Journal of Prosthetic Dentistry

Restoration using gingiva-colored ceramic and a ridge lap pontic with circumferential pressure: A clinical report

Tae Hyung Kim, Domenico Cascione, Alena Knezevic, Hessam Nowzari — 2010-08-01

Achieving an optimal esthetic result when replacing missing teeth with implant-supported restorations in the esthetic zone is a demanding surgical and restorative challenge. This clinical report describes the use of a cantilevered, cemented, implant-supported restoration with gingiva-colored ceramics and a circumferential pressure-ridge lap pontic to replace 2 incisors and the adjacent tissue.

Clinical outcome of three-unit lithium-disilicate glass-ceramic fixed dental prostheses: up to 8 years results

2010-08-01

Wolfart S, Eschbach S, Scherrer S, Kern M. Dent Mater 2009;25:e63-71. Epub 2009 Jun 11.

Use of zirconia collar to prevent interproximal porcelain fracture: A clinical report

Carl M. Pogoncheff, Renee E. Duff — 2010-08-01

Ensuring the longevity of crown restorations is an important objective for the clinician. Veneering porcelain fracture needs to be addressed when considering restoration longevity. This clinical report presents the use of a CAD/CAM-aided design to produce a zirconia substructure with a collar that will acheive the same supportive results as a substructure fabricated by full contour waxing and cut back.

Strategic considerations in treatment planning: Deciding when to treat, extract, or replace a questionable tooth

2010-08-01

Prosthodontists face the difficult task of judging the influence and significance of multiple risk factors of periodontal, endodontic, or prosthetic origin that can affect the prognosis of an abutment tooth. The purpose of this review is to summarize the critical factors involved in deciding whether a questionable tooth should be treated and maintained, or extracted and possibly replaced by dental implants. A MEDLINE (PubMed) search of the English, peer-reviewed literature published from 1966 to August 2009 was conducted using different keyword combinations including treatment planning, in addition to decision making, periodontics, endodontics, dental implants, or prosthodontics. Further, bibliographies of all relevant papers and previous review articles were hand searched. Tooth maintenance and the acceptance of risks are suitable when: the tooth is not extensively diseased; the tooth has a high strategic value, particularly in patients with implant contraindications; the tooth is located in an intact arch; and the preservation of gingival structures is paramount. When complete-mouth restorations are planned, the strategic use of dental implants and smaller units (short-span fixed dental prostheses), either tooth- or implant-supported, as well as natural tooth abutments with good prognoses for long-span FDPs, is recommended to minimize the risk of failure of the entire restoration.

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2010-08-01

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Effect of pretest storage conditions of extracted teeth on their dentin bond strengths

Enas H. Mobarak, Wafa El-Badrawy, David H. Pashley, Hana Jamjoom — 2010-08-01

Statement of problem: It is becoming increasingly difficult to obtain sufficient freshly extracted human teeth to utilize in in vitro studies, particularly for bonding investigations. Purpose: The purpose of this study was to investigate the effect of different storage conditions for human extracted teeth prior to their use in microtensile bond strength (μTBS) testing. Material and methods: Thirty incisors were divided into groups according to their storage time and condition. The first group consisted of freshly extracted teeth. Teeth of the second group were stored in chloramine-T at 4°C for 2 years ±1 month. The last group was stored dry for up to 2 years ±2 months, after which teeth were rehydrated in distilled water for 2 weeks before use. All teeth were disinfected using 0.5% chloramine-T. Dentin surfaces were exposed and then bonded using Scotchbond Multi-Purpose or Clearfil SE Bond to composite resin foundations (Esthet-X). Following 24-hour storage, bonded teeth (n=30) were sectioned into beams with a cross-section of 0.9 ±0.1 mm2 and subjected to μTBS testing using a microtensile testing machine (Micro Tensile Tester). Data were calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (α=.05). Failure modes were determined using a stereomicroscope at ×40 magnification. Results: Statistical analysis revealed no significant difference between the different storage conditions nor between the 2 adhesive systems for each storage condition (P>.05). Modes of failure for all tested groups were predominantly adhesive followed by mixed. Conclusions: Within the limitations of this study, it was concluded that aging of teeth and storage conditions had no significant effect on dentin microtensile bond strength to composite resin.

Dental implants in patients with ectodermal dysplasia and tooth agenesis: A critical review of the literature

2010-08-01

Yap AK, Klineberg I. Int J Prosthodont 2009;22:268-76.

