Journal of Prosthetic Dentistry

Survey of United States dental schools on cementation protocols for implant crown restorations

Diane Yoshinobu Tarica, Veronica M. Alvarado, Samantha T. Truong — 2010-02-01

Statement of problem: With conflicting results in the literature and various manufacturer recommendations, it is not known what cementation protocols are currently being used for implant restorations in US dental schools. Purpose: The purpose of this survey was to determine what dental cementation protocols are taught and recommended by 62 US dental schools and postgraduate programs. Material and methods: From February to September 2008, 96 questionnaires consisting of 8 questions were sent to the chairperson or director of restorative departments, advanced prosthodontics programs, and implant programs. The questionnaire asked recipients which implant manufacturers provided the products used at their dental schools. Additionally, recipients were queried as to the choice of material and techniques for abutment and restoration preparations prior to definitive cementation. Data were analyzed with descriptive statistics. Results: A total of 68 (71%) surveys were returned, and 52 (84%) of the 62 predoctoral and postgraduate programs were represented. After deleting duplicate responses, 31 surveys were returned from restorative department chairpersons, 29 from advanced prosthodontic program directors, and 2 from implant program directors. Frequency of responses to each question was tabulated, and results are presented in 3 sections. For all 3 types of programs, Nobel Biocare was reported to be the most widely used implant system, followed by Biomet 3i, Straumann, Astra Tech, and Zimmer Dental systems. The most commonly used technique prior to definitive cementation is to airborne-particle abrade the intaglio surface of the restoration. Resin-modified glass ionomer is the most frequently used luting agent for cementing implant restorations. The 5 most commonly used materials to fill screw access openings are cotton pellets, composite resin, rubber-based material, gutta-percha, and light-polymerized provisional composite resin. Most predoctoral and postgraduate programs teach students to fill the screw access opening completely to the occlusal surface. Conclusions: There are a wide range of implant cementation protocols and materials used; however, some common trends were identified among predoctoral and postgraduate programs.

Three-year clinical evaluation of two ceramic crown systems: A preliminary study

Maged K. Etman, M.J. Woolford — 2010-02-01

Statement of problem: The clinical performance and failure mechanisms of recently introduced ceramic crown systems used to restore posterior teeth have not been adequately examined. Purpose: The purpose of this prospective clinical study was to evaluate and compare the clinical performance of 2 new ceramic crown systems with that of metal ceramic crowns using modified United States Public Health Services (USPHS) criteria. Material and methods: Ninety posterior teeth requiring crown restorations in 48 patients were randomized into 3 equal groups (n=30) for which different crown systems were used: an experimental hot-pressed glass ceramic based on a modified lithium disilicate ceramic (IPS e.max Press), an alumina-coping-based ceramic (Procera AllCeram), and a metal ceramic (Simidur S 2 veneered with IPS Classic Porcelain). The crowns were assessed over 3 years using the modified USPHS criteria. Crowns that developed visible cracks were sectioned and removed, and the surfaces were analyzed using a scanning electron microscope (SEM). The data were analyzed using the Kruskal-Wallis nonparametric statistical test, followed by the Mann-Whitney test with Bonferroni correction (α=.05). Results: USPHS evaluation showed that the IPS e.max Press and metal ceramic crowns experienced fewer clinical changes than Procera AllCeram. Visible roughness, wear, and deformity were noticed in occlusal contact areas of Procera AllCeram crowns. SEM images showed well defined wear facets in both ceramic crown systems. Kruskal-Wallis tests showed a significant difference (P<.05) in Alpha scores among the 3 crown systems. Mann-Whitney tests showed significant differences among groups. Conclusions: IPS e.max Press crowns demonstrated clinical behavior comparable to Procera AllCeram and metal ceramic crowns, but the wear resistance of this crown type was superior to the Procera AllCeram crowns, according to modified USPHS criteria.

Receive Tables of Contents by E-mail

2010-02-01

To receive tables of contents by e-mail, sign up through our Web site at http://www.journals.elsevierhealth.com/periodicals/ympr. Log on and click “Register” in the upper right-hand corner. After completing the registration process, click on “My Alerts,” then “Add Table of Contents Alert.” Select the category “Mosby” or type The Journal of Prosthetic Dentistry in the search field and click on the Journal title. The title will then appear, and having already completed the Registration process, you may add tables of contents alerts by accessing an issue of the Journal and clicking on the “Add TOC Alert” link.

