Dávid Pammer

Investigation of the mechanical and chemical characteristics of nanotubular and nano-pitted anodic films on grade 2 titanium dental implant materials

OBJECTIVE The objective of this study was to investigate the reproducibility, mechanical integrity, surface characteristics and corrosion behavior of nanotubular (NT) titanium oxide arrays in comparison with a novel nano-pitted (NP) anodic film. METHODS Surface treatment processes were developed to grow homogenous NT and NP anodic films on the surface of grade 2 titanium discs and dental implants. The effect of process parameters on the surface characteristics and reproducibility of the anodic films was investigated and optimized. The mechanical integrity of the NT and NP anodic films were investigated by scanning electron microscopy, surface roughness measurement, scratch resistance and screwing tests, while the chemical and physicochemical properties were investigated in corrosion tests, contact angle measurement and X-ray photoelectron spectroscopy (XPS). RESULTS AND DISCUSSION The growth of NT anodic films was highly affected by process parameters, especially by temperature, and they were apt to corrosion and exfoliation. In contrast, the anodic growth of NP film showed high reproducibility even on the surface of 3-dimensional screw dental implants and they did not show signs of corrosion and exfoliation. The underlying reason of the difference in the tendency for exfoliation of the NT and NP anodic films is unclear; however the XPS analysis revealed fluorine dopants in a magnitude larger concentration on NT anodic film than on NP surface, which was identified as a possible causative. Concerning other surface characteristics that are supposed to affect the biological behavior of titanium implants, surface roughness values were found to be similar, whereas considerable differences were revealed in the wettability of the NT and NP anodic films. CONCLUSION Our findings suggest that the applicability of NT anodic films on the surface of titanium bone implants may be limited because of mechanical considerations. In contrast, it is worth to consider the applicability of nano-pitted anodic films over nanotubular arrays for the enhancement of the biological properties of titanium implants.

Insertion Torque Function Analysis of Novel Dental Implant Geometry

Since the discovery of the osseointegration implant stability has an increasing relevance. Determination of stability is particularly important for dental implants. Two types of stabilities give us information about the success of implantation; primary and secondary stability. There are many stability indicators, but their meanings are not exactly defined theoretically. The aim of our study was to examine and evaluate the insertion and removal torque of novel implant geometry in polyurethane artificial bone blocks with different densities, corresponding to the standard living bone density classification (D1-D4). Protocols given to implantation were followed during the drilling and insertion.

Examination of bone like materials

The aim of this research is to develop a new minimally invasive measurement procedure. With this method implantologist could determine the local mechanical and structural properties of the cellular solids materials (e.g. bones) into which implants are placed. The currently applied methods are based on image measurement procedures (CT, Hounsfield scale etc.). The dentists, with the knowledge of the determined mechanical properties of the bone, can choose the ideal surgical parameters (flap size, diameter of drill, hole-depth, healing time, etc.) and the ideal implant type for the patients. During the development of the measuring procedure, was used bone modeling materials (“bone-like materials”) instead of bone. With these materials it is easier to do tests, than with living tissues. The bone like materials needs to have the same mechanical and structural properties as the given bone. The following bone like materials was used during the measurement: woods (Amaranth, Alnus, Ipe, Iroko, Robinia, Pyrus, Zebrano), and on the market available polyurethane solid foams (Sawbones D1 and D2). Among the literatures are summaries, which include the biomechanical assessments for implant stability. These technics are good to determine the implant stability in different bones and bone like materials after the implantation. In this work torsional test were used. This test is based on the determination of the insertion torque as a function of the implant displacement. Used the insertion torque functions and the screw geometrical parameters, the rotational work was determined. The different materials insertion torque functions have different slope values. The slopes and the rotational work results show which bone like material has similar insertion parameters (insertion torque function, rotational work) as a mandible during the insertion of an implant. With this torsional test and the knowledge of the bone like materials insertion torque functions and the rotational works it is possible to find the best material for the modeling of an implantation. Using this material, medical students can practice and improved the surgical techniques.