoride release may decrease the rate of progression.


Asunto(s)
Resinas Compuestas/química , Recubrimiento Dental Adhesivo/métodos , Filtración Dental/diagnóstico , Cementos de Resina/química , Desmineralización Dental/inducido químicamente , Desmineralización Dental/diagnóstico , Animales , Bovinos , Adaptación Marginal Dental , Técnicas In Vitro , Metacrilatos , Microscopía Confocal , Tomografía de Coherencia Óptica
12.
J Dent ; 43(5): 589-96, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25681642

RESUMEN

OBJECTIVES: Understanding morphological changes and mineral content of tooth hard tissues may influence dental treatment. In this study, the effect of Type 1 Diabetes Mellitus (T1DM) on tooth structure was examined. METHODS: Experimental T1DM was induced in 3-week old male Wistar rats (n=10) by a single dose of 60mg/kg body weight of Streprozotocin. All rats were injected with calcein twice during the experiment and sacrificed at the age of 7 weeks old. Micro-computed tomography (micro-CT) was used to determine the mineral density and thickness of enamel and dentine. Also, a histomorphometery study was conducted to detect the rates of dentine mineral apposition and formation. The examined area was in the crown analogue of the rat mandibular incisor parallel to the long axis of the mesial surface of the first molar. All results were compared using Students' t-test (p<0.05). RESULTS: Results showed that the enamel and dentine thickness were significantly reduced (hypoplasia) and there was a significant reduction of the rate of dentine mineral apposition and formation, while there was no significant effect of the T1DM condition on the mineral density of enamel and dentine. CONCLUSIONS: T1DM has a detrimental influence on the formation of enamel and dentine in the early growth stage. CLINICAL SIGNIFICANCE: T1DM condition may alter treatment planning of orthodontic treatment as it is associated with decreased enamel and dentin thickness that may affect teeth size and their resistance to caries.


Asunto(s)
Esmalte Dental/metabolismo , Dentina/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Animales , Esmalte Dental/anatomía & histología , Esmalte Dental/efectos de los fármacos , Dentina/anatomía & histología , Dentina/efectos de los fármacos , Diabetes Mellitus Experimental/patología , Diabetes Mellitus Tipo 1/patología , Fluoresceínas/farmacología , Incisivo/efectos de los fármacos , Incisivo/crecimiento & desarrollo , Masculino , Mandíbula , Diente Molar/efectos de los fármacos , Diente Molar/crecimiento & desarrollo , Distribución Aleatoria , Ratas , Ratas Wistar , Calcificación de Dientes/efectos de los fármacos , Calcificación de Dientes/fisiología , Corona del Diente , Raíz del Diente/anatomía & histología , Microtomografía por Rayos X
13.
Int Endod J ; 48(11): 1023-32, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25314030

RESUMEN

AIM: To investigate interfacial stress distribution in restored root filled teeth with various post lengths and crown heights. METHODOLOGY: Three-dimensional mathematical models of a root filled mandibular premolar tooth were constructed. Parts of the tooth structures were replaced with ceramic crowns having three crown heights incorporating, either a cast post and core or a resin post and cores with fibre post or metallic post with four post lengths. Finite element linear analysis was performed to calculate equivalent and shear stress distribution at the interfaces between the teeth and post and cores under mesiodistal symmetrical boundary conditions and an oblique static load of 400 N. RESULTS: For the resin post and core with fibre and metallic posts, shear stress at the interface was greater in the cervical area than the post area, depending on the crown height. The resin post and core with metallic post had lower shear stress at the interface of cervical area than that of the fibre post model; however, the metallic post models produced a high concentration of shear stress at the interface between the post and resin composite. On the other hand, for the cast post and core, the shear stress at the interface was mainly produced in the post end area, which increased with decrease of post length. CONCLUSIONS: For the resin post and core, bonding integrity to the cervical area would play a critical role in the survival of the restored tooth, whereas for the cast post and core, the bond of the post would be essential.


