Response to Nobelpharma Letter: Postsettlement Disclaimer #2
OPEN LETTER TO THE DENTAL PROFESSION
Nobelpharma and Core-Vent Corporation, according to the Joint Settlement Announcement of January 15, 1989, reached "an amicable end to the controversy between the two companies." Unfortunately, in just six weeks following the settlement agreement, Nobelpharma sent two open letters to the profession that contained misleading statements regarding the settlement and other related issues. Core-Vent responded to Nobelpharma’s January 15th letter (copies available upon request) regarding the extent and significance of the license granted to Core-Vent Corporation for the patents issued to P-I Brånemark, including U.S. Patent No. 4,330,891. Core-Vent must now respond to Nobelpharma’s February 20, 1989 letter which makes a number of statements allegedly in response to questions from Nobelpharma’s customers who "were told of a supposed relationship between Nobelpharma USA, Inc., and Core-Vent Corporation."
Nobelpharma’s February 20th letter by its president, Mr. Bill Ryan, makes several factual statements that leave the reader with the false impression that Core-Vent Corporation has made statements to the contrary. The letter then claims that a failure of Core-Vent to respond must be construed as an agreement with Nobelpharma’s position: "When you have truth on your side, you are NEVER afraid to put it in writing. I have been asked to do so and here it is. Anyone who tells you something to the contrary also should put it in writing. If they will not, then you know the value of their words."
The Nobelpharma letter implies that Core-Vent Corporation has claimed to be a "distributor or agent" for Nobelpharma or "authorized by Nobelpharma to provide training in the Brånemark System." Nobelpharma’s transparent attempt to gain credibility by raising non-issues and challenging Core-Vent to disagree would not be worthy of a response if it were not for the false impression that would be left if Core-Vent did not accept Nobelpharma’s invitation to respond in writing. This cycle of Nobelpharma’s misleading letters and Core-Vent’s responses will end when Nobelpharma is made to realize by the profession that this type of marketing rhetoric is counter productive. Nobelpharma’s letter does raise several issues which, I believe, deserve a scientifically supported response.
The letter falsely states that the Swede-Vent’s surface may be both sandblasted and acid etched:
Core-Vent Implants, including Swede-Vent, DO NOT HAVE AN IDENTICAL SURFACE to the Brånemark System™ implants –– they are either sandblasted, acid etched (or both), or coated with hydroxylapatite. The Brånemark System™ implants have a precision machined surface.
Core-Vent, Screw-Vent and Swede-Vent implants are only sold with an acid-etched surface in order to remove surface contamination from machining and deburring procedures. Although the Swede-Vent and Screw-Vent implants now have the surface patented by Brånemark, Core-Vent Corporation has never claimed that the surface is identical to Nobelpharma’s. Core-Vent has emphasized in its literature and lectures the important differences between the surfaces.
SWEDE-VENT AND SCREW-VENT OFFER BRÅNEMARK’S PATENTED SURFACE
Brånemark’s U.S. Patent No. 4,330,891, granted in 1982, states: "An analysis of jaw implants in homo" showed that "the bio-optimal result" could be achieved using "a biologically flawless material with a porous, i.e., micro-pitted surface intended to face the tissue."
The Swede-Vent and Screw-Vent pure titanium implants from Core-Vent Corporation, ACCORDING TO AN INDEPENDENT EXPERT NOMINATED BY NOBELPHARMA, do provide the type of micro-pitted surface specified in Brånemark’s patent. According to Brånemark’s statements under oath to the U.S. Patent Office, this surface will provide "inextricable anchoring in the living bone tissue." According to a study funded by Nobelpharma, it was found that machined titanium surfaces "are not metallurgically satisfactory and can detract from the suitability of the implants for service." The report by Taussig Metallurgical Engineers strongly recommended Nobelpharma to wash their implants in acid (passivation) to "eat out any metallic particles." Core-Vent instituted acid etching procedures in 1986 and, during the last three years, has conducted extensive tests using SEM, EDAX and Auger analysis, and built its own Class 10,000 Clean Room facility in an attempt to perfect the cleaning process and provide the profession with "a biologically flawless" or superclean surface.
