A 55-year-old man dislodges the crown at #14 twice recently (2 years 3 months post cementation) (Fig.4). There is 2nd caries distally (*). The clearance between the margin of prep and the crestal bone is .9 mm (Fig.2). Ideally it should be 2 mm (Fig.3). Therefore the bone should be trimmed (crown lengthening, Fig.4 (black area)) before taking impression for crown redo.
In fact the crown was reprep after 2nd crown dislodgement without crown lengthening. Instead, electrosurg was used to remove the distal gingiva. The hemorrhage was profuse. The impression was difficult to take.
When the patient returns for crown cementation, crown lengthening may be needed. After crown seating, take BW to determine the clearance. If it is not enough, the surgical procedure is to be done. What instruments should be prepared? The crown may be cemented before the last step of the surgery.
Xin Wei, DDS, PhD, MS 1st edition 03/12/2017, last revision 03/12/2017