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1.
J Endod ; 36(7): 1222-5, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20630303

RESUMEN

INTRODUCTION: The purpose of this study was to evaluate the direct pulp capping response to a novel resin-based calcium phosphate cement (RCPC). METHODS: The RCPC was placed in contact with the exposed healthy pulps of dog teeth and in a follow-up study on the healthy or inflamed pulps of ferret teeth. The inflamed ferret teeth had reversible pulpitis induced with Salmonella typhimurium lipopolysaccharides. After direct pulp capping with RCPC or visible light-curing resin-modified calcium hydroxide material (VLCCH) as a control, the restorations were bonded using a composite resin. The pulp responses and dentin repair were evaluated histologically in dog teeth after 7, 28, or 90 days and in ferret teeth after 45 days. RESULTS: Most of the RCPC-treated healthy pulps and 75% of the RCPC-treated inflamed ferret teeth had dentin healing and repair, whereas those teeth treated with VLCCH had minimal healing and dentin repair. CONCLUSIONS: The direct pulp capping of ferret and dog teeth with RCPC was associated with superior healing in comparison to VLCCH.


Asunto(s)
Fosfatos de Calcio/uso terapéutico , Recubrimiento de la Pulpa Dental , Pulpa Dental/efectos de los fármacos , Cementos de Resina/uso terapéutico , Animales , Benzoatos/uso terapéutico , Hidróxido de Calcio/uso terapéutico , Resinas Compuestas/química , Materiales Dentales/química , Exposición de la Pulpa Dental/terapia , Restauración Dental Permanente/métodos , Dentina Secundaria/efectos de los fármacos , Perros , Evaluación Preclínica de Medicamentos , Hurones , Fluoruros/uso terapéutico , Lipopolisacáridos/efectos adversos , Masculino , Metacrilatos/química , Metacrilatos/uso terapéutico , Pulpitis/tratamiento farmacológico , Distribución Aleatoria , Salmonella typhimurium , Ácido Silícico/uso terapéutico , Factores de Tiempo
2.
Dent Mater ; 26(7): 675-81, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20362326

RESUMEN

OBJECTIVES: To establish the relationship of resin composition and resin hydrophilicity (indicated by solubility parameters and logP) to water sorption (WS), solubility, and degree of double bond conversion (DC) of resin mixtures designed for adhesive restoratives by varying the concentration of pyromellitic glycerol dimethacrylate (PMGDM) and various co-monomers. METHODS: Sixteen resin mixtures were prepared with (30-70) mass fraction % PMGDM. At given PMGDM concentrations there were up to five compositions with increasing logP. Polymer disks (13 mm x 0.7 mm) were exposed to 96% relative humidity (RH) to determine water sorption in humid atmosphere (WSH) and subsequently immersed in water for immersion water sorption (WSI) and solubility. DC was assessed by near infrared spectroscopy. RESULTS: WSI was somewhat higher than WSH, which ranged from (2.1 to 5.3) mass fraction %. Both data were positively correlated to PMGDM concentrations [Pearson correlation, p<0.02; R(2)=0.74, 0.73 (WSI)] and solubility (R(2)=0.64), but not to logP. When grouped by structural similarities, i.e., base resins with bisphenol A core (Group B), Group O containing diluent monomers, or Group U containing urethane dimethacrylate, WS within each group was inversely correlated to logP with R(2)=0.98, 0.81, 0.95, and WS/solubility correlation improved with R(2)=0.88, 0.92 and 0.75, respectively. Solubility ranging from 0.3% to 2.3% was inversely related to DC (r=-0.872). Conversion ranging from 41% to 81% was lower for resins with high base monomer concentrations and highest in mixtures with UDMA. SIGNIFICANCE: LogP was a good predictor of WS after grouping the resins according to functional, compositional and structural similarities. WS and conversion were reasonably well predicted from Hoy's solubility parameters and other physical resin properties.


