Observations of an Experienced Implant Practitioner

Figure 1. The i3D Smart (Vatech) is an example of a cone beam device on the lower end of the cost range that meets the needs of most general dentists, including planning implant placement. Several companies have similar models.

INTRODUCTION
About 35 years ago, I was invited by one of my oral surgeon colleagues to take a course with him at the Mayo Clinic that was taught by a person I had not yet had the opportunity to meet—Dr. Per-Ingvar Brånemark. We attended the course, and that simple 2-day course changed my life in dentistry. I went home enthused and immediately started placing and restoring root-form dental implants in our practice. With due respect to my oral surgeon friends, I soon found the need to place at least some of the implants myself to allow optimal parallelism and placement locations. Now, many years later, that course and its content seem prehistoric because so much has changed.

When I was asked to write this article, I thought that my experience over the years in placing and restoring implants would be worth sharing with you. Since all of you have computers and access to PubMed, Google Scholar, and Cochran, it seems futile for me to list an exhausting group of references that almost none of you will take the time to look up.

This article contains many short questions and answers that are my conclusions on each topic based on the available research and my observations as a “surgical” prosthodontist. I hope it will stimulate you to make conