Evaluation of interface pressure and temperature management in five wheelchair seat cushions and their effects on user satisfaction.

BACKGROUND: Factors such as the manufacturing materials, shape or even the mechanical and thermal response of sitting Pressure Redistribution Support Surfaces (PRSS) can be potential contributors to pressure ulcers. However, few studies have compared a number of characteristics of the most frequently used devices. OBJECTIVE: To compare three potential contributors to pressure ulcers in five commercial PRSS: pressure redistribution, temperature and perceived comfort. METHOD: Study with a cross-over randomized design in healthy volunteer participants. Data was collected in a temperature and relative humidity controlled environment. To assess thermal response, the temperature (Flir-E60) of the region of interest was captured before and after use of each PRSS for further analysis. The region of interest was the gluteal zone. To assess the pressure redistribution a pressure mat (XSensor®) was used between the 5 cushion and each study participant using a standardized method. Finally, a subjective perception questionnaire recorded comfort, adaptability and thermal sensation parameters. Data analysis levels of significance were set at 0.05. RESULTS: A total of 22 participants completed the assessments. There were no statistically significant differences in baseline temperatures between PRSS (>0.05). Pressure redistribution analysis showed significant differences between all PRSS in all variables evaluated except in the maximum and peak pressure index al sacrum. The subjective assessment suggested no major user-perceived differences between PRSS. CONCLUSION: Seat cushions made of open cell polyurethane foam blocks of variable hardness and the horseshoe cushion (also open cell polyurethane foam) seem to provide a more effective pressure relief characteristic than those injected with polyurethane foam and gel in most of the studied pressure variables. However, the cushions provide similar thermal response and perceived comfort.

Denture Liners: A Systematic Review Relative to Adhesion and Mechanical Properties.

PURPOSE: The objective of this systematic review is to compare results concerning the properties of adhesion, roughness, and hardness of dental liners obtained in the last ten years. METHODS: Searches on the databases LILACS, PubMed/Medline, Web of Science, and Cochrane Database of Systematic Reviews were supplemented with manual searches conducted between February and April of 2018. The inclusion criteria included experimental in vitro and in vivo, clinical, and laboratory studies on resilient and/or hard liners, assessment of hardness, roughness, and/or adhesion to the denture base, and physical/mechanical changes resulting from the disinfection process and changes in liners' composition or application. RESULTS: A total of 406 articles were identified and, from those, 44 are discussed. Twenty-four studies examined the bond strength, 13 surface roughness, and 19 the hardness. Of these 44 studies, 12 evaluated more than one property. Different substances were used in the attempt to improve adhesion. Considering roughness and hardness, the benefits of sealants have been tested, and the changes resulting from antimicrobial agents' incorporation have been assessed. CONCLUSION: Adhesion to the prosthesis base is improved with surface treatments. Rough surfaces and changes in hardness compromise the material's serviceability.

A Prospective Randomized Clinical Trial of a Novel, Noninvasive Perfusion Enhancement System for the Prevention of Hospital-Acquired Sacral Pressure Injuries.

PURPOSE: The purpose of this study was to determine the effectiveness of a novel, noninvasive perfusion enhancement system versus beds with integrated alternating pressure capabilities for the prevention of hospital-acquired sacral region (sacral, coccygeal, and ischium) pressure injuries in a high-risk, acute care patient population. DESIGN: A prospective randomized trial of high-risk inpatients without preexisting sacral region pressure injuries was conducted. SUBJECTS AND SETTING: The sample comprised 431 randomly enrolled adult patients in a 300-bed tertiary care community teaching hospital. METHODS: Subjects were randomly allocated to one of 2 groups: control and experimental. Both groups received "standard-of-care" pressure injury prevention measures per hospital policy, and both were placed on alternating pressure beds during their hospital stays. In addition, patients in the experimental group used a noninvasive perfusion enhancement system placed on top of their alternating pressure beds and recovery chairs throughout their hospital stay. Fischer's exact probability test was used to compare group differences, and odds ratio (OR) were calculated for comparing pressure injury rates in the experimental and control groups. RESULTS: Three hundred ninety-nine patients completed the trial; 186 patients were allocated to the experimental group and 213 patients to the control group. Eleven patients in the control group versus 2 in the experimental group developed hospital-acquired sacral region pressure injuries (51.6% vs 1.07%; P = .024). Control patients were 5.04 times more likely to develop hospital-acquired sacral region pressure injuries (OR = 0.1996; 95% CI, 0.0437-0.9125). CONCLUSIONS: Patients using a noninvasive perfusion enhancement system developed significantly fewer hospital-acquired sacral pressure injuries than those using an alternating pressure bed without the perfusion enhancement system. These findings suggest that a perfusion enhancement system enhances the success of use of pressure redistributing beds for prevention of hospital-acquired sacral pressure injuries.

Effect of incorporating seed oils on the antifungal property, surface roughness, wettability, weight change, and glucose sorption of a soft liner.

