Abstract
We studied the relationship between interdental spaces in deciduous dentition and arrangement of permanent dentition. We used 28 subjects whose deciduous dentition had been observed annually and had become permanent dentition, classifying them according to the total volume of interdental space in their deciduous dentition into Type I (spaced type), Type II (normal type) and Type III (closed type). Changes in deciduous dentition were compared among the three types. The results obtained were as follows:
1. Type I subjects exhibited no differences in dental arch, basal arch length (A-M1), or basal arch width (d-d) in either their maxillary or mandibular deciduous dentition or permanent dentition. The total volume of space and the degree of discrepancy decreased when the teeth became permanent in Type I patients. Type II patients displayed findings similar to those in the Type I cases in both maxillary and mandibular dentition. In Type III patients, the length of the anterior basal arch was shortened in both the maxillary and mandibular permanent dentition.
2. The volume of space in the deciduous dentition of the Type I cases decreased more in the maxillary dentition. There was a decrease in the Type II cases in the mandibular dentition, and a slight increase in the Type III cases.
3. There was a significant difference in the mandibular Leeway space in all three types, but no significant difference among them in maxillary Leeway space.
4. As far as the relationship between the individual types of deciduous dentition and the arrangement of the permanent dentition is concerned, maxillary arrangement was normal in 75% of the Type I cases,64.3% of the Type II cases and 50% of the Type III cases, and mandibular arrangement was normal in 80% of the Type I cases,92% of the Type II cases, and all the Type III cases.
5. When Type I and the normal group were compared with respect to the maxilla, dental arches and basal arches were found to be similar in each case. Dental arches and bassal arches of maloculusion groups are similar in shape to Type III.
6. Total volume of space in the deciduous dentition appears to be related to the development of the maxillary into normal permanent dentition. Volume of Leeway space appears to be related to the normal permanent dentition of the mandible.
