RESUMEN
OBJECTIVE: The improvement of the optical properties of new generation dental ceramics enables more esthetic and durable restorations. This study aimed to investigate the color changes, caused by exposure to different beverages on composite, hybrid ceramic, and zirconia-reinforced lithium silicate (ZLS) CAD/CAM blocks. MATERIALS AND METHODS: CAD/CAM blocks 40 samples (1.5 × 7 × 12 mm) were obtained from each material under water cooling. Following the polishing process and the initial color measurement, the prepared samples were exposed to red wine, coffee, cola, energy drink, and distilled water. Color changes were measured by spectrophotometer at the end of the 1st, 7th, and 30th days. To analyze the color change results, one-way analysis of variance (ANOVA) test was performed. RESULTS: In all restorative material groups, the most prominent color changes were observed on the red wine-exposed samples, then the coffee-exposed ones. No significant discoloration was observed on the samples exposed to cola and energy drink, compared to the control group (P > .05). Among the samples exposed to red wine and coffee, the highest discoloration values were observed in composite CAD/CAM material. CONCLUSIONS: At the end of the 30th day, all materials exposed to wine and coffee showed color change above the clinically acceptable value (ΔE00 :2.25). CLINICAL SIGNIFICANCE: Hybrid ceramic and ZLS CAD/CAM blocks recently used more often by clinicians have shown similar color changes. The results of our study indicate the necessity of choosing esthetic materials according to the dietary habits of individuals.
Asunto(s)
Cerámica , Diseño Asistido por Computadora , Color , Resinas Compuestas , Materiales Dentales , Porcelana Dental , Humanos , Ensayo de Materiales , Propiedades de SuperficieRESUMEN
STATEMENT OF PROBLEM: Surface treatment methods used for resin bonding to conventional silica-based dental ceramics are not reliable for zirconium-oxide ceramics. PURPOSE: The aim of this study was to compare the effects of airborne-particle abrasion, silanization, tribochemical silica coating, and a combination of bonding/silane coupling agent surface treatment methods on the bond strength of zirconium-oxide ceramic to a resin luting agent. MATERIAL AND METHODS: Sixty square-shaped (5 x 5 x 1.5 mm) zirconium-oxide ceramic (Cercon) specimens and composite resin (Z-250) cylinders (3 x 3 mm) were prepared. The ceramic surfaces were airborne-particle abraded with 125-microm aluminum-oxide (Al(2)O(3)) particles and then divided into 6 groups (n = 10) that were subsequently treated as follows: Group C, no treatment (control); Group SIL, silanized with a silane coupling agent (Clearfil Porcelain Bond Activator); Group BSIL, application of the adhesive 10-methacryloyloxydecyl dihydrogen phosphate monomer (MDP)-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/ Porcelain Bond Activator); Group SC, silica coating using 30-microm Al(2)O(3) particles modified by silica (CoJet System); Group SCSIL, silica coating and silanization (CoJet System); and Group SCBSIL, silica coating and application of an MDP-containing bonding/silane coupling agent mixture (Clearfil Liner Bond 2V/Porcelain Bond Activator). The composite resin cylinders were bonded to the treated ceramic surfaces using an adhesive phosphate monomer-containing resin luting agent (Panavia F). After the specimens were stored in distilled water at 37 degrees C for 24 hours, their shear bonding strength was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. Debonded specimen surfaces were examined with a stereomicroscope to assess the mode of failure, and the treated surfaces were observed by scanning electron microscopy. Bond strength data were analyzed using 1-way analysis of variance and the Duncan test (alpha = .05). RESULTS: The bond strengths (mean +/- SD; MPa) in the groups were as follows: Group C, 15.7 +/- 2.9; Group SIL, 16.5 +/- 3.4; Group BSIL, 18.8 +/- 2.8; Group SC, 21.6 +/- 3.6; Group SCSIL, 21.9 +/- 3.9; and Group SCBSIL, 22.9 +/- 3.1. The bond strength was significantly higher in Group SCBSIL than in Groups C, SIL, and BSIL (P<.001), but did not differ significantly from those in Groups SC and SCSIL. Failure modes were primarily adhesive at the interface between zirconium and the resin luting agent in Groups C and SIL, and primarily mixed and cohesive in Groups SC, SCSIL, and SCBSIL. CONCLUSION: Tribochemical silica coating (CoJet System) and the application of an MDP-containing bonding/silane coupling agent mixture increased the shear bond strength between zirconium-oxide ceramic and resin luting agent (Panavia F).