Asunto(s)
Materiales Dentales/química , Cavidad Pulpar/fisiopatología , Análisis del Estrés Dental , Técnica de Perno Muñón , Fracturas de los Dientes/fisiopatología , Diente Premolar , Resinas Compuestas/química , Fuerza Compresiva , Coronas , Análisis de Elementos Finitos , Humanos , Ensayo de Materiales , Preparación del Conducto Radicular/métodos , Estrés Mecánico , Propiedades de Superficie , Corona del Diente , Raíz del Diente/fisiopatología , Diente no Vital
14.
J Dent ; 43(2): 253-60, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25242100

RESUMEN

OBJECTIVES: The purpose of this study was to investigate the effect of tooth age on colour adjustment potential of resin composite restorations in human teeth. METHODS: Twenty extracted human premolars with an A2 shade, extracted for orthodontic reasons from younger patients (20-28yrs) (younger teeth) and periodontal reasons from older patients (45-69yrs) (older teeth), were used in this study. Cylindrical shaped cavities (3.0mm depth; 2.0mm diameter) were prepared in the centre of the crowns on the buccal surface. One of four resin composites of A2 shade (Kalore, KA; Solare, SO; Clearfil Majesty, MJ; Beautifil II, BF) was placed in the cavity, and the colour was measured at four areas (0.4mm×0.4mm) on the restored teeth (area 1; tooth area 1.0mm away from the border of resin composite restoration: area 2; tooth border area 0.3mm away from margin of resin composite restoration: area 3; resin composite border area 0.3mm away from margin of resin composite restoration: area 4; resin composite area at the centre of resin composite restoration) using a spectrophotometer (Crystaleye). The colour of each area was determined according to the CIELAB colour scale. Colour differences (ΔE*) between the areas of 1 and 2, 2 and 3, 3 and 4 and 1 and 4 were calculated, and also the ratio of ΔE*area2-3 to ΔE*area1-4 (ΔE*area2-3/1-4), ΔE*area3-4 to ΔE*area1-4 (ΔE*area3-4/1-4) and ΔE*area1-2 to ΔE*area1-4 (ΔE*area1-2/1-4) as a parameter of the colour shift in resin composite restoration, were determined. Moreover, the light transmission characteristics of the resin materials and dentine discs from the younger and older teeth were measured using a goniophotometer. The data were statistically analyzed using two-way ANOVA, and Dunnett's T3 and t-test for the post hoc test. RESULTS: ΔE*area2-3 (colour difference between resin composite and tooth at the border) and ΔE*area1-4 (colour difference between resin composite and tooth) of the older teeth groups were significantly larger than those of younger teeth groups (p<0.05). The ΔE*area2-3/1-4 (mis-match rate in colour shifting at the border) of the older teeth groups was larger than that of the younger teeth groups (p<0.05). ΔE*area3-4/1-4 (colour shifting rate of resin composite side) was significantly larger in older teeth than younger teeth (p<0.05), while ΔE*area1-2/1-4 (colour shifting rate of tooth side), was significantly smaller in older teeth than younger teeth (p<0.05). In each tooth group, there were no significant differences in ΔE*area2-3, ΔE*area1-4, ΔE*area2-3/1-4, ΔE*area3-4/1-4 and ΔE*area1-2/1-4 between the materials (p>0.05). Analysis of the light transmission properties indicated that older dentine transmitted more light, while younger dentine exhibited greater light diffusion and transmitted less light. CONCLUSIONS: The colour shifting effects at the border of the resin composite restorations were influenced by the age of the tooth. This behaviour might be influenced by the light transmission characteristics of dentine in restored teeth. CLINICAL SIGNIFICANCE: The potential for colour adjustment of resin composite restorations may be less in older teeth than younger teeth.


