Biomedical subjects

Gary R Goldstein

Publications and source records attributed to Gary R Goldstein.

8 recordsLinked to original sources

PubMed2005

Marginal fit of leucite-glass pressable ceramic restorations and ceramic-pressed-to-metal restorations.

STATEMENT OF PROBLEM: Fabricating a feldspathic porcelain margin on a metal-ceramic restoration with a clinically acceptable marginal fit has proven to be a technique-sensitive procedure. Pressable ceramics are advocated to solve this problem. PURPOSE: The purpose of this in vitro study was to compare the marginal adaptation of a pressable ceramic system when used with both all-ceramic and metal-ceramic crowns, with a traditional metal-ceramic restoration. MATERIAL AND METHODS: A 1.5-mm, 360-degree chamfer margin was prepared on a typodont maxillary central incisor. Polyether impressions were made and poured in a Type IV dental stone, and the following crowns were fabricated on individual dies: 15 metal ceramic restorations (MCR) (Ceramco II, Ceramco, and Argelite 60), 15 pressed-to-metal restorations (PTM) (CPC-MK, and Argelite 60), and 15 pressed ceramic restorations (PCR) (CPC-MK). The marginal fit of the crowns was evaluated every 90 degrees around the crown margin circumference under a microscope at original magnification x 45. A 1-way analysis of variance (ANOVA) was used to compare data (alpha=.05). RESULTS: The mean marginal discrepancy for MCRs was 94 +/- 41 microm, for PTMs, 88 +/- 29 microm, and for PCRs, 81 +/- 25 microm. The 1-way ANOVA showed no significant difference between groups ( P =.568). CONCLUSION: The marginal fit of pressed-to-metal (PTMs) and pressed all-ceramic crowns (PCRs) was similar to that of traditional metal-ceramic crowns (MCRs).

Aluminum Silicates↗

PubMed2005

Comparison of bond strength of a pressed ceramic fused to metal versus feldspathic porcelain fused to metal.

PURPOSE: To compare the debonding/crack initiation strength (D/CIS) of a low-fusing pressable leucite-based glass ceramic (PC) fused to metal to a feldspathic porcelain (FP) fused to metal. MATERIALS & METHODS: As per ISO 9693:1999, 40 rectangular metal specimens (25.0 mm x 0.5 mm x 3.0 mm) were prepared. Twenty of the specimens were cast in a base metal nickel-chromium alloy (BA), and 20 were cast in a noble metal palladium-silver alloy (NA). Ten randomly selected NA and BA alloy specimens had FP applied. The remaining 10 NA and BA alloy specimens had ash-free wax patterns applied, the metal-wax complexes invested, and were pressed with a PC. The dimensions of the ceramic specimens were 8.0 mm x 1.0 mm x 3.0 mm, creating a combined metal-ceramic complex thickness of 1.5 mm. All specimens were subject to a three-point bending test at a crosshead speed of 1.5 mm/min. Fracture loads were recorded in Newtons and D/CISs calculated by the formula tau(b)=k x F(fail). RESULTS: Mean D/CISs, measured in MPa (standard deviations): NA-FP 32.56 (4.62), NA-PC 30.23 (5.06), BA-FP 30.98 (4.41), and BA-PC 31.81 (3.48). A two-way ANOVA (p > 0.05) did not demonstrate significant difference between groups. CONCLUSION: The debonding/crack initiation strength of a low-fusing pressable leucite-based glass ceramic fused to metal was equivalent to that of a feldspathic porcelain fused to metal.

Aluminum Silicates↗

PubMed2003

An in vitro comparison of tensile bond strengths of noble and base metal alloys to enamel.