NOBELPHARMA STUDY CONFIRMS ADVANTAGES OF ACID ETCHING SURFACE
Taussig Metallurgical Engineers Report #74305-1/August 27, 1987 (copies available from Core Vent Corporation), examined Nobelpharma implants that "had been packaged in sealed glass containers" with "a representative of the Brånemark Company being present." Examination using "scanning electron microscope and Energy Dispersion X-ray Analysis of two samples representing titanium dental implants" revealed the following:
It appeared that the grinding of the surface of the implant produced a number of titanium particles that were partially dislodged, and/or folded over onto the surface of the implants.
THE NOBELPHARMA SURFACE ANALYSIS REPORT CONCLUDED:
"Brånemark implants exhibited evidence of nonmetallic particles on the surface of the implants while the implants had been sealed in glass containers. Even though the implants have been rendered biologically sterile, the contamination of the metal surface by metallic particles had resulted in the implants being not sterile from a metallurgical point of view. It is our opinion that the metallic particles and nonmetallic particles that we observed on the Brånemark implant surfaces, as well as the numerous areas where the apparently ground surfaces have been folded over, are not metallurgically satisfactory and can detract from the suitability of the implants for service. The titanium surface can be and should be passivated (i.e. acid washed –– explanation added) similar to that process performed on stainless steel to eat out any metallic particles and to help reinforce the passive oxide film on the surface of the titanium. The dentist, periodontist or oral surgeon has every right to expect that the surfaces of the implants that they are inserting are clean and free from any particles that could possibly adversely affect the serviceability of that implant."
The Brånemark System is an exclusive trademark of Nobelpharma. U.S. Patent No. 4,330,891.
THE CORE-VENT ANALYSIS CONFIRMS ETCHED SURFACE IS "METALLURGICALLY IMPROVED"
Taussig Laboratories recently evaluated Core-Vent Corporations’s cleaning procedures and concluded:
The general surface appearance of the Core-Vent, Screw-Vent and Swede-Vent implants, in our opinion, appear to be metallurgically improved over that of the Brånemark implants previously examined for Nobelpharma by our laboratory because the surface has been chemically passivated (acid etched) to "eat-out" any embedded metal particles. The surface of the Nobelpharma implant is machined which causes microscopic machining laps. These laps fold over metal particles and adhere these particles to the implant surface.
The acid etching procedure used to clean the machined surfaces of the Screw-Vent and Swede-Vent implants increases the number of micro-pits in the 1-3 micron range. This is the important range Brånemark’s patent claims was shown by his research to "approach the order of magnitude of the cell diameter" and give "operation results" that were "noticeably improved."
SURFACE CONTAMINATION MAY BE CAUSE OF "SECONDARY FAILURE OF OSSEOINTEGRATION"
Albrektsson, in an article in Dental Clinics of North America, January 1986, stated:
Secondary failure of osseointegration, when a primarily achieved bone anchorage is lost, sometimes years after insertion, may depend on a slight incompatibility of the used material, an unsuitable surface finish of the implant or an overloading.
CLINICAL STUDIES SHOW "SECONDARY FAILURE" WITH NOBELPHARMA IMPLANT
Studies have shown that the success rates of the Nobelpharma implant in the maxilla dropped dramatically with time:
1. Albrektsson reported on a multi-national study with 90% success in the 1-7 year group dropping to 85% for the 5-7 years group –– Journal of Periodontology, May 1988.
2. Adell reported upper bridge success of 96% after 1-4 years dripping to under 91% by the 6-10 year follow-up. Report on Brånemark Implants (unpublished) presented at Harvard University, November 1987.
3. Moy et al. documented UCLA’s declining success rate with Nobelpharma implants in the maxilla in figure #1: "No fixtures were reported as failures at the second surgical appointment as they all appeared non-mobile at the time of exposure."
IMPLANT SUCCESS OVER TIME
These "secondary failures" are in contrast with the results of a Core-Vent Study by Dr. Patrick, Dr. Lubar, Dr. Buchs and Dr. Zosky (submitted for publication -- abstract available from Core Vent Corporation). The study showed a 98% success rate with 342 maxillary Core-Vent implants placed in partially edentulous jaws over a 3-64 month observation period. Only one implant was reported lost after the first year in function.
EXTRAPOLATION OF BRÅNEMARK RESEARCH TO SWEDE-VENT IMPLANT
The Nobelpharma February 20th letter states: "The success rates relating to the Brånemark System™ ARE NOT applicable to Core-Vent implants, including Swede-Vent."
