Submerging of deciduous molars was examined in 1,042 preschool children. The process of submerging was detected as early as the age of 3 years. First deciduous molars were affected more often than second deciduous molars. Submerging was more frequent in the mandible than in the maxilla. Differences were found between sexes and between age groups.The phenomenon of submerged teeth appears clinically as a disruption in the continuity of the occlusal plane of the dental arch. The distance from the marginal ridges of the submerged tooth to the existing occlusal plane can vary between fractions of a millimeter to complete "submerging" of the tooth within bone.Reports on the epidemiology of submerged teeth based on random samples are sparse, although the subject itself has received considerable attention in the literature. It is not clear at which age this local disturbance first becomes apparent clinically because most of the investigations on submerged teeth have been carried out with children older than 7 years of age.1-4

Periapical radiographs of 540 children with submerged and normal deciduous molars were checked for rate of deciduous root resorption and development of permanent successors. Statistical analysis showed no difference between the normal and submerged deciduous molars. The latter should not be extracted unnecessarily.

Bony ankylosis of submerged teeth has been related to delayed resorption of their roots as a result of congenital absence of the tooth buds of their successors (VORHIES ET AL, JADA 44: 68-73, 1952; BIEDERMAN, Am J Orthodont 48: 67-684, 1962). To verify this hypothesis, 270 children (115, 4 to 6 years old and 155, 7 to 10 years old) with submerged, cariesfree deciduous molars were selected from a random sample of 2,000 children (PECHT, unpublished DMD thesis, 1964; STEIGMAN, KOYOUMDTISKY-KAYE, and MA-TRAI, J Dent Res 52: 322-326, 1973) . A group of 270 children of comparable ages with normal molars from the same sample served as controls.Intraoral periapical radiographs of the deciduous molars of both groups were taken to determine the presence or absence of premolar buds. The rate of congenital absence of premolars was estimated for the combined sample, as well as for each of the groups. Congenital absence of premolars does not occur with the same frequency in first and second premolars, so frequency was analyzed separately for deciduous first and second molars of each group. The chisquare test was used for statistical evaluation.In the sample of 1,077 deciduous molars, the rate of congenital absence of premolar buds was 1.7%. Of the first premolars, 0.2 were missing; 3.3% of the second premolars were missing.To check the reliability of the sample as representative of a broader population, the findings were compared with reports in the literature Based on a thesis submitted to the Faculty of Dental Medicine in partial fulfillment of the requirements of the DMD degree.