Asunto(s)
Resinas Acrílicas/farmacología , Envejecimiento/fisiología , Diente Premolar/fisiología , Resinas Compuestas/farmacología , Restauración Dental Permanente , Poliuretanos/farmacología , Adulto , Anciano , Diente Premolar/efectos de los fármacos , Color , Dentina/química , Humanos , Persona de Mediana Edad , Adulto Joven
15.
Oper Dent ; 40(1): E28-39, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25299704

RESUMEN

This study assessed dentin-resin interface integration in Class I cavities restored with simplified adhesives by using a focused ion-beam milling (FIB) and transmission electron microscope (TEM). Class I cavities (1.5-mm depth with dentin thickness of ∼0.5 mm, 4-mm length, and 2-mm width) were prepared on freshly extracted, sound human molars. Two all-in-one adhesive systems (Scotchbond/Single Bond Universal [SUD] and Xeno-V(+) [X5D]) were used and compared with a two-step etch-and-rinse system (Prime&Bond NT [NTD]). The adhesives were applied according to the manufacturers' guidelines. A universal resin composite (Filtek Z350 XT Universal) was used to restore the cavities in one bulk filling and was irradiated at 550 mW/cm(2) for 40 seconds by a quartz-tungsten-halogen light (Optilux 501). After exposure to liquid nitrogen coolant, the specimens were milled to nanoscale thickness by FIB to view and then assess the area of dentin-resin interface by TEM. Unlike the unfilled X5D, a noticeably smooth transition zone at the dentin-resin interface was shown for the SUD and NTD adhesives. The SUD demonstrated an uneven hybrid layer with clearly demineralized collagen bundles. Ultramorphologically, dispersed needlelike apatite crystals were detected within the partially demineralized dentin or the hybrid layer of both compositionally different all-in-one simplified adhesives. Conversely, these crystals were entirely absent from the hybrid layer of the etch-and-rinse NTD adhesive. In the X5D group, a bright band was noted beneath the hybrid layer. The methacryloxydecyl dihydrogen phosphate monomer containing ultramild self-etch adhesive (SUD) was still validated in terms of its capability in dentin adhesion.


Asunto(s)
Cementos Dentales/uso terapéutico , Dentina/ultraestructura , Resinas Sintéticas/uso terapéutico , Grabado Dental/métodos , Restauración Dental Permanente/métodos , Recubrimientos Dentinarios/uso terapéutico , Humanos , Microscopía Electrónica de Transmisión , Cementos de Resina/uso terapéutico
16.
J Dent Res ; 93(3): 288-93, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24378366

RESUMEN

Dendritic cell (DC) migration to regional lymph nodes (RLNs) is an essential step in adaptive immunity, and cell-surface antigens on migrating DCs greatly affect the quality and quantity of subsequent immune responses. Although MHC class II(+) DC-like cells exist in the dental pulp, the lineage and function of these cells remain unknown. Here, we identified migratory DCs from the dental pulp after cusp trimming and acid etching in KikGR mice, in which the photoconvertible fluorescent protein changed from green to red upon violet light exposure. Two major cell fractions from the dental pulp had migrated to the RLNs at 16 hrs after cusp treatment, which showed the following lineage markers in the main and second fractions: CD11c(high)CD11b(++)Ly6C(low) Ly6G(low) F4/80(+) and CD11c(med)CD11b(+++)Ly6C(++)Ly6G(+++)F4/80(-), respectively. These lineage markers indicate that the former cells were DCs that had migrated through afferent lymphoid vessels, and the latter were granulocytes recruited via blood circulation. Migratory dental pulp DCs were mature, expressing the highest levels of CD273 (B7-DC) and CD86 co-stimulators and MHC class II. Our results suggest that cariogenic-bacteria-exposed dental pulp DCs migrate to RLNs and there trigger adaptive immune responses.