Core-Vent continues to believe that the Brånemark implant research relates to long-term predictability of any implant that achieves osseointegration and maintains it for nine months in function. Core-Vent has not claimed that the results, good or bad, "relating to the Brånemark System™ are applicable to the Core-Vent implants, including Swede-Vent."
Core-Vent believes, based on the aforementioned studies, that, in the maxillary arch (and possibly in the lower posterior arch), the hollow-vented design of the Core-Vent Implant offers advantages with regard to maintaining osseointegration compared to solid screw design. Core-Vent does not recommend use of its Swede-Vent Implant in these applications for this reason and because it requires countersinking which further reduces cortical bone support.
The Brånemark System™ and the Swede-Vent® System have the following features in common –– the profession can decide for itself the significance of this with regard to extrapolation of success rates.
1. The Swede-Vent and Nobelpharma fixtures both achieve osseointegration when properly inserted.
2. Swede-Vent matches the original Brånemark implant in design, material and dimensions and has the surface that Brånemark stated in his patent would provide "the bio-optimal result."
3. Swede-Vent can be inserted using the Nobelpharma instruments and surgical protocol or placed using Swede-Vent internally irrigated drills that minimize heat generation and simplify the surgical procedures.
4. Swede-Vent implants accept Nobelpharma’s prosthetic abutments as well as Swede-Vent’s new one-piece prosthetic abutments that have been shown by an Ohio State University study to be 30% stronger than Nobelpharma’s abutments.
Nobelpharma’s February 20th letter makes the claim that "the success rates relating to the Brånemark System™ are not applicable to the...Swede-Vent,™" which has the aforementioned similarities to the original Brånemark implant. It is interesting to note that Nobelpharma has made no distinction between the success rates of the original Brånemark implant and Nobelpharma’s newly introduced (1988) self-tapping fixtures, which differ in thread design, neck design and surgical protocol from the original Brånemark implant reported in published research. Today’s Nobelpharma implants may also differ from those used in the long-term Brånemark clinical studies in surface oxide as a result of high heat sterilization of glass vials and changes over the years in cleaning solutions.
Those dentists who have selected the Nobelpharma System in the past because of their confidence in Professor ‘s research can now feel more comfortable with the Screw-Vent and Swede-Vent implants knowing that an independent expert nominated by Nobelpharma found that the Screw Vent and Swede-Vent implants have the type of micro-pitted surface that Brånemark determined from his research to be important. Furthermore, these implants offer a superclean, acid-etched surface. Core-Vent believes, based on Albrektsson’s statements about "secondary failures" related to "slight incompatibility" that, if anything, the "metallurgically improved" surface available on the Screw-Vent and Swede-Vent implants may enhance long-term results compared to the type of surface that all implant initially have after machining.
IMPLANTOLOGY IN THE 1990s –– THE DECADE OF PROSTHETIC VERSATILITY, SERVICE & VALUE
Core-Vent Corporation has been a leader in implant innovation since 1982 and has grown from four employees in September 1984 to over 120 employees by 1988. The simplified surgical procedures and versatile prosthetics have made Core-Vent products well accepted by the profession and led to Core-Vent’s position as being the world’s largest supplier of dental implants. Core-Vent Corporation believes that quality products, customer service and reasonable prices have contributed to this growth. The success of the Core-Vent Implant has now been recognized by the American Dental Association with its recent decision to grant the Core-Vent Implant Provisional Acceptance after a thorough evaluation of clinical results and manufacturing practices. Hopefully this response letter will close the final chapter on the controversy between Nobelpharma and Core-Vent Corporation and both companies can now devote their financial resources and energies to competing on customer satisfaction, quality of products and value. Core-Vent Corporation welcomes the opportunity of earning the profession's business on this basis.
CORE-VENT RECEIVES ADA PROVISIONAL ACCEPTANCE
THE CORE-VENT® SYSTEM
"The Core-Vent Implant System is Provisionally Acceptable for use in selected cases. Responsibility for proper selection of patients, for adequate training and experience in the placement of the implant and for providing appropriate information for informed consent rests with the dentist."
Council on Dental Materials, Instruments and Equipment
American Dental Association