STATEMENT OF PROBLEM: The colonization of Candida albicans on soft liners causes the deterioration of material surface properties and denture stomatitis. PURPOSE: The purpose of this in vitro study was to investigate the effect of incorporating seed oil on the antifungal properties, surface roughness, wettability, weight changes, and glucose adsorption/absorption of a soft liner. MATERIAL AND METHODS: Centratherum anthelminticum, Ocimum sanctum Linn, and Linum usitatissimum seed oils were incorporated into a soft liner, and the diameter of the inhibition zone (DIZ) was calculated relative to the growth of C albicans at 24, 48, and 72 hours and 7 days. The effect of incorporating oil on wettability was evaluated with the contact angle analyzer, and effect on surface roughness was evaluated with scanning electron microscopy. Weight changes and absorption/adsorption of glucose to the soft liner were estimated. Data were analyzed by using paired Student t tests and 2-way ANOVA (α=.01). RESULTS: Soft liner with 800 µL each of C anthelminticum and O sanctum oils showed complete inhibition at 72 hours; the DIZ on day 7 were 31.66 ±1.20 mm and 29.66 ±1.46 mm, respectively. The change in weight between time intervals differed significantly between conditions (P<.01). The addition of oils decreased the surface roughness and improved wettability significantly for O sanctum and C anthelminticum specimens (P<.01). At 72 hours, 5.5 mg of glucose was detected in the positive control, whereas no glucose was detected in the oil specimens. CONCLUSIONS: The addition of the seed oils of C anthelminticum and O sanctum to the soft liner significantly reduced the growth of C albicans, improved wettability, reduced surface roughness, and minimized the absorption and adsorption of glucose.

Dynamic viscoelastic properties of vinyl polysiloxane denture soft lining materials.

The aim of this study was to investigate the dynamic viscoelastic properties of seven commercially available vinyl polysiloxane denture soft lining materials. Five rectangular specimens (2 x 10 x 30 mm) were prepared from each material. The complex modulus E* (MPa) and loss tangent (tan delta) of each specimen were determined with a non-resonance forced vibration method using an automatic dynamic viscoelastometer at 1 Hz after 1 day of dry storage, and after 1, 30, 60, 90 and 180 days of wet storage at 37 degrees C. All data were analysed using one-way anova and Bonferroni/Dunn's test for multiple comparisons with a significance level of P < 0.01. All materials varied widely in terms of viscoelasticities and showed both an increase in E* and a decrease in tan delta at 1 Hz after the 1-day wet storage. After 60 days of wet storage, both E* and tan delta did not change significantly. The stiffer materials (>30% filler content) with high E* values (>2.00 MPa) showed elastic behaviour with tan delta values of around 0.03. The softer materials (6% filler content) with high tan delta values (initial value > 0.10) showed viscous behaviour and were easily affected by water absorption after the 1-day wet storage. It can be concluded that for the proper selection of vinyl polysiloxane denture soft lining materials, it is very important to evaluate the viscoelastic properties after 60 days of wet storage.

Durability of peel bond of resilient denture liners to acrylic denture base resin.

PURPOSE: The purpose of this study was to determine the durability of the peel bond of commercial resilient denture liners to a denture base resin using a thermal cycling test. METHODS: Eight commercial resilient denture liners (five silicone and three acrylic) were used in the study. The samples were exposed to thermal cycles between 5°C and 55°C for 1 min for 0, 1,250, 2,500, 5,000 and 10,000 cycles. The test samples were placed under tension until failure in a materials testing machine using a crosshead speed of 20 mm/min. The modes of debonding were characterized as tear, peel or snap. Statistical analysis was performed using one-way and two-way analysis of variance and Student-Newman-Keuls multiple comparison tests (α=.05). RESULTS: A significant difference was found between different resilient denture liners for peel bond strength at 0 cycles. No extreme influence on the peel bond strength was observed under any of the thermal cycles. The snap mode of debonding was observed in most samples of all materials for all cycles. CONCLUSION: All resilient denture liners tested had a sufficiently strong bond to the denture base resin. Within the limitations of this study, the results show that all of the materials were acceptable for clinical use, having met the accepted adequate bond strength for resilient denture liners of 0.45 MPa.

[Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin.

Color stability of long-term soft denture liners.

The use of resilient denture liners in complete denture construction has become increasingly popular for providing comfort for denture wearers. The primary disadvantage of these materials is that the physical and mechanical properties change rapidly with time in a service environment. The purpose of this study is to evaluate the color stability of five commercially available soft denture liners as a function of accelerated aging. Color measurements were made before aging with a colorimeter and data processor. The samples were then weathered for 100 hours in an accelerated aging chamber in the presence of a xenon ultraviolet visible-light source, an intermittent water spray at 110 degrees F, and 90% humidity. After aging, color measurements were made again and color differences (delta E) were calculated. Results were statistically tested with analysis of variance and Scheffé intervals were calculated at 0.96. It was concluded that accelerated aging can be used to evaluate color stability of soft denture liners.

Consistency and softness of soft liners.

Consistency is evaluated by an initial flow test that allows the clinician to select the material of choice for relining procedures according to the size and shape of the ridge and the condition of the soft tissue. In this study, the consistency of four autopolymerized soft liners was compared and tested to determine whether they meet the new International Standards Organization (ISO) 10139-1 specifications. Softness, assessed with a Shore A durometer, was compared with that of two heat-cured silicone soft liners, because the latter are known for their steady softness over long periods of time. The consistencies of all four autopolymerized soft liners complied with ISO specifications and their disk diameter ranged from 41.3 to 72.2 mm. The softness of all four soft liners changed with time, unlike the silicones whose softness remained consistent. Softness readings varied significantly with sample thickness and indicated the need to develop criteria for measuring softness properties and determining the minimal thickness required for clinical performance.