On an OPG evaluation of a child, the following features were noted. 


Completion of the roots of the mandibular incisor teeth and near completion of the roots of the maxillary lateral incisors.
Great amount of root resorption of the primary canines and molars and root development of their permanent successors. 
Approximately one half of the roots of the mandibular canine and mandibular first premolar have been completed.
Nearly half the root of the upper first premolar was complete. 
Significant root development of the mandibular second premolar, maxillary canine, and maxillary second premolar.
 
What is the dental age of this patient ?
Dental age 10 is characterized by a greater amount of both root resorption of the primary canines and molars, and root development of their permanent successors. At dental age 10, approximately one half of the roots of the mandibular canine and mandibular first premolar have been completed; nearly half the root of the upper first premolar is complete; and there is significant root development of the mandibular second premolar, maxillary canine, and maxillary second premolar. Teeth usually emerge when three fourths of their roots are completed. Thus a signal that a tooth should be appearing in the mouth is root development approaching this level. It takes 2 to 3 years for roots to be completed after a tooth has erupted into occlusion. Another indicator of dental age 10, therefore, would be completion of the roots of the mandibular incisor teeth and near completion of the roots of the maxillary laterals.
7 years
9 years
10 years
12 years