STATEMENT OF PURPOSE: Many different surface treatments have been used to increase the bond strength of noble and base metal alloys to enamel, but only a few have been studied. PURPOSE: The purpose of this in vitro study was to compare the tensile bond strength of a tin-plated noble alloy, an Alloy Primer-treated noble alloy, and an airborne particle-abraded base metal alloy, all bonded to enamel with a phosphate-methacrylate resin luting agent. MATERIAL AND METHODS: Seventy noncarious molar teeth were extracted, cleaned, and embedded in autopolymerizing acrylic resin with the buccal surface of the teeth exposed. Seventy wax patterns (4-mm diameter x 2-mm thickness) were waxed, invested, and cast-50 with a noble alloy (Argedent 52) and 20 with a base metal alloy (Argeloy N.P.). Twenty of the noble alloy specimens were tin-plated (TP), 20 noble alloy specimens were treated with Alloy Primer (AP), and 20 base metal alloy specimens were airborne particle abraded (AA). All specimens were luted with a phosphate-methacrylate resin luting agent (Panavia F) and stored in 100% humidity at 37 degrees C, half for 24 hours and half for 7 days. Ten noble alloy specimens were tin-plated and stored in water for 48 hours (aged) before cementation and then stored in water for 24 hours after cementation. These specimens were used to test whether there is an advantage to aging the tin-plated surface in water before cementation. All specimens were thermocycled (5 degrees to 55 degrees C) for 500 cycles and then tested for tensile bond strength (TBS), measured in MPa, with a universal testing machine at a crosshead speed of 0.5mm/min. Various castings (n=6 per test group) were randomly selected from each group and inspected under a scanning electronic microscope to determine mode of failure. The mean values and standard deviations of all specimens were calculated for each group. A 2-way analysis of variance (ANOVA) was performed, and multiple pairwise comparisons were then completed with post hoc Tukey test (alpha=.05). RESULTS: The TBS of the tin-plated noble alloy specimens bonded to enamel (24 hours: 9.33 +/- 1.31 MPa; 7 days: 11.65 +/- 1.55 MPa) was significantly greater than the Alloy Primer noble alloy specimens (24 hours: 6.11 +/- 1.01 MPa; 7 days: 5.45 +/- 1.22 MPa) (P <.001). The Alloy Primer noble alloy group showed the lowest TBS compared with the tin-plated noble alloy and airborne particle-abraded base metal alloy group (24 hours: 10.61 +/- 1.41 MPa; 7 days: 6.94 +/- 1.40 MPa). The tin-plated noble alloy specimens showed greater TBS after storage for 7 days in distilled water compared with storage for 24 hours (24 hours: 9.33 +/- 1.31 MPa; 7 days: 11.65 +/- 1.55 MPa). Aging the tin-plated noble alloy for 48 hours in 37 degrees C (9.17 +/- 1.68 MPa) prior to cementation did not increase the TBS to enamel. The airborne particle-abraded base metal alloy showed significantly lower TBS at the 7-day storage time compared to the 24-hour storage time (24 hours: 10.61 +/- 1.41 MPa; 7 days: 6.94 +/- 1.40 MPa) (P <.001). SEM examination of the debonded metal and enamel surfaces showed mixed (adhesive and cohesive) failures for all groups. CONCLUSION: Tin-plating a noble alloy produced the highest bond strength to enamel. Storing the tin-plated noble alloy in 37 degrees C distilled water for 48 hours before cementation did not result in a change in TBS. Using an Alloy Primer with a noble alloy resulted in statistically significant lower TBS than tin-plating.

Analysis of Variance↗

PubMed2002

What is evidence based dentistry?

The insurmountable mass of literature and lectures that the modern practitioner is exposed to has created problems. The resolution of often contradictory information is not easy to discern. Evidence based dentistry presents guidelines to determine the validity of the results and whether they can be applied to clinical practice. This article introduces the reader to the basic principles to be used in and evidence based practice.

Clinical Trials as Topic↗

PubMed2002

Therapy: anecdote, experience, or evidence?

In dentistry, most changes in therapy come from new techniques and products that are introduced to the market. Clinicians (and patients) can be overwhelmed by advertisements and marketing, some obvious and some (e.g., paid clinical reports in non-peer-reviewed journals) not so obvious. Because most advances are made with small case studies, which are at a lower level of evidence, it is imperative that data clinicians read or see have the greatest validity possible. This validity is imperative to achieve evidence-based dentistry that uses relevant, high-quality, clinically oriented research that provides better information for the clinician and better treatment for the patient.

Decision Making↗

PubMed2002

New paradigms in prosthodontic treatment planning: a literature review.

