RESUMEN
We evaluated electromyograms of masticatory muscles after denture relining with soft and hard liners. In total, 44 patients with complete dentures were studied: 22 underwent chairside relining of mandibular dentures with a soft, silicone-based liner (Mucopren Soft); the other 22 underwent relining with a hard, acrylic resin-based liner (Kooliner). Electromyograms of the masseter and temporal muscles were obtained before (T0) and 90 days after (T90) relining. Participants performed a maximum voluntary contraction (static test), on which percentage-overlapping coefficient (%), mandibular displacement (%), and standardized electromyographic activity, i.e., impact, (µV / µVs %) were analyzed. Participants were also asked to chew a wafer, cereal bar, and peanuts (dynamic test) to determine symmetrical mastication index (SMI%), frequency (Hz), and impact. The data were analyzed using a generalized linear model (α= 0.05). On the static test, mandibular displacement was lower and impact was higher at T90, as compared with baseline. On the dynamic test, SMI and impact were higher after relining for all foods. Frequency at T90 was higher only during cereal and peanut mastication. There were no differences between groups except for greatest impact during wafer chewing in patients with hard liners. Relining with hard and soft materials increased electromyographic activity and improved masticatory function. There was little difference between groups.
Asunto(s)
Alineadores Dentales , Músculos Masticadores/fisiología , Anciano , Electromiografía , Humanos , Persona de Mediana Edad , SiliconasRESUMEN
OBJECTIVES: To evaluate the color stability and hardness of two denture liners obtained by direct and indirect techniques, after thermal cycling and immersion in beverages that can cause staining of teeth. MATERIAL AND METHODS: Seventy disc-shaped specimens (18 x 3 mm) processed by direct (DT) and indirect techniques (IT) were made from Elite soft (n=35) and Kooliner (n=35) denture liners. For each material and technique, 10 specimens were subjected to thermal cycling (3,000 cycles) and 25 specimens were stored in water, coffee, tea, soda and red wine for 36 days. The values of color change, Shore A hardness (Elite soft) and Knoop hardness (Kooliner) were obtained. The data were subjected to ANOVA, Tukey's multiple-comparison test, and Kruskal-Wallis test (P<0.05). RESULTS: The thermal cycling promoted a decrease on hardness of Kooliner regardless of the technique used (Initial: 9.09± 1.61; Thermal cycling: 7.77± 1.47) and promoted an increase in the hardness in the DT for Elite Soft (Initial: 40.63± 1.07; Thermal cycling: 43.53± 1.03); hardness of Kooliner (DT: 8.76± 0.95; IT: 7.70± 1.62) and Elite Soft (DT: 42.75± 1.54; IT=39.30± 2.31) from the DT suffered an increase after the immersion in the beverages. The thermal cycling promoted color change only for Kooliner in the IT. Immersion in the beverages did not promote color change for Elite in both techniques. The control group of the DT of Kooliner showed a significant color change. Wine and coffee produced the greatest color change in the DT only for Elite Soft when compared to the other beverages. CONCLUSION: The three variation factors promoted alteration on hardness and color of the tested denture lining materials.
Asunto(s)
Bebidas , Materiales Dentales/química , Alineadores Dentales , Resinas Acrílicas/química , Bebidas Gaseosas , Café/química , Color , Colorimetría , Dureza , Humanos , Inmersión , Ensayo de Materiales , Polimerizacion , Polimetil Metacrilato/química , Elastómeros de Silicona/química , Espectrofotometría , Propiedades de Superficie , Té/química , Temperatura , Factores de Tiempo , Agua/química , VinoRESUMEN
OBJECTIVES: To evaluate the color stability and hardness of two denture liners obtained by direct and indirect techniques, after thermal cycling and immersion in beverages that can cause staining of teeth. MATERIAL AND METHODS: Seventy disc-shaped specimens (18 x 3 mm) processed by direct (DT) and indirect techniques (IT) were made from Elite soft (n=35) and Kooliner (n=35) denture liners. For each material and technique, 10 specimens were subjected to thermal cycling (3,000 cycles) and 25 specimens were stored in water, coffee, tea, soda and red wine for 36 days. The values of color change, Shore A hardness (Elite soft) and Knoop hardness (Kooliner) were obtained. The data were subjected to ANOVA, Tukey's multiple-comparison test, and Kruskal-Wallis test (P<0.05). RESULTS: The thermal cycling promoted a decrease on hardness of Kooliner regardless of the technique used (Initial: 9.09± 1.61; Thermal cycling: 7.77± 1.47) and promoted an increase in the hardness in the DT for Elite Soft (Initial: 40.63± 1.07; Thermal cycling: 43.53± 1.03); hardness of Kooliner (DT: 8.76± 0.95; IT: 7.70± 1.62) and Elite Soft (DT: 42.75± 1.54; IT=39.30± 2.31) from the DT suffered an increase after the immersion in the beverages. The thermal cycling promoted color change only for Kooliner in the IT. Immersion in the beverages did not promote color change for Elite in both techniques. The control group of the DT of Kooliner showed a significant color change. Wine and coffee produced the greatest color change in the DT only for Elite Soft when compared to the other beverages. CONCLUSION: The three variation factors promoted alteration on hardness and color of the tested denture lining materials.
