Frekuensi Kasus Impaksi Molar Tiga Maksila Berdasarkan Klasifikasi Pell-Gregory, Winter, dan Hubungan dengan Sinus pada Radiograf Panoramik di RSKGM FKG UI = Frequency of Maxillary Third Molar Impaction Cases based on Pell-Gregory, Winter Classification, and it's Relationship to Sinus in Panoramic Radiograph at RSKGM FKG UI