CONTROVERSIES IN IMPLANTOLOGY –– 1988
ADA Approval • NIH Conference • Statistics • Swede-Vent™
Biomedical Business International, an independent research organization, recently published their 1988 analysis of the dental implant market. They reported that Core-Vent Corporation accounted for 49% of all osseo- integrated implants sold, but only a 33% share of the dollar sales of the market. According to the report, Nobelpharma Inc., distributors of the Brånemark System,™ accounted for 29% of the market share in numbers of implants sold but 38% in dollar sales. Nobelpharma has, in a recent publication, pointed to the 38% figure as evidence of their leadership in the implant industry. Core-Vent Corporation s proud of the fact that it is the "cost containment leader" of the dental implant industry. Core-Vent Corporation’s large customer base of approximately 5,000 systems sold worldwide has made it possible to provide a wide selection of implants, prosthetic abutments and instruments at reasonable prices. This has allowed a greater number of dentists the opportunity to offer their patients the benefits of aesthetic functional restorations supported by osseointegrated implants.
The Core-Vent system has evolved over the last six years from one implant design and size accepting only cemented abutments to a variety of five cylindrical designs with equal emphasis on cemented and threaded abutments. The growth of the implant industry was paralleled by a growth by Core-Vent Corporation from four employees in 1984 to 110 by 1988. As the acceptance of implants by organized dentistry expanded, so did the standards by which implants were judged. Core-Vent Corporation is again in the forefront of setting these standards in precision fit, prosthetic versatility, surface cleanliness and state-of-the-art packaging.
Clinical Predictability - Risk Perception
Predictability in both achieving and maintaining osseointegration is a function of the skill and judgement of the surgeon, as well as the user-friendliness of the system. Being able to accomplish the desired prosthetic result is also of paramount importance in selecting an implant system. Risk perception has been an important factor in deciding which system to use. In this regard, two recent events bare consideration:
• ADA Limits Nobelpharma’s Approval to Totally Edentulous Patients
Nobelpharma was granted ADA Provisional Approval in 1985 based on its Swedish and University of Toronto Studies, the latter showing about 85% implant success in totally edentulous jaws. With provisional approval set to expire in September 1988, the ADA granted the Brånemark Implant full approval but clarified that this approval of the Brånemark System does not include its use in partially edentulous patients at this time.
Core-Vent’s pending application with the ADA is for approval in completely and partially edentulous jaws. Core-Vent Corporation has been informed that its application is in the final stages of review.
• NIH/FDA Implant Consensus Conference
On June 13-15, 1988 in Bethesda, MD, the National institutes of Health (NIH) in concert with Food and Drug Administration (FDA) convened a Consensus Development Conference to formulate an Implant Consensus Statement. A panel of twelve researchers and clinicians was appointed to evaluate information from a number of presenters and formulate a consensus statement on dental implants.
The position of the Brånemark system and its research was well represented by Drs. Brånemark and Zarb (co-authors of the textbook on the Brånemark System) and Drs. Worthington and Bolender (co-directors of the Seattle Brånemark Teaching Center). Dr. Paul Schnitman, head of the department of Implantology, Harvard University presented results on a number of implants including the Core-Vent System. The format of the conference allowed an opportunity for questions, short slide presentations and statements from members of the audience numbering over 1,000.
Core-Vent/Brånemark Statistics Presented
The Core-Vent clinical study (Drs. Patrick, Lubar, Zosky and Buchs - submitted for publication) was reported to the panel. It analyzed the success of 1,605 consecutively placed Core-Vent Implants with up to 5 years of follow-up. These Core-Vent Implants were placed in both totally and partially edentulous jaws and also included 95 free-standing implants. The overall results documented a 96.2% success rate with 628 maxillary implants and 96.7% success rate with 977 mandibular implants. Over half of the implants had been in partially edentulous jaws. The results of Core-Vent Implants in partially edentulous jaws showed approximately a 98% success rate with no significant difference between upper and lower jaws. This was contrasted with results reported by Albrektsson (May 1988 Article, Journal of Periodontology) on the Brånemark Implant. The Albrektsson article documented maxillary implants with a 1-7 year follow-up showing 90% success and with a 5-7 year follow-up showing 85% success. When sleeper implants (0.8%) were included in the statistics along with failures, the Brånemark fixtures, by the 5-7 year period, had about 15% greater failure rate in the edentulous upper jaws than fixture reported in edentulous lower jaws in this study.
NIH Consensus Panel Statement
The NIH Consensus panel, after reviewing written and oral presentations on the Brånemark System, Core-Vent System and others, concluded in their published statement that:
There is evidence from a number of case series studies that a large proportion of specific types of dental implants remain in place for periods of 10 years or more when inserted by clinicians experienced with the respective techniques. However, it is difficult to make definitive statements on the long-term effectiveness of dental implants from these case series studies because of unreported information and the lack of uniform application of proper research designs. Although the ideal research techniques should be a randomized, controlled clinical trial, case series studies are capable of providing limited evidence when proper methods are used.
