The original sample in this investigation included 48 children within the age groups of seven to eight years that the majority of extractions occured (by J. A. Maclaughlin), at the beginning of the study. The examinations were conducted every six months for one year. In order to evaluate the changes of adjacent teeth and dental arch following the premature loss of the mandibular primary first and second molars, measurements were taken from the study casts.
The results were as follows;
1. The primary molars, especially the primary second molar should be maintained in a healthycondition to support the integrity of dental arch and permit normal eruption of permanent teeth.
2. Space in premature loss of the primary second molar was decreased 1.0mm greater after six months, 1.5mm greater after 12 months than the case in the primary first molar.
3. Mandibular arch length was continually increased between the ages of seven to nine, but in premature loss of the primary first molar, arch length was increased about two times more than the case in the primary second molar.
4. Mandibular arch width was scarcely changed, however the width in premature loss of primary first molar was increased just a little more than the case in the primary second molar.
5. Maxillaryarch length and width were continually increased between the ages of seven to nine.
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