Effect of surface treatment on flexural strength of zirconia bars

Moustafa N. Aboushelib, Hang Wang — 2010-08-01

Statement of problem: Clinical and laboratory processing techniques induce damage to the surface of zirconia frameworks, which significantly lessens their strength. Purpose: The purpose of this study was to investigate the influence of 3 surface restoration methods on the flexural strength of zirconia bars. Material and methods: Bar-shaped specimens were polished and received 1 of 2 surface treatments (n=20): airborne-particle abrasion with 110-μm aluminum oxide particles at a pressure of 0.2 MPa, or grinding with a diamond point under water cooling and a load of 2 N using an air turbine. Polished specimens served as the control (n=20). The induced surface damage was restored using one of the following restoration methods: polishing of the specimens using an aluminum oxide polishing point (2-μm grit) coated with 0.5-μm diamond polishing paste, application of a thin coat of glazing porcelain according to the manufacturer's instructions, or application of a phosphate ester monomer (MDP) containing an adhesive resin. The specimens were subjected to a 4-point flexural strength test and then examined using a scanning electron microscope (SEM). Two-way ANOVA and the Bonferroni post hoc test were used to analyze the data (α=.05). Results: There was a significant interaction between the type of surface damage and the restoration method (P<.001). For the ground specimens, all restoration methods resulted in a statistically significant regain in strength, with the polishing procedure being the most effective (1027 MPa). For airborne-particle-abraded specimens, application of the bonding agent was the only effective restoration method. SEM analysis of the fractured surfaces of specimens indicated that application of the bonding agent resulted in sealing of the surface damage produced by airborne-particle abrasion, while polishing was successful in removing the grinding lines produced by the diamond point. Conclusions: Within the limitations of this in vitro study, restoration of surface damage improved the flexural strength of zirconia specimens.

Interfacial corrections of maxillofacial elastomers for Kubelka-Munk theory using non-contact measurements

2010-08-01

Hu X, Gilbert AB, Johnston WM. Dent Mater 2009;25:1163-8. Epub 2009 May 21.

Two-body wear of different ceramic materials opposed to zirconia ceramic

Zakereyya S.M. Albashaireh, Muhamad Ghazal, Matthias Kern — 2010-08-01

Statement of problem: Little is known about the wear behavior of ceramics opposed to unveneered zirconia and whether wear varies according to microstructure, surface toughness, and flexural strength of the ceramics. Purpose: The purpose of this study was to evaluate the 2-body wear resistance of 5 ceramics opposing unveneered zirconia ceramic. Material and methods: Yttrium-stabilized zirconia, lithium disilicate glass ceramic, leucite-reinforced glass ceramic, fluorapatite glass ceramic, and nanofluorapatite glass ceramic specimens (n=8) were tested against standardized zirconia balls. Wear tests were performed in a dual-axis mastication simulator. Wear resistance was calculated by measuring the vertical and volumetric substance loss using a laser scanner. Specimen surfaces were evaluated at x50 and x500 magnification using SEM. Data were statistically analyzed using 1-way ANOVA and Fisher's exact test (α=.05). Results: Zirconia specimens demonstrated significantly lower vertical and volumetric loss than other ceramics (P<.05). The wear of fluorapatite and nanofluorapatite glass ceramics was significantly greater than that of leucite-reinforced and lithium disilicate glass ceramics (P<.05). SEM images showed no cracks or flaws in the zirconia and leucite-reinforced glass-ceramic specimens, indicating a mixture of attritional and adhesive wear. Other ceramic specimens exhibited cracks and chipped particle spaces which were consistent with fatigue wear. Zirconia demonstrated the lowest vertical and volumetric wear values. Leucite-reinforced and lithium disilicate glass ceramics demonstrated nonsignificant differences in volumetric wear, but these values were significantly lower than those observed for nanofluorapatite and fluorapatite glass ceramics (P<.05). Conclusions: Wear varied according to the structure of the ceramic tested. Wear was of the fatigue type, and was significantly lowest in the zirconia specimens tested.

Effects of investment type and casting system on permeability and castability of CP titanium

Fazal Reza, Hidekazu Takahashi, Naohiko Iwasaki, Yukimichi Tamaki — 2010-08-01

Statement of problem: Several factors, such as casting systems and investment properties, are important to obtain a sound titanium casting. Although various casting systems and investments for titanium are commercially available, their effects on CP titanium castability are not clear. Purpose: The purpose of this study was to determine permeability of investments and to evaluate the effects of investment type and casting system on titanium castability. Material and methods: Three investments for titanium (experimental gypsum-bonded investment, Selevest CB, and Speed Titan) and 4 titanium casting systems (Cyclarc, Ti-Cascom, Vulcan T, and Ticast Super R) were used. Permeability was measured using a flow meter and argon gas at 0.1, 0.2, and 0.3 MPa. Castability was calculated as the percentage of reproduced holes compared to a perforated wax pattern. Data for castability and permeability were analyzed separately with 2-way ANOVA and the Tukey HSD test (α=.05). Results: The ANOVA for permeability and castability showed significant interaction (P<.001 and P=.004, respectively). Differences in permeability among the 3 investments increased with a higher gas pressure. Permeability of the experimental investment at each pressure level was significantly greater than that of the other investments, except for Speed Titan at 0.1 MPa (P<.05). The permeability of Selevest CB at each pressure level was significantly less than that of the other investments (P<.05). Cyclarc and Ti-Cascom specimens were not significantly different, in terms of castability, using the investments evaluated, but castability of Vulcan T and Ticast specimens varied significantly by the investment used (P<.05). Conclusions: Within the limitations of this study, investment type, pressure level, and their combinations influenced permeability. Castability of titanium was influenced by investment type, casting system, and their combinations. The investment with the highest permeability did not demonstrate the best result for castability.

