Attempts to obtain re-osseointegration following experimental peri-implantitis in dogs

The purpose of this study was to examine the hearing potential and reosseoi ntegration in peri-implant infection defects adjacent to various implant su rfaces. In 7 female Beagle dogs, a total of 41 titanium oral implants (ITI, Straumann, Waldenburg; Switzerland) with a sink depth of 6 mm (diameter 2. 8 mm) were placed transmucosally. Four different surface configurations (TP S: titanium plasma sprayed (10); SLA: sand blasted and acid-etched (13); M: machined and smooth (11); TPS furc.: titanium plasma sprayed with coronall y placed perforation to mimic a furcation (7) were distributed among the an imals and locations. Following a healing period of 3 months, silk ligatures were placed and oral cleaning procedures abolished for 4 months to induce a vertical bone loss of about 40%. Following mechanical and chemical cleans ing (chlorhexidine and metronidazole) and disinfection, the lesions were ei ther sham operated (11) or subjected to a GTR procedure using ePTFE (30). A fter 6 months of healing the animals were killed and the jaws histologicall y evaluated. Six membranes were lost TPS: (I); SLA: (2); M: (2); TPS furc: (1) and 3 membranes exposed TPS: (1); M: (2) and excluded from further eval uation. Owing to the loss of I implant and infection of the membranes in th e TPS furc group, this implant configuration was discarded from further ana lysis. For TPS surfaces, bone fill was 2.6 mm (73% of the distance from the bottom of the defect to the shoulder of the implant) sites with (4 GTR) an d 0.33 mm (14%) for sites without membrane (2 controls). Re-osseointegratio n was 0.5 mm (14%) in the test group and 0.3 mm (14%) in the control. For S LA surfaces bone fill was 2.3 mm (83%) for sites with (7 GTR) and 0.41 mm ( 15%) for sites without membranes (4 controls). Re-osseointegration was 0.6 mm (20%) and 0.3 mm (11%) respectively. Corresponding values for M surfaces were 2.2 mm (62%) with 4 GTR) and 0.82 mm (31%) without membranes. Re-osse ointegration was 0.07 mm (2%) and 0.19 mn (7%) respectively. This study has documented that peri-implant infections defects may heal with bone fill pr ovided that the infection is controlled through effective antibacterial the rapy. However, true reosseointegration appears to be difficult to achieve.