Early bone healing to implants with different surface characteristics. A pre-clinical in vivo study.

AIM: To examine early bone healing around implants with non-modified and modified surfaces. MATERIAL & METHODS: Four implants with 4 different surface characteristics were installed in one side of the mandible following tooth extraction in 6 dogs. Implants in group A had a non-modified, turned surface, while implants in group B had a surface modification consisting of TiO-blasting and sequential acid-etching in oxalic and hydrofluoric acid. The surface modification of implants in group C was confined to sequential acid-etching in oxalic and hydrofluoric acid and Group D implants had a surface modification of TiO-blasting and acid-etching in hydrofluoric acid. The implant installation procedures were repeated in the opposite side of the mandible 4 weeks later. Biopsies were obtained and prepared for histological analysis 2 weeks later. RESULTS: B and C implants had a higher degree of bone-to-implant contact (BIC%) than A and D implants at 2 weeks of healing. At 6 weeks of healing, the BIC% was higher at B than at A, C and D implants, and higher at C implants than at A implants. The amount of newly formed bone in contact with the implant within the defect area at 2 weeks was higher at implants with modified surfaces (groups B, C and D) than at implants with a non-modified surface (group A). Corresponding results at 6 weeks were superior at B implants. CONCLUSION: It is suggested that an implant surface modification with acid-etching in oxalic and hydrofluoric acid promotes early formation of bone-to-implant contact.

Surgical treatment of experimental peri-implantitis using mechanical and chemical decontamination procedures: A pre-clinical in vivo study.

AIM: To evaluate the effect of surgical treatment of experimental peri-implantitis at implants with different surface characteristics using mechanical and chemical decontamination methods. MATERIALS AND METHODS: Following extraction of mandibular premolars, four implants with two different surface characteristics (A, moderately rough and B, smooth) were placed in each side of the mandible of six dogs. Experimental peri-implantitis was induced. Surgical treatment of the peri-implantitis sites was carried out using four implant surface decontamination protocols: (i) deposition of a citric acid gel, (ii) mechanical cleaning using a rotating titanium brush, (iii) a combination of the mechanical and chemical procedures, and (iv) saline (control). Clinical and radiographic examinations were performed. Block biopsies were obtained 6 months after therapy and prepared for histological analysis. RESULTS: Irrespective of the treatment group, treatment resulted in 0.63 ± 0.92 and 0.65 ± 0.67 mm radiographic bone gain around implants A and B, respectively. Histological analyses revealed that persisting soft tissue inflammation as assessed using an infiltrated connective tissue (ICT) score was significantly lower at implant type B than at implant type A for all treatment groups. The test decontamination procedures did not demonstrate better results regarding resolution of peri-implantitis lesions, as indicated by the ICT scores, than the control procedure. The control treatment resulted in significantly superior outcomes of resolution of peri-implantitis lesions than the citric acid regimen. CONCLUSIONS: It is concluded that decontamination procedures including citric acid gel or rotating titanium brush did not improve outcomes following surgical treatment of experimental peri-implantitis. Results were, however, influenced by the implant surface characteristics.

Accuracy of bone-level assessments following reconstructive surgical treatment of experimental peri-implantitis.

AIMS: The purpose of this study was to evaluate the accuracy of bone-level assessments using either cone-beam computed tomography (CBCT), intra-oral peri-apical (PA) radiographs or histology following reconstructive treatment of experimental peri-implantitis. MATERIALS AND METHODS: Six Labrador dogs were used. Experimental peri-implantitis was induced 3 months after implant placement. Surgical treatment of peri-implantitis was performed and peri-implant defects were allocated to one of four treatment categories; no augmentation, bone graft materials with or without a barrier membrane. Six months later, intra-oral PA radiographs and block biopsies from all implants sites were obtained. Marginal bone levels (MBLs) were measured using PA radiographs, CBCT and histology. RESULTS: Significant correlations of MBL assessments were observed between the three methods. The measurements in PA radiographs consistently resulted in an overestimation of the bone level of about 0.3-0.4 mm. The agreement between the methods was not influenced by the use of bone substitute materials in the management of the osseous defects. CONCLUSIONS: Although MBL assessments obtained from PA radiographs showed an overestimation compared to MBL assessments on corresponding CBCT images and histological sections, PA radiographs can be considered a reliable technique for peri-implant bone-level evaluations following reconstructive surgical therapy of experimental peri-implantitis.

Effect of biofilm formation on implant abutments with an anti-bacterial coating: A pre-clinical in vivo study.

OBJECTIVES: To analyse the long-term effect of plaque formation on implant abutments with an antibacterial coating and the ensuing host response in peri-implant tissues. MATERIALS AND METHODS: Four implants were installed in each mandibular premolar region following tooth extraction in six dogs. Three months later, two test abutments with a titanium-bismuth-gallium (Ti-Bi-Ga) coating and two control titanium abutments were connected to the implants on each side of the mandible. After 2 months, ligatures were placed around the implants in one side of the mandible and plaque formation was allowed until the end of the experiment. The ligatures were removed after 4 weeks. Radiographs and microbiological samples were obtained from each implant site during the plaque formation period. Biopsies were obtained 8 months after abutment connection and prepared for histological analysis. RESULTS: The analysis did not reveal any statistically significant differences in bone loss, bacterial growth and size of inflammatory lesions between implant units with and without the Ti-Bi-Ga coating. Implant sites exposed to the short period of ligature-induced breakdown demonstrated more pronounced bone loss and bacterial growth than non-ligature sites. CONCLUSIONS: It is suggested that a Ti-Bi-Ga coating does not prevent biofilm formation on the implant device and does not influence the ensuing host response in the adjacent peri-implant mucosa.

Re-osseointegration following reconstructive surgical therapy of experimental peri-implantitis. A pre-clinical in vivo study.

OBJECTIVE: To evaluate the effect of bone substitute materials on hard and soft tissue healing in reconstructive surgical therapy of experimental peri-implantitis at implants with different surface characteristics. MATERIAL AND METHODS: Six female, Labrador dogs were used. 3 months after tooth extraction, four implants with two different surface characteristics (A and B) were installed on each side of the mandible. Experimental peri-implantitis was induced 3 months later. During surgical treatment of peri-implantitis, the implants were cleaned with curettes and cotton pellets soaked in saline. The implant sites were allocated to one of four treatment categories; (a) Group C; no augmentation, (b) Group T1; bone defect filled with deproteinized bovine bone mineral (c) Group T2; bone defect filled with a biphasic bone graft material, (d) Group T3; bone defect filled as T1 and covered with a collagen membrane. Clinical and radiological examinations were performed, and biopsies were obtained and prepared for histological analysis 6 months after peri-implantitis surgery. RESULTS: Implant B (smooth surface) sites showed significantly (a) larger radiographic bone level gain, (b) enhanced resolution of peri-implantitis lesions, and (c) larger frequency of re-osseointegration than implant A (moderately rough surface) sites. Implant B sites also showed superior preservation of the mucosal margin. Differences between bone substitute materials and control procedures were overall small with limited advantages for T1 and T2 sites. CONCLUSION: Healing following reconstructive surgical treatment of experimental peri-implantitis was superior around implants with a smooth surface than implants with a moderately rough surface. Benefits of using bone substitute materials during surgical therapy were overall small.