Histometric Analysis of Bone Repair in Bone-Implant Interface Using a Polylactic/Polyglycolic Acid Copolymer Associated With Implants in Rabbit Tibia
The purpose of this study was to evaluate the association of the combination of polylactic/polyglycolic acid around implants installed with and without primary stability through the histometric analysis of bone-implant interface. We used male rabbits, each of which received 2 titanium implants in each tibial metaphysis. The animals were divided into 4 groups: control with primary stability (CPS), control without primary stability (C), polymer with primary stability (PPS), and polymer without primary stability (P). Euthanasia was performed at postoperative days 40 and 90. The pieces were embedded in resin, sectioned, scraped, and stained with alizarin red and Stevenel blue. Histometric analysis evaluated the linear extension of contact between the bone and implant surface on the implant collar (CIC) and contact between the bone and implant surface on the first thread (CFT). Also evaluated was the area of newly formed bone (ANB) in the first thread. The results showed that there was new bone formation in all groups and during all periods. At 40 days, the ANB was higher in the PPS group than in the P group (P < .001); the CFT was statistically higher in the CPS group than the PPS group (P < .001) and was higher in the CPS group than the C group (P < .001). At 40 and 90 days, the CIC was higher in the P group than in the C group (P < .001). In conclusion, the copolymer had biocompatibility, enhanced bone healing, and presented osteoconductive properties, thus raising the contact between bone and implant, even without primary stability.
Figure 1. Clinical analysis of the left tibia at (a) 40 and (b) 90 postoperative days. The arrow indicates that the polymer without primary stability group implant has a smaller inclination than the control without primary stability group implant. At 90 days the implant was under bone tissue. Figure 2. The bone tissue filled the areas of the implant collar in (a) the control with primary stability group and (b) at the coronal first thread in the polymer with primary stability (PPS) group at postoperative day 40. On the implant collar in the PPS there was contact with fibrous tissue.
Figure 3. (a) At 90 days, the bone tissue also filled the areas of the implant collar in the control with primary stability. (b) Bone tissue filled the areas on the first coronal thread in the polymer with primary stability (PPS) group. On the implant collar in the PPS group there was contact with fibrous tissue. Figure 4. (a) The control without primary stability (C) group showed the bone tissue located at the areas of the implant collar. (b) In the polymer without primary stability (P) group, there was contact between bone and the threads in the medullar area at 40 days. Note the presence of the polylactic acid/polygalactic acid copolymer located in the medullar space. Figure 5. At 90 days, in (a) there was discontinuance between the bone tissue and the implant surface on the implant collar (C group). (b) In the P group, the bone filled the implant collar and the first coronal thread areas, and there was major contact between the implant surfaces.
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