1. 2.2 Pericoronal radiolucencies
Dental Follicle
2-2-2 Pericoronitis
2-2-3 Paradental Cyst
2-2-4 Dentigerous Cyst
2-2-5 Mural ameloblastoma
2-2-6 AOT

2. 2-2-1 Dental follicle ＊ Well-defined, unilocular,
round-shaped radiolucence
＊ A well-corticated margin
＊ Surround the crown of
an impact tooth
＊ Size

3. 2-2-1 Dental follicle ＊dental follicle：a supporting tissue
in the period of tooth developing
＊cap stage、bell stage
＊impaction of upper canine

4. 2-2-2 Pericoronitis ＊locate at distal aspect of lower 3rd molar
＊extend from distal aspect of the lower 3rd molar’s crown to the ramus of mandibular bone
＊radiolucence
poor-defined
＊surrouned by：
soft tissue (gingiva)
the crown of tooth 38.

5. 2-2-2 Pericoronitis ＊Site：distal aspect of lower 3rd molar
＊The space for developing lower 3rd molar is not enough.
＊Failure degeneration of enamel epithelium
(臨時ppt)