ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00139.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Several methods are currently available to restore the partially edentulous patient with osseointegrated implants. The UCLA abutment eliminates the unesthetic, traditional transmucosal abutment and can provide esthetic crowns, fixed prostheses, and subgingival porcelain margins without the need for excessive instrumentation and components. A clinical report for the fabrication of a direct, implant‐borne fixed prosthesis using the UCLA abutment is presente

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00140.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeThe purpose of this study was to evaluate the in vitro bond strength of adhesive and traditional composites to several materials that might be encountered in clinical practice.Materials and MethodsAn adhesive composite, an adhesive composite with a bonding agent, and a traditional composite with a bonding agent were bonded to enamel, dentin, amalgam, porcelain, and nickel‐chromium‐beryllium (Ni‐Cr‐Be) alloy. Tensile bond strengths were determined after 24 hours storage at 23°C or thermocycling.ResultsThe use of an adhesive composite with a bonding agent resulted in increased bond strength to amalgam, porcelain, and dentin, but not to enamel or Ni‐Cr‐Be alloy at 23°C, when compared with the adhesive composite alone. The adhesive composite with a bonding agent had higher bond strengths to amalgam, porcelain, and dentin than did the traditional composite with bonding agent, but not to enamel or Ni‐Cr‐Be alloy at 23°C.ConclusionsThe use of a bonding agent with an adhesive composite produced higher bond strengths than the adhesive composite alone. The traditional composite bonded better to enamel and Ni‐Cr‐Be alloy than did the adhesive composite. Thermocycling generally had no effect on bond strengths or i

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00141.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposePolishing and glazing porcelain surfaces of restorations is thought to help reduce the wear on the opposing occlusion because of reduced roughness.Materials and MethodsTo test this theory, samples of a variety of dental porcelains were prepared and subjected to various polishing and self‐glazing treatments commonly used in dentistry and then viewed using scanning electron microscope (SEM). Fine cracks were discovered in the surface of the samples that had been polished and then self‐glazed. These cracks were typically greater than 50 μm in length with submicron surface openings and crack depths less than 20 μm. To establish the treatments responsible for the formation of these cracks, a more controlled study was performed. Samples of Vita VMK 68 no. 559 incisal porcelain (Vita Zahnfabrik, Bad Såchingen, Germany) were prepared and subjected to six treatments (sample size = 3): treatment no. 1, as‐fired condition; treatment no. 2, self‐glazed (32°C per minute to 960°C, then cooled); treatments no. 3 and 4, wet ground followed by 1 μm diamond polish (no. 4 was then self‐glazed); treatments no. 5 and 6, ground and polished using a Shofu porcelain adjustment kit (Shofu Inc, Kyoto, Japan) (no. 6 was then self‐glazed). The samples were observed using SEM.ResultsTreatments no. 1, 2, 3, and 5 showed no cracking; however, treatments no. 4 and 6 showed cracking in all specimens (approximate levels 5,100 μm/mm2and 3,600 μm/mm2, respectively).ConclusionsPolishing followed by self‐glazing produces fine surface cracks. The rougher surface resulting from the surface cracks and subsequent porcelain chipping may cause wear of oppos

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00142.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeTo study the viscosities of eight interocclusal registration materials at 30 seconds after the start of mixing and to compare the time (Tcv) required for various interocclusal registration materials to reach a proposed critical viscosity of 5,000 poise.Materials and MethodsOne zinc‐oxide eugenol, one polyether, and six vinyl‐polysiloxane interocclusal registration materials were studied. The viscosities of the polymerizing materials were monitored with a cone and plate viscometer.ResultsOne‐way analysis of variance showed significant difference in the viscosity at 30 seconds and in the Tcv among the materials. A zinc oxide eugenol interocclusal registration material was found to possess the lowest viscosity at 30 seconds and the longest Tcv.ConclusionsThe criteria for the selection of an interocclusal registration material should include its viscous properties because all materials behaved differ