Asunto(s)
Células Dendríticas/inmunología , Pulpa Dental/citología , Ganglios Linfáticos/inmunología , Grabado Ácido Dental/métodos , Inmunidad Adaptativa/inmunología , Animales , Antígenos de Diferenciación/análisis , Antígenos de Diferenciación Mielomonocítica/análisis , Antígenos Ly/análisis , Antígeno B7-2/análisis , Antígeno CD11b/análisis , Antígeno CD11c/análisis , Linaje de la Célula/inmunología , Movimiento Celular/inmunología , Femenino , Colorantes Fluorescentes , Técnicas de Sustitución del Gen , Antígenos de Histocompatibilidad Clase II/análisis , Glicoproteínas de Membrana/análisis , Ratones , Ratones Endogámicos BALB C , Proteína 2 Ligando de Muerte Celular Programada 1/análisis , Preparación del Diente/métodos
17.
Dent Mater ; 30(3): 314-20, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24433821

RESUMEN

Bioglass 45S5 is a silica-based bioactive glass capable of depositing a layer of hydroxyl carbonate apatite on the surface of the glass when immersed in body fluids. The present paper studies a new technique for treating early human dental enamel caries lesions by using a paste composed of 45S5 bioglass and phosphoric acid. Artificial caries lesions were induced in enamel flat surfaces by means of a decalcification solution. All specimens were exposed to a brushing-abrasion challenge to test the durability of any newly formed layer resulting from the application of 45S5 bioglass paste. The specimens treated with bioglass paste showed complete coverage with a layer of brushite crystals. The brushing-abrasion challenge did not statistically affect the percentage of enamel coverage with the crystalline layer formed by the application of bioglass (p<0.05). These crystals were converted to hydroxyapatite crystals when stored in artificial saliva for 14 days. The current technique suggests the possibility of restoring incipient enamel erosive lesion with an abrasion durable layer of hydroxyapatite crystals.


Asunto(s)
Cerámica/farmacología , Esmalte Dental/química , Desmineralización Dental/terapia , Fosfatos de Calcio/química , Materiales Biocompatibles Revestidos , Caries Dental/terapia , Durapatita/química , Vidrio , Humanos , Técnicas In Vitro , Ensayo de Materiales , Diente Molar , Saliva Artificial , Propiedades de Superficie , Factores de Tiempo , Difracción de Rayos X
18.
Int Endod J ; 47(7): 652-8, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24117849

RESUMEN

AIM: To evaluate the influence of reduced glutathione (GSH) application on 2-hydroxyethylmethacrylate (HEMA) cytotoxicity on rat pulpal cells and evaluate the effect of etched-dentine treatment with GSH on the immediate microtensile bond strength (µTBS) of etch-and-rinse adhesive. METHODOLOGY: The cytotoxicity of 10 mmol L(-1) HEMA, 10 mmol L(-1) HEMA + 1 mmol L(-1) GSH, 10 mmol L(-1) HEMA + 5 mmol L(-1) GSH and 10 mmol L(-1) HEMA + 10 mmol L(-1) GSH was compared (6 h and 24 h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, followed by morphological observation of cells. Etched-dentine surfaces were rinsed and treated with one of the following solutions: 2% GSH, 5% GSH or 10% GSH, bonded with Adper Single Bond Plus (3M, ESPE, St. Paul, MN, USA) and restored with resin composite. The control group received no GSH treatment. After 1 day of water-storage at 37 °C, the specimens were subjected to µTBS testing. Cytotoxicity and µTBS data were analysed by one-way anova and Tukey post hoc tests (P < 0.05). RESULTS: There were significant differences between the groups. HEMA elicited a remarkable toxic effect. 10 mmol L(-1) GSH prevented HEMA-induced damage at both exposure times. Whilst 5 mmol L(-1) GSH lost its protective effect at 24-h exposure time and 1 mmol L(-1) GSH showed no protective effect at both exposure times, GSH had no significant effect on the immediate µTBS; however, 5% GSH had higher bond strength value when compared to 10% GSH (P = 0.003). CONCLUSION: Controlled concentrations of GSH had a protective effect against HEMA cytotoxicity. GSH had neither positive nor negative influence on µTBS.


