Response to Albrektsson T, Jacobsson M: Bone-metal interface in osseointegration. J Prosthet Dent 1987;57(5):597-607.

I take issue with many of the statements in the article, "Bone-metal interface in osseointegration," by T. Albrektsson and M. Jacobsson (J Prosthet Dent 1987;57:597-607).

The recurring theme of this article appears to be that medical grade titanium alloy (90% titanium 6% aluminum-4% vanadium) used in dental implants such as the Core-Vent is a potential health hazard and, as yet, unproven to achieve osseointegration. the authors’ carefully constructed premise quickly unravels when the article is closely examined, revealing an underlying bias.

In the first paragraph, the authors state, by way of reference to a previous article of Albrektsson et al.,1 that "of all the currently used dental implants, only two passed the defined success criteria: the Small transosteal implant and the Brånemark osseointegrated screw." That the Small staple implant is made from Ti-6Al-4V alloy is not found anywhere in the article, nor is reference to an article2 in the Journal of the American Dental Association that confirmed that a staple implant, examined histologically (light and scanning electron microscopy) after 5 years of function, had achieved and maintained osseointegration.

The authors claim that they "compared interfacial reaction to magnetron-sputtered CP titanium and titanium-6Al-4V" (a high-temperature evaporation process used to create a thin specimen) and found the proteoglycan interface between implant and bone greater with the alloy. The significance of this finding must be viewed with skepticism, considering that in a previous article, Albrektsson3 had qualified the validity of this technique:

"It must be remembered that high temperature evaporation of titanium onto a surface may create different surface conditions compared to those of a titanium implant with a surface created by, for instance, machine cutting."

There is no biological reason why the bone should not react the same way to Ti-6Al-4V as to CP titanium since they both have been shown at the angstrom level by using Auger analysis, to have the same TiO2 on the surface.4 Albrektsson3 confirmed the "unique tissue acceptance of titanium oxide." Zarb5 stated that, "Because the surface exposed to the biologic host system consists of a metal oxide, not a metal, it is the oxide that governs the chemistry at the implant-biotissue interface." Paar et al.6 concluded that "Titanium, both as a pure metal and as an alloy, is easily passivated, forming a stable TiO2 surface oxide that makes the metal corrosion resistant...The clinical significance of the data is substantiated by more than 20 years of clinical experience with pure Ti and Ti-6Al-4V alloys." Andersson et al.7 reported on 10-year results conducted on baboons, demonstrating microscopically a bone/implant interface with both the pure titanium and Ti-6Al-4V alloy.

The authors also raise the issue of neurotoxicity relative to the aluminum leaching from the alloy. Considering that the FDA has approved the use of Ti-6Al-4V alloy and the orthopedic industry uses the alloy for most of its implants, the minuscule size of a dental implant compared with an orthopedic hip implant makes this point moot.

The authors state that Core-Vent implants "lack proper evidence of a bony integration." Apparently, the authors’ bias will not let them accept the extensive histologic and clinical evidence that Core-Vent implants have demonstrated osseointegration. Laskin8 reported on the results of five independent dentists having placed 609 Core-Vent implants with a 96.6% incidence of osseointegration. Lum and Beirne9 placed Core-Vent implant in dogs and reported that "the bone metal interface involved almost the entire surface of the embedded implant." An article evaluating the surface of a Core-Vent demonstrated an overall bone-implant interface at both the light and scanning electron microscopic level.10 A study by Chase11 of various types of implants, including the Brånemark and Core-Vent, confirmed histomorphometrically that the degree of mineralization, as tested at six points on the bone/metal interface, was equivalent. Lum and Beirne12 compared Core-Vent with Brånemark implants loaded in monkeys and reported that "light microscopic examination revealed that both the Brånemark and the Core-Vent implants were in direct contact with bone." The surface contact area appeared to be the same.

The authors have demonstrated in this article repeated attempts to link the osseointegrated Core Vent implant to fibrous encapsulated blade and subperiosteal implants and to ignore published animal and clinical research. It is unfortunate when those who have successfully climbed the ladder from basic science research to clinical reality attempt to pull the ladder up behind them.

Gerald A. Niznick, DMD, MSD

Core-Vent Corporation

16030 Ventura Blvd., Ste. 690

Encino, CA 91436

REFERENCES

1. Albrektsson T, Zarb G, Worthington P, Eriksson A. The long-term efficacy of currently used dental implants: A review and proposed criteria of success. JOMI 1986;1.

2. Walker C, Aufdemorte T. the mandibular staple bone plate: a 5 1/2-year follow-up. J Am Dent Assoc 1987;114:189-92.

3. Albrektsson T. The response of bone to titanium implants. CRC Critical Reviews in Biocompatibility 1984;1:53-84.

4. Niznick G. Through the eyes of the editor. J Prosthet Dent 1983;49:747.

5. Zarb G. Through the eyes of the editor. J Prosthet Dent 1983;49:747.

6. Parr G, Gardner L, Toth W. Titanium: The mystery metal of implant dentistry. J Prosthet Dent 1985;54:410-4.

7. Andersson G, Gaechter A, Galante J, Rostocker W. Segmental replacement of long bone in baboons using a fiber titanium implant. J Bone Joint Surg [Am] 1978;60:31.

8. Laskin D. Presentation 1986 AAOMS national meeting. New Orleans.

9. Lum L, Beirne R. Viability of the retained bone core in the Core-Vent dental implant. J Oral Maxillofac Surg 1986;44:341-5.

10. Niznick G. Destinations Magazine, 1986;10.

11. Chase D. Comparative evaluation of endosseous implant systems in edentulous dogs. Presentation at AAOMS meeting, Anaheim, Calif, Sept 1987.

12. Lum L, Beirne R. [Abstract]. Second International Congress on Preprosthetic Surgery, Palm Springs, Calif., May 1987.