The color of the chewing gum changed over a wide range, which was sufficient to evaluate the masticatory performance of individuals with natural dentition and those with complete dentures. Changes in the color values of the gum reliably reflected masticatory performance. These findings indicate that the color-changeable chewing gum will be useful for evaluating masticatory performance under any dental status.
The purpose of this study was to investigate the relationship between masticatory performance as determined using a colour-changeable chewing gum and mandibular movements. Subjects comprised 45 fully dentate adults (23 men, 22 women; mean age, 28·1 years). The gum was chewed for a specified number of chewing strokes (20, 40, 60, 80, 120 or 160 strokes) without any instructions as to chewing side. A colourimeter was used to measure L*, a* and b* values (CIE-L*a*b* colour system) for the chewed gum, then the difference between two colours in the CIE-L*a*b* colour space (ΔE) for each number of chewing strokes was calculated according to a formula. Index of masticatory performance (ΔE60) for each subject was obtained using ΔE for 20, 40, 60, 80, 120 and 160 strokes. Mandibular movements were recorded using an opto-electric system with six degrees of freedom. Twelve parameters of mandibular movements relating to amplitude, duration, velocity and angle were computed for each cycle, and mean values for 10 cycles (from cycle 11 to 20) were calculated separately. Stepwise multiple regression analysis identified maximum closing velocity and closing angle as predictors accounting for 18% of the variation in ΔE60. These results suggest that lower angles of approach to intercuspation and faster speed during closing duration are associated with colour changes in the colour-changeable chewing gum.
Soft denture lining materials are required to be minimally contaminated from the viewpoint of oral hygiene. The experimental materials containing fluorinated monomers showed high flexibility and high contamination resistance. The use of monomers with a large number of fluorine atoms could give clinically-useful properties to these materials. AbstractPurpose: To develop a new fluorine-containing soft denture lining material, the influences of fluorinated monomers on physical properties and contamination resistance were examined. Methods:Five experimental materials of different chemical compositions in fluorinated monomer and two plasticized acrylics (Supersoft, VertexSoft) were used to evaluate water sorption, solubility, staining resistance, Shore A hardness, and contact angle. Five specimens for each test were fabricated. The results were analyzed with one-way analysis of variance (ANOVA) and Tukey's HSD test using statistical software at p = 0.05. Results: The amount of water sorption tended to decrease as the number of the fluorine atoms in fluorinated monomers increased. Similar solubility was shown regardless of the type of fluorinated monomer. The use of fluorinated monomers for immersion in coffee allowed suppression of discoloration. In b-carotene, there were no significant differences in color changes among four experimental materials with fluorinated monomer. Shore A hardness was decreased and the contact angles tended to increase as the number of fluorine atoms in fluorinated monomers increased. When comparing the experimental materials and commercially available materials, the experimental materials containing fluorinated monomers with large numbers of fluorine atoms showed adequate clinical properties except for staining test of b-carotene. Conclusion:Monomers with a large number of fluorine atoms can be used to develop applicable soft denture lining materials in clinical practice.
: An occlusal diagnostic system was evaluated for clinical applications.This system consists of pressure sensitive sheets (DENTAL PRESCALE (R), Fuji Photo Film Co.) and the analyzing computer (OCCLUZER FPD 703 (R), Fuji Photo Film Co.). Effects of velocity and duration of pressure and temperature upon color forming of pressure sensitive sheets were examined. While simulating intraoral applications, the accuracy of this system was examined using maxillary and mandibular casts.The results were as follows:1. There was no effect velocity of pressure and temperature upon color forming.2. There was no statistical difference in color forming between the sheets pressed of one second and five seconds. But the sheets pressed for ten seconds showed higher color forming than the sheets pressed for one second.3. When the forces measured by this system were subtracted from the load on the maxillary and mandibular casts, the mean values of the remainders were -0.68 kgf (Type-R, 30H) and -0 .65 kgf (Type-R, 50H). The standard deviations were 1.57 kgf (30H) and 1.09 kgf (50H).
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