Changes of occlusal force and masticatory muscle activity with age in extremely low and very low birthweight infants

Abstract

The purpose of the present study was to investigate changes with age in the occlusal force and the masticatory muscle activity in extremely low birthweight (ELBW) and very low birthweight (VLBW) infants, longitudinally. The subjects were eight EVLBW (ELBW and VLBW combined) infants in Hellman's Dental Stage IIA (mean age: 5 years and 0 months) 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: mean age 5 years and 4 months, IIIA: mean age 8 years and 3 months). The occlusal force of EVLBW infants at dental stage IIA was 266.4 N and different from the standard value of 391.8 N, however, no difference was observed between EVLBW infants (565.2 N) and the standard value (520.0 N) at dental stage IIIA. 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. and that their parents or caregivers (hereafter "guardians") were anxious about child rearing immediately after birth. They often limited the child's voluntary behavior and were continuously overly concerned about the child's growth and development and diet. Regarding dental problems, ELBW and VLBW (EVLBW: ELBW and VLBW combined) infants are cared for in incubators in a neonatal intensive care unit (NICU), and are fed by nasogastric tube and by bottle for several months-this may have an influence on oral and maxillofacial anatomy, including dentition and the development of sucking and masticatory functions 3-6). Matsubara et al. (2005) 7) indicated that a short sucking cycle time, poor sucking pressure and unstable sucking rhythm