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Biomedical subjects

T A Lynde

Publications and source records attributed to T A Lynde.

10 recordsLinked to original sources
PubMed2000

In vitro comparison of fluoride release of six direct core materials.

STATEMENT OF PROBLEM: Fluoride has been shown to deter caries and has been incorporated into core build-up materials. However, there is considerable variation in the formulation and release of fluoride from core build-up materials. PURPOSE: This in vitro study compared the fluoride released by 6 commercially available fluoride-releasing core materials over time. METHODS AND MATERIAL: Ten specimen disks (9 for Corestore) of each of the 6 core materials were fabricated, finished, measured, and immersed in deionized water in individual polystyrene jars. The jars were stored in a humidor at 37 degrees C between test periods. At the same time each day for 7 consecutive days, then at days 14, 22, 28, 59, and 89, the fluoride release was measured from each specimen disk in parts per million by testing the storage medium. The data were analyzed using 1-way ANOVA and Tukey-Kramer multiple comparison tests (P <.05). RESULTS: Five of the 6 core build-up materials tested showed an initial high concentration of fluoride release during the first day and gradually tapered over the study period. Fuji II LC consistently released more fluoride than any other material throughout the 89-day testing period. CONCLUSION: Fuji II LC released the most fluoride and was significantly different from the other materials tested. The maximum amount of fluoride was released by 5 of the 6 materials during the first 24 hours and gradually tapered over the 89-day testing period.

Analysis of Variance↗
PubMed1999

Fluoride release of glass ionomer-based luting cements in vitro.

STATEMENT OF PROBLEM: There is considerable variation in generic formulation and in reported fluoride release from resin-modified glass ionomer luting cements. PURPOSE: This study compared fluoride release from 2 generically similar resin-modified glass ionomer luting cements (Vitremer and Advance) with release from 2 conventional glass ionomer luting cements (Ketac-Cem and Fuji I). MATERIAL AND METHODS: Ten specimen disks of each of the 4 luting cements were fabricated and immersed in deionized water in individual polystyrene jars. The jars were stored in a humidor at 37 degrees C between test periods. At the same time each day, for 28 days, fluoride release from each specimen disk was measured in parts per million by testing the storage water. RESULTS: The 4 luting cements tested showed an initial high concentration of fluoride release during the first week, followed by a gradual decrease over the study period. Vitremer luting cement demonstrated the greatest mean cumulative fluoride release in parts per million over the study period (198), followed by Fuji I (140), Ketac-Cem (110), and Advance (99) luting cements. CONCLUSIONS: Resin-modified glass ionomer luting cements showed fluoride release comparable to the conventional glass ionomer luting cements. Vitremer luting cement released more fluoride over the 28-day period than the other cements.

Analysis of Variance↗
PubMed1996

In vivo testing of an experimental endosseous implant design.

PURPOSE: The purpose of this study was to test a new implant system with apically expanding, double-hinged wing stabilizers in dogs before human testing. METHODS: Twenty-seven HA-coated endosseous implants were placed in five dog mandibles. The implants were placed into function for 12-weeks after a 12-week healing period. At the end of this period, the implants were evaluated clinically and radiographically. The animals then were killed, allowing for the implants to be evaluated mechanically and histologically. RESULTS: After the initial healing period, 24 of 27 implants demonstrated osseointegration. Seven of eight implants restored with acrylic resin-fixed partial dentures were stable after the 12-week period of function. However, 17 of 27 implants failed to satisfactorily deploy the apical wing stabilizer system. CONCLUSION: This new implant system has a number of design flaws that must be addressed before testing in humans.

Animals↗
PubMed1996

The bond strength of an adhesive resin luting cement to a variety of surface treatments of a high-palladium copper alloy.

