ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00127.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Anterior, partially edentulous residual ridges often have hard‐tissue and soft‐tissue defects that create esthetic and functional problems when conventional fixed prostheses are used to replace the missing teeth. However, tissue‐tinted porcelain can be used in conjunction with fixed prostheses to solve many of these problems. Proper prosthesis design and shade matching are important considerations in the fabrication of fixed prostheses that incorporate tissue‐tinted porcelain to restore hard‐tissue and soft‐tis

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00128.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Maxillary ridge augmentation and vestibuloplasty are often adjuncts to mandibular implant reconstructions. Careful management of the augmented ridge after surgery is critical to the success of the maxillary prosthesis and osseointegration of the mandibular implant. A technique is described for alteration of an existing maxillary complete denture after ridge augmentation. Precautions regarding prosthesis function during the osseointegration phase of different types of mandibular reconstructions are noted. Technique and rationale for denture flange modification when a prosthesis is rebased for a patient who received simultaneous vestibuloplasty and ridge augmentation are described.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00129.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The success of a bar superstructure for an orbital prosthesis may be compromised by the placement and angulation of implants. The following technique describes a modification to a bar superstructure that provided the advantages of convenience, security, and consistent positioning even though one implant was lost and the angulation of implants limited accuracy.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00130.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeInstructions for patient positioning during panoramic radiography usually describe positioning dentate patients, and errors in patient positioning are commonly identified by distortion of the dentition. The purposes of this study were to identify common errors in panoramic radiography of edentulous patients, describe the image distortions that can be expected with positioning errors in edentulous patients, and review quality assurance methods that improve the diagnostic value of panoramic films.Materials and MethodsPanoramic films were randomly selected from the inactive files of 75 edentulous patients seen at the dental school for complete denture construction. The radiographs were numbered and reviewed by a board‐certified oral and maxillofacial radiologist trained to identify errors in panoramic radiography.ResultsOf the 75 panoramic radiographs examined, only 6 films (8.0%) were free of errors, and 67 films (89.3%) had one or more errors in patient positioning and 33 films (44.0%) had one or more technical errors. The most common positioning errors in were positioning the chin too high (32 films, 41.3%) and positioning the patient too far forward (26 films, 34.7%).ConclusionsWithout modification, manufacturer's instructions for positioning dentate patients during panoramic radiography may result in positioning errors on the panoramic radiographs of edentulous patients. Proper training and appropriate attention to detail while exposing and developing panoramic films are required to ensure maximum diagnostic benefits for edentulous patient

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00131.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeAlthough traditional ideal convergence (the sum of taper of the opposite sides) for crown proparation has been arbitrarily set at 4° to 10°, some believe absolute parallelism yields the highest retention. This study examined the relationship between the degree of convergence of a machined metal die and the retention of its casting.Materials and MethodsThe method used was that of cementing cast metal crowns onto full crown preparations on brass dies with varying convergence angles, and then recording the force required to remove the crowns from the dies in a vertical direction using a Tate‐Emery Testing Machine and Load Indicator.ResultsIt was found that retention (ie, the force needed to remove the cemented castings from the die in their common long axis) increases from O° convergence to peak between 6° to 12° convergence. It also seems that a critical film thickness does exist for optimum retention, and that film thicknesses smaller than the critical thickness may be responsible for the phenomenon that we have observed and directly related to the convergence angle itself.ConclusionsThere seems to be experimental data supporting the use of traditionally taught convergence. Our study found that convergence angles between 6° and 12° seem to be optimum for tooth crown preparation when one plans to use zinc phosphate cement. Convergence angles of less than 6° may not be desirable even if they can be clinically achieved. The results of our study indicate that a relationship exists between the convergence angle and the critical cement thickness that is necessary to realize the maximum strength properties of zinc phospha

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00132.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeSeveral authors have reported a preference for the use of high palladium alloys in the construction of implant‐fixed partial denture (IFPD) substructures. Heat‐polymerized polymethyl methacrylate resins (PMMR) are used to secure denture teeth to IFPD substructures. Metadent (Sun Medical Co, Kyoto, Japan), a heat‐polymerized PMMR containing 5% 4‐methacryloxyethyl trimellitate anhydride (4‐META), could possibly improve the overall design of the prosthesis because this resin adheres to resin and ceramic denture teeth and noble metals. However, adhesive bonding between Metadent and elemental palladium has been shown to be poor. The purpose of this study was to evaluate the potential for adhesive bonding between Metadent, titanate primers, and a ceramic layer pyrolytically fused to a high palladium alloy.Materials and MethodsFive groups of 10 specimens were prepared. A layer of opaque porcelain was baked on all of the specimens under vacuum at 1760°F. The specimens were grouped as follows: (1) Metadent resin processed on ceramic with no primer, (2) Metadent resin with 10% ethyl acetoacetate titanate (DC) processed on ceramic with no primer, (3) Metadent resin with 10% DC processed to ceramic with a 2% tetraisopropyl (TPT) surface primer, (4) 4‐Metadent resin with 10% DC processed to ceramic with a 2% isopropyl dimethacryloyl isostearoyl titanate (KR‐7) surface primer, and (5) Metadent resin with 10% DC processed to ceramic with a titanium dioxide layer on the opaque and a KR‐7 surface primer. The primers were in a methyl methacrylate (MMA) solution. All of the specimens were heat‐polymerized under pressure at 212°F for 1 hour. One‐half (25) of the specimens (5 from each group) were hydro‐thermocycled at 4°C to 55°C, 0.5 minute dwell per bath for 3,000 cycles. All specimens were tested in shear on an MTS Universal machine at cross head speed of 0.5/mm/min.ResultsThe results showed adhesion between the resin‐ceramic layer in virtually all groups regardless of thermocycling effects. The control (heat cure without 10% DC and no primer) and the 10% DC with KR‐7 and TPT primer groups had an average MPa of 7.5, 7.7, and 7.0, respectively. The failure mode of the specimens was adhesive, with the site of failure being the porcelain‐metal interfaceConclusionIt was concluded that adhesion between palladium alloy and Metadent was possible when a ceramic layer was used as an intermediary interface. The limitation seemed to be the adhes

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00133.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeAn absolutely passive fit at the interface with the superstructure and the abutment cylinders is needed for implant longevity. In this study, a method of cast framework correction using electric discharge machining (EDM) was evaluated.Materials and MethodsAn original research model incorporating strain gages was devised to measure the fit of implant superstructures in three dimensions as cast and to compare this relationship with the fit following framework machining with EDM.ResultsVisually, the fit of the frameworks was excellent, and the results of ANOVA demonstrated that the mean fit of the frameworks significantly improved (P>.04) after machining with EDM.ConclusionsThe EDM process offers a rapid, accurate, and simple technique to correct for casting inaccuracies in the fabrication of hybrid implant prostheses.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00134.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeThis study investigated the use of ultraviolet‐absorbing or photoprotective agents as a method of decreasing the color changes caused by ultraviolet radiation on an intrinsically tinted facial prosthetic material.Materials and MethodsSilastic MDX 4‐4210 (Dow Corning Corp, Midland, MI) was the facial prosthetic material studied. It was intrinsically tinted with talc and nylon flock to approximate the color of skin. Three brands of commercially available sunscreens with sun protective factor (SPF) of 15 were placed on the surface of the cured silicone samples. The samples were rotated in an ultraviolet radiation chamber for 300 hours. A control group was placed in the dark for 300 hours. The second phase of the experiment had para‐aminobenzoic acid (PABA) added to the tinted silicone. All samples were measured with a spectrophotometer at the beginning and at the end of 300 hours, and a ΔE was obtained.ResultsNone of the sunscreens provided any ultraviolet radiation protection to the silicone. The addition of PABA caused a significant color degradation of the silicone.Conclusions: No photoprotective agent tested provided any significant level of ultraviolet radiation protection for silastic MDX

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00135.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

PurposeThe purpose of this study was to investigate the effects of two air‐abrasive prophylaxis systems and the effect of inlet air pressure on the surface of Brånemark titanium abutment cylinders.Materials and MethodsSingle abutment cylinders were treated with either the Prophy‐Jet system (sodium bicarbonate abrasive) (Dentsply International, York, PA) or the Microprophy system (aluminum oxide abrasive) (Danville Engineering Co, Danville, CA) for 60 seconds at an inlet air pressure of 60 psi or 90 psi. The effects on the surface of each abutment cylinder were visually inspected by scanning electron microscopy.ResultsA comparison of abutment cylinder surfaces after treatment showed that the Prophy Jet system removed machining marks to a greater degree than the Microprophy system. Sodium bicarbonate particles from the Prophy‐Jet system were significantly larger than the aluminum oxide particles used with the Microprophy system, potentially accounting for the difference in abrasivity. In addition, inlet air pressure of 60 psi caused removal of machining marks to a greater degree than an inlet air pressure of 90 psi. The principle of phase separation may account for the lower inlet air pressure causing more removal of machining marks than the higher inlet air pressure.ConclusionsUnder the experimental conditions tested, neither of the two systems tested seemed to cause significant abrasion of the surface of titanium abutment cyl

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1994.tb00136.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY