Flapless dental implant surgery may improve hard and soft tissue outcomes

Two hundred forty-one patients (108 men, 133 women, age range 19-73 years, mean age 54 years) were recruited from a single clinic at the Wonju College of Medicine, Yonsei University, Seoul, South Korea. Patients were included who needed single tooth replacements or partial-arch or full-arch reconstruction. A total of 432 implants were placed; most patients (50%) received single implants, and 31% received 2 implants, 14% received 3 implants, and 5% received 4 or more implants. Most implants (42%) were placed in the mandibular first molar position. Patients were systemically healthy with good periodontal health, although patients with mild to moderate gingivitis were included. Patients requiring ridge augmentation or bone grafts were excluded.

All patients had Osstem GSII bone level implants placed under local anesthetic. Access through the soft tissues was achieved using a 3-mm tissue punch over the crestal bone site. The implant osteotomy was performed through this soft tissue access. A range of sizes of implants was used (3.5-, 4.0-, 4.5-, or 5.0-mm diameter), with lengths ranging from 8.5 to 15.0 mm. A 1-stage surgical procedure was used with healing abutments connected to the implant fixtures. The surgery was performed by experienced senior clinicians. Restoration of the implants was undertaken at 3 to 4 months after surgery by restorative dentists using screw-retained metal-ceramic or metal-resin prostheses.

Gingival soft tissues were evaluatedby a single clinician at 12 months after the surgical placement. The following were measured: probing pocket depth, gingival index, bleeding on probing, and the presence or absence of keratinized mucosa around the implants. The thickness of the soft tissue overlying the bone at the osteotomy site was also measured at the time of surgery. The crestal bone levels were assessed using digitized images at ×8 magnification of conventional intraoral dental radiographs taken at baseline, postoperatively, and 12 months later. Measurements were made at the mesial and distal aspects of the implant fixture and the mean per case was calculated. Two assessors who were blinded to the methods of the intervention undertook the measurements.

At 1 year, the mean pocket probing depth was 2.1 mm (SD 0.7), bleeding on probing index was 0.1 (SD 0.3), and the average gingival index score was 0.1 (SD 0.3). Keratinized mucosa was absent around the buccal gingival surface in only 6 implants. There was a 100% survival of the implants, and with maximal crestal bone loss recorded at 1.1 mm, according to Albrektsson et al's success criteria,(1) a 100% success rate. The mean marginal bone loss was 0.3 mm (SD 0.4 mm, range 0.0 to 1.1 mm), with 125 implants exhibiting no bone loss. There was no significant difference in bone loss between those cases with thick (≥3 mm) compared with those with thinner (<3 mm) overlying mucosa.

The authors concluded that a flapless surgical procedure for dental implant placement is advantageous for preserving crestal bone and mucosal health, and that this technique increases the success rate of dental implants.