Effect of varying the vertical dimension of connectors of cantilever cross-arch fixed dental prostheses in patients with severely reduced osseous support: A three-dimensional finite element analysis

2010-02-01

Statement of problem: Inadequate dimensioning of the connectors in a cantilever cross-arch fixed dental prosthesis (FDP) in perioprosthetic patients jeopardizes the prognosis of the restoration. Purpose: The purpose of this study was to investigate the effect of increasing the vertical dimension (VD) on the maximum stress developed within the connectors during the static loading of a cross-arch FDP extended as a 1- and 2-unit cantilever. Material and methods: Six digital models were developed, derived from a 3-dimensional (3-D) initial model. In the initial model, the teeth were prepared for metal ceramic restorations and splinted with a cross-arch FDP, extended as a 1- or 2-unit cantilever. The VDs of the connectors proximal to the retaining abutment were 3, 4, or 5 mm. A 3-D finite element analysis (FEA) was performed. Results: The VD increase, from 3 to 4 mm and from 3 to 5 mm, of the connector distal to the retaining abutment, for each FDP, presented a maximum stress value decrease of approximately 25% and 48%, respectively. The similar VD increase of the connector mesial to the retaining abutment, for each FDP, resulted in relatively smaller stress changes. For the 2-unit cantilever restoration, the stress decreases were approximately 9% and 15%, respectively, whereas in the 1-unit cantilever restoration, the decrease was about 10% for the 4-mm connector. Further increase of the VD to 5 mm did not relieve the peak stress. The highest stress value was measured on the 3-mm connector distal to the retaining abutment in the 2-unit cantilever restoration. Despite the VD increase, the connectors proximal to the retaining abutment still developed the highest stress values of all the connectors for every model. Conclusions: The connector with the highest risk of failure is the 3-mm connector distal to the retaining abutment of the 2-unit cantilever restoration. Increasing the vertical dimension is beneficial for the connector distal to the retaining abutment, while the resultant stress changes are not substantial for the connectors mesial to the retaining abutment. (J Prosthet Dent 2010;103:91-100)

Comparison of cutting efficiencies between electric and air-turbine dental handpieces

Charlson Choi, Carl F. Driscoll, Elaine Romberg — 2010-02-01

Statement of problem: Dentistry is gravitating toward the increased use of electric handpieces. The dental professional should have sufficient evidence to validate the switch from an air-turbine handpiece to an electric handpiece. However, there is little research quantifying the cutting efficiency of electric and air-turbine handpieces. Studies that do quantify cutting efficiency typically do so with only a single material. Purpose: The purpose of this study was to compare the cutting efficiency of an electric handpiece and an air-turbine handpiece, using various materials commonly used in dentistry. Material and methods: Seven materials: Macor (machinable glass ceramic), silver amalgam, aluminum oxide, zirconium oxide, high noble metal alloy, noble metal alloy, and base metal alloy, were each cut with a bur 220 times; 110 times with an electric handpiece, and 110 times with an air-turbine handpiece. The weight difference of the material was calculated by subtracting the weight of the material after a cut from the weight of the material before the cut. The cutting efficiency was calculated by dividing the weight difference by the duration of the cut (g/s). Data were analyzed by a 2-way analysis of variance followed by Tukey's Honestly Significant Difference (HSD) test (α=.05). Results: The electric handpiece cut more efficiently than the air-turbine handpiece (F=3098.9, P<.001). In particular, the high noble metal alloy, silver amalgam, and Macor were cut more efficiently with the electric handpiece (0.0383 ±0.0002 g/s, 0.0260 ±0.0002 g/s, and 0.0122 ±0.0002 g/s, respectively) than with the air-turbine handpiece (0.0125 ±0.0002 g/s, 0.0142 ±0.0002 g/s, and 0.008 ±0.0002 g/s, respectively). Conclusions: The electric handpiece is more efficient at cutting various materials used in dentistry, especially machinable glass ceramic, silver amalgam, and high noble alloy, than the air-turbine handpiece.

Three-body wear of resin denture teeth with and without nanofillers

2010-02-01

Statement of problem: The wear behavior of newly developed denture teeth with nanofillers may be different from teeth with other chemical formulations. Purpose: The purpose of this study was to examine the 3-body wear resistance of 11 different commercially available resin denture teeth. Material and methods: The materials tested were conventional (SR Orthotyp PE, Orthognath) and cross-linked acrylic resin teeth without inorganic fillers (Premium 8, SR Postaris DCL, Trubyte Portrait, Artiplus), composite resin teeth with inorganic fillers (SR Orthosit PE, Vitapan), and composite resin teeth (experimental materials) with inorganic nanofillers (NC Veracia Posterior, e-Ha, Mondial). Human enamel and a ceramic denture tooth (Lumin Vacuum) were used as reference materials. The 3-body wear test was performed in a wear machine developed by the Academic Center for Dentistry Amsterdam (ACTA), with millet suspension acting as an abrasive medium (n=10, test load: 15 N, slip rate: 20%, number of cycles: 100,000). Wear was determined with the aid of a profilometer. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test using the closed testing approach (significance level for familywise error rate, α=.05). Results: None of the acrylic and composite resin materials tested in this study demonstrated the 3-body wear resistance of ceramic teeth or human enamel. Teeth with inorganic fillers demonstrated significantly lower wear values than conventional or cross-linked acrylic resin teeth without fillers. Composite resin teeth with traditional fillers showed significantly lower wear than composite resin teeth with nanofillers. Conclusions: Denture teeth with and without inorganic fillers differed significantly with regard to the degree of wear generated in the ACTA wear simulator. The incorporation of nanofillers did not improve the wear resistance compared to teeth with traditional fillers.

