Ichiro Arakawa

The Nippon Dental University, Tokyo, Tokyo-to, Japan

Are you Ichiro Arakawa?

Claim your profile

Publications (12)3.92 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To clarify whether there might be a gender difference in masticatory performance in dentate adults. Thirty male subjects and thirty female subjects were asked to chew gummy jelly on their habitual chewing side for 10, 15 and 20s and the amounts of glucose extraction were measured. The changes of both glucose extraction and standardized glucose extraction from 10 to 20s were investigated differently for males and females. The amount of glucose extraction was compared between males and females for each chewing duration. In addition, in order to confirm a gender difference in occlusal force, the maximum occlusal force was compared between males and females. For both males and females, the amount of glucose extraction was lowest for 10-s chewing and increased significantly for 15-s and 20-s chewing. The mean standardized glucose extraction values increased in proportion with the duration of chewing. The standard deviations of the standardized glucose extraction were very small (below 0.02) for all chewing durations in both males and females. With regard to comparison of the glucose extraction between males and females, the amount of glucose extraction was significantly larger for males than for females for all chewing durations. The maximum occlusal force was significantly larger for males. It was suggested that it might be important to take into consideration gender-related differences while analyzing masticatory performance in dentate adults.
    Journal of prosthodontic research. 05/2012; 56(3):166-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to clarify whether differences in masticating conditions affected masticatory path stabilities of healthy subjects and TMD patients. Twenty healthy female subjects as the healthy group, and 20 female Temporomandibular Disorders (TMD) patients as the TMD group, were selected. Incisal point movement of during mastication of both masticating condition 1 (mc1; crispy bread chewed until swallowing on the free side) and masticating condition 2 (mc2; softened chewing-gum chewed for 20s on the habitual side) were recorded by MKG. As for mc1, out of all cycles during mastication only those cycles on the habitual chewing side were analyzed. As for mc2, the ten cycles from the fifth cycle were analyzed. For these analyzed sections, the indicators representing movement path stability were calculated and compared between the two groups. As for mc1, though the values of the indicators representing path stability were larger for the TMD group, there were cases where no significant differences were found between the two groups. As for mc2, the values were significantly larger for the TMD group (SDs; P<0.05, SD/ODs; P<0.01). From these results, it was suggested that the differences in masticating conditions affected the assessment of masticatory path stabilities of healthy subjects and TMD patients and the conditions should be considered for analyzing masticatory movement.
    Journal of prosthodontic research. 08/2011; 56(2):125-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to clarify whether there was a difference in the masticatory function between two masticatory path patterns: a convex closing path and a concave closing path. For 80 healthy subjects, the masticatory function (masticatory muscular activity, mandibular movement, and masticatory performance) when chewing a gummy jelly was recorded. Out of the 160 chewing cases (80 subjects chewing on either side), 65 cases (Group I) in which the incisal point opened in a linear or concave manner toward the working side and closed in a convex manner, and 15 cases (Group II) in which the opening path was the same as that in Group I, but the closing followed a concave path, were selected. For the masticatory function, the integral values per unit time of masseter and temporal muscular activities, the gape and masticatory width, the indicators representing the stability of movement path, and the glucose extraction from chewing gummy jelly were measured and compared between the two groups. The integral values of muscular activities and the amount of glucose extraction were significantly greater in Group I. The gape and masticatory width were not significantly different between the groups. The values of the indicators representing the stability of path were smaller in Group I than in Group II. From these results, it was suggested that there was a functional difference between Group I (with a convex closing path) and Group II (with a concave closing path), and that Group I had a superior masticatory function to Group II.
    Journal of prosthodontic research. 08/2009; 53(3):142-5.
  • Source
    Journal of Prosthodontic Research 04/2009; 53(2):101.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study is to clarify whether the state of occlusal contact on lateral excursion is related to the pattern of masticatory movement path. The masticatory movement during mastication of softened chewing gum and the occlusal contact on lateral sliding of the mandible by 1 mm (L1), 2 mm (L2) and 3 mm (L3) were recorded in 50 healthy subjects. The path of masticatory movement was classified into one of seven patterns. The number of teeth involved in the occlusal contact in each pattern was investigated and compared among different lateral occlusal positions. The occlusal contact was then classified into 15 types based on one or a combination of the following four regions; incisal region, canine region, premolar region and molar region. The number of occlusal contact type for each pattern was investigated and compared among patterns. The number of teeth involved in occlusal contact decreased as the degree of lateral excursion increased, and significant differences were observed among the lateral occlusal positions (P < 0.001). The occlusal contact tended to decrease in the molar region and increase in the canine or premolar regions as the degree of the lateral excursion increased. When comparing among patterns, significant differences were observed at L2 and L3 (L2; P < 0.001, L3; P = 0.030) but not at L1 (P = 0.318). The difference was remarkable at L2. It was suggested that the state of occlusal contact at L2 and L3, particularly at L2 was related to the masticatory path pattern.
