Alcohol and light-polymerizing glaze effect on the physical and mechanical properties of a bisacrylate composite resin before and after immersion in chlorhexidine gluconate

STATEMENT OF PROBLEM

The use of 0.12% chlorhexidine gluconate (CHX) may damage bisacrylate composite resin interim restorations, but whether they can be protected with an application of alcohol and/or the use of a glaze is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of applying a 70% alcohol solution on the physical and mechanical properties of a bisacrylate composite resin, with and without the application of a light-polymerizing glaze subjected to 0.12% CHX twice a day for 7 days.

MATERIAL AND METHODS

Forty specimens of an autopolymerized bisacrylate composite resin were divided into 4 groups (n=10): Group C (without alcohol, without glaze), Group G (without alcohol, with glaze), Group A (with alcohol, without glaze), and Group AG (with alcohol, with glaze). All specimens were submitted to in vitro treatment with 0.12% CHX for 7 days, and tests of color alteration (ΔE₀₀), microhardness, roughness, and surface were performed initially and after treatment. Data were submitted to analysis of variance (ANOVA) and the Tukey HSD test (α=.05).

RESULTS

Group A had the lowest mean value of ΔE₀₀ with a significant statistical difference from Group C. The groups with alcohol presented higher microhardness mean values compared with groups without alcohol in both periods of analysis, except for the groups with glaze in the final period. Group C showed higher mean roughness values in comparison with Group A in both periods. Group AG presented higher mean roughness values than Group G. Surface energy values did not vary significantly among groups, except between Groups C and A in the final period.

CONCLUSIONS

The application of alcohol optimized the properties of the autopolymerized bisacrylate composite resin analyzed, with and without the application of glaze. Overall, the use of CHX changed the microhardness and roughness when the glaze was applied.

Antimicrobial effects of photodynamic therapy on Staphylococcus aureus biofilm grown on a specific acrylic resin surface for ocular prostheses

BACKGROUND

Photodynamic therapy (PDT) is a treatment for the specific control of oral biofilms. However, its effects on maxillofacial prostheses have been barely explored. In this study, we evaluated the antimicrobial effect of PDT using methylene blue (MB) and laser against a Staphylococcus aureus biofilm developed on the surface of scleral acrylic resin.

METHODS

Sixty-six specimens of acrylic resin designed for ocular prostheses were fabricated in a disk-shaped format (3 × 10 mm). S. aureus biofilm was grown on the surface of the specimens for 24 h and the disks were then treated with MB at different concentrations (25, 50, 75 or 100 μg/mL), with or without PDT (GaAlAs diode laser; 660 nm; 100 mW; 9 J; 321.4 J.cm^-2; 3.5 W.cm^-2 and 90 s). Control groups were treated with 2% chlorhexidine gluconate (CHX) or phosphate buffered saline. After the treatments, colony forming units (CFU) were counted and the samples were qualitatively evaluated by scanning electron microscopy (SEM). Data were analyzed descriptively and by nested ANOVA and the Tukey test (α = .05).

RESULTS

PDT groups with MB concentrations at 75 and 100 μg/mL formed fewer CFU compared to the other groups (P < 0.001) and the 2% CHX group did not form any CFU. SEM images revealed that the surface of the polymers in these groups did not show bacterial colonies.

CONCLUSIONS

PDT significantly reduced S. aureus biofilm in the scleral acrylic resin when associated with an MB dilution of 75 μg/mL or higher. Thus, PDT can be a promising candidate for disinfecting ocular prostheses.

Evaluating the Color Stability of Ocular Prosthesis after Immersion in Three Different Immersion Media: An In Vitro Study

Background:

Immersion media such as ophthalmic irrigation solution, eye lubricant solution, and neutral soap solution will be the best, which will help in the longevity as well as the color stability of ocular prostheses.

Aim:

The aim of this study was to evaluate and compare color stability of ocular prosthesis after immersion in three different immersion media.

Materials and Methods:

A total of 90 samples of scleral acrylic resin were prepared, which were painted with natural dry earth pigment NEAS and then were divided into three groups. These samples were checked before and after immersion in respective media after 8 weeks. To assess the color change, a spectrophotometry test was performed and the results were statistically analyzed by one-way analysis of variance and post hoc Tukey’s test.

Results:

Among all the three groups, the samples immersed in neutral soap solution proved to be most color stable, followed by eye lubricant solution, and the least color stable among the three was ophthalmic irrigating solution.

Conclusion:

The neutral soap solution proved to be the most color stable.