New treatment modalities have expanded the choices available to prosthodontists and their patients. At the same time, an explosion of data has called into question the validity and efficacy of certain forms of traditional prosthodontic treatment. Together, these factors have greatly complicated the treatment-planning process. The purpose of this article is to provide a framework for the prosthodontic treatment-planning process that incorporates the latest evidence-based information available. A review of the literature was undertaken through a Medline search. Articles published in English from 1975 through 2001 were evaluated; selected articles were chosen for review on the basis of a subjective judgment of their relevancy and significance to the clinician.

Dental Prosthesis↗

PubMed2002

In vivo evaluation of three cleansing techniques for prepared abutment teeth.

STATEMENT OF PROBLEM: Residual provisional cement and debris on prepared teeth may have the potential to negatively influence the performance of the definitive luting agent. PURPOSE: This in vivo study quantified the adherence of provisional cement to abutment teeth prepared with 1 of 2 textures (coarse or fine) and cleaned with 1 of 3 common cleansing techniques. MATERIAL AND METHODS: One hundred ten provisional restorations in 22 patients were luted to maxillary anterior abutment teeth. The teeth were prepared for complete veneer restorations with either a coarse-grit diamond bur or a coarse-grit diamond bur followed by a fine-grit diamond bur. After removal of the restoration, abutment teeth were randomly cleansed with either a No. 23 dental explorer and air-water spray, a prophy cup with fine flour pumice, or a cotton pellet soaked in chlorhexidine gluconate, 0.12%. After the abutments were cleansed, they were evaluated intraorally under a light microscope (magnification, x64) by 2 blinded examiners. The teeth were given scores based on the number of specks of residual cement found on the surface after the cleansing techniques were performed. Pearson correlation coefficients (alpha=.96), 3-way analysis of variance, and post hoc Scheffé tests (P<.05) were used to analyze the data. RESULTS: As determined with Pearson correlation coefficient, the interexaminer reliability was alpha=.96. Three-way analysis of variance revealed significant effects for the cleansing techniques but not for the interaction between cleansing techniques and preparation texture. A post hoc Scheffé test showed that the pumice cleansing technique (1.8 specks/tooth) was significantly better than the explorer or the cotton pellet/chlorhexidine gluconate technique (3.6 and 3.5 specks/tooth, respectively) (P<.05). CONCLUSION: Within the limitations of this study, abutment teeth cleansed with a prophy cup and flour pumice exhibited the least amount of residual provisional cement.

Analysis of Variance↗

PubMed2002

The repeatability of an intraoral dental colorimeter.

STATEMENT OF PROBLEM: Characterizing and reproducing color remain one of the most challenging aspects of dentistry. A relatively new intraoral colorimeter measures the color of natural teeth and metal-ceramic restorations and prints out a color recipe for the Vintage Halo Porcelain System. The reliability of the colorimeter is unknown. PURPOSE: The purpose of this study was to evaluate the reliability of a contact dental colorimeter and to correlate the shade registered by the colorimeter with the shade selected by experienced clinicians. MATERIALS AND METHODS: In part I of the study, 2 examiners (A and B) took 2 colorimeter measurements from the maxillary right central incisors of 11 subjects. The examiners were blinded to their own data and those of other investigators. The readings were repeated 3 weeks later with the same protocol. The Cronbach alpha reliability coefficient was used to analyze the collected data. In part II of the study, 2 experienced clinicians (examiners D and E) selected a shade from the classic Vita Lumin Vacuum shade guide for the maxillary right central incisors of the same 11 subjects. The clinicians were blinded to each other's selections and the colorimeter readings. It should be noted that the manufacturer of the colorimeter uses the terms shade, value, and hue to represent chroma, value, and hue, respectively, as defined in the Glossary of Prosthodontic Terms (J Prosthet Dent 1999;81:39-110). RESULTS: The reliability analysis results for each of the combined trials for shade, value, and hue were all >.94. The interexaminer reliability alpha values were >.9 for shade and value and.64 to.74 for hue. The interexaminer alpha represented the value range of each of 4 measurements. The intraexaminer reliability alpha values for shade, value, and hue were.99,.95, and.96 for examiner A and.99,.93, and.97 for examiner B, respectively. In part II of the study, the colorimeter agreed with itself 82% of the time, whereas clinicians agreed with each other on the selected shade 73% of the time. Selections made by the colorimeter and the clinicians matched 55% to 64% of the time. CONCLUSIONS: Within the limitations of this study, the colorimeter reliably measured the color of natural teeth.

Ceramics↗