Effect of Primary Molar Extraction on Gingival Emergence of Succedaneous Tooth

¹ College of Dentistry, University of Iowa, Iowa City, Iowa

Specific aims of this report centered on (1) whether gingival emergence time of bicuspid teeth differed for subjects with bilaterally comparable primary molar teeth, one of which was extracted and the other exfoliated naturally, and (2) whether primary molar pathology, pulpotomy, space accessibility, and "early" or "late" extraction were of significance in succedaneous tooth eruption time.

The data were obtained from serial dental roentgenograms and casts (available at semiannual ages from early childhood to age 12 years and annually thereafter) and extraction records. The subjects were twenty North American Caucasian boys and girls.

When factors of age, tooth location, pathology, pulpotomy, available space, and extraction-eruption interval were disregarded, the mean age of bicuspid gingival emergence did not differ between the extraction and non-extraction sides of the dental arches.

The variance of the distribution of differences in eruption age for bicuspid teeth on extraction and non-extraction sides was found to be significantly greater than that occurring in a large group of subjects with no primary molar extractions.

There was no over-all correlation between age at molar extraction and the difference in eruption age of bicuspid teeth on the extraction and non-extraction sides of the dental arch.

Ten of eleven second bicuspid teeth on the extraction side erupted before the corresponding bicuspid teeth on the other side of the dental arch. The average interval was 8 months.

Accelerated bicuspid eruption on the extraction side was found for subjects in which primary molar extraction occurred within the 2 year period before successor eruption and when no molar pathology was present. Pathology of the primary first molar teeth (extracted more than 2 years before succedaneous eruption) was associated with retardation in age of emergence of first bicuspid teeth.

Bicuspid eruption was earlier on the extraction side in three instances of pulpotomy of the extracted primary molar tooth.

The over-all influence of space accessibility was minimal, but bicuspid eruption time on the extraction side may have been influenced by space inadequacy in a few instances.