Journal Back Issues Available to Subscribers

2010-08-01

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The effect of equilibrating mounted dental stone casts on the occlusal harmony of cast metal complete crowns

Joe C. Meng, William W. Nagy, Carl G. Wirth, Peter H. Buschang — 2010-08-01

Statement of problem: Fabrication of indirect complete crowns that are in occlusal harmony upon insertion remains a problem in restorative dentistry, and dental stone cast expansion may play a role. Purpose: This 3-part investigation compared occlusal contacts in a simulated patient with a harmonious occlusion with centric occlusion equal to maximum intercuspation (CO=MI) and an inharmonious occlusion (CO≠MI) with mounted stone casts, and compared the occlusal contacts after fabrication of a posterior complete crown fabricated on equilibrated and nonequilibrated dental stone casts. Material and methods: A dentoform mounted in a semi-adjustable articulator served as the simulated patient and control. In part 1, a single set of maxillary and mandibular ADA type IV and V derived dental stone casts were fabricated and mounted (CO≠MI), and occlusal contacts/near contacts were compared. In part 2, 10 type IV and 10 type V cast mountings (CO=MI) were compared. In part 3, 10 type IV cast mountings were fabricated for adjustment (experimental) and 10 for no adjustment (control). A mandibular ADA type IV gold alloy complete crown was fabricated and adjusted on each set of casts and then returned to the dentoform. Vinyl polysiloxane interocclusal records of all mountings were scanned for optical density, and contacts were used to quantify occlusal contacts as exhibiting contact or near contact. Data were analyzed with Kruskal-Wallis ANOVA and Mann-Whitney U tests (α=.05). Results: The cast adjustment protocol (intervention) was successful in eliminating the majority of the occlusal disharmony in the casts believed to be caused by the effects of stone expansion. Actual and near contact areas for cast mountings of the equilibrated simulated patient were significantly different from those of the simulated patient (P<.001; P=.001, respectively). Actual and near contact areas for inserted crowns fabricated from adjusted casts were significantly different from those of the simulated patient (P<.001; P=.007, respectively), but actual contact areas were not different from those of the simulated patient with no crown inserted. Conclusions: In this study, occlusal contacts of a simulated patient (dentoform) could not be accurately replicated with mounted dental stone casts. A cast adjustment procedure can aid in fabrication of a crown with a more accurate occlusion.

Effect of titanium surface characteristics on the behavior and function of oral fibroblasts

2010-08-01

Att W, Yamada M, Ogawa T. Int J Oral Maxillofac Implants 2009;24:419-31.

Defining available restorative space for implant overdentures

Swati Ahuja, David R. Cagna — 2010-08-01

It is important to diagnostically evaluate available restorative space prior to implant placement. Failure to accurately assess restorative space may result in esthetically and structurally compromised prostheses and patient dissatisfaction. This article describes various techniques for evaluating restorative space in edentulous patients. Information gained will help dentists during treatment planning, attachment selection, and prosthesis design prior to surgical implant placement.

Mold filling and dimensional accuracy of titanium castings in a spinel-based investment

2010-08-01

Fischer J, Ebinger A, Hågi T, Stawarczyk B, Wenger A, Keller E. Dent Mater 2009;25:1376-82. Epub 2009 Aug 7.

Method to simplify a direct implant impression using an extended guide pin

Soong-Ryong Jung, Jill D. Bashutski — 2010-08-01

Implant impression techniques can be subdivided into indirect (transfer) and direct (pickup) types. The direct impression technique requires a 2-piece impression coping with a removable guide pin that screws directly into the abutment or onto the implant. An open-tray impression technique allows access to the guide pin after the material has polymerized so that the copings can be removed without disturbing their orientation within the impression during removal from the mouth.

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2010-08-01

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2010-08-01

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2010-08-01

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2010-08-01

Information for Authors

Carol A. Lefebvre — 2010-08-01

Authors must adhere to the Journal guidelines, which are provided to ensure the expeditious processing of manuscripts. Complete information on manuscript submission may be found at http://journals.elsevierhealth.com/periodicals/ympr. Failure to follow Journal guidelines may result in the rejection of manuscripts or delays in the review process and publication.

Information for Readers

2010-08-01

If you have questions or comments regarding original articles and editorial management, please contact: Dr Carol A. Lefebvre, School of Dentistry, Medical College of Georgia, 1120 15th St, AD-2943, Augusta, GA 30912-1255; telephone (706) 721-4558; fax (706) 721-4571.