Asunto(s)
Pulpa Dental/citología , Dentina/química , Glutatión/farmacología , Metacrilatos/química , Cementos de Resina/química , Animales , Línea Celular , Humanos , Ratas
19.
Acta Biomater ; 9(12): 9522-8, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23928333

RESUMEN

The mineral phase of dentin is located primarily within collagen fibrils. During development, bone or dentin collagen fibrils are formed first and then water within the fibril is replaced with apatite crystallites. Mineralized collagen contains very little water. During dentin bonding, acid-etching of mineralized dentin solubilizes the mineral crystallites and replaces them with water. During the infiltration phase of dentin bonding, adhesive comonomers are supposed to replace all of the collagen water with adhesive monomers that are then polymerized into copolymers. The authors of a recently published review suggested that dental monomers were too large to enter and displace water from collagen fibrils. If that were true, the endogenous proteases bound to dentin collagen could be responsible for unimpeded collagen degradation that is responsible for the poor durability of resin-dentin bonds. The current work studied the size-exclusion characteristics of dentin collagen, using a gel-filtration-like column chromatography technique, using dentin powder instead of Sephadex. The elution volumes of test molecules, including adhesive monomers, revealed that adhesive monomers smaller than ∼1000 Da can freely diffuse into collagen water, while molecules of 10,000 Da begin to be excluded, and bovine serum albumin (66,000 Da) was fully excluded. These results validate the concept that dental monomers can permeate between collagen molecules during infiltration by etch-and-rinse adhesives in water-saturated matrices.


Asunto(s)
Cromatografía en Gel , Colágeno Tipo I/química , Colágeno Tipo I/metabolismo , Dentina/metabolismo , Matriz Extracelular/metabolismo , Animales , Calcificación Fisiológica , Bovinos , Polvos
20.
Int Endod J ; 46(11): 1023-31, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23521044

RESUMEN

AIM: To evaluate the efficacy of different solvent evaporation strategies on bonding of one-step self-etch adhesives to root canal dentine. METHODOLOGY: Two dual-cure resin core systems (Clearfil DC Bond/Clearfil DC Core Automix and Clearfil Tri-S Bond Plus/Clearfil DC Core Plus; Kuraray Noritake Dental, Tokyo, Japan) were equally applied in 24 post spaces from extracted human mandibular premolars. After the adhesive application, specimens were randomly assigned into four water/solvent evaporation strategies as follows (I) insertion of absorbent paper point for 10 s: P, (II) 10 s air-blowing: A, (III) as (II) followed by insertion of absorbent paper point: AP, (IV) as (III) followed by 10 s additional air-blowing: APA. Then, the adhesives were light cured, and resin core materials were placed into the post space, followed by light curing for 60 s. After water storage for 24 h, 0.6 × 0.6 mm-thick beams were prepared to measure the regional µTBS. The mode of failure was also observed. The µTBS values were statistically analysed using three-way anova and Duncan HSD test (α = 0.05). RESULTS: In the coronal region, there were no significant differences in µTBS between each evaporation strategy (P > 0.05), except P group. However, in the apical region, APA and AP groups significantly increased in µTBS compared with A and P groups (P < 0.05). Only in the APA group of Clearfil Tri-S Bond Plus/Clearfil DC Core Plus, was there no significant difference in µTBS between the coronal and apical regions (P > 0.05). CONCLUSION: The use of paper points with additional air-blowing for removing excessive adhesive and evaporating residual water/solvent would be effective in producing higher bond strength for the tested one-step self-etch adhesives and fewer blister formations in deeper regions of the post space.


Asunto(s)
Cementos Dentales , Cavidad Pulpar , Dentina , Solventes/química , Niño , Humanos , Microscopía Electrónica de Rastreo
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