-
[show abstract]
[hide abstract]
ABSTRACT: The aim of this in vitro study was to investigate the effect of accelerated aging on the color stability of six autopolymerized silicone and acrylic soft reliners. Ten specimens for each material were fabricated. Initial color was measured with a tri-stimulus colorimeter. One set of five specimens was placed in distilled water at 37 °C under dark for 15 days, while the remaining were subjected to photoaging initially for 1 and then for 6 days. Color changes (ΔE) then calculated. Data were analysed by ANOVA, Tukey and t tests at a = 0.05. All the reliners after storage in water showed ΔE ranged from 2.8 (Mucopren Soft) to 7.9 (Vertex Soft). After accelerated aging for 1 day, ΔE ranged from 4.6 (Vertex Soft) to 12.4 (Eversoft) whereas after 6 days from 1.7 (Ufigel SC) to 11.8 (Eversoft). All the reliners showed perceptible ΔE except Ufigel SC in 6 days aging and clinically unacceptable ΔE except Sofreliner S and Vertex Soft after aging for 1 day. Eversoft showed the highest discoloration after aging.
Odontology 05/2012; · 1.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to investigate the effect of four commercially available denture adhesives on the incisal and premolar dislodgement forces of maxillary complete dentures by using an electronic and disposable gnathodynamometer and compare the measured incisal forces for differences. This study was conducted with 12 complete maxillary denture wearers. Four commercially available denture adhesives Super Corega(®), Corega Ultra(®), Super Corega Powder(®) and Fittydent Cationic(®) were investigated. Testing protocol and sequence included baseline measurements without adhesives (control) for previous and new dentures and then replications of measurements with the four adhesives. Maximum dislodgement forces were recorded in two sites between central incisors and the left 2nd premolars by using an electronic and disposable gnathodynamometer. To estimate the effect of the different adhesives on the dislodgement forces, data were analyzed by a 2- and 3-way ANOVA, while for estimating the agreement of the two devices a Bland-Altman and Mountain plots were used. ANOVAs indicated significant differences between adhesives (p < 0.05), denture types (p < 0.05) and biting sites (p < 0.05) with both devices. Bland-Altman plot and Mountain plots indicated a poor agreement of the two devices. It was concluded that denture adhesives increase the denture dislodgement forces, but with differences among them. The two devices do not highly agree with each other, but each one alone is useful in estimating dislodgement forces in clinical practice and research.
Odontology 04/2011; 99(2):155-61. · 1.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The purpose of this study was to assess the colour stability of seven visible light-cured (VLC) hard and soft denture liners by an in vitro accelerated ageing test and compare them with two autopolymerised hard and soft liners.
Ten specimens of each material were fabricated. The initial colour was measured with a tri-stimulus colorimeter. One set of five specimens was placed in distilled water at 37°C in the dark for 15 days, while the remaining were subjected to UV/visible light-accelerated ageing initially for 24 h and then for 144 h. Colour change (ΔΕ) was calculated. Data were statistically analysed by anova, Tukey and t-tests at α = 0.05.
All the liners showed clinically acceptable colour change (ΔΕ ≤ 6.8) in distilled water. The colour changes after ageing for Triad DuaLine, Lightdon U, Ufi Gel H and Light Liner Hard were clinically unacceptable (ΔΕ ≥ 6.8), whereas LightLiner Soft, Astron LC Soft, Triad Resiline and Flexacryl Soft presented slighter and clinically acceptable colour change (ΔΕ ≤ 6.8).
Accelerated ageing affected significantly the colour stability of all denture liners tested except Astron LC Soft. Soft VLC denture liners were more colour-stable than hard VLC liners.
Gerodontology 03/2011; 29(2):e239-45. · 1.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We aimed to evaluate the effect of a denture cleanser and NaOCl 5.25% solution on the modulus of elasticity, the ultimate stress, and the weight changes of Co-Cr and Ti-6Al-7Nb alloys. To evaluate the modulus of elasticity and ultimate stress, 24 Co-Cr and 24 Ti-6Al-7Nb castings were fabricated, immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Thirty-six castings were produced to evaluate weight changes, 18 Co-Cr and 18 Ti-6Al-7Nb, and immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Changes in the modulus of elasticity, ultimate stress, and weight were calculated before and after immersion in the cleanser or NaOCl 5.25% solution for 45 cycles of 10 min each. Two-way analysis of variance ANOVA and Tukey's test at α = 0.05 were used to analyze the data. The modulus of elasticity and the ultimate stress of Co-Cr decreased after immersion in the solutions. The same properties of Ti-6Al-7Nb decreased in NaOCl 5.25% and increased in the other solutions. Weight loss was observed in Co-Cr alloy in both Corega Extradent and NaOCl 5.25%. A weight increase was observed in Co-Cr in water. An increase was observed in Ti-6Al-7Nb in Corega Extradent, NaOCl 5.25%, and water. The highest decrease (P = 0.05) in the modulus of elasticity and ultimate stress in Co-Cr were observed in NaOCl 5.25%, whereas no statistically significant differences (P > 0.05) were observed in Ti-6Al-7Nb in any of the solutions. A statistically significant weight loss (P < 0.05) was observed when Co-Cr was immersed in NaOCl 5.25%, and a statistically significant weight increase (P > 0.05) was observed when Ti-6Al-7Nb was immersed in Corega Extradent. The Co-Cr alloy bending properties after immersion fulfilled ADA Specification No. 14 for satisfactory clinical performance.
Odontology 01/2011; 99(1):77-82. · 1.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Acrylic denture base fracture is a common mode of failure. Heat-cured, auto-polymerized, visible light-cured, and microwaveable acrylic resins have been used as repair materials. The aim of this study was to evaluate the shear bond strength of two microwaveable resins (Acron MC and Justi) and one auto-polymerizing acrylic resin (ProBase Cold) as denture repair materials as opposed to a heat-cured one using the non-flasking procedure after thermocycling and photoaging.
Ninety cylindrical specimens were made using the Vertex Rapid Simplified heat-cured acrylic resin. Each repair acrylic resin was poured on the specimen's surface using a cylindrical rubber mold with an internal diameter of 8.5 mm. Thirty specimens for each repair material were made. The control group consisted of 10 specimens from each group which were stored in water for 24 h at 37 degrees C; another 10 specimens from each group were subjected to a thermocycling procedure (5-55 degrees C for 1,000 cycles), while the remaining 10 specimens were subjected to a photoaging procedure. Shear bond strength was measured on a universal testing machine and mode of bond failure was examined under a stereomicroscope. Two-way ANOVA and the Bonferroni post hoc test were performed to identify statistical differences at alpha = 0.05.
Justi's shear bond values were significantly inferior to those of ProBase Cold (p <0.05) and Acron MC (p <0.05). ProBase Cold and Acron MC acrylic resins exhibited similar values (p >0.05) of shear bond strength. Thermocycling and photoaging did not affect the shear bond values of any of the materials under investigation (p >0.05).
ProBase Cold and Acron MC exhibited similar shear bond values. Justi repair material exhibited inferior bond strength compared with that of ProBase Cold and Acron MC. Aging procedures did not affect the bonding properties of any of the repair materials.
Acta Odontologica Scandinavica 08/2006; 64(4):244-8. · 1.07 Impact Factor
