by Carl E. Misch, BS, DDS, MDS, PhD (hc)
The U.S. population will increase by 49 percent by the year 2030, yet the number of dental schools has increased by only 10 percent during the last 10 years. The largest percentage of the adult population increase will be above the age of 50 years. The first permanent tooth lost today in the U.S. is usually after the age of 35, and the older the patient, the higher the prevalence of tooth loss.
In fact, by 65 years of age, over 10 percent of the adult population is completely edentulous. Implants have evolved into a primary method of tooth replacement, rather than a last alternative. In 1975 — the infancy of implants — the total sales of implants to dentists were $1 million. In 1985 — the adolescence of implants – the total sales were $100 million. Today, the discipline is becoming more mature, and the sales of implants to dentists are more than $1 billion each year.
Dental implants are a better alternative to replacing missing teeth in partially edentulous patients, rather than attaching missing teeth to prepared and crowned natural tooth abutments. When a tooth is prepared for a crown, a 5.7 percent risk of irreversible pulpal injury and subsequent need for endodontic treatment exists. The pontic acts as a large overhang next to the crown and a reservoir for plaque. The percentage of adults who use floss threaders is less than 3 percent. As a result, the crown margin next to the pontic of a fixed prosthesis is more at risk for decay and/or endodontics. Caries and endodontic failure of the abutment teeth are the most common causes of fixed prostheses failure. As much as 22 percent of the complications of an FPD are related to decay, and 15 percent of abutment teeth for a fixed restoration require endodontic therapy, compared with less than 6 percent of nonabutment teeth with a crown preparation.
Unfavorable outcomes of FPD failure include not only the need to replace the failed prosthesis, but also the loss of an abutment tooth and the need for additional tooth replacement. Since 20 percent of FPD complications are related to caries of abutment teeth (which can cause a structural failure), and 15 percent of FPD abutment teeth require endodontics (which may be 90 percent successful at the eight-year mark), and fracture of abutment teeth after endodontics is a four times higher risk than a single crown, many abutment teeth of a fixed prosthesis may be lost. Reports indicate 8 percent to 18 percent of the abutment teeth holding an FPD are lost within 10 years. The abutment teeth of an FPD may be lost at rates up to 30 percent for eight to 14 years. This is most disturbing, since 80 percent of abutment teeth have no previous decay or are minimally restored before the fabrication of the FPD.
Although posterior single-tooth replacement is a relatively new primary treatment alternative, more articles have been published on this option than for any other treatment alternative to replacing a missing tooth. If early reports are excluded, survival rates range from 95 percent to 100 percent for one to 10 years. For example, 10-year reports indicate the posterior single-tooth implant was more than 97 percent successful. In a 2007 study, Misch et al. reported a 99 percent survival rate (11 initial healing failures and three late failures) for 1,377 posterior single-tooth implants for as long as 10 years. Perhaps of more significance, no adjacent teeth to the implant crowns were lost from endodontic failure or caries, and few teeth required endodontic therapy or crown preparation after implant insertion. In a 2005 report by Misch et al., 276 anterior implant sites were followed for up to 15 years with 97 percent survival. A review of the literature by Goodacre et al. from 1981 to 2003 found single-tooth replacement with an implant had the highest implant prosthesis survival rate and averaged 97 percent survival. In a consensus statement, Salinas et al. reported pooled success for single-tooth restorations exceeded the success rate of traditional fixed partial dentures. These reports clearly identify that the adjacent teeth are least at risk when the missing tooth is replaced with an implant.
As a profit center, the restoration of one implant appears less productive than a three-unit fixed partial denture. However, the dentist is able to fabricate five implant crowns in the time it takes to prepare the teeth and make a transitional restoration for a three-unit prosthesis on natural teeth. Less abutment preparation time and the fact that a transitional prosthesis is not required when restoring teeth out of the esthetic zone allow much less chair time to restore the implant. After all, the patient rarely uses a transitional prosthesis in the esthetic zone while the implant is healing. As a consequence, the restoring dentist can generate more income when using implants as prosthetic abutments.
Another profit center for a general practice is related to the surgery for the insertion of the implant. Implant insertion surgery in the posterior regions of the mouth is easier than one-canal endodontic therapy. Preparing a round hole with a round shaped drill and obturating the hole with a round implant is much easier than preparing and obturating a tooth during endodontic therapy. Several dental schools now teach undergraduate dentists how to surgically place and restore a posterior, single-tooth implant. In fact, studies at Tufts and San Antonio dental schools demonstrated predoctoral dental students can place implants with a five-year survival rate of almost 100 percent.
It is safer to train a dental student in implant surgery than a natural tooth crown preparation. If a crown is overprepared or the pulp is encroached upon, it is a nonreversible procedure. If an implant site preparation is wrong, the doctor can stop the surgery and allow the site to heal for three months. During this timeframe, the bone fills the defect like a small extraction socket and the implant surgery may be reperformed without consequences. Since the undergraduate dentist has more experience at the revisit surgery, the risk of making the same mistake is less.
When a tooth requires extraction, the site may be prepared for an implant by socket grafting (also called ridge preservation). This relatively simple procedure takes less time than the extraction of the tooth. Since the fee is often equal to or greater than the extraction fee, it is also an income center for the dentist.
Most current practicing dentists — specialist and generalist — did not learn about implant surgery in their training or residency. It is important for anyone learning about implant surgery to have a supervised training program during their learning curve. This is necessary for both specialists and general dentists. Several programs are available to extend the training of the profession in a supervised, hands-on experience. Several dental schools and private institutes offer the same program for both specialists and generalists. For example, the Misch Implant Institute (cosponsored by Temple Dental School) has trained graduate residents from periodontics, oral surgery, endodontics, and prosthodontic programs in the fundamental and advanced concepts of implant surgery and bone grafting. This same program has trained more than 2,500 general dentists during the last 25 years.
Do not begin your implant surgical training by going to an implant meeting with 50 different lecturers, each presenting for 30 to 45 minutes. Each person shows his or her best cases, and very little knowledge is gained for the beginner in the field. The scientific material presented at these meetings is designed for experienced colleagues, who can separate the wheat from the chaff. Do not take an implant manufacturer"s one-day course. It is designed to sell you a product. These courses are best for experienced dentists who are changing the implant system they use and take manufacturers" courses to understand the subtle differences in one product compared to another.
Do get involved. Do take a structured course over an extended period. I suggest a program where one person does most of the lectures, in order to provide a consistent approach. When you first learn to cook, and you hear one person, you learn about a particular cuisine and style that works. If you are a beginner and hear one person talk about Chinese food, the next person presents Italian, the next person explains French cuisine, and the next person, Mexican — all in three days — you still can"t cook a meal.
Once you perform implant surgery and/or prosthetics in your practice, joining an implant organization allows you to be exposed to and develop current concepts for your patients. The largest implant organization composed primarily of general dentists around the world is the International Congress of Oral Implantologists (ICOI). More than 90 countries are represented in this organization, and at least five implant programs are held every year around the world at various times. Two of these meetings are always in the U.S. One meeting focuses on implant prosthetics, and the other on implant and bone graft surgery. Each portion of the meeting also has a practice management topic designed to help with case presentations of more than $10,000 to $20,000, or topics more unique to an implant practice.
The official publication of the ICOI, Implant Dentistry, is primarily directed at the general dentist and provides a wide range of current research, clinical studies, and techniques. The ICOI also has created a branch of the organization for laboratory technicians and staff members (receptionists, chairside assistants, and hygienists). There is a certifying program for doctors in the form of Fellowship, Mastership, and Diplomate. The ICOI Web sites, www.icoi.org or www.dentalimplants.com, have separate sections for patients and professionals. The ICOI can be reached for additional questions or membership at (888) 449-4294.
Editor's Note: References available upon request.
Carl E. Misch, BS, DDS, MDS, PhD (hc), is currently a clinical professor and director of oral implantology at Temple University School of Dentistry in the Department of Periodontology and Oral Implantology. Dr. Misch is a Fellow of 13 different societies, including the American College of Dentists and the International College of Dentists. In 1984, Dr. Misch founded the Misch International Implant Institute, which has locations in Michigan, Chicago, and California. As director, he has trained more than 3,500 doctors in this hands-on, yearly forum of education in implant dentistry. For more information, go to www.misch.com.