    Journal of Oral Rehabilitation 02/2009; 36(4):250-6. · 2.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To clarify the masticatory path patterns of the mandibular incisal point during mastication of softened chewing gum with regard to gender difference. One hundred healthy subjects (50 males and 50 females) were asked to chew softened chewing gum on one side at a time (right side and left side) and the movement of the mandibular incisal point was recorded using MKG K6I. After a catalog of path patterns was made, the movement path was classified into one of the pattern groups, and then the frequency of each pattern was investigated. A catalog of path patterns consisting of the three types of opening path (op1, linear or concave path; op2, path toward the chewing side after toward the non-working side; op3, convex path) and two types of closing path (cl1, convex path; cl2, concave path) was made. The movement path was classified into one of seven patterns, with six patterns being from the catalog and a final extra pattern in which the opening and closing paths crossed. The most common pattern among the subjects was Pattern I, followed by Patterns III, II, IV, V, VII, and VI, in that order. The majority of cases, 149 (74.5%) of 200 cases, showed either Pattern I (op1 and cl1) or Pattern III (op2 and cl1). There was no significant difference between the two genders in the frequency of each pattern. The movement path could be classified into seven patterns and no gender-related difference was found in the frequency of each pattern.
    Journal of prosthodontic research. 02/2009; 53(1):11-4.
  • [Show abstract] [Hide abstract]
    ABSTRACT: To clarify the usefulness of the standard deviation (SD) and SD divided by the opening distance (SD/OD) of the opening lateral, closing lateral, and vertical components of the masticatory path as indicators of the stability of masticatory movement path. Fifty subjects masticated softened chewing gum on the unilateral side for 20s, and the movement of the mandibular incisal point was recorded. For 10 cycles from the 5th cycle of 100 cases (50 subjects chewing on either side), a picture comprising each cycle path was displayed and classified subjectively into three categories (stable, unstable, and unknown) by three evaluators. The 18, 17, and 19 cases that were assessed as stable, unknown, and unstable were classified as Groups A, B, and C, respectively. For 10 cycles from the 5th cycle, the SD and SD/OD of the opening lateral, closing lateral, and vertical components representing the movement path as indicators for the stability of the path were calculated and compared among the three groups. The SD and SD/OD of the opening lateral, closing lateral, and vertical components were small in Group A, increased in Group B, and increased further in Group C. Significant differences were observed among the groups. These differences were more apparent in the assessment using the SD/OD than in the assessment using the SD. The SD and SD/OD of the components representing the movement path were useful as indicators for the stability of the movement path and the SD/OD appeared to be particularly useful.
    Journal of prosthodontic research. 02/2009; 53(1):48-51.
  • Prosthodontic Research & Practice 01/2008; 7(1):55-59.
  • Prosthodontic Research & Practice 01/2007; 6(2):127-131.
  • Prosthodontic Research & Practice 01/2006; 5(1):15-20.
  • Prosthodontic Research & Practice 01/2006; 5(2):104-108.
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to find the most suitable food and chewing side for evaluating the stability of masticatory movement, three types of food with varying textures, as well as both free chewing and unilateral chewing, were utilized in analyzing the masticatory path during mastication. A piece of chewing gum, one peanut, and a slice of crispy bread were used as test foods. For 20 healthy subjects, movement of the incisal point while masticating a test food for 10 s on the free side and the habitual side was recorded. Indicators representing movement path stability were calculated and compared among the foods and between the chewing sides. Masticatory movement was most stable when masticating chewing gum, and less stable for the peanut, and most unstable for the crispy bread. There was a statistically significant difference between each pair of foods for almost all of the indicators. The indicators for peanut were approximately 1.5 times larger than those for masticating chewing gum and the indicators for crispy bread were double those for the chewing gum. When comparing free chewing with unilateral chewing, the masticatory movement of unilateral chewing was significantly more stable than that of free chewing for all test foods. From these results it was suggested that, for evaluating masticatory movement path stability, the most suitable type of food was softened chewing gum and the most suitable chewing method was unilateral chewing on the habitual chewing side.
    Odontology 10/2003; 91(1):26-30. · 1.58 Impact Factor