Masticatory performance with one missing molar.

PURPOSE: This study aimed to evaluate masticatory performance in cases where one molar was missing. METHODS: Participants were 156 adults with one molar missing from their natural teeth, who were divided into group A (without prosthetic treatment) and group B (with prosthetic treatment). The non-missing side was designated as A1 or B1, and the missing side was designated as A2 or B2. The amount of glucose eluted (AG) when the participants chewed a gummy jelly was measured and used as a parameter for masticatory performance. AG was compared between the non-missing side (A1, B1) and missing side (A2, B2), and between the first molar missing group and second molar missing group. RESULTS: AG was significantly greater on the dentate side (P < 0.001) and was significantly less in the A2 group when the first molar was missing (P = 0.002). The rate of decrease of AG was 11.1%, 14.3%, and 8.4% in groups A+B, A, and B, respectively. CONCLUSION: Masticatory performance appears to decrease even with only one missing molar. Although improvement is achieved by prosthetic treatment, performance remains inferior to that on the dentate side.

Path pattern and movement during mastication on habitual and non-habitual chewing sides.

PURPOSE: To clarify the presence or absence of differences in path pattern and movement during mastication between the habitual and non-habitual chewing sides. METHODS: Participants were 225 healthy adults with natural dentition. Mandibular movement while chewing gummy jelly on each side was recorded, and masticatory path pattern was classified into five types (one normal and four abnormal). The frequency of each pattern was measured and compared between chewing sides. The amount, rhythm, velocity, and stability of movement and masticatory performance were measured and compared between chewing sides. RESULTS: A normal pattern was observed on the habitual chewing side in 84.4% of participants. There was a significant difference between chewing sides in masticatory path pattern (χ2 = 35.971, P < 0.001). Values of parameters regarding the amount and velocity of movement and masticatory performance were significantly higher on the habitual chewing side. Values of parameters regarding rhythm and stability of movement were significantly lower on the habitual chewing side. CONCLUSION: The present findings of functional differences between chewing sides in terms of path pattern and movement during mastication suggest that these factors should be analyzed on the habitual chewing side.

Validity of analysis of masticatory movement using a two-dimensional mandibular movement recording device.

To clarify the validity of analysis of masticatory movement using a two-dimensional (2D) mandibular movement recording device, masticatory movements (pattern of movement path, opening distance, masticatory width, and cycle time) were compared between simultaneous recordings made by 2D and three-dimensional (3D) devices in healthy adults. The 2D device can perform the same level of mandibular movement analysis as the 3D device if the distance between LED and camera is fixed (15 cm), and the findings indicated the suitability of the 2D device for clinical application.

Usefulness of newly devised food intake score in removable denture wearers.

BACKGROUND: Although the food intake score (FIS) from conventional food intake questionnaires is widely used, the evaluation method, number of foods and food selection used in the questionnaire can be improved. OBJECTIVE: This study aimed to evaluate the usefulness of a newly devised FIS in removable denture wearers. METHODS: A total of 219 removable denture wearers were asked about their food intake, and three types of FIS (FIS1, FIS2 and FIS3) were calculated as subjective parameters. FIS1 and FIS2 are conventional FISs, while FIS3 is the FIS devised in this study. The amount of glucose extracted (AGE) when participants chewed gummy jelly was used as an objective parameter. The relationship between the three FISs and that between each FIS and AGE were investigated. Stepwise multiple linear regression analysis was performed with AGE as the dependent variable and age, sex and FIS as independent variables. RESULTS: The three types of FISs were positively correlated. A positive correlation was also found between FIS and AGE. The correlation coefficient was the largest in FIS2 and decreased in the order of FIS3 > FIS1; however, the values of FIS2 > FIS3 were similar. Multiple linear regression analysis revealed that sex and FIS were significantly associated with AGE. CONCLUSION: For denture wearers, the newly devised FIS3 was useful and evaluated masticatory performance, as well as or better than FIS1 and FIS2.

Masticatory path pattern and masticatory performance while chewing gummy jelly.

The purpose of this study was to clarify masticatory path pattern and masticatory performance during gummy jelly chewing. A total of 235 healthy adults were asked to chew gummy jelly for 20 s on each side, and the masticatory movement was recorded using a Motion Visi-Trainer (MVT V1). Next, the amount of glucose extraction was measured as a parameter of masticatory performance. The masticatory path was classified into one of five patterns newly devised: normal pattern (N, opening: straight or concave, closing: convex) and abnormal patterns (A1-A4). The number of occurrences of each pattern was investigated and compared by sex and path pattern. Next, masticatory performance was compared between the normal pattern and the abnormal patterns by sex. Pattern N was the most frequently expressed in 346 cases out of 470 cases (73.6%), followed by patterns A1, A4, A2, and A3 in that order. Regarding the number of patterns observed, pattern N was the most common in both sexes, followed by pattern A1, with no significant difference between sexes. The amount of glucose extraction in each pattern was the highest in pattern N for both sexes, followed by A2 and others in that order, and a significant difference was observed between the normal pattern and the abnormal patterns. From these results, the existence of sex difference in masticatory path patterns during gummy jelly chewing was not proven, and that masticatory performance was higher with normal patterns than with abnormal patterns.

