Assessment of peri-implant tissue dimensions following surgical therapy of advanced ligature-induced peri-implantitis defects

Abstract

Background: To evaluate peri-implant tissue dimensions following implantoplasty and/or regenerative therapy of advanced ligature-induced peri-implantitis in dogs.

Material and methods: At all defect sites (n = 6 dogs, n = 48 implants), the intrabony component was filled with a particulate bovine-derived natural bone mineral (NBM). The supracrestal component was treated by either the application of an equine bone block (EB) or implantoplasty. In a split-mouth design, NBM and EB were soak-loaded with rhBMP-2 or sterile saline. All sites were covered using a native collagen membrane and left to heal in a submerged position for 12 weeks. The horizontal mucosal thickness (hMT) and bone thickness (hBT) were measured at four reference points: (v0) at the level of implant shoulder (IS), (v1) 50% of the distance IS-bone crest (BC), (v2) at the BC, and (v3) at the most coronal extension of the bone-to-implant contact.

Results: The general tendency indicated a gradual increase in hMT from the IS (v0) toward BC (v2), which was more pronounced at implant sites treated with the regenerative approach. The hBT values increased from v2 to v3, with the highest values at the v3 region measured for implant sites treated with adjunctive rhBMP-2. For sites treated with implantoplasty, the linear regression model demonstrated an inverse correlation between hMT and hBT, whereas a positive correlation was observed at those sites treated with the regenerative approach.

Conclusion: Horizontal soft and hard tissue dimensions were similar among different treatment groups.

Keywords: Animal experiments; Bone regeneration; Dental implant soft tissue; Peri-implantitis treatment.

Fig. 1

Surgical procedures. a Ligature-induced chronic-type peri-implantitis defects after phase 3. b Supra was randomly allocated to either the application of EB or implantoplasty (two implants at the right). c At all implant sites, the intrabony defect component was homogeneously filled with NBM. d EB blocks were applied over the exposed implants following preparation of a central core (Ø 3.8 mm). NBM and EB were randomly soak-loaded with rhBMP-2 or sterile saline

Fig. 2

The following reference points served for the assessment of hMT (red lines) and hBT (turquois lines) values (specimen of the EB group): IS: implant shoulder, BC: bone crest, 50% IS-BC, CBI coronal extension of bone-to-implant contact

Fig. 3

Boxplots indicating hMT and hBT values in different groups. a EB. b P. c EB + rhBMP-2. d P + rhBMP-2

Fig. 4

Regression plots depicting the dependency between mucosal thickness (hMT) and bone thickness (hBT) values at v0-v3. a EB (R² = 0.029, B = 0.396, p = 0.532). b P (R² = 0.247, B = − 0.426, p = 0.026). c EB + rhBMP-2 (R² = 0.495, B = 0.50, p = 0.002). d P + rhBMP-2 (R² = 0.045, B = − 0.217, p = 0.345)