| Co-Investigator(Kenkyū-buntansha) |
IINUMA Mitsuo Asahi University, School of Dentistry, Associate Professor, 歯学部, 助教授 (70184364)
HASEGAWA Shinobu Asahi University, School of Dentistry, Assistant Professor, 歯学部, 講師 (50278206)
NAKAOKA Yoshihiko Asahi University, School of Dentistry, Assistant, 歯学部, 助手 (50319125)
KONDO Tsuguko Asahi University, School of Dentistry, Assistant, 歯学部, 助手 (10350878)
西 英光 朝日大学, 歯学部, 助手 (90340083)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2003: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2002: ¥3,500,000 (Direct Cost: ¥3,500,000)
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| Research Abstract |
This project consisted of two studies. We first conducted a questionnaire study about the development of mastication of EVLBW (Extremely low and very low birthweight) infants aged 2 to 4 years in 1998, and results showed that they tended to "dislike firm foods", to be "picky eaters" and to have "trouble swallowing foods with a mouth full of food/drink", when compared with the normal birthweight (NBW) infants. The purpose of the first study is so designed to investigate moreover the development of masticatory function, the oral and facial shape, dental problems, and the relationship between systemic growth and these issues in EVLBW infants. We carried out a follow-up questionnaire study 5 years later in 2003 and compared current masticatory function among EVLBW infants, the low birthweight (LBW) and NBW infants. A significantly higher number of EVLBW infants were considered to be "small eaters", but no differences were found in the items : "picky eating", "dislike of firm foods" and "tr
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ouble swallowing foods with a mouth full of food/drink." This differed from a study conducted 5 years earlier. The guardians of the EVLBW infants were worried about language delay significantly and still worried about the shape of the child's head and face significantly more often. No significant differences were found in the results of dental screening in school. In conclusion, the guardians of the EVLBW infants felt that masticatory problems decreased as their children grew. The EVLBW infants were suggested to catch up with normal infants in masticatory function by early school age.
In the second study, changes with age in the occlusal force and the masticatory muscle activity in ELBW and VLBW infants were investigated, longitudinally. The subjects were eight EVLBW infants in Hellman's Dental Stage IIA (mean age : 5 years arid 0 month) and IIIA (mean age : 8 years and 3 months), and as controls eleven full-term infants who visited the Pediatric Dental Clinic of Asahi University for dental checkups (IIA : 5 years and 4 months, IIIA : 8 years and 3 months). The occlusal force of EVLBW infants 5 years previously was 234.9 N and different from the standard value of 391.8 N, however, there no difference was observed between EVLBW infants (565.1 N) and the standard value (520.0 N). Total muscle activity reduced with age and showed a tendency to be closer to the values of full-term infants. When changes with age in occlusal force and total muscle activity of EVLBW infants were investigated, occlusal force increased with age but total muscle activity decreased with age, suggesting a negative correlation. In conclusion, the results of the present study show that they gradually gain on the full-term children in masticatory function by the time of the deciduous dentition period, therefore, it is considered that problems in relation to eating behavior are temporary and that delayed masticatory function is normalized before catching up with the full-term children in systemic physical growth, i.e., 8 to 15 years of age. Less
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