Nowhere in the 15-page statement (available upon written request from Core-Vent Corporation) is there any reference to the Brånemark Implant research being more valid or its clinical results being superior to the research or clinical results reported for the Core-Vent Implant. All implant studies presented were collectively referred to as "case series studies." The statement further confirmed that "...technological advances in the construction and insertion of various implants, will likely result in a trend toward improved long-term success rates."
The findings of the Consensus Development Panel heralded a new era in Implantology. They appeared to refute the claims by proponents of the Nobelpharma System that Brånemark research offers "the only clinical implant study that has survived scientific scrutiny" (Dr. Zarb, Nobelpharma brochure).
From a comparison of the Patrick et al. study and the Albrektsson study, Core-Vent’s hollow vented, self-tapping screw design may offer advantages in the porous maxillary bone to a solid screw design inserted following use of a bone-tap instrument. Nobelpharma’s 1988 introduction of two self-tapping fixtures, one with a new conical neck (similar to the neck of the Screw-Vent Implant), appears to confirm that Nobelpharma now agrees with this. It also appears from the sale of this new implant that Nobelpharma may have abandoned its marketing position that implants should have 5-10 year multi-center clinical studies reported in refereed journals before being sold. One should inquire whether the new implants, which differ in design and surgical protocol form the clinical studies submitted to the ADA, have ADA approval even for use in fully edentulous jaws.
Nobelpharma’s Unsubstantiated Claims
Over the last few years, Nobelpharma has become aggressive in its comparative advertising with claims of superiority in clinical results and quality manufacturing. Nobelpharma appears to have chosen this route rather than compete with Core-Vent Corporation on price or product versatility. Core-Vent Corporation believes that many of these claims are unsubstantiated:
Claim 1: "...only one (Nobelpharma) offers the complete system essential to long-term success of your practice."
Fact 1: The Core-Vent System of Osseointegrated Implants offers five cylindrical designs in a variety of dimensions and provides abutment options that include a selection of cemented or threaded connections and bendable or castable abutments. The Core-Vent System was found to be the only "complete system" according to a recent report by Clinical Research Associates, an independent clinical research organization (available upon request from Core-Vent Corporation). Long-term success of anyone’s practice will not depend on any one system or procedure, but on the knowledge, skill and care given to patients.
Claim 2: "No other method guarantees its results, and no other procedure puts the healthy glow back into living."
Fact 2: Nobelpharma does not guarantee its results.
Claim 3: "99% long-term and complication-free success for bridges anchored in the lower jaw."
Fact 3: The textbook, Osseointegration in Clinical Dentistry, by Brånemark, Zarb and Albrektsson report that 3% of the cases experienced fractures in one or more fixtures. The University of Toronto Brånemark Replication Study showed that, in the first 4 years of the 30 bridges supported by Brånemark fixtures, 26.6% experienced one or more screw fractures and 60% reported fractures of the frameworks.
Claim 4: "Here is the only system that used the revolutionary method of osseointegration to attach a dental prosthesis permanently to the very jawbone itself."
Fact 4: Primate studies by Lum and Beirne comparing Core-Vent to Brånemark implants placed side-by-side and loaded for up to one year (presented AADR meeting 1987, accepted for publication , JPD) showed that the Core-Vent Implant osseointegrated as well as the Brånemark Implant and both maintained osseointegration for up to one year of observation.
Claim 5: 5-12 years’ results where "the success rate of prosthesis registered 96% in the upper jaw."
Fact 5: Adell (1983 article, JPD) reported 96% continuous function of upper jaw bridges with 1 4 year follow-up referred to as group 2B. He later reported (November 1987, Harvard meeting) that the results of this group, then with 6-10 year observation, dropped to under 91% bridge success.
Nobelpharma Attempts to Patent TiO2
In 1986, Nobelpharma sued Core-Vent Corporation for patent infringement. Core-Vent counter sued, alleging that Nobelpharma and Dr. Brånemark "applied for a U.S. patent but failed to disclose either the prior art found by the Swedish Patent Office, Dr. Brånemark’s own 1977 publication, or Dr. Brånemark’s 1972 UK patent."
1972 –– Dr. Brånemark (through a Swedish company) receives a UK patent #1291470 for his titanium implant. The patent was never issued in Sweden or the United States. This patent states: "The best material hitherto known, however, certainly is pure or weakly alloyed titanium."