Retrospective study of treatment outcomes with implant-retained extraoral prostheses: Survival rates and prosthetic complications

Secil Karakoca, Cemal Aydin, Handan Yilmaz, Bilge Turhan Bal — 2010-02-01

Statement of problem: Implant-retained extraoral prostheses are an acceptable solution for patients with facial defects. However, these prostheses have a limited service life. Little has been reported on survival periods of implant-retained extraoral prostheses and prosthetic complications of this treatment modality. Purpose: The purpose of this study was to estimate the survival rates of implant-retained extraoral prostheses and to analyze the frequency of prosthetic complications. Material and methods: Seventy patients were treated with implant-retained extraoral prostheses. Each patient was examined with respect to the prosthesis appearance and abutment and attachment component complications at 6-month intervals over a period of 10 to 46 months. The Kaplan-Meier survival estimation method was used for the first and subsequent prostheses. The reasons for remaking prostheses were recorded. Complications of the abutment and attachment components and the prostheses were recorded. Frequency of complications was evaluated. Data were analyzed using the Fisher exact test (α=.05). Results: Thirty-two auricular, 25 orbital, and 13 nasal prostheses were evaluated. The Kaplan-Meier analysis revealed an estimated mean survival time of 14.5 months for the patients' first prostheses. The survival times for the first implant-retained auricular, orbital, and nasal prostheses were 14.1, 13.4, and 17.6 months, respectively. The survival times for the second implant-retained auricular, orbital, and nasal prostheses were 14.4, 15.3, and 14.0 months, respectively. Conclusions: Implant-retained extraoral prostheses had limited survival rates. The primary reasons for making new prostheses were discoloration, tearing, and mechanical failures of the acrylic resin substructure or retentive elements. Common complications were the need for clip activation, loosening of bar screws and abutments, and loss of attachment between silicone and the acrylic resin substructure. (J Prosthet Dent 2010;103:118-126)

Controlled airborne-particle abrasion of zirconia ceramic restorations

Matthias Kern — 2010-02-01

Airborne-particle abrasion is a surface-conditioning procedure to achieve durable resin bonding to zirconia ceramics chairside. Alternate surface-conditioning methods may be used in the dental laboratory during fabrication of the restoration to avoid airborne-particle abrasion. These surface-conditioning methods include plasma spraying with hexamethyldisiloxane, applying a low-fusing porcelain pearl layer, a so-called selective infiltration-etching technique, or using a newly patented modified ceramic surface (tentatively named NobelBond; Nobel Biocare AB, Göteborg, Sweden). However, it is not clear whether such preconditioned bonding surfaces can be effectively cleaned following unavoidable contamination with saliva during intraoral evaluation of a restoration. In contrast, airborne-particle abrasion is an easy and effective cleaning procedure, which can be applied chairside.

Availability of Journal Back Issues

2010-02-01

As a service to our subscribers, copies of back issues of The Journal of Prosthetic Dentistry for the preceding 5 years are maintained and are available for purchase from Elsevier, Inc until inventory is depleted. Please write to Elsevier, Inc, Subscription Customer Service, 6277 Sea Harbor Dr, Orlando, FL 32887, or call 800-654-2452 or 407-345-4000 for information on availability of particular issues and prices.

Chairside repair of worn or lost denture teeth using nanofilled composite resin bonded to the denture base

Walter Renne — 2010-02-01

When a patient fractures or displaces a tooth in his or her denture, it creates a problem not only for the patient, but also for the dentist. If the dentist has the required shade and mold of the prosthetic tooth on hand, the repair can be accomplished in the office. However, it is expensive to maintain an adequate inventory of various shades and molds of denture teeth, so the prosthesis is often sent to a dental laboratory for repair. The patient may then be without his or her denture for an extended time period.

News and Notes

2010-02-01

All items for this section must be in the Editor's office 10 weeks before month of issue.

Sponsoring Organizations and Liaisons

2010-02-01

Editorial Board

2010-02-01

Display Ad

2010-02-01

Display Ad

2010-02-01

Information for Authors

Carol A. Lefebvre — 2010-02-01

Authors must adhere to the following guidelines, which are provided to ensure the expeditious processing of manuscripts. Failure to follow these guidelines may result in the rejection of manuscripts or delays in the review process and publication.

Display Ads

2010-02-01

Information for Readers

2010-02-01

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.