In vitro comparison of titanium surface conditioning via boron-compounds and sand-blasting acid-etching

Objectives: The aim of this study was to compare the effect of a boron-based titanium (Ti) surface treatment method against the conventional sand-blasted & acid-etched Ti implant surfaces. Material and Methods: A total of 216 machined titanium (Ti) discs were divided into four equal groups and the following surface treatments were applied; Aluminum oxide (Al 2 O 3 ) sand-blasting and hydrochloric/ sulfuric acid (HCl/H 2 SO 4 ) etching (SLA). Aluminum oxide (Al 2 O 3 ) with boric acid (H 3 BO 3 ) particle sand-blasting and tetrafluoroboric acid (HBF 4 ) etching (SBF). Wetting of the SBF surface by boric acid-solution (SBF-B). Aluminium oxide (Al 2 O 3 ) sand-blasting and tetrafluoroboric acid (HBF 4 ) etching (SAF). Confocal laser scanning microscopy, stylus profilometry, scanning electron microscopy and X-ray photoelectron spectroscopy was used for the quantification of the surface characteristics. Adhesion and viability of Porphyromonas gingivalis and Streptococcus mutans and cell adhesion, osteocalcin production and viability of human fetal osteoblastic cells was quantified by cell cultures and lysate analyses. Results were analyzed by non-parametric tests (p<0.05). Results: Surface area roughness parameters were similar in all specimens with an arithmetical mean height (Sa) of 1.6 (SD: 0.6) μm. SBF-B surface yielded the highest cell viability/proliferation (187.5%, IQR: 37.5; p=0.0231), osteocalcin production (228.9 ng/ml IQR: 14.1; p<0.0001), and also the lowest adhesion rate for both bacteria (45x102 CFU/ml (IQR: 22.5x102)) and (290x103 CFU/ml (IQR: 45.5x103)) for P.gingivalis and S.mutans, respectively; p=0.0002). SLA, SBF and SAF surfaces revealed inferior outcomes as compared to the SBF-B surface. Conclusion: Within the limits of the in-vitro investigation it can be concluded that, boric acid-wetting of the aluminum-oxide and boric-acid blasted and tetrafluoroboric acid etched Ti surfaces (SBF-B) increase osteoblast adhesion and reduce the bacterial adherence. Key words: Boron, Boric acid, Tetrafluoroboric acid, Titanium, Osteoblast, Bacteria, Surface characteristics.