RESUMEN
Fetal bovine mandible-derived osteoblasts were cultured for the purpose of obtaining a spatiotemporal assessment of bone matrix protein expression during in vitro differentiation. The results obtained from electron microscopic, immunohistological, biochemical, and molecular biological analyses indicated that these primary cultured osteoblasts produce an abundant extracellular matrix which mineralizes during a 14-day culture period. During this process, a restricted, spatiotemporal pattern of bone sialoprotein expression was indicated by immunohistological and molecular evaluations. To test the possibility that bone sialoprotein promoted the continued morphodifferentiation of osteoblastic cells, cultures were grown in the presence of anti-bone sialoprotein antibodies known to interfere with cell-bone sialoprotein attachment. Compared with cultures grown in the presence of normal rabbit serum (1:150), cultures grown in the media containing anti-bone sialoprotein antibody (1:150) failed to mineralize as demonstrated by von Kossa staining and failed to express osteocalcin and osteopontin as shown by the reverse transcription polymerase chain reaction. These results contribute to the growing evidence that bone sialoprotein is an important determinant of osteoblast differentiation and bone formation. Matrix protein-cell interactions may be examined using this spatiotemporally defined model.
Asunto(s)
Calcificación Fisiológica/genética , Diferenciación Celular , Osteoblastos/citología , Sialoglicoproteínas/fisiología , Animales , Anticuerpos/farmacología , Secuencia de Bases , Bovinos , Adhesión Celular/efectos de los fármacos , Adhesión Celular/genética , División Celular/efectos de los fármacos , División Celular/genética , Células Cultivadas , Medios de Cultivo , ADN Complementario/genética , Regulación del Desarrollo de la Expresión Génica , Inmunohistoquímica , Sialoproteína de Unión a Integrina , Mandíbula/embriología , Datos de Secuencia Molecular , Osteoblastos/ultraestructura , Osteocalcina/biosíntesis , Osteocalcina/genética , Osteopontina , Fenotipo , Sialoglicoproteínas/biosíntesis , Sialoglicoproteínas/inmunologíaRESUMEN
Two-dimensional finite-element analysis was used to study levels and distribution patterns of stress within three-unit fixed partial dentures (mandibular first premolar to first molar) constructed of different materials (Type III gold alloy, Dicor, and In-Ceram) and with different connector heights (3.0 mm versus 4.0 mm). In the computer models, 10 MPa of stress was applied centrally to the prosthesis. Resultant von Mises stresses were concentrated within the connectors; the greatest stress occurred at the axial location of the connector. Stresses were 40% to 50% lower for 4.0-mm connectors. Patterns of stress distribution were similar for premolar and molar connectors. Stress levels within In-Ceram models were lower than for the other two materials and represented a lower percentage of the ultimate strength of the material. Based on a two-dimensional finite-element analysis model, In-Ceram would appear to be the best choice for posterior fixed partial dentures.
Asunto(s)
Porcelana Dental , Análisis del Estrés Dental , Diseño de Dentadura , Dentadura Parcial Fija , Óxido de Aluminio , Diente Premolar , Fuerza de la Mordida , Simulación por Computador , Análisis del Estrés Dental/métodos , Aleaciones de Oro , Mandíbula , Ensayo de Materiales/métodos , Modelos TeóricosRESUMEN
This clinical trial assessed the ability of Gluma Dentin Bond to inhibit dentinal sensitivity in teeth prepared to receive complete cast restorations. Twenty patients provided 76 teeth for the study. Following tooth preparation, dentinal surfaces were coated with either sterile water (control) or two 30-second applications of Gluma Dentin Bond (test) on either intact or removed smear layers. Patients were recalled after 14 days for a test of sensitivity of the prepared dentin to compressed air, osmotic stimulus (saturated CaCl2 solution), and tactile stimulation via a scratch test under controlled loads. A significantly lower number of teeth responded to the test stimuli for both Gluma groups when compared to the controls (P less than .01). No difference was noted between teeth with smear layers intact or removed prior to treatment with Gluma.
Asunto(s)
Recubrimiento de la Cavidad Dental , Sensibilidad de la Dentina/prevención & control , Glutaral/uso terapéutico , Ácidos Polimetacrílicos/uso terapéutico , Distribución de Chi-Cuadrado , Coronas , Dentadura Parcial Fija , Humanos , Estimulación Física , Capa de Barro DentinarioRESUMEN
Air abrasion of castings for metal ceramic crowns is a routine procedure in ceramics laboratories for cleaning, seating, and preparing casts for porcelain application. This technique can result in damage to the margins of castings. This investigation evaluated the extent and significance of this procedure. Marginal abrasion ranged from 5 to 110 microns. ANOVA, followed by Tukey's post hoc evaluation revealed no difference between abrasives, but significant differences were noted among alloys and margin configurations (p less than 0.05). Marginal loss by alloy was as follows: [Jelenko O] greater than [Olympia = Cameo] greater than [Jelstar] greater than [Genesis II]. Marginal loss by marginal configuration was as follows: [beveled shoulder] greater than [chamfer = shoulder]. Significant marginal damage can occur during air abrasion of dental castings.