A 68-year-old lady has had a lower right bridge for 10 years (Fig.1 (CBCT sagittal section)).  There is caries underneath #20 retainer (mesiolingual) with symptom.  The retainer and the pontic at #19 will be removed.  The tooth #20 may need root canal therapy.  An implant will be placed at #19.  The Inferior Alveolar Canal is indistinct.  The bone height seems to be enough, 17.57 mm, but since the crest is narrow (Fig.2), the implant length may not be promising.

Narrow Crest with Low Bone Density

Xin Wei, DDS, PhD, MS 1st edition 09/26/2015, last revision 09/26/2015