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Cerámica/química , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Cementos de Resina/química , Circonio/química , Abrasión Dental por Aire/métodos , Óxido de Aluminio/química , Resinas Compuestas/química , Humanos , Ensayo de Materiales , Metacrilatos/química , Microscopía Electrónica de Rastreo , Resistencia al Corte , Silanos/química , Dióxido de Silicio/química , Estrés Mecánico , Propiedades de Superficie , Temperatura , Factores de Tiempo , Agua/químicaRESUMEN
STATEMENT OF PROBLEM: Available information on the dimensions of the enamel and pulp tissues of tooth structure, as well as their correlation with chronologic age, is limited. However, this information is a significant determinate in planning the tooth reduction for a porcelain laminate veneer (PLV) restoration. PURPOSE: This study examined variations in tooth enamel thickness and its correlation with chronologic age as it relates to available tooth substrate for PLV restorations. MATERIAL AND METHODS: Forty human maxillary central incisors extracted from patients within the age range of 30 to 69 years were used to evaluate the thickness of tooth layers. Measurements were made for the following tooth areas using scanning electron microscopy (SEM): facial enamel thickness at 1, 3, and 5 mm above the cemento-enamel junction (CEJ), palatal enamel thickness at 5 mm above the CEJ, facial and palatal enamel thickness at the incisal edge, maximum facial-palatal (MFP) width at incisal edge, physiologic secondary dentin (PSD) height, facial-cervical enamel-pulp (FCEP) distance, and the incisal edge enamel-pulp (IEP) distance. The relationship between thickness and age was evaluated with a regression analysis (alpha=.05). RESULTS: Significant differences (P<.001) were observed in all of the relationships between tooth thicknesses and chronological age. Outcome variables of enamel thickness related to age showed a steady decrease, beginning at approximately age 50. Mean values of facial enamel thickness at 1, 3, and 5 mm above the CEJ were 0.31 +/- 0.01, 0.54 +/- 0.01, and 0.75 +/- 0.02 mm, respectively, for the age range of 30 to 69 years. The thickness of maximum incisal width (R(2) = 0.95), PSD height (R(2) = 0.76), and IEP distance (R(2) = 0.99) indicated that all are subject to an increase in relation to age. CONCLUSION: Facial enamel thickness above the CEJ decreases, while MFP increases in relation to age. The PSD height and IEP distance also increased with age.
Asunto(s)
Envejecimiento/patología , Esmalte Dental/ultraestructura , Porcelana Dental , Coronas con Frente Estético , Adulto , Anciano , Pulpa Dental/ultraestructura , Dentina Secundaria/ultraestructura , Humanos , Incisivo , Microscopía Electrónica de Rastreo , Persona de Mediana Edad , Odontometría , Cuello del Diente/ultraestructura , Corona del Diente/ultraestructuraRESUMEN
STATEMENT OF PROBLEM: Inlay-retained resin-bonded fixed partial dentures (RBFPDs) are conservative prosthetic restorations; however, their resistance to fracture is not clear. PURPOSE: The purpose of this study was to compare fracture loads of posterior complete coverage metal-ceramic restorations with all-ceramic inlay-retained RBFPDs. MATERIAL AND METHODS: Thirty-two posterior ceramic RBFPD restorations were divided into 4 groups (n=8): (1) Complete metal-ceramic fixed partial dentures (MC-FPDs) fabricated of Ni-Cr-based alloy (Wirolloy) and veneered with a ceramic (IPS d.SIGN) as the control group; (2) inlay-retained metal-ceramic (MC RBFPDs) with the same materials as the control; (3) inlay-retained lithium disilicate (LD) glass-ceramic (IPS Empress 2) RBFPDs; and (4) inlay-retained zirconia-based (Z) ceramic (Cercon) RBFPDs. Control specimens were prepared to receive conventional complete MC-FPDs designed to include a 1.3-mm-circumferential, 90-degree flat shoulder with rounded angles. Inlay-retained RBFPD specimens were prepared with 2-mm occlusal reduction but without bevels at the occlusal or gingival margins. Specimens were loaded and fracture loads (N) measured at fracture with a universal testing machine at a crosshead speed of 1.0 mm/min and 250 kgf load cell. Data were analyzed with 1-way ANOVA and Duncan test (alpha=.001). RESULTS: Fracture loads (mean +/- SD) were greatest for control specimens (1318.43 +/- 211.00 N) and Z-RBFPD (1247.70 +/- 262.51 N) specimens as compared to MC-RBFPD or LD-RBFPD (P < .001). MC-RBFPD exhibited the next highest fracture loads (958.01 +/- 194.29 N), and LD-RBFPD exhibited the significantly lowest values (303.23 +/- 92.54 N) of the materials tested (P < .001). CONCLUSION: Inlay-retained zirconia-based ceramic RBFPDs demonstrated the greatest fracture resistance among all inlay-retained restorations tested.