Asunto(s)
Resinas Compuestas/química , Absorción , Benzoatos , Bisfenol A Glicidil Metacrilato , Interacciones Hidrofóbicas e Hidrofílicas , Ensayo de Materiales , Metacrilatos , Solubilidad , Agua , Humectabilidad
3.
Dent Mater ; 24(9): 1273-80, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18359510

RESUMEN

OBJECTIVES: To test whether fluoride in a resin-based Ca-PO4 ion releasing cement or coating with an acidic bonding agent for improved adhesion compromised the cement remineralization potential. METHODS: Cements were formulated without fluoride (Cement A) or with fluoride (Cement B). The treatment groups were A=Cement A; A2=Cement A+bonding agent; B=Cement B; B2=Cement B+bonding agent. The calcium, phosphate, and fluoride ion release in saliva-like solution (SLS) was determined from hardened cement disks without or with a coating of bonding agent. For the remineralization, two cavities were prepared in dentin of extracted human molars and demineralized. One cavity received composite resin (control); the other received treatment A, A2, B or B2. After 6 week incubation in SLS, 180 microm cross-sections were cut. The percentage remineralization was determined by transverse microradiography comparing the dentin mineral density under the cement to that under the control. RESULTS: The percentage of remineralization (mean+/-S.D.) was A (39+/-14)=B (37+/-18), A2 (23+/-13), B2 (14+/-7). Two-way analysis of variance (ANOVA) and Holm-Sidak test showed a significant effect from the presence of bonding agent (p<0.05), but not from fluoride (p>0.05). The ion solution concentrations of all groups showed undersaturation with respect to dicalcium phosphate dihydrate and calcium fluoride and supersaturation for fluorapatite and hydroxyapatite suggesting a positive remineralization potential. SIGNIFICANCE: Compared to the control all treatments resulted in mineral increase. The remineralization was negatively affected by the presence of the bonding agent.


Asunto(s)
Fosfatos de Calcio/química , Cariostáticos/química , Cementos Dentales/química , Recubrimientos Dentinarios/química , Fluoruros/química , Remineralización Dental , Apatitas/química , Benzoatos/química , Calcio/química , Fluoruro de Calcio/química , Dentina/patología , Durapatita/química , Humanos , Ensayo de Materiales , Metacrilatos/química , Microrradiografía , Fosfatos/química , Ácidos Polimetacrílicos/química , Saliva Artificial/química , Desmineralización Dental/patología , Desmineralización Dental/terapia
4.
Biomaterials ; 29(12): 1901-11, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18242689

RESUMEN

We have developed a combinatorial method for determining optimum tissue scaffold composition for several X-ray imaging techniques. X-ray radiography and X-ray microcomputed tomography enable non-invasive imaging of implants in vivo and in vitro. However, highly porous polymeric scaffolds do not always possess sufficient X-ray contrast and are therefore difficult to image with X-ray-based techniques. Incorporation of high radiocontrast atoms, such as iodine, into the polymer structure improves X-ray radiopacity but also affects physicochemical properties and material performance. Thus, we have developed a combinatorial library approach to efficiently determine the minimum amount of contrast agent necessary for X-ray-based imaging. The combinatorial approach is demonstrated in a polymer blend scaffold system where X-ray imaging of poly(desaminotyrosyl-tyrosine ethyl ester carbonate) (pDTEc) scaffolds is improved through a controlled composition variation with an iodinated-pDTEc analog (pI(2)DTEc). The results show that pDTEc scaffolds must include at least 9%, 16%, 38% or 46% pI(2)DTEc (by mass) to enable effective imaging by microradiography, dental radiography, dental radiography through 0.75cm of muscle tissue or microcomputed tomography, respectively. Only two scaffold libraries were required to determine these minimum pI(2)DTEc percentages required for X-ray imaging, which demonstrates the efficiency of this new combinatorial approach for optimizing scaffold formulations.


Asunto(s)
Absorciometría de Fotón/métodos , Materiales Biocompatibles/química , Técnicas de Cultivo de Célula/métodos , Técnicas Químicas Combinatorias/métodos , Ensayo de Materiales/métodos , Ingeniería de Tejidos/métodos , Técnicas de Cultivo de Célula/instrumentación , Ingeniería de Tejidos/instrumentación
5.
Dent Mater ; 21(6): 520-9, 2005 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15904694

RESUMEN

OBJECTIVES: The aim of this study was to explore novel polymeric dental restorative composites, in which polyhedral oligomeric silsesquioxane methacrylate monomer (POSS-MA) was used to partially (or completely) replace the commonly used base monomer 2,2'-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA). METHODS: The composites were cured (hardened) by photo-initiated free radical polymerization. Mechanical properties (i.e. flexural strength, Young's modulus and diametral tensile strength) of the composites were tested by a universal mechanical testing machine; photopolymerization induced volumetric shrinkage was measured using a mercury dilatometer; and near infrared (NIR) technique was used to study the degree of methacrylate double bond conversion and photopolymerization rate. RESULTS: Small percentage POSS-MA substitution of Bis-GMA (i.e. mass fraction of 10% or less) in the resin system improved the mechanical properties of the composites; while large amount substitution led to less desirable mechanical properties, lower methacrylate double bond conversion, and slower photopolymerization rate. Statistical examinations showed the maximum flexural strength of the composites occurred when 10% (mass fraction) of Bis-GMA was replaced by POSS-MA, while the highest modulus occurred when the mass fraction of POSS-MA was 2%. SIGNIFICANCE: Polymeric dental restorative composites with improved mechanical properties may be designed by judicious choice of monomer (POSS-MA, Bis-GMA and TEGDMA) compositions.


