Management of Advanced Peri-Implantitis by Guided Bone Regeneration in Combination with Trabecular Metal Fixtures, Two Months after Removal of the Failed Implants: Two-Year Results of a Single-Cohort Clinical Study

Abstract

Background: Implant replacement is among the treatment options for severe peri-implantitis. The aim of this single-cohort study was to evaluate the feasibility of replacing compromised implants affected by advanced peri-implantitis with new implants with a porous trabecular metal (TM) structure. Materials and Methods: Patients with one or more implants in the posterior region showing a defect depth >50% of implant length, measured from the residual crest, were consecutively included. Two months after implant removal, patients received a TM implant combined with a xenograft and a resorbable membrane. The implant stability quotient (ISQ) was measured at placement and re-assessed five months later (at uncovering), then after 6, 12, and 24 months of function. Marginal bone loss was radiographically evaluated. Results: Twenty consecutive cases were included. One patient dropped out due to COVID-19 infection, and nineteen cases were evaluated up to 24 months. At placement, the mean ISQ was 53.08 ± 13.65 (standard deviation), which increased significantly to 69.74 ± 9.01 after five months of healing (p < 0.001) and to 78.00 ± 7.29 after six months of loading (p < 0.001). Thereafter, the ISQ remained stable for up to 24 months (80.55 ± 4.73). All implants successfully osseointegrated and were restored as planned. After two years, the average marginal bone level change was -0.41 ± 0.38 mm (95% confidence interval -0.60, -0.21), which was limited yet significantly different from the baseline (p < 0.05). Conclusions: The treatment of advanced peri-implant defects using TM implants inserted two months after explantation in combination with guided bone regeneration may achieve successful outcomes up to two years follow-up, even in the presence of low primary stability.

Keywords: dental implants; guided bone regeneration; implant explantation; implant stability; osseointegration; peri-implantitis; surgical treatment.

Figure 1

(a) Radiograph of a compromised implant positioned in the right first molar region. Although less evident on the X-ray than in case 1, peri-implantitis is more severe. In fact, the depths are 8.4 mm mesially and 9.5 mm distally, measured from the crestal level and calibrated on the actual length of the implant (13 mm). It is probable that the original positioning of this implant was subcrestal. At the time of visit, bleeding on probing and inflammation of the gingiva around the crown were noted. (b) After implant removal, the width of the defect is evident. Calibrated on the real distance between the teeth, the size of the bone defect was 11.0 mm mesio-distally at crestal level and 6.2 mm at the middle and apical part.

Figure 2

Two months after implant removal. (a) Radiograph taken the day of insertion of the TM implant. After TM implant placement, the gap between the implant surface and the bone wall was filled with small particles for augmentation. To keep a distance of at least 1.5 mm from the implant surface to the buccal/lingual outer walls, a 4.7 × 11.5 mm implant was chosen. The ISQ values at placement were 54 and 53 in the vestibulo-lingual and mesio-distal directions, respectively, indicating a low primary stability. (b) After implant positioning, the gap all around the implant is visible. We chose to fill the gap only after implant positioning, to allow for the blood to fill the spaces of the trabecular structure, thus promoting the osseoincorporation process. (c) The augmentation material consisted of small particles (0.25–1 mm) of porcine bone, which were chosen to completely fill the defect without compression. (d) After the placement of a covering pericardium membrane, the flaps were closed without tension using PTFE suture, which was removed after 10 days.

Figure 3

(a) Periapical X-ray after 5 months at provisional crown delivery. After 6 months, the provisional crown was removed and the soft tissue was evaluated and the ISQ values were assessed at 74 and 72 in the vestibulo-lingual and mesio-distal directions, respectively (b). The final ceramic crown was delivered (c); no bone loss was visible (d).

Figure 4

After 2 years of loading, the ISQ values improved to 84 and 83 in the vestibulo-lingual and mesio-distal directions, respectively. The marginal bone level remained stable (as in the previous controls).

Figure 5

Study timeline and variables measured at each timepoint. ISQ = implant stability quotient; MBL = marginal bone level; pos = at implant positioning; T0 = at baseline.

Figure 6

Box-and-whiskers plot showing ISQ pattern up to 24 months of loading. ISQ = implant stability quotient; pos = at implant positioning; T0 = at baseline. The X inside the box represents the mean value.

Figure 7

Box-and-whiskers plot showing change in marginal bone level (MBL) pattern up to 24 months of loading. X is the mean value; the horizontal line is the median; upper and lower box limits are the 95% confidence intervals. Dots outside the whiskers represent data outside the 95% CI.