67.病人左下第二小臼齒處腫脹疼痛,X光檢查結果如圖,其左下第二小臼齒有何形態異常? (A)第一型牙本質發育不良(dentin dysplasia type I) (B)雙生齒(gemination) (C)齒中齒(dens invaginatus) (D)齒外齒(dens evaginatus)