Asunto(s)
Resinas Compuestas/química , Metacrilatos/química , Compuestos de Organosilicio/química , Bisfenol A Glicidil Metacrilato/química , Adaptación Marginal Dental , Restauración Dental Permanente/métodos , Análisis del Estrés Dental , Elasticidad , Ensayo de Materiales , Estructura Molecular , Transición de Fase , Docilidad , Espectroscopía Infrarroja Corta , Resistencia a la Tracción , Difracción de Rayos X
6.
Eur J Oral Sci ; 112(5): 452-7, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15458506

RESUMEN

An experimental resin-based bioactive calcium phosphate cement, intended as a pulp capping and basing material, was evaluated for dentin shear bond strength and microleakage. The interfacial morphology was examined by scanning electron microscopy (SEM). For microleakage, dentin cavities without (Group A) or after (Group B) acid etching were restored with the calcium phosphate cement. A resin-based calcium hydroxide (VLC Dycal; Group C) was used as control material according to the manufacturer's instructions. After water storage and thermocycling, the microleakage was scored using a AgNO(3) staining procedure. For the shear bond strength, flat exposed dentin surfaces were treated as for the microleakage test. Metal irises pressed against the dentin surface were filled with the cements, which were photocured. Both tests were carried out after 1 wk. While acid etching did not result in significantly greater microleakage, it led to higher shear bond strength, and allowed, as shown by SEM, the formation of a hybrid layer and resin tags. Both groups treated with the calcium phosphate cement had significantly lower microleakage scores and higher mean shear bond strength values than the groups treated with the control material.


Asunto(s)
Fosfatos de Calcio/química , Recubrimiento Dental Adhesivo , Recubrimiento de la Cavidad Dental , Filtración Dental/clasificación , Recubrimiento de la Pulpa Dental , Dentina/ultraestructura , Cementos de Resina/química , Grabado Ácido Dental , Benzoatos/química , Hidróxido de Calcio/química , Humanos , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Minerales/química , Resistencia al Corte , Tinción con Nitrato de Plata , Propiedades de Superficie
7.
Dent Mater ; 19(6): 558-66, 2003 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-12837405

RESUMEN

OBJECTIVE: This study examined strength and bioactive (remineralizing) properties of a powder/liquid formulation (Cement I) and a more practical two-paste formulation (Cement II) of a fluoride-releasing resin-based Ca-PO(4) cement. METHODS: For the remineralization potential, the dissolution of calcium, total ionic phosphate and fluoride from set cement specimens were determined in buffered saline and saliva-like solution (SLS). Artificial caries lesions were produced on coronal dentin of extracted human molars. On each tooth, two defined areas were coated, one with a composite resin (calcium-free control), the other with either Cement I or II. After incubation in SLS, the mineral loss under the cement was analyzed by digitized microradiography and compared to that under the control. RESULTS: The diametral tensile strength of Cement II of approximately 30 MPa after 24 h and 23 MPa after 4 weeks was 2 to 3 times higher than that of Cement I (ANOVA, t-test, p<0.05). Calculations of the ion-activity products and Gibb's free energy from solution ion concentrations indicated a significant potential for the formation of fluor- and/or hydroxyapatite. Concurrently, both cements caused increases of 47% (Cement I) and 38% (Cement II) in the lesion mineral content over that underneath the corresponding controls. SIGNIFICANCE: These in vitro results suggest that the stronger Cement II could serve as a restoration-supporting lining material and could remineralize dentin in areas where complete removal of carious tissue is contra-indicated.


Asunto(s)
Fosfatos de Calcio/farmacocinética , Recubrimiento de la Cavidad Dental , Cementos de Resina/química , Remineralización Dental , Apatitas/farmacocinética , Fosfatos de Calcio/química , Dentina/metabolismo , Durapatita/farmacocinética , Fluoruros/farmacocinética , Humanos , Ensayo de Materiales , Diente Molar , Resistencia a la Tracción
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