One abutment at one time: non-removal of an immediate abutment and its effect on bone healing around subcrestal tapered implants.

OBJECTIVES

The aim of this prospective study was to assess the effects of abutment removal after 6 months on bone healing after the subcrestal placement of immediately restored, tapered implants in cases of partial posterior mandibular edentulism.

MATERIAL AND METHODS

Each of the 24 patients with partial posterior mandibular edentulism was consecutively treated with two immediately restored 3.5 mm diameter tapered implants. A total of 48 implants were placed in healed sites and immediately splinted with a temporary restoration, which was placed in such a way as to avoid occlusal contact. Twenty-four weeks after surgery, 12 patients underwent the standard prosthetic protocol: the abutments were removed and impressions were made directly on the implant platform. Twelve patients underwent the "one abutment at one time" protocol: impressions were made of the abutments using snap-on abutment copies. The final restoration was delivered approximately 6 months after implant insertion. Vertical and horizontal bone changes were assessed using periapical radiographs immediately after surgery and at 6-, 12-, 24- and 36-month follow-up examinations.

RESULTS

All implants osseointegrated and were clinically stable at the 6-month follow-up. No statistically significant difference was evidenced between the two groups regarding the measurement of vertical bone healing. A small but significant horizontal bone loss was evidenced in the hard tissue portion over the implant platform in the period of time between the 6-month and 1-year follow-up in the control group.

CONCLUSIONS

The non-removal of an abutment placed at the time of surgery results in a statistically significant reduction of the horizontal bone remodeling around the immediately restored, subcrestally placed, tapered implant in cases of partial posterior mandibular edentulism.