Biomedical subjects

S A Yannikakis

Publications and source records attributed to S A Yannikakis.

5 recordsLinked to original sources

PubMed1998

Color stability of provisional resin restorative materials.

STATEMENT OF PROBLEM: Use of temporary crowns and fixed partial dentures is especially relevant when the treatment plan requires restorations for long interim periods, and the in-service discoloration of provisional restorative materials is a major drawback. PURPOSE: This study evaluated the discoloration effect of coffee and tea on some materials that are commonly used in the fabrication of provisional restorations. MATERIAL AND METHODS: Six commercially available provisional resins (Jet, Caulk TBR, Protemp Garant, Luxatemp Solar, Provipont DC and SR-Ivocron-PE) were evaluated after 1 day, 7 days, and 30 days of immersion in various staining solutions. Color measurements were obtained by using a Dr Lange Micro Color tristimulus colorimeter and color differences (delta E*) were estimated. RESULTS: The 2 chemically activated resins (Jet and Caulk TBR) and the heat-cured resin (SR-Ivocron PE) exhibited the least color changes, whereas the Provipont-DC resin was the least color stable. After immersion for 30 days, the combination with the coffee solution resulted in unacceptable discoloration for all the tested materials. CONCLUSIONS: Provisional restorative materials, staining solutions, and immersion time were significant factors that affected color stability. After immersion for 7 days, all materials showed observable color changes. The composite-based materials, especially light-curing composites, were the least color stable. The coffee solution exhibited more staining capacity than the tea solution.

Analysis of Variance↗

PubMedDate not supplied

Color stability of visible light-cured, hard direct denture reliners: an in vitro investigation.

PURPOSE: Previous studies have disclosed the unsatisfactory color stability of autopolymerizing, hard direct denture reliners (HDDR). The present study investigated the color stability of the newly introduced visible light-cured and dual-cured HDDRs. MATERIALS AND METHODS: Five HDDRs were evaluated after 1 hour, 1 day, 7 days, and 30 days of immersion in coffee, tea, and water. Color measurements were obtained with a tristimulus colorimeter, and color differences (delta E*) were calculated. RESULTS: After 30 days of immersion one visible light-cured material exhibited the highest delta E* value (17.8). The other materials showed acceptable color stability in water and coffee. However, tea strongly affected their color. CONCLUSION: Reliners, staining solutions, and immersion time are significant factors that affect color stability. After 7 days of immersion, all of the materials showed perceptible color differences. Tea exhibited higher staining capacity than coffee.

Analysis of Variance↗

PubMedDate not supplied

Roughness of denture materials: a comparative study.

PURPOSE: Surface properties of denture materials are of clinical importance since they may affect plaque accumulation and staining. This in vitro study investigated the roughness of 20 commercially available denture materials. MATERIALS AND METHODS: Four denture base resins, nine hard lining materials, and seven soft denture lining materials were evaluated for roughness. Roughness measurements were made using a Mitutoyo Surftest SV-400, and the mean arithmetic roughness values (Ra) obtained were used for the comparisons. RESULTS: The overall Ra values ranged from 0.7 to 7.6 microns. The denture base materials group exhibited Ra values from 3.4 to 7.6 microns, whereas the hard liners were from 0.7 to 4.4 microns. The autopolymerized and visible light-cured soft liners presented Ra values from 0.7 to 3.5 microns, while the heat-cured soft liners ranged from 3.5 to 4.0 microns. CONCLUSION: The roughness exhibited by all of the materials tested (Ra values greater than 0.7 micron) indicates that there is a possibility for plaque accumulation, since 0.2 micron is considered the threshold below which no further bacterial adherence can be expected.

Acrylic Resins↗

PubMedDate not supplied

The effect of glutaraldehyde and microwave disinfection on some properties of acrylic denture resin.

This study evaluated the effect of disinfection methods on the dimensional stability, flexural properties, and microhardness of a heat-polymerized denture acrylic resin. A 1- and 12-hour immersion period in 2% alkaline glutaraldehyde, and 3- and 15-minutes exposure to microwaves were employed as disinfection or sterilization procedures. Storage in water for 1 and 12 hours were used as the control. For each procedure 10 specimens were used. The results indicated that the linear changes observed were of no clinical importance. The same conclusion can be drawn for flexural properties and microhardness. The microwave method is a useful alternative to immersion disinfection.

Acrylic Resins↗

PubMedDate not supplied

Color changes of denture base materials after disinfection and sterilization immersion.

This study evaluated the effects of chemical disinfectants on the color of denture base materials. Materials tested included Paladon 65 (Kulzer, Friedrichdorf, Germany), Triad VLC (Dentsply Int, York, PA), and ProBase Cold (Ivoclar, Schaan, Liechtenstein). The disinfectants were Klinex (Lever Hellas, Athens, Greece), Cidex-7 (Johnson & Johnson, East Windsor, NJ), Hibitane (Imperial Chemical, Macclesfield, UK), and Cabadol (Detax Karl Huber, Ettlingen, Germany). Denture material samples were placed in the various disinfectants and evaluated for color changes (delta E*) at intervals of 10 minutes, 10 hours, and 7 days. Changes in color were measured using a tristimulus colorimeter on 10 samples for each denture material and disinfectant combination. It was concluded that if the recommended disinfecting times are followed, no observable color changes should be anticipated for the denture materials tested. Even the long-term (7-day) immersion caused observable color changes only with Cabadol, a phenol-based disinfectant, and ProBase and Triad denture materials.

Acrylic Resins↗