PURPOSE: This study evaluated the tensile bond strength of a bisphenol glycidyl methacrylate (Bis-GMA) resin luting cement with four different surface treatments of a high Pd-Cu alloy. MATERIALS AND METHODS: For each surface treatment type (tin-plated, porcelain furnace oxide, air-abraded, and finished-only), 15 opposing half-dumbbell-shaped samples were cast and prepared in new Pd-Cu alloy. Samples were luted with a Bis-GMA resin luting cement at a film thickness of 80 microns using a custom alignment apparatus. Samples were stored in distilled water at 37 degrees C for 24 hours, thermocycled for 1,000 cycles, and then stored for 30 days in distilled water at 37 degrees C. Samples were then subjected to fracture in tension at a loading rate of 0.5 cm/min with the bond strengths calculated in megapascals (MPa). The fractured surfaces were examined using stereomicroscopy and scanning electron microscopy at various magnifications ranging from 5.5x to 500x to determine the type of bond failure (adhesive, cohesive, or mixed). RESULTS: Tensile bond strengths (mean +/- SD MPa) were: tin-plated, 30 +/- 15.7; porcelain furnace oxide, 23 +/-n 8.6; air-abraded, 8 +/- 8.1; and finished-only, 4 +/- 4.5. Statistical analysis of the tensile bond values using an ANCOVA and Tukey's multiple comparison test at a significance level of 0.05 indicated that there was no difference between the tin-plated and the furnace oxide groups, as well as between the air-abraded and the furnace oxide groups. However, there was significant difference between the tin-plated, the air-abraded, and the finished-only groups. The observed bond failures were predominantly mixed and cohesive in nature with only one adhesive failure. CONCLUSIONS: There was no significant difference in the tensile bond strengths between the tin-plated group or the porcelain furnace oxide surface group. This suggests that the less-technique-sensitive porcelain furnace oxide surface treatment offers an alternative for achieving high metal-resin bonds to a high Pd-Cu alloy.

Aluminum Oxide↗
PubMed1996

Dimensional stability of two visible light-cured indirect inlay/onlay resin composite materials.

PURPOSE: To evaluate the dimensional stability over time of two visible light-cured indirect inlay/onlay resin composites. MATERIALS AND METHODS: Twenty working dies of a Class II preparation were constructed in type IV die stone from impressions of a master metal die. Working dies were randomly divided into two groups of 10 with Class II resin composite inlays fabricated using Brilliant Dentin (n = 10) and Triad inlay material (n = 10). Inlays were seated on the master metal die 1, 3 and 10 days after fabrication and resin replicas were made of the proximal gingival margin surface which were gold-sputtered and used for the measurement of gingival margin gap distances at four locations using an SEM micron measurement system. RESULTS: Triad inlays mean gingival margin gap measurement was significantly (P < 0.05) greater at 10 days versus 1 day. Brilliant Dentin inlays had no significant mean gingival margin gap measurement differences between any time periods. As a material, Triad inlays had significantly less gingival margin gap distances than the Brilliant Dentin inlays at all three time intervals.

Acrylic Resins↗
PubMed1995

Preparation of the denture-bearing area--an essential component of successful complete-denture treatment.

Success in complete-denture treatment is often directly related to the health and condition of the hard and soft tissues that make up the denture-bearing areas. Surgical alteration of the denture-bearing area is frequently necessary to ensure a morphologically correct form capable of providing adequate support for the prosthesis. A number of these anatomic hard and soft tissue obstacles are discussed, and methods for managing these hindrances to complete-denture treatment are suggested.

Alveolar Process↗
PubMed1975

Factors affecting airborne beryllium concentrations in dental spaces.

Air sampling for beryllium concentrations produced during finishing procedures for a beryllium-containing alloy was conducted in two rooms with capacities of 700 and 10,000 cubic feet. The clearance rate of beryllium in the air and the effect of ventilation and room size on these concentrations were investigated. With local lathe ventilation, no beryllium was found. Without local lathe ventilation, mean 10 minutes concentrations of about 23 mug per cubic meter were found at the breathing zone of the lathe operator in both rooms. At 4 and 8 feet from the breathing zone, sizable concentrations of beryllium above the maximum acceptable standard were found only in the small room. These levels decreased to zero 10 minutes after completion of the finishing and polishing procedure. It was concluded that there was little hazard to dental personnel when local lathe ventilation was used; however, our finding of high concentrations of beryllium in the air when lathe ventilation was not used indicates that continued vigilance must be maintained.

Air↗