1977 –– Dr. Brånemark published a book on his experience with titanium implants. The review of the literature referred to a 1972 article by Morse that had reported irregularities from machining and pitted areas from formation of titanium oxide corrosion products on titanium implants:
The new and used implants exhibited surface striation and irregularities which had apparently resulted from the tooling process, and some dark pitted areas representing surface corrosion, primarily from titanium. The main corrosion product was titanium oxide, believed to be relatively inert.
1979 –– Dr. Brånemark and an employee of Bofors, the Swedish conglomerate that later formed the Nobelpharma Corporation, filed a Swedish and American patent on a micro-pitted, titanium dioxide surface on titanium implants. The United States patent was issued in 1982 and is the subject of the current litigation. Included among the patent claims is the following:
Claim #3: "An element according to claim 1, wherein said material is titanium having a decreasing oxygen content from a titanium dioxide micro-pitted surface inwardly."
THE 1972 BRITISH PATENT AND THE 1977 ARTICLE WERE NOT REVEALED TO THE UNITED STATES PATENT AND TRADEMARK OFFICE AS IS REQUIRED OF ALL MATERIAL PRIOR ART.
1986 –– Dr. Brånemark and an employee of Nobelpharma filed European Patent Application #86850348.3 claiming:
Claim #1: "A material of unalloyed titanium for implantation in body tissue, characterized in that the surface of inorganic atomic layer of the material contains: Ti 29-33, O 61-67 expressed in atomic percent."
This European patent application appears to claim to have discovered a surface of titanium that is approximately 1 part titanium and 2 parts oxygen –– i.e. TiO2. The Nobelpharma/Brånemark 1982 United States patent had already disclosed the following:
When stored, titanium (and even low-alloyed titanium after machining) quickly acquires an oxidized surface equivalent to a crystallized surface of rutile TiO2..
THE SWEDE-VENT SYSTEM: American Price, Prosthetics and Practicality
In this environment of marketing rhetoric and professional polarization, Core-Vent Corporation decided to introduce the Swede-Vent fixture, a "Nobelpharma look-alike." This is not to be construed as an endorsement of the Brånemark design, but provides American competition to another inexpensive foreign product. The Swede-Vent fixture, made from commercially pure titanium, is being sold at the same price as Core-Vent, Screw-Vent and Micro-Vent implants. The wider neck of the Swede-Vent and Brånemark fixtures requires countersinking the crest of the ridge during the surgical procedure. This step initially removes several millimeters of valuable supporting bone. The wider neck concentrates the stress at the crest of the ridge during loading, resulting in a reported 1+ mm of additional bone loss in the first year of function, according to the Brånemark clinical studies.
The Brånemark System was developed over 20 years ago and has undergone little change. One only has to look at changes in the computer industry in the last five years to see how modern technology and manufacturing has resulted in better, more cost-effective products.
In 1986, Core-Vent Corporation introduced the Screw-Vent Implant
The Screw-Vent Implant is a solid screw design made from commercially pure titanium matching the dimensions and pitch of threads of the original Brånemark fixture. Nobelpharma, in their 1988 Catalog, has now introduced a new fixture which also has a conical neck and is self-tapping. It sells for twice the cost of the Screw-Vent fixture, $230 vs. $115 (price includes cover screw or surgical insert). Compared to the original 3.75mm diameter Brånemark fixture (single-unit price, March 1988). Core-Vent Corporation charges the same $115 for its 3.75mm and 4.0mm diameter Swede-Vent fixtures and for its conical, self-tapping Screw-Vent fixture, because there is no significant differences in manufacturing costs. The Swede-Vent and Screw-Vent fixtures are acid etched to provide a metallurgically clean surface and they offer the following advantages:
SCREW-VENT DESIGN ADVANTAGES compared to Swede-Vent and Nobelpharma
1. Conical Neck with Internal Hex –– this will mean:
a. No countersinking of crestal bone required.
b. No exposed threads with bone loss up to 2.5mm.
c. No reflection of periosteum needed to expose implant for connection of abutments –– less invasive & less time consuming.
d. Accepts both screw-in abutments (6 options) and castable cemented abutments that can overcome undesirable angled implant placement.
e. Matching internal bevel of internally threaded implant and bevel of abutment for greater lateral support and stability.
2. Threads all the way to the end –– this will mean:
a. Elimination of bone tap procedure in all but the most dense bone for immediate congruency with vital bone.
b. Increases initial stability of fixture with self-threading and apical threads engaging cortical bone under the nose and at the inferior border of the symphysis.
SWEDE-VENT SURGICAL ADVANTAGES compared to Nobelpharma System:
1. The Swede-Vent instruments are stainless steel coated with titanium nitride for increased hardness and lubricity for long-lasting cutting efficiency. This provides further cost savings over Nobelpharma’s disposable drills, which are not autoclavable and are to be discarded after each surgery (even if only a single implant site was prepared).
2.. The Swede-Vent instruments are internally irrigated for more efficient cooling, therefore eliminating one of the cutting steps for further economy of time and money.
3. The Swede-Vent fixtures are provided suspended on a handle inside a double-vial sterile package for easy delivery to the surgical site. The Nobelpharma fixtures are provided in a titanium casing inside a glass ampule requiring breaking of the glass. Before the Nobelpharma fixture can be carried to the surgical site, additional steps and instruments are needed:
Nobelpharma Insertion Procedures
1. Pick up the titanium tube containing the fixture and transport it to a titanium holding tray.
2. Attach a fixture mount device to the top of the Nobelpharma fixture.
3. Carry the assembly of fixture and fixture mount to the surgical site with a contra-angle mandrel.
4. Screw the fixture into place with slow-speed motor and complete with ratchet.
5. Unscrew the fixture mount device.
Swede-Vent Insertion Procedures
1. Carry the fixture to the surgical site on the plastic handle used to suspend the implant in the inner vial.
2. Remove the stopper and screw the fixture into place using the hex drill turning at 15 rpm. Finalize the seating with ratchet and hex tool. Both hex instruments interlock with the external hex on the implant and are, therefore, easily disengaged.
SWEDE-VENT PROSTHETIC ADVANTAGES compared to Nobelpharma System
The Swede-Vent System offers 5 abutment options with one of the designs (straight walled, 1 piece abutment in 3 lengths) accepting 4 different screws for overdenture applications (ball and magnet attachments, rigid and resilient bar attachments). The titanium and plastic castable Crown & Bridge abutments for the Swede-Vent bring conventional restorative procedures to the Brånemark fixture design. Surgical specialists are able to accept referrals from general dentists and prosthodontists without requiring that they take expensive Nobelpharma sponsored training programs. All the Swede-Vent prosthetic abutments are compatible with Nobelpharma fixtures and provide up to 70% savings (abutment and laboratory components needed per fixture) compared to Nobelpharma’s single-unit prices. The cost savings will add to your net income and allow more patients to take advantage of your skills and training.
IMPLANTOLOGY –– PAST AND PRESENT
Since the Core-Vent and Brånemark Systems of Osseointegrated Implants were first introduced to the North American continent in 1982, dentistry has experienced an implant revolution. The Core Vent System has undergone rapid evolution in the past six years. Core-Vent Corporation has received patents on the Core-Vent Implant and has patents pending on the SUB-Vent®, Micro Vent® and Bio-Vent™ Implants, and on its innovative Hex-Thread™ connection that accepts both cemented cast posts and a variety of screw-in abutments. In addition, patents on prosthetic abutments have been awarded for the flush-fitting, castable head, the bendable heads and the Core Vent Attachment. Core-Vent Corporation funded the development of Ion Sputter Application of Hydroxylapatite to provide a thinner, denser coating on titanium implants. This coating is now available on the Micro-Vent® Implants offering both mechanical retention and the firmly adherent HA coating in a tap-in/screw-in design. Core-Vent Corporation has been able to provide these advances to the dental profession while maintaining its leadership in cost containment because of a large customer base.
Core-Vent Corporation’s variety of implant systems provides design and dimensional options to overcome limitations in quality and quantity of bone. The Core-Vent®, Screw-Vent®, Micro Vent®, SUB-Vent® (submergible blade) and Swede-Vent Systems provide the dentist with a choice of materials, design and surgical procedures to meet his/her individual training, experience and personal preferences. For those dentists who prefer a non-threaded, cylindrical design, such as the IMZ (Interpore Inc.) or Integral Implant (Calcitek Inc.), but would like the advantages of the Core-Vent System’s price and prosthetics, Core-Vent Corporation has developed the Bio-Vent™ Implant. This is a plasma-sprayed, HA-coated cylinder with vertical, anti-rotation grooves and an apical vent(pat. pend.) to allow escape of trapped blood for full seating. Expected delivery date is December 1988.
THE TRUE SYSTEM™ OF OSSEOINTEGRATED IMPLANTS
The surgical goal of the dentist should be to fit the implant to the patient, rather than fit the patient to the particular design or size of the implant. With this principle in mind, Core-Vent Corporation has developed a "System of Systems." In selecting an implant system, it is also important to consider the strength of the company and whether it will be here to service your needs in the future. Core-Vent Corporation has grown from 4 employees in 1984 to 110 in 1988 with offices in 4 countries and distributors in 15 additional countries. Core-Vent Corporation has sold approximately 5,000 systems worldwide.
IMPLANTOLOGY –– THE FUTURE
Core-Vent Corporation will continue to be successful in this competitive market by providing the profession with what it needs: simplified surgical procedures, versatile prosthetic applications, accessible educational programs, technical and marketing support and prices that have allowed implantology to take its rightful place in the mainstream of conventional dentistry.