Objective: To observe the crystal character of the attached end and free end of dentalcalculus.
目的：观察牙结石附着面和游离面晶体构型的差异。
2
The detection rates of gingival bleeding, dentalcalculus, periodontal pocket and periodontal attachment loss were 93.
牙龈出血、牙石、牙周袋、牙周附着丧失的检出率分别为93。
3
Results 15-year-old group is significantly higher than 12-year-old group in gingival bleeding detection frequency; dentalcalculus detection frequency and average section count.