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00143.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeFailed crowns and failure load data were studied to gain insights into the fracture behavior of prostheses under incisal‐directed, load‐to‐failure testing.Materials and MethodsIncisor crowns (n = 68) were fabricated: two all‐ceramic groups (feldspathic veneer on high‐strength core), differing in core design, and two metal‐ceramic groups, differing in metal oxidation time (30 seconds v 3 minutes). Crowns were loaded to failure on their incisal edge. Gross visual, microscopic, and elemental microprobe analyses of failed crowns were coupled with Weibull analysis of the failure load data.ResultsFailure loads were higher for the normal oxidation time (TN) than for the extended oxidation time (TE) metal‐ceramic crowns (P<.02), but both groups had indistinguishable Weibull moduli indicating the possibility of a common failure origin. Fracture behavior and Weibull results both implicated the oxide layer as being the origin of failure. The ratio of fracture loads (TE/TN) corresponded well with calculated oxide‐volume ratios. Failure loads were lower for the all‐ceramic than for the metal‐ceramic crowns (P<.001). Fifty percent of the all‐ceramic crowns failed by delamination of veneering glass alone, leaving a thin layer of residual glass on the core surface. Scanning electron microscope views showed that delamination occurred 10 to 50 μm away from the core‐veneer interface. Electron microprobe elemental analysis of the core‐veneer interface showed that residual core infiltration glass was not present on the core surface and that chemical alterations in the veneering glass were apparently limited to less than a 2‐ to 3‐μm thick layer.ConclusionsFailure for both restorative systems involved interfacial stresses with crack propagation occurring at or near the core‐veneer interface. The weaker interface in the metal‐ceramic system probably resulted from an increase in surface oxide volume, irrespective of any change in its adherence or physical properties. For the ceramic crowns, delamination crack fronts appeared to propagate through chemically unaltered veneering porcelain. Both the Weibull moduli and characteristic strengths were indistinguishable between either of the two ceramic core designs or between groups failing from delamination with or without core cracking/failure. This is consistent with delamination being the primary fracture process during failure. Clinical implications should not be drawn from results of this study because no correlation is known to have ever been established between clinical behavior

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00144.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeThis study measured the accuracy of two impression techniques recommended by Noblepharma to be used with their CeraOne single tooth implant restoration. The first technique was to lute the impression transfer coping to the impression tray with autopolymerizing acrylic resin. The second was to leave the transfer coping free‐standing in the impression material.Materials and MethodsThirty‐five samples were made of a polyvinyl impression of the CeraOne transfer coping free‐standing in the set impression material. Thirty‐five samples were made of a polyvinyl impression of the CeraOne transfer coping luted to the impression tray with autopolymerizing acrylic resin. A jig was fabricated and used to record the spatial relations of the impressions and the transfer copings in reference to the jig. A light microscope was used to measure the distance between fixed markings on pressure sensitive paper, representing impression variations.ResultsThe mean discrepancy in the horizontal plane for nonluted impressions was 0.094 mm, and for luted impressions, it was 0.275 mm. The mean discrepancy in the vertical plane for nonluted impressions was 0.154 mm, and for luted impressions, it was 0.192 mm. The differences found between the group with the luted impression tray and the group with the nonluted impression tray were found to be statistically significant.ConclusionsThe more accurate of the two techniques is to transfer the impression coping without luting it to the impressi

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00145.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeThis study investigates the effect of selected properties of a restorative material (type, shade, and thickness) on the cure of a photoactivated resin cement.Materials and MethodsDisks of ceramic and resin‐based restorative materials of two extreme shades were made to provide thicknesses of 0.5 to 3.0 mm in 0.5‐mm intervals. Light transmission was measured through various thicknesses and shades of each restorative material type. The effect of light transmission, as influenced by restorative material type, shade, and thickness on resin cement cure was also determined.ResultsThickness and shade of restorative material had the greatest influence on light transmission. For simulated restoration thicknesses 1.5 mm and greater, Dicor (Dentsply International Inc, York, PA) had greater transmission of light than the other materials, regardless of shade. At equal restorative material thicknesses, light transmission was similar for identical shades of the other three materials. Restoration shade and thickness also had the greatest influence on resin cement cure. Material type, although significant, had only a minor influence. At thicknesses of 1 to 2 mm, Dicor consistently yielded greater resin cement cure values than any other material tested.ConclusionsWhen considering the ability of restorative materials to transmit light for curing of photo‐activated resin cements, the thickness of the restoration and its shade are much more influential than the choice of restorative material. Dicor provides greater light transmission that results in the ability to photobond restorations of greater thicknesses than the other materials. For restorations greater than 1 mm in thickness, a dual cure or chemical cure resin cement should be used to provide maximal cement prope

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00146.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

This is a brief overview of the progress of design philosophies of removable partial dentures. It begins in 1711 with the first published description of a removable partial denture prosthesis and continues, with discussion of the most significant discoveries, through 1990.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00147.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

This article reports the data of a survey of private prosthodontic practitioners. It reports incomes, overhead expenses, staff size, and character of prosthodontic practices. The study also develops a profile for a median prosthodontic practice and practitioner.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00148.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY