ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00319.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A series of destructive changes occurring in the jaws of patients wearing a complete maxillary denture opposed by a mandibular distal extension removable partial denture have been described as the combination syndrome. However, the syndrome does not occur in all patients. Those patients who have not developed signs of the combination syndrome and whose mandibular anterior teeth are well preserved and not overerupted may be treated conservatively with a mandibular removable partial denture. A properly designed removable partial denture that distributes occlusal stresses over hard and soft tissues minimizes the risk of developing the combination syndrome. Nevertheless, the overdenture seems to provide a more predictable prognosis, especially for patients who already have the combination syndrome or whose mandibular anterior teeth are structurally or periodontally compromised or overerupted. The treatment modality is determined by the apparent potential of the patient to develop the combination syndrome and by the condition of the remaining mandibular anterior teeth.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00320.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

This article presents the advantages of design modifications and fabrication techniques for mandibular osseointegrated fixed prostheses. These design features provide definite mechanical advantages and access for oral hygiene maintenance. A review of implant surface properties is presented that affect bacterial plaque and food debris adherence. The suggested design involves a lingual contour of the cast alloy suprastructure to yield an environment for reduced plaque and debris accumulation. The right angle cross‐section ensures strength and increased stress distribution in structurally compromised areas when compared with conventional implant framework design

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

PurposeThis study evaluated 17 edentulous cadavers for bone quantity and quality of the alveolar process of the maxilla for the purpose of dental implant placement.Materials and MethodsThe maxillary arch was divided into four anatomically defined regions for measurements of bone quantity. Bone quality was assessed histologically and described by trabecular bone patterns and tissue composition.ResultsAverage bone height with a minimum thickness of 4 mm was as follows: region 1, 12.1 ± 4.9 mm; region 2, 14.1 ± 7.2 mm; region 3, 6.1 ± 2.8 mm; and region 4, 8.5 ± 2.2 mm. Histological evaluation showed increased trabeculation and thicker cortex in the maxillary anterior area, regions 1 and 2. Region 3, the floor of the maxillary sinus area, had the least amount of bone; however, the quality of bone was superior to that of region 4, the maxillary tuberosity area. Trabecular distance or marrow spaces ranged from 40 μm to 2 mm with larger spaces associated with the posterior maxilla.ConclusionsMaxillary tuberosity is the least desirable site for the placement of implants in the maxilla. The area corresponding to the first and second molars had the least bone thickness. All measures of bone preservation need to be considered, especially in this

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00322.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

PurposeA three‐dimensional mathematical model of the maxilla was developed that was used to analyze the stresses and strains produced by an abutment system capable of three abutment angulations.Materials and MethodsComputed tomography was used to derive the geometry and density values used for the maxillary model. A 3.8 × 10–mm cylindrical implant was embedded in the right central incisor position at a 35° angle to the horizontal plane and parallel to the angulation of the bone site. All geometric and elastic properties for the fixture and the surrounding bone were included in the model. A simulated occlusal load of 178 N was applied along the long axis of 0°, 15°, and 20° abutments. The mathematical models were solved by the Cray Y/MP Ohio Supercomputer (Cray, Eagan, MN) using the ABAQUS software program (Hibbitt, Karlsson, and Sorenson, Providence, RI).ResultsNumerical and graphic results were generated for the maximum (tensile) and minimum (compressive) stresses and strains. Principal stresses occurred predominantly in the cortical bone layers, whereas strains occurred mostly in the cancellous bone.ConclusionsIn general, there was an increase in the magnitude of stress and strain as the abutment angulation increased. Reported stresses and strains for all three angles were within or slightly above the physiological zone derived from animal studies. A need to investigate the response of human bone to stress and strain was i

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00323.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

PurposeThe purpose of this study was to compare the bond strengths and fracture modes of soldered joints formed by infrared and gas‐oxygen torch heating of a high‐fusing, gold‐based solder in two metal‐ceramic alloys.Materials and MethodsPairs of half‐dumbbell–shaped specimens of either an Au‐Pd or a Co‐Cr alloy were positioned with a 0.25‐mm gap and were joined using a high‐fusing, gold‐based solder by either gas‐oxygen torch heating or infrared heating. The resulting specimens were subjected to a heat treatment that simulated ceramic firing. Each specimen was fractured in tension at a loading rate of 0.5 cm/min, and its bond strength was measured. The halves of the specimen were rejoined using the other heating method and were heat treated, and the specimen's bond strength was again measured. Fractured cross‐sections were examined at a magnification of 40× to determine the following: the fracture mode (adhesive, cohesive, or mixed); the percentage of adhesive fracture; the presence or absence of voids, porosities, or flux inclusions; and the percentage of the cross‐section that was discolored.ResultsThree‐factor analyses of variance showed that neither the heating method, the particular specimen tested, nor the order of testing significantly affected the bond strength (P<.05). For each alloy, significantly fewer infrared‐heated joints than torch‐heated joints contained voids, porosities, or flux inclusions visible at 40× (χ2test,P<.05). All fractures were either entirely cohesive in the solder or mixed cohesive and adhesive. When infrared heating was used, entirely cohesive fractures occurred more frequently in the Au‐Pd alloy specimens than in the Co‐Cr alloy specimens (χ2test,P<.05). The coefficients of variation of the bond strengths for the infrared‐heated joints were smaller than those for the torch‐heated joints.ConclusionsAlthough the two heating methods produced solder joints that had strengths that were not significantly different, infrared‐heated joints showed less scatter in bond strengths. It was suggested that, in the hands of most technicians, fewer infrared‐heated joints would contain defects visible at a magnification of 40×. The presence of such defects may increase the probab

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00324.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

PurposeThe color stability and surface roughness of three commercial hybrid ionomers were determined in vitro after accelerated aging. Three shades of each hybrid ionomer prepared in light‐cured and dark‐cured conditions were tested.Materials and MethodsSamples were aged in an artificial aging chamber by subjecting them to total ultraviolet light irradiation of 150 kJ/m2over a period of 77 hours. Color (CIE LAB system) was measured before and after aging on a reflection spectrophotometer. Surface roughness was measured with a profilometer.ResultsAfter accelerated aging, all samples became lighter. Photac‐Fil Aplicap (ESPE‐Premier, Norristown, PA) and Fuji II LC (GC America, Chicago, IL) also became less chromatic (less red and less yellow). Among the light‐cured samples, Fuji II LC had the greatest change in color followed by Photac‐Fil Aplicap and Vitremer (3M Dental Products, St Paul, MN). For the dark‐cured samples, Fuji II LC had the greatest change in color followed by Vitremer and Photac‐Fil Aplicap. There were no differences in delta E* between the two lightest shades, but the darker shades of each product showed the greatest changes in color. All samples became significantly rougher after aging.ConclusionsHybrid ionomers changed color significantly and perceptibly after in vitro accelerated aging. Surfaces became significantly rougher and showed evidence of cracking

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00325.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Surveys of US dental schools over the last 20 years have reported a continual increase in the number and types of predoctoral and postdoctoral implant dentistry programs being taught. The purpose of the following article is to report on the results of a survey intended to update the status of predoctoral programs with respect to their curricular placement, departmental jurisdictions, and course contents. In June 1993, 54 US dental schools received the implant dentistry curriculum survey, and 50 of the schools (93%) returned responses. Results indicate that the trend toward implementation of more predoctoral implant dentistry programs has been sustained, with 86% of schools reporting the existence of implant curricula. This compares with 33% and 73% of US schools having such programs in 1974 and 1989, respectively. The major reasons that schools gave for not having implant dentistry courses for predoctoral students are a lack of curriculum time and scarce financial resources. The dental disciplines most frequently guiding such programs are oral surgery and periodontics. Schools offer varying degrees of lectures, laboratories, and clinical experiences in predoctoral implant dentistry, with the number of curriculum hours peaking in years three and four. General curricular topics most commonly include a historical overview of implant dentistry, diagnosis and treatment planning, classifications and types of dental implants, and surgical and prosthodontic procedures. Seventeen percent of schools require some form of undergraduate clinical implant dentistry exposure for all of their students.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00326.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The final part of this literature review series presents guidelines for the optimal preparation of teeth to receive posts and cores.

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00327.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A urethane dimethacrylate and tinting powder lamination, chemically bonded to a methyl methacrylate denture base, produces a natural‐appearing distribution of the tints. The characterization is protected by a hard, clear layer of urethane. Procedures are described that achieve this lamination either in the laboratory, before processing the dentures, or after the dentures have been fabricate

ISSN:1059-941X    

DOI:10.1111/j.1532-849X.1995.tb00328.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY