Nonremoval of immediate abutments in cases involving subcrestally placed postextractive tapered single implants: a randomized controlled clinical study

The aim of this trial was to assess if the nonremoval of abutments placed at the time of surgery would improve bone and gingival healing around single immediately restored implants placed in postextraction sockets.

All patients received a single square-threaded tapered implant placed in postextraction sockets and immediately restored. All the implants were placed 2.0 mm below the bone crest, avoiding any contact with the coronal portion of the buccal wall. Six months after surgery, 35 patients were treated following the control standard prosthetic protocol: the abutments were removed and impressions were made directly on the implant platform. Thirty-three patients underwent the "one abutment at one time" test protocol: impressions were made of the abutments using snap-on abutment copies. The dimensional changes of the soft and hard tissues were assessed using digital photography and cone beam computed tomography radiographs immediately after surgery and at 6-, 12-, and 24-month follow-up examinations.

All implants were osseointegrated and clinically stable at the follow-up examinations. No statistically significant difference was evidenced between the two groups regarding the measurement of vertical bone healing. After the placement of the final restoration, a significant horizontal loss in the hard tissue portion over the implant platform was assessed (p = .03 mesial sites; p = .04 distal sites). An 87% increase of the mean recession of the buccal soft tissue was observed in the control group (+0.27 mm) in the same time frame.

The nonremoval of abutments placed at the time of the surgery improves the stability of healed soft and hard tissues around the immediately restored, subcrestally placed tapered single maxillary implant.