Reference value of masticatory performance by measuring the amount of glucose extraction from chewing gummy jelly.

PURPOSE: The purpose of this study was to determine a reference value for masticatory performance (MP) by measuring the amount of glucose extraction (AGE) from chewing gummy jelly. METHODS: A total of 237 young adults (young group, 20-39 years), 147 middle-aged adults (middle-aged group, 40-59 years), and 177 older adults (old group, 60-87 years) participated in this study. All participants had natural dentition, excluding the third molars. AGE was measured when the participant chewed gummy jelly and used as a parameter of MP. AGE was compared among the three groups. Next, AGE in each group was compared between the habitual chewing side and non-habitual chewing side, and between males and females. The correlation between age and AGE was also investigated. RESULTS: AGE in the young, middle, and old groups were similar, and no significant differences were observed. AGE was significantly higher in the habitual chewing side compared to the non-habitual chewing side, and in males than that in females. No significant correlations were found between age and AGE. AGE in the habitual chewing side of all ages was 221.9 ± 34.4 mg/dL for males and 206.0 ± 28.7 mg/dL for females. The mean-2SD (standard deviation) value representing the reference value of healthy adults was 153.1 mg/dL for males and 148.6 mg/dL for females, which was close to 150 mg/dL. CONCLUSION: It was concluded that the reference value of masticatory performance as measured by the amount of glucose extraction after chewing gummy jelly was 150 mg/dL.

Comparison of two dental prescale systems used for the measurement of occlusal force.

The purpose of this study was to clarify the relationship between two types of dental prescale systems. Forty healthy subjects were asked to maximally clench for about 3 s, and the maximum occlusal force before and after cleaning was calculated using an Occluzer FPD707 for dental prescale (P1) and a bite force analyzing system for dental prescale II (P2). The maximum occlusal forces measured by P1 and P2 were compared before cleaning and after cleaning. Next, the relationship between the maximum occlusal force by P1 and maximum occlusal force by P2 was investigated. In addition, comparisons were made between males and females. The maximum occlusal force after cleaning was significantly smaller than before cleaning for both P1 and P2. The reduction rate of the occlusal force was 4.1% for P1 and 25.9% for P2. Significant linearity was observed between the maximum occlusal forces of P1 and P2 (regression linear equation: y = 1.191x - 30.521, r = 0.980, p < 0.001). The maximum occlusal forces measured by P1 and P2 were both significantly larger in males than in females. It was suggested that there was a certain relationship between the maximum occlusal forces measured by dental prescale and dental prescale II, suggesting that it is possible to compare the results of both by applying corrections using a regression equation.

Relationship between masticatory performance using a gummy jelly and masticatory movement.

PURPOSE: The purpose of this study was to clarify the relationship between masticatory performance using a gummy jelly and masticatory movement. METHODS: Thirty healthy males were asked to chew a gummy jelly on their habitual chewing side for 20s, and the parameters of masticatory performance and masticatory movement were calculated as follows. For evaluating the masticatory performance, the amount of glucose extraction during chewing of a gummy jelly was measured. For evaluating the masticatory movement, the movement of the mandibular incisal point was recorded using the MKG K6-I, and ten parameters of the movement path (opening distance and masticatory width), movement rhythm (opening time, closing time, occluding time, and cycle time), stability of movement (stability of path and stability of rhythm), and movement velocity (opening maximum velocity and closing maximum velocity) were calculated from 10 cycles of chewing beginning with the fifth cycle. The relationship between the amount of glucose extraction and parameters representing masticatory movement was investigated and then stepwise multiple linear regression analysis was performed. RESULTS: The amount of glucose extraction was associated with 7 parameters representing the masticatory movement. Stepwise multiple linear regression analysis showed that the opening distance, closing time, stability of rhythm, and closing maximum velocity were the most important factors affecting the glucose extraction. CONCLUSION: From these results it was suggested that there was a close relation between masticatory performance and masticatory movement, and that the masticatory performance could be increased by rhythmic, rapid and stable mastication with a large opening distance.