Effect of Disinfection on the Bond Strength between Denture Teeth and Microwave-Cured Acrylic Resin Denture Base

PURPOSE

Denture tooth debonding is a common complication for denture wearers; however, the effect of complete denture disinfection on bonding between denture teeth and acrylic resin remains unclear. The aim of this study was to evaluate the effect of disinfection methods on the bond strength between denture teeth and microwave-cured acrylic resin denture base.

MATERIALS AND METHODS

Three commercial brands of denture teeth (Trilux, Biolux, Vipi Dent Plus) and one microwave-cured acrylic resin denture base were tested. Each brand of denture teeth was divided into seven groups (n = 6; estimated by partial Eta squared). The specimenss of groups H and Cl were immersed in 1% sodium hypochlorite and 4% chlorhexidine digluconate for 7 days, respectively. In group Br, the specimens were subjected to toothbrush simulation under 200 g of force for 20,000 cycles. In groups Br-H and Br-Cl, the specimens were brushed and further disinfected with 1% sodium hypochlorite and 4% chlorhexidine digluconate, respectively. In control groups 1 (Co1) and 2 (Co2), the specimens were stored in distilled water for 50 ± 2 hours and 7 days, respectively. Shear bond strength testing was performed at the resin/tooth interface in a universal testing machine at a 1 mm/min crosshead speed. The failure pattern was quantified and classified into adhesive, cohesive, or mixed. Data were analyzed using two-way ANOVA and Tukey HSD test (α = 0.05).

RESULTS

Disinfection with 1% sodium hypochlorite (p = 0.031), brushing (p < 0.0001), and association of brushing with either 1% sodium hypochlorite (p < 0.0001) or 4% chlorhexidine digluconate (p = 0.01) reduced the bond strength between denture teeth and microwave-cured acrylic resin denture base. All commercial brands of denture teeth presented a similar bond strength (p > 0.05). The failure pattern was predominantly adhesive independent of the disinfection method and denture tooth brand.

CONCLUSIONS

Disinfection with sodium hypochlorite, brushing, and the association of mechanical and chemical methods reduced the bond strength between denture tooth and microwave-cured acrylic resin denture base.

Recommendations for post-adaption care of an ocular prosthesis: A review

An ocular prosthesis must be maintained in a suitable state of cleanliness, fit and preservation. Otherwise its functioning may be compromised, leading to a variety of diseases. However, there is a lack of consensus on the care of such prostheses. This review assembles and attempts to update existing knowledge in this area and discusses the most appropriate care regimes.

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis

The aim of this study was to assess the effect of adding nanoparticles to N1 acrylic resin intended for artificial sclera, in terms of the color stability, microhardness, and flexural strength of the resin. Three hundred samples of N1 acrylic resin were used: 100 samples for color stability and microhardness tests (each test was performed on the opposite side of each sample), and 200 samples for flexural strength testing (100 samples before and after 1,008 hours of accelerated aging). Samples for each test were separated into ten groups (n=10), ie, without nanoparticles (control group) or with nanoparticles of zinc oxide, titanium dioxide (TiO₂), and barium sulfate at weight concentrations of 1%, 2%, and 2.5% (nanoparticle groups). Data were subjected to statistical analysis with nested analysis of variance and Tukey’s test (P<0.05 significance level). Among the nanoparticle groups, the TiO₂ groups showed better color stability at all concentrations. Microhardness values increased after artificial aging, except for the control and zinc oxide groups. After aging, the 1%–2% TiO₂ groups had significantly higher microhardness values compared with the other nanoparticle groups. Before aging, there was a significant difference in flexural strength between the control and nanoparticle groups. After aging, the control and TiO₂ groups, regardless of concentration, showed the lowest flexural strength values. Incorporation of nanoparticles directly influenced the acrylic resin properties, with TiO₂ being the most influential nanoparticle in terms of the evaluated properties.

Influence of natural weathering on colour stability of materials used for facial prosthesis

Colour stability of resin and silicone is an important factor for longevity of facial prostheses. The aim of this study was to evaluate the colour stability of resins and silicone for facial prostheses. Three brands of acrylic resin and one of facial silicone were evaluated considering pigment incorporation for the colourless materials. Ten samples of each material were fabricated and submitted to measurements of chromatic alteration initially and after 90 and 180 days of weathering natural through visual analysis and spectrophotometry. Data were evaluated by ANOVA and Tukey test (p < 0.05). Statistically significant colour alteration was observed among some materials regardless of the period. The materials did not present a statistical difference between 90 and 180 days except for the pigmented heat-polymerized resin. The colour difference between pigmented Silastic MDX4-4210 and colourless Silastic was statistically significant (p < 0.01) in both periods as well as between pigmented and colourless heat-polymerized resin, and between the resins Rapidaflex and Lentaflex. The visual method demonstrated colour alteration in all materials evaluated during the first 90 days of ageing. All materials exhibited colour alteration due to exposure to environment.

Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing

Esthetics and durability of materials used to fabricate artificial eyes has been an important eissue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin.

Craniofacial implant-retained auricular prosthesis: a case report

Implants provide patients with a safe and reliable method for anchoring auricular prostheses that enable restoration of their normal appearance and offer improved quality of life. In this case report, an auricular prosthesis was fabricated for a patient who had lost his right external ear in a traffic accident. Extraoral implants and bar-and-clip retention for the proper connection of the auricular prosthesis to the implant were used.

Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging

The purpose of this study was to evaluate the color stability of a maxillofacial elastomer with the addition of a nanoparticle pigment and∕or an opacifier submitted to chemical disinfection and artificial aging. Specimens were divided into four groups (n = 30): group I: silicone without pigment or opacifier, group II: ceramic powder pigment, group III: Barium sulfate (BaSO(4)) opacifier, and group IV: ceramic powder and BaSO(4) opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was done three times a week during two months. Afterward, specimens were submitted to different periods of artificial aging. Color evaluation was initially done, after 60 days (disinfection period) and after 252, 504, and 1008 h of artificial aging with aid of a reflection spectrophotometer. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05). The isolated factor disinfection did not statistically influence the values of color stability among groups. The association between pigment and BaSO(4) opacifier (GIV) was more stable in relationship to color change (△E). All values of △E obtained, independent of the disinfectant and the period of artificial aging, were considered acceptable in agreement with the norms presented in literature.

Effect of disinfection and accelerated aging on color stability of colorless and pigmented facial silicone

PURPOSE

The aim of this study was to evaluate the color stability of a facial silicone with different pigmentations submitted to disinfection and accelerated aging.

MATERIALS AND METHODS

Sixty replicas were fabricated with the silicone Silastic MDX 4-4210 and divided into three groups: no pigmentation, pigmentation with makeup powder, and pigmentation with ceramic powder. Half the replicas of each group were submitted to disinfection with Efferdent and the other with neutral soap for 60 days (n = 10). After this period, all replicas were inserted in a chamber for accelerated aging of nonmetallic specimens. The color measurements were carried out initially, after disinfection, and after accelerated aging (252, 504, 1008 hours). Color stability was evaluated through spectrophotometry. The values were submitted to ANOVA and the means to Tukey's test (p < 0.01).

RESULTS

The specimens disinfected with neutral soap exhibited higher ΔE values regardless of the type of pigmentation. The colorless replicas and the specimens pigmented with ceramic exhibited a statistically significant difference between the methods of disinfection in all periods. The specimens pigmented with makeup powder did not demonstrate a statistically significant difference.

CONCLUSIONS

The ceramic pigment presented greater color stability regardless of disinfection and period. On the other hand, the makeup pigment exhibited the highest values of chromatic alteration.

Influence of opacifiers on dimensional stability and detail reproduction of maxillofacial silicone elastomer

BACKGROUND

We evaluated the influence of chemical disinfection and accelerated aging on the dimensional stability and detail reproduction of a silicone elastomer containing one of two opacifiers.

METHODS

A total of 90 samples were fabricated from Silastic MDX 4-4210 silicone and divided into groups (n = 10) according to opacifier content (barium sulfate or titanium dioxide) and disinfectant solution (neutral soap, Efferdent, or 4% chlorhexidine). The specimens were disinfected 3 times per week during 60 days and then subjected to accelerated aging for 1008 hours. Dimensional stability and detail reproduction tests were performed after specimens' fabrication (baseline), chemical disinfection and periodically during accelerated aging (252, 504, and 1008 hours). The results were analyzed using 3-way repeated-measures ANOVA and the Tukey HSD test (α = 0.05).

RESULTS

All groups exhibited dimensional changes over time. The opacifier (p = .314), period (p < .0001) and their interactions (p = .0041) affected the dimensional stability of the silicone. Statistical significant dimensional differences occurred between groups with (0.071) and without opacifiers (0.053). Accelerated aging influenced the dimensional stability of the samples. All groups scored 2 in the detail reproduction tests, which represents the fully reproducing of three test grooves with accurate angles.

CONCLUSIONS

Incorporation of opacifiers alters the dimensional stability of silicones used in facial prosthetics, but seems to have no influence on detail reproduction. Accelerated aging is responsible for most of the dimensional changes in Silastic MDX4 4210, but all dimensional changes measured in this study remained within the limits of stability necessary for this application.