Scaling around Titanium Implants No Good Deed Goes Unpunished

Objectives: Titanium(Ti) and its alloys are widely used as dental implants due to their biocompatibility, mechanical strength, corrosion resistance and osseointegration. To date, virtually all-available implants undergo surface roughening in order to accelerate osseointegration and shorten healing time. Peri-implantitis is a major clinical concern and main cause of long term implant failure. Triggered by specific oral bacteria, it consists of an inflammatory process that leads to bone resorption around dental implants. Treatment includes mechanical cleaning of the surrounding oral flora by ultrasonic scaling. We hypothesize that the scaling process releases Titanium particles into the implant microenvironment and that these particles aggravate or even trigger the inflammatory response.
Methods: We performed US of Titanium discs with various surface types. The released particles were then added to bone marrow-derived mouse macrophages(BMDM) cultures. Bacterial lipopolysaccharides (LPS) were added to parallel cultures as positive control and in addition to Titanium particles to assess additive/synergistic effects in the RNA expression of inflammatory cytokines. Atomic force microscopy and electron scanning microscopy were used for profilometry of the released particle and post-cleaning titanium surface. Using SEM we compared the profile, size and quantity of Ti particles obtained from all 3 different surface types, namely machined, SLA and sand-blasted (SB). BMDM were then cultured with the particles released from each surface type.
Results: RT-qPCR indicated that Ti particles originating from sand-blasted/acid etched (SLA) implants stimulated gene expression of pro-inflammatory cytokines (TNFα, IL1β, IL6) to a greater extent than LPS. Particles originating from SB implants yielded the most severe inflammatory response, while particles from machined implants induced the mildest response
Conclusions: Our results showed that both the amount and the shape of particles have an effect on the inflammatory response. These data suggest that scaling of Ti implants, intended at preventing peri-implantitis, may in fact aggravate the osteolytic inflammatory response by causing an accumulation of Ti particles in the peri-implant environment. This adverse reaction is likely to be even more severe around roughened Ti implants.