Question

"Patient: Male, 22-years

Chief complaint: Requests routine checkup.
Background: Recently moved to your town and seeks regular care. He has no relevant medical history.
Current Findings: The patient has good oral hygiene and low caries experience. Several of his posterior teeth have been fissure sealed. You notice that his tooth #T is present, so that in this quadrant there appears to be one premolar, and three molars. Radiographs show that all third molars are absent, and there are no unerupted teeth. The patient was aware that he still had a ""baby tooth"", but it has never bothered him.

The retained deciduous molar indicates the absence of tooth;
a. 28
b. 20
c. 29
d. 21"

Answer 1

The retained deciduous molar likely indicates the absence of its adult successor, which in the Universal Numbering System corresponds to tooth #20, the second premolar in the lower left quadrant.

Step-by-step explanation:

The retained deciduous molar in the patient's case likely indicates the absence of the adult tooth that would normally replace it. Considering the fact that tooth #T is a deciduous molar and given that there is the presence of only one premolar and three molars in that quadrant without any radiographic evidence of unerupted teeth, it is reasonable to deduce that the corresponding permanent premolar tooth, which should have replaced the deciduous molar, is absent.

The tooth numbering system used follows the Universal Numbering System, which is widely utilized in the United States, where tooth #20 is the adult second premolar in the lower left quadrant. Hence, since tooth #T is a deciduous molar and is retained, this suggests that the permanent tooth that is absent, and should have replaced the deciduous molar, is the adult second premolar, which according to the Universal Numbering System is tooth #20.