The influence of implant placement depth on peri-implant tissues in immediate implant placement: A randomized controlled clinical trial with 1-year follow-up.

Purpose

This clinical trial was carried out to compare the outcomes of immediate implants positioned 4 mm below free gingival margin versus deeper placement of 6 mm after a period of 1 year.

Materials And Methods

Seventy platform-switching implants with a Morse taper conical connection and 1 mm of machined neck were placed in a flapless approach in the molar or premolar region immediately after tooth extraction. A total of 35 implants were positioned 4 mm below the buccal gingival margin (control group), and another 35 were placed 6 mm below the gingival margin (test group). All implant sites were grafted with an allogenic bone substitute and received individual healing abutments (IHAs) made chairside. After 4 months, the implants were restored with final screw-retained zirconia restorations. Radiographic marginal bone loss (MBL) was measured at the delivery of the final restoration (T1) and after 1 year (T2). Peri-implant clinical parameters (probing depth [PD], bleeding on probing [BOP], and plaque index [PI]) were recorded at 1-year follow-up appointment (T2).

Results

In total, 70 implants were evaluated after 1 year of follow-up (35 control and 35 test groups). The test group showed significantly lower (p < 0.001) MBL than the control group at both T1 (mean ± standard deviation: 0.11 ± 0.32 vs. 0.76 ± 0.68 mm) and T2 (0.12 ± 0.23 vs. 0.54 ± 0.49 mm). The PD mean was 3.46 ± 0.74 in the control group and 3.49 ± 1.20 in the test group, with a p-value of 0.890. PI and BOP were also similar in both groups: PI-11% for the control and 8% for the test groups (p = 0.551), BOP-13% for the control and 7% for the test groups (p = 0.214).

Conclusions

Immediate implants placed 6 mm below the mid-buccal gingival level showed significantly less short-term (up to 1 year) MBL than immediate implants placed 4 mm below the gingiva.