[A study on interdental spaces of the deciduous dental arch in Indian sample]

The primate spaces are described as a genetic characteristic of all primate dentitions. In homo sapiens, they are limited to the deciduous dentition. We have now investigated the prevalence of primate spaces and interdental spaces in the deciduous dentition by sex and arch in samples from Indian children and the relationship between these spaces and other morphological characteristics of the deciduous dental arches. The samples were taken from 55 school children, 26 males and 29 females aged 5-7 years, belonging to the middle class of socio-economic status and living in New Delhi. The samples were taken during January of 1988. All were free of dental malformations, extractions or caries and a certain children had erupted permanent first molars. The result were as follows: 1. There was a wide variation in the pattern of the interdental spacing. The most common areas of spacing were mesial to the maxillary primary canine (primate spaces) and mesial to the mandibular primary canine (developmental spaces) for all ages. The mandibular primate spaces were considerably less frequent than the maxillary ones. The prevalence of primate spaces and developmental spaces were higher in the maxillary deciduous arch than in the mandibular deciduous arch. 2. Frequent distribution of the occlusal termination type were found to be more variable. The bilateral vertical terminal plane was found in about 50% at ages 5 to 6 of both sexes. The vertical terminal occlusal pattern existed even in the deciduous arches in which the first permanent molars had erupted. 3. The mesiodistal crown diameters of each deciduous tooth were greater in males than in females. The sex differences in mesiodistal crown diameters were significant for mandibular second deciduous molars. The sum of mesiodistal crown diameter in the closed deciduous arches was larger than in the spaced deciduous arches. 4. The dental arch increased slightly in width but decreased a little in length with changes in age during the deciduous dentition period. The deciduous arch diameters in the spaced arches were larger than in the closed arches. Statistically significant differences were found between the spaced arches and the closed arches for the mandibular anterior or posterior arch lengths and the anterior arch width for both arches. Generally, spacing of the deciduous arches was significantly related to the mesiodistal crown diameter, intercanine width and intermolar width, but there was no significant relationship to the eruption of the permanent first molars.