Osseointegration of implants placed in the maxillary sinus with a surface modified by conditioning with and without β-tricalcium- phosphate deposition

NRYKU ePOSTER BASIC RESEARCH

Background: Surface modification processes of dental implants aim to increase the contact between titanium and the bone tissue, allowing an increase in mechanical resistance, corrosion and also favoring the biological responses of osseointegration. The deposition of biomaterials on a previously modified surface has shown favorable results in the process of healing around bone tissue and implant surface, allowing greater removal torque values and bone interface contact.

Aim/Hypothesis: The aim of this study was to evaluate the effects of β-tricalcium phosphate coating on the surface of acid-conditioned modified implants implanted in rabbit maxillary sinuses immediately after elevation of the sinus membrane.

Materials and Methods: Topographic characterization of implant surfaces was performed. Eighteen rabbits underwent surgery to elevate the bilateral sinus membrane by nasal access. After the animals received randomly in each maxillary sinus implant with surface acid modified followed by body fluid solution deposition (SBF) or implant with acid conditioned surface followed by SBF and β-tricalcium phosphate (TCP) deposition. After periods of 7, 15 and 40 days the animals were anesthetized and was measured primary stability coefficient followed by euthanasia. Afterwards, processing was performed for demineralized tissue. It was performed histometric analysis to measure the bone implant contact (BIC%) and the area of newly formed bone tissue (NBA%). In 2 animals of each group in all periods, the micro tomographic analysis was performed to evaluate. Followed it was performed processing for demineralized tissue and was measured BIC% and NBA%. Data obtained were submitted to statistical analysis.

Results: In the analysis by SEM and EDX the formation of an apatite layer with higher amounts of Ca and P was observed in implants with biomimetic deposition with β-tricalcium phosphate. The microtomographic analysis showed statistical difference between the TCP 40 days and SBF 15 days groups, regarding bone volume (BV / TV), number (Tb.n) and porosity (Tb.tot) of the trabeculae, respectively. The BIC% and NBA% values in demineralized tissue showed no statistical differences (P > 0.05) between the SBF and TCP groups. Immunohistochemical analysis showed an expression of OC and TRAP in both groups at 7, 15 and 40 days with more pronounced expression of OC at 40 days for the TCP group. Histometric analysis in mineralized tissues showed a statistical difference (P < 0.05) when comparing the different SBF and TCP groups mainly in the BIC% and NBA% for medullary segment.

Conclusions and Clinical Implications: It was concluded that the incorporation of β-tricalcium phosphate by the biomimetic method on the surface previously modified by double acid etching was efficient due to the characterization of the implant topography. The influence of this type of bioactive surface was observed on bone repair around osseointegrated implants, thus constituting an option for modification of implant surfaces.

Acknowledgements: The authors would like to thank the Implalife Indústria de Produtos Médico-Odontológicos, Jales, São Paulo, Brazil for providing the dental implants and disks used in this study and would like FAPESP (São Paulo State Research Support Foundation) – processes number: 2017/13010-5 and 2018/22108-1.

Keywords: Dental Implants, Bone substitutes, Bone regeneration, Biomaterials, β-tricalcium phosphate