Microscopic (SEM, EDX) investigations on a new material/implant for dental use.

Comaneanu, Raluca Monica ; Ghergic, Doina Lucia ; Smatrea, Oana 等

1. INTRODUCTION

The fibrous tissue interface around an osseous implant can be easily engendered, but the difficulty lies in avoiding its formation and maintenance of a direct bone anchorage on decades of clinical functioning (Misch, 1999).

Basically, osseous-integration depends on preventing heat generation during the intervention, on the chemical composition of the implant and its design. If prevention of heat generation depends exclusively on the accuracy which the dentist perform the intervention, the other two parameters is the challenge for producers of dental implants (Babbush, 2001).

Cylindrical implants covered with hydroxyapatite were used on alveolar bone of dogs, as a substitute of the natural tooth (Block et al., 1989). The alveolar ridge revealed stabilization for periods of more than two years after implantation, with no signs of inflammation, irritation or flaking of surrounding tissue. It appeared that all implants are closely related to adjacent bone which was filled in time, no encapsulation of any soft tissue appeared (Ganuta et al., 1997).

Unfortunately, although there are several procedures for submitting hydroxyapatite on titanium, there were not found possibilities to prevent the uprooting of the titanium core from hydroxyapatite sleeve which adheres to bone.

This new solution (porous material) offer strong, rapid growth of new forming bone through its ultra-porous scaffold.

During design steps for the implant, several manufacturing nonconformities were revealed through microscopic investigations: contaminations with Cu and Zn form electro-erosion, residues form cleaning procedures, etc.

The intensive co-operation between the producer (Vital Implant) and our research group (UPB-BIOMAT) allows for solving of each these non-conformities step-by-step. The final result is a better design solution for the implant and an almost perfect manufacturing technology, which allows for a clean product with certain biological and biomechanical compatibility.

2. INVESTIGATED DENTAL IMPLANTS

Cylindrical implant BioMaxil (recently launched at the International Dental Show, Cologne, Germany) is produced by Vital Implant Company (France). It is consists of a titanium alloy core surrounded by Actipore[TM].

Actipore[TM], a porous biocompatible material NiTi-based, is produced by Biorthex Inc., Canada, and it is used successfully for more than 10 years in Orthopedics Surgery (Hip, Knee and Lumbar discs) (Comaneanu et al., 2009).

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Actipore[TM] is a unique product with a structure consisting of ultra-porous interconnected lattice, allowing cell penetration, long-term bone cell survival and their integration within material. The phenomenon of attraction by capillarity of fluids and nutrients essential elements in Actipore[TM] network enables rapid growth of new cells (fig. 1). As a result, it is not necessary the use of bone graft material.

Actipore[TM] has a porosity of approximately 65% and an average pore size of 230 microns, allowing strong, rapid growth of newly forming bone trough its ultra-porous scaffold. Although porous, Actipore[TM] has a higher resistance to compression compared to the bone, but with elastic modulus similar to this.

Vital Implant Company initially proposed a design (fig. 2) which was abandoned because of the risk of failure by uprooting of the central portion of the implant. The final design (fig. 3) of the implant was SEM analyzed before being made widely, in order to detect any faulty manufacturing.

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3. MICROSCOPIC INVESTIGATIONS

General aspects of the BioMaxil implant are revealed by electron microscopy in fig. 4; the great porosity of the material is obvious. The isotropic (equal in all directions) interconnected pores create a capillary wicking force that actively draws blood, essential nutrients and bone marrow into inter-body device accelerating osseous-integration. This feature is determined by the technology used for Actipore[TM] obtaining: combustion synthesis.

EDX analysis of the inner part of implant has confirmed the composition of Ti6Al4V alloy. Porous outer sheath, made of material Actipore[TM], confirmed the purity of NiTi alloy used.

4. CONCLUSIONS

As microscopic investigations revealed, the Actipore[TM] material has best controlled characteristics due to adequate technological obtaining procedures.

The machining technology applied to obtain BioMaxil implants is also best controlled, giving enough assurance both to patients and dentists to use this new and original solution.

Actipore[TM] high porosity (~65%) promotes rapid bone growth and survival of long-term around and inside implants. Because these structural features, cylindrical type implants BioMaxil can be loaded after a period 3 times shorter than the time needed to load screw type implants.

Elasticity of the material is almost identical to that of bone, conducting to mechanical load dissipation.

5. DISCUSSIONS

With the declared target of shortening the time needed to obtain osseous-integration, different companies producing implants provide permanent improvements as regards the shape of dental implants and the details of surface materials that are covered.

BioMaxil implants have emerged as a more interesting alternative to cylindrical implants coated with hydroxyapatite.

Its thick porous sleeve that allows bone growth is sustained by a core of titanium alloy; the reason of this inner part is only mechanical one. Constructive form and their mode of fixation of the porous sleeve core allow for greater stability over time against all implants covered with hydroxyapatite and a prosthetic loaded faster than the screw-type implants.

It should be further investigated the way that chewing stress is transmitted through the bone structure by the porous implant surface.

6. REFERENCES

Babbush, C.A., (2001). Dental Implants The Art and Science, Elsevier Saunders, ISBN 0-7216-7747-9, Missouri

Block, M.S., Finger, I.M., Fontenot, M.G. & Kent, J.N. (1989). Loaded hydroxylapatite-coated and grit-blasted titanium implants in dogs, International Journal of Oral & Maxillo-facial Implants, pp 219-226, ISSN: 0882-2786, Quintessence Publishing Co, Inc.

Comaneanu, R.M., Smatrea, O., Haineala, C., Ghergic, D.L., Miculescu, F. & Tarcolea, M. (2009). Investigatii de microscopie asupra unui nou material pentru implante dentare, The VII-th International Congress of Oral Health and Dental Management in The Black Sea Countries, pp 79, ISSN 1583-5588, Istanbul-Mamaia, May 2009

Ganuta, N., Bucur, A. & Ganuta, A., (1997). Tratat de implantologie orala, Ed. National, ISBN 973-9308-16-3, Bucuresti

Misch, C.E., (1999). Contemporary Implant Dentistry, Elsevier Mosby, ISBN 0-8151-7059-9, Missouri