Response to Weiss CM: Tissue integration of Dental endosseous implants: Description and comparative analysis of the fibro-osseous and osseous integration systems. Int J Oral Implant 1986;XII(2).
Journal of Oral Implantology, Vol. XIII, No. 1, 1987, Pages 10-14
In his article in Oral Implantology, Vol. XII, No. 2, 1986, Dr. Charles Weiss argues the advantages of titanium blade-vent implants surrounded by fibrous connective tissue –– which he terms "fibrous-osseous integration" –– over titanium cylindrical screw implants that are in direct contact with vital bone commonly referred to as "osseointegration."
Weiss’s entire article, in fact, is replete with errors, inaccuracies, and misinformation. His liberal interpretation of references are based on false assumptions that lead ultimately to invalid conclusions –– all of which serves to support a glaringly evident bias toward the particular design, surface, and material incorporated into blade-vent implants sold by Oratronics.
Whether a fibrous connective tissue interface offers the same support capabilities and long-term predictability as an osseointegrated interface seems to still be an issue for some Academy members –– as evidenced by the committee report from the Ixtapa, Mexico meeting, January 17-20, 1985, on "Criteria for Accepted Dental Implants and Modalities." It is not an issue with the vast majority of academicians and specialists now entering the field of implantology, as can be seen by the large number that are either using the Brånemark or Core-Vent osseointegrated Implants.
Inaccuracies in Weiss’s article:
1. Weiss states, "Biocompatibility tests and basic biomechanical principles indicate that CP (commercially pure) Titanium is the biomaterial of choice for endosseous dental implants," and then gives no references to support his contention. Titanium alloy Ti-6Al-4V, in fact, has proven to be equally biocompatible1 as well as 60% stronger than pure titanium, thus allowing the design of an implant that, made of less material, leaves more bony support.
2. The Brånemark implants, says Weiss, "yield long-term results slightly less than 80%," referencing Brånemark’s textbook. Adell2 evaluated the statistics over the least ten years of the study (after the initial developmental period) and found that 81% of the maxillary implants and 91% of the mandibular implants achieved and maintained osseointegration for the five- to ten-year observation period. During the last five of these years, 95% of the maxillary implants and 99% of the mandibular implants successfully osseointegrated in the Swedish study. From 1973 to 1983, 100% of the lower fixed bridges supported by osseointegrated implants in the Brånemark study remained in continuous function, even though a few implants failed to achieve initial osseointegration or were subsequently removed.
To the patient, continuous function is tantamount to continuous success. Most of the maxillary implants and all of the mandibular ones that maintained osseointegration for one year remained directly anchored to bone the entire period. It is noteworthy that, although the Swedish researchers experienced a learning and developmental curve, the real legacy of the Brånemark research was that, if one could get a titanium implant to osseointegrate, there was little chance the implant would ever be lost. This was confirmed in a recent article by Albrektsson, Zarb et al.3, which stated:
The Brånemark results...clearly underscore the basic concept of osseointegration as being the major, if not the exclusive, reason for a successful long-term dental attachment...The results [in reference to a Brånemark personal communication] indicate that any implant losses after the first one to two years of function seem to be unlikely, provided osseointegration has occurred.
Since the Brånemark research didn’t test implants of different material, design or insertion techniques in any controlled studies, the long-term predictability of an osseointegrated titanium oxide-bone interface is the basic principle he proved. This was the analysis of the Brånemark statistics that I noted in my articles, which Weiss pejoratively referred to.
Weiss’s idea of valid statistical reporting is: "Experience indicates that one out of ten fibro-osseous integrated blade abutments will falter when used, according to Harvard Conference Guidelines," followed by six references, none of which supports his contention. One article he refers to is "Differential Diagnosis and Treatment Planning" that he wrote in 1982. Although Weiss had been doing blade implants of over a decade by that time, there is no mention of his results, in either that article or in the present one, nor are there any statistics.
Two others of his references in the current article refer to the Harvard Consensus document in which Dr. Linkow and Dr. Cranin, reporting their experiences with blade implants, exhibited a 30% difference in their success rates. Smithloff and Fritz4 reported the outcome of 33 Linkow blade-vents. At five years, 14 implants were considered acceptable, eight showed adjacent radiolucent areas of approximately 4mm square and pocket depths of 4-5mm, while the remaining 11 implants (33%) demonstrated large radiolucent areas and pocket depths exceeding 6mm. Depending on the criteria used, the five-year success would be 42% - 66%. The ten-year results did not exceed a 50% success rate. This underscores the problem of establishing criteria for success if it is to be other than osseointegration as evidenced by absolute lack of clinical mobility.
The achievement and maintenance of osseointegration in the Core-Vent Implant has been confirmed by an independent study now in its third year by the Drs. Lubar and Katin,5 who report an osseointegration success rate of 98 out of 100 consecutively placed implants. Lum and Beirne’s animal study,6 published in JOMS in May, 1986, shows Core-Vent implants in the research achieved osseointegration, with vital bone in the center and through the vents of the implants.
3. Weiss’s claims of how many blade implants were "supplied to the profession" are preposterous. His estimate 1,250,000 implants sold between 1980-1985 at an average cost of $70, would indicate yearly sales of $17,500,000. Since Oratronics, the largest producer of blade implants in the last five years and a publicly-held company, realized approximately $1,000,000 in annual sales, Weiss’ inference that the millions of blade implants used are "the broad base from which experienced clinicians draw conclusions" is widely exaggerated.
