Topography and surface energy of dental implants: a methodological approach

The surfaces of dental implants are generally modified as an attempt to improve osseointegration. Three surface characteristics of implants are regarded as relevant in the process of bone formation: chemical composition, surface energy and topography. The topography of threaded implants is difficult to measure by conventional equipments with mechanical contact, so optical measuring equipments are preferred. However, implants with large thread angles may have the topography overestimated by the optical measuring equipment due to errors caused by scattering of the reflected light. This paper proposes a new methodology to measure implants with internal thread angle larger than 70° via laser interferometry, positioning the implant with an inclination angle in relation to the equipment base. The results were compared with results for flat discs, produced with the same surface treatment of the implant. Regarding surface energy of implants, most studies use measurements for flat discs, but it is questionable whether the results represent the implant itself. Here, two new methods were proposed to characterize the surface energy of real implants: a qualitative method related to the phenomenon of capillarity and a quantitative method with different liquids of known surface tension. It was found that the topography of the thread flanks is considerably different from the topography of the discs and it is believed that the geometry of the implant influences the surface treatment. The proposed quantitative methodology to analyze the surface energy allowed to detect differences between two commercial implants tested.