Adhesive durability of bone cements containing gentamicin or gentamicin/clindamycin-based antibiotics on titanium used for oral implants

Abstract

This study investigated the durability of adhesion of bone cements containing antibiotics to titanium. Titanium plates (15 mm × 15 mm × 1 mm) (N = 80, n = 10 per group) were obtained representing oral implants. Half of the titanium plates were air-abraded (30 μm CoJet) (distance: 10 mm; pressure: 2.8 bar; duration: 15 s/cm2) and silanized. They were then randomly divided into two subgroups and chemically polymerized bone cements containing either (a) gentamicin (Refobacin Bone Cement R, Biomet) (GT) or (b) gentamicin/clindamycin (Refobacin Bone Cement Revision, Biomet) (GTC) were bonded to the substrates. Half of the specimens were kept dry and the other half were thermocycled (5–55 °C, 6000 cycles). Shear force was applied to the adhesive interface until failure occurred (0.5 mm/min). Failure types were categorized considering the amount of cement on the substrate. Data (MPa) were analysed using one-, three-way ANOVAs and K-N-S tests (α = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Surface conditioning (p < 0.01) and ageing (p < 0.01) significantly affected the results, but bone cement did not (p > 0.05). In dry conditions, GT (without: 19.5 ± 2, with: 31.6 ± 1) showed higher bond strength than that of GTC (without: 14.1 ± 1.6, with: 20.4 ± 2.9) (p < 0.01). Thermocycling significantly increased the results for both cements without (GT: 50 ± 3; GTC: 48.6 ± 5.6) and with air-abrasion (GT: 74 ± 1.6; GTC: 76.1 ± 2.4) (p < 0.01). Weibull distribution presented the highest shape (0) for GT (Dry: 12.65; Thermocyled: 17.22). Failure types were predominantly Type 2 (46/80) (Mixed, cement remnants <¼ left on the substrate). Bone cements containing gentamicin may adhere to titanium surface more reliable but both cements benefited from air abrasion and silanization.