Bactericidal nanotopography of titanium dental implants: in vitro and in vivo studies.

Abstract

Objective: A new passivation method for titanium dental implants has been studied, where the nanotextured layer features spikes that provide a high bactericidal capacity without compromising the degree of osseointegration of the dental implants.

Materials and methods: This layer has been obtained through a sulfuric acid treatment with hydrogen peroxide. It has been characterized using electron microscopy, the roughness was determined by confocal microscopy and wettability and surface energy assessed through contact angle. The incorporation of hydrogen was assessed using a fusion spectrometer. Fatigue behavior was evaluated with a servo-hydraulic testing machine. The adhesion of human osteoblastic cells SaOs-2 at 3 and 7 days was measured, and the level of mineralization was analyzed by alkaline phosphatase levels. Bacterial colonization assays were conducted using four strains to assess their bactericidal capacity. Implants were inserted into rabbit tibiae. After 21 days, the animals were sacrificed, and bone index contact determined.

Results: A uniform surface created by nanospikes was obtained, exhibiting the same roughness as the control implant, no hydrogen was incorporated inside the titanium. The fatigue behavior showed no variation compared to the control. An increased wettability and higher surface energy compared to the control implant were noted. Enhanced osteoblastic adhesion was observed for the nanospikes surface in comparison with control at 3 days, with a significant level of alkaline phosphatase at 14 days, indicating a good degree of mineralization. The bactericidal capacity of nanospike surface is evidenced showing reductions ranging from 70 to 90%. In vivo tests demonstrate higher bone contact index values for dental implants with nanospikes (56%) compared to the control (41%).

Conclusions: The surface formed by nanospikes maintains the mechanical properties of the control and improves the wettability of the surface which improves the behavior of the osteoblasts generating a better osseointegration. At the same time, it has a high bactericidal capacity that prevents microbiological colonization.

Clinical relevance: Peri-implantitis has become one of the major problems for the success of implant dentistry and this new surface may be a solution for the prevention of the disease.