Microtomographic evaluation of a nanometric implant surface associated to L‐PRF: Study in osteoporotic rats

Abstract

Background Osteoporosis is associated to decrease of bone mineral density, leading to an increase of skeletal frailty and fracture risk. Surface characteristics of dental implants may influence bone response, modulating cell proliferation and differentiation. Nanostructures applied to biomaterials may contribute to a higher bone to implant contact. Previous studies have shown that Leukocyte platelet rich fibrin (L-PRF) can increase the amount and formation rate of new bone around implants. Aim/Hypothesis To micro-tomographically evaluate, in osteoporotic rats, the bone repair around two implant surfaces, associated of not to L-PRF, analyzing Bone to Implant Contact (IS TS,%), Bone Volume Fraction (BV TV,%), Bone Surface Volume (BS BV,%) Trabecular Thickness (Tb.Th,mm), and Total Porosity (To.Po,%). Materials and Methods Mini implants with 2 types of surface (double acid etched=DAE, or with the addition of nano-hydroxyapatite = NHA + 24 implants of each type) were installed in the tibias of osteoporotic rats. In 24 rats, L-PRF was obtained with blood collection by means of cardiac puncture and posterior centrifugation, and inserted in the prepared bone site before implant insertion. The 48 rats were randomly divided into 4 experimental groups of 12 rats each- G1- DAE implants installed+ G2- NHA implants installed+ G3- DAE implants installed in association to L-PRF+ G4- NHA implants installed in association to L-PRF. All the mini implants were prepared for the study, measured 2.7 mm in length x 1.4 mm in diameter, and had the same macrostructure. The animals were euthanized 7 and 30 days (7d and 30d) after implants placement (6 from each group period). The tibias were removed for microtomographic evaluation of the bone between the threads of the implants, analyzing the previously described parameters. Results Inter-groups differences were assessed using One-way Analysis of Variance (P < 0.05 was considered). For IS TS, statistically significant differences were found in L-PRF treated rats between DAE (45.31 ± 5.06) versus NHA (52.81 ± 4.43) implants. For BV TV, there were statistically significant differences between G3 7d (44.08 ± 6.98) versus G4 7d (58.95 ± 5.53) and between G3 30d (54.33 ± 4.18) versus G4 30d (68.09 ± 6.56) + for the NHA surface, there were also statistical differences between rats without (49.57 ± 4.94) or with (63.52 ± 5.09) L-PRF treatment association. The results of BS BV showed statistically significant differences between DAE (36.71 ± 3.31) and NHA (32.13 ± 2.95) implant surfaces in L-PRF treated animals. For Tb.Th, there were statistically significant differences between G3 30d (0.093 ± 0.010) versus G4 30d (0.115 ± 0.012). For To.Po, statistically significant differences were found in L-PRF treated rats between DAE (53.69 ± 5.80) versus NHA (45.25 ± 4.98) implants. Conclusion and Clinical Implications Microtomographic analysis showed that the nano-hydroxyapatite implant surface presented more tridimensional bone to implant contact, bone volume fraction and trabecular thickness, and also less bone surface volume and porosity, when compared to DAE surface. Furthermore, the NHA surface was the most benefited by the association to L-PRF treatment. These results suggest that this treatment protocol (NHA + L-PRF) should be tested in humans, in trials evaluating challenging clinical situations.