The purpose of this investigation was to study the relation between changes in amount of interdental space accompanying growth and development of deciduous dentition, plaque deposits and interproximal caries in deciduous maxillary anterior teeth, and to determine whether the presence or absence of interdental space is useful for dental health guidance. Oral examinations were carried out on the same 2074 children at the age of 1 year and 6 months and 3 years and 6 months in Nagasaki City in Japan. Interdental spaces were examined by inserting an explorer. About two thirds of the subjects showed no individual changes in the interdental spaces between the right and left central incisors in the upper jaw. In most of the remaining subjects, spacing occurred gradually.
Between the right and left maxillary deciduous central incisors, the proximal caries incidence in individuals with no space at the age of 1 year and 6 months was greater than that of those with space at the age of 1 year and 6 months. When there was no space at the age of 1 year and 6 months, the proximal caries incidence was related to plaque score. Between maxillary deciduous central incisors and lateral incisors, the proximal caries incidence was lower than between the maxillary deciduous central incisors and the proximal caries incidence was not affected by changes in amount of interdental space and plaque score. Between maxillary deciduous lateral incisors and canines, the proximal caries incidence was the lowest of the observed sites. It is important to take into consideration with deciduous dentition for caries prevention the space between the right and left maxillary deciduous central incisors.
