Abstract
Delayed eruption of first permanent molars was examined on panoramic tomograms using Kunitake's age-eruption diagram. Eighty-four Japanese patients (37 male/47 female) out of 2,245 were screened as having delayed eruption. The cases revealed the following clinical findings.
1. One first molar or bilateral first molars were affected in 89.3% cases.
2. Tooth formation of the affected teeth was also retarded in 46.3% cases.
3. Delayed eruption was generally localized on first molars or molar segments. Only 9.5% of the patients had a delayed dental age.
4. Delayed formation or congenital missing of second molars proximal to the affected first molars were also found. The affected rate of maxillary second molars was 44.4%, while only 1.3% of mandibular teeth were found to be affected.
5. The shape and size of the affected first molar could be varied. Maxillary first molars with 3 cusps and 5 cusps were observed, and the affected group had a significantly smaller size of mandibular first molars.
6. Delayed eruption of first molars was associated with ectopic eruption in some cases. Tooth formation was not usually retarded.