4. Weiss contends that the esthetics with the blade implants are better than cylindrical implants "because the peripheral dimension of the peri-gingival cuff is so much greater," contraindicating "ridge lap." In fact, ridge lap on the buccal and lingual of the small blade post (as shown in Weiss’ article) is contraindicated by an elementary understanding of basic fixed prosthetic principles of maintaining hygienic contours. If anything, it is the prosthetic principles of maintaining hygienic contours. If anything, it is the larger cylindrical head of the Core-Vent implant –– especially the plastic castable post, which can be added to with acrylic before casting –– that allows the greatest latitude for a simulated, natural tooth abutment. In further supporting the blade implant versus the Brånemark implant with the larger permucosal site, Weiss goes on to say, "Clinical experience indicates that the gingival sulci of these larger perigingival sites seem to be more prone to periodontal breakdown no matter how well hygiene is performed. This is not true of fibro-osseous integrated abutments."
This contention is unsubstantiated by the long-term results with the Brånemark implant, which showed only a tenth of a millimeter of crestal bone loss per year with minimal pocket depth, compared to the results of the study of Smithloff and Fritz.4
5. Weiss’s chart comparing the "typical case, elapsed time" for treatment with osseointegrated implants versus blades plays fast and loose with the facts to favor blade implants. Both the Brånemark and Core-Vent System can be uncovered in three months in the lower jaw and four months in the upper; one can assume that the prosthesis can be constructed in less than one month. How many full mouth reconstructions can be completed in a busy dental practice in less time? Isn’t it better to take a three-month period to evaluate the results of intervention with implants prior to prosthetic reconstruction? Doesn’t the patient’s long-term welfare justify a conservative approach that allows the implants to heal unloaded, thus increasing the chance of achieving osseointegration at the interface –– with its long-term predictability –– rather than connective tissue?
6. Weiss sees a problem of parallelism that would be present with the bendable neck of the blade implant. There is no problem with the Core-Vent or Screw-Vent Systems from Core-Vent Corporation, because both of these implants can accept the five bendable heads with a variety of abutment attachments. Even more opportunity for contour and parallelism can be obtained by a castable head. If the neck of a blade implant breaks, as can happen with any metal that is bent, the implant is rendered useless. With a Core-Vent insert, on the other hand, the fracture of a bendable neck can be corrected by recementing another insert.
7. The claim that osseointegrated implants cannot be used "in conjunction with natural abutments" is false. Both the Core-Vent and Brånemark implants are in use connected to natural teeth, either rigidly or with stress-breaking precision attachments. Unlike the fibro-osseous blade implants, the osseointegrated implant can function free-standing as a single tooth replacement, or splinted to other osseointegrated implants in the partially edentulous mouth to support a fixed prosthesis, without relying on a natural tooth for added support.
8. It is patently not true that osseointegrated implants must be used with acrylic teeth as the shock absorber, while the shock absorber with the fibrous encapsulated blade implants is physiologic, as Weiss claims in his chart. Osseointegrated Core-Vent Implants have been used for over four years with both porcelain and acrylic occlusal surfaces. In the totally edentulous jaw, the plastic is recommended because of its ease of use and resistance to fracture in detachable prostheses.
9. More "creative" statistics in Weiss’s chart: "90% of the jaws have adequate bone for the blade implant, but only 20% of the jaws have enough bone for cylindrical implants and then only in the anterior area."
This is unsubstantiated speculation and has no place in a scientific publication. If Dr. Weiss did either Core-Vent or Brånemark implants, he would know this isn’t true. By flattening the crest of the ridge in the symphysis, and by angling to the palate in the maxilla, there are very few cases that cannot be done with the smallest (4.3mm OD, 3.5mm ID) cylindrical Core-Vent Implants when adequate height of bone exists. The Brånemark and Screw-Vent implants are 1/2mm smaller (3.75mm OD). Osseointegration can be achieved with the new SUB-Vent (Submergible Universal Blade-Vent) Implant from Core-Vent Corporation when the slow-speed surgical protocol and unloaded healing period is followed.
The question is not whether one must accept a fibrous encapsulation because of the amount of bone or the patient’s demands for an immediate solution to their long-standing problem. Since osseointegration can so consistently be achieved and since osseointegration offers such long-term predictability, can we professionally or financially afford to settle for less?
1. Andersson, G. et al.: Segmental replacement of long bone in baboons using a fiber titanium implant. J Bone Joint Surg, 60:31, 1978.
2. Adell, R.: clinical results of osseointegrated implants supporting fixed prosthesis in edentulous jaws. J Prosthet Dent, Vol. 50, No. 2, 1983.
3. Albrektsson, T., Zarb, G., et al.: The long-term efficacy of currently used dental implants: A review and proposed criteria of success. J Oral Maxillofac Imp, Vol. 1, No. 1, 1986.
4. Smithloff, J., Fritz, M.E.: The use of blade implants in a population of partially edentulous adults. J Periodontal 47:19-26, 1982.
5. Lubar, R., Katin, R.: Clinical results with Core-Vent Implants. Abstract of presentation to LSU Symposium, March 1986.