Although many types of dental implants have been used to replace missing teeth, including blade, subperiosteal and staple implants, the majority of implants used for tooth replacement in the modern era of implant dentistry (over the past 20 years) are root form osseointegrated implants, most commonly made of titanium. Among the root form osseointegrated implants, there are significant differences, including:
- Implant design elements — implant shape, thread pattern, presence or absence of a machined surfaced implant collar, type and location of abutment connection, superior or central shifting of micro-gap, and presence of macroscopic grooves on the implant body to encourage greater bone anchorage.
- Implant surface characteristics (microtopograhpy) and surface chemistry, which both influence the rate and percentage of osseointegration measured as bone to implant contact (BIC).
- Stability of bone to implant anchorage under functional loading.
- Scientific documentation to support the product, company replacement warranties, and cost.
Because there has been a rapid evolution as a result of extensive research and development commitments made by the major implant manufacturers, clinicians and patients need to educate themselves about the current technology available to them and how to avoid selecting an outdated technology—or even worse, an implant sold on the “Black Market” that may have been manufactured by a company that is no longer in business. In this article, I review a little history, talk about the latest advancements, and make some recommendations.
A short history of the technology advancement follows.
Extensive scientific research and clinical studies were conducted by Dr. Per-Ingvar Brånemark and co-workers in Sweden on root form titanium implants in the early 1970’s. These studies demonstrated tremendous biocompatibility and also dramatically improved clinical success and predictability of titanium implants compared to previous dental implants made of various metals that were not biocompatible and did not achieve osseointegration, making them susceptible to infection and rejection.
Since their introduction in the United States in the mid 1980’s, the success level of titanium implants has risen to 97-99% or greater, due to such improvements in osseointegration as:
- New implant designs that improve primary stability and bone to implant contact (BIC) in all types of bone.
- New implant surfaces that mimic the microscopic structure of bone and increase the speed and amounts of osseointegration through contact osteogenesis, extending from the implant preparation bed, and distance osteogenesis, resulting in de-novo bone formation directly on implant surfaces due to surface mediated influence on the phenotypic expression of osteocompetent cells located adjacent to the implant body at a distance from the osteotomy preparation.
- Bio-active implant surface enhancements technologies that are designed to improve the amount of distance osteogenesis, including the addition of highly crystalline and phosphate enriched titanium oxide surface, e.g., Nobel BioCare TiUnite ® (Sweden); fluoride ions, e.g., Astra Tech OsseoSpeed TM (Sweden); and discrete nanometer sized crystalline particles of calcium phosphate, e.g., Biomet3i NanoTite TM (Palm Beach Gardens, FL).
- Bio-active implant surface chemistry enhancements, including manufacturing of implants in oxygen-free environments to reduce oxidation contaminants, combined with storage in sterile saline to improve early blood and protein surface absorption leading to greater distance osteogenesis and secondary implant stability, e.g., Straumann SLActiveTM (Switzerland) — and chair side treatments with hydroxide solution to encourage surface absorption of blood and protein that lead to greater distance osteogenesis, e.g., Thommen Medical INICELL ® (Switzerland).
Recent advancements in dental implant biotechnology have provided additional benefits for patients.
- Novel changes to the implant shape and screw thread designs have resulted in improved initial implant stability at the time of placement.
- Improvements in abutment connections have reduced bacterial micro leakage and redirection of biomechanical loads away from crestal bone. The result is enhanced maintenance of the crestal supporting bone with better load distribution and improved esthetics.
- Recently, tantalum has been used to create a new dental implant that includes a trabecular metal design that emulates human cancellous bone. Tantalum is stronger and more flexible than titanium (as its modulus of elasticity is similar to cancellous bone), and the trabecular architecture has up to 80% porosity allowing approximately 2-3 times greater bone ingrowth, compared to conventional porous coatings, and double the interface shear strength. The pore size and high volume porosity supports vascularization and the opportunity for a significant increase in the amount of osseointegration measured as bone to implant contact (BIC). Trabecular metal implant technology has enjoyed excellent results for orthopedic implants, and now Zimmer Dental (Carlsbad, CA) has introduced their Trabecular MetalTM Technology implants for use in implant dentistry.
- Ceramic “tooth colored” root form implants made from zirconium are also now available with similar surface characteristics found in titanium implants. Although zirconium dental implants are not as well documented as titanium implants, they are gaining popularity with patients and doctors seeking a “metal free” alternative. When zirconium implants are ideally placed and restored, they provide significant esthetic advantages. Recently, Z-Systems (Switzerland) upgraded their zirconium implant system by incorporating the advanced surface technology found on the premiere titanium implants.
To take advantage of current, beneficial technology, the implant you select for your patient should include the following.
- A “rough surface” that encourages greater bone anchorage.
- Precise site preparation and implant placement instrumentation.
- Shape and screw thread design for optimal primary stability, according to the type of bone encountered at a particular site.
- Stable internal abutment connection with high fidelity to better distribute functional loads and diminish bacterial micro leakage, thereby preserving crestal bone.
- Implant surface and surface chemistry enhancements to increase the amount of secondary stability (distance osteogenesis).
- FDA approval and scientific documentation with clinical studies and prospective studies to verify clinical efficacy.
- A reputable biomedical manufacturing company that:
- Is currently in business.
- Is in good standing with the FDA.
- Provides a replacement warranty.
- Provides professional technical support.
- Provides an efficient cooperative system for ordering and returning implants and components.
- Provides sterile packaging with expiration dates for implants and prosthetic components.
- Provides continuing education for users.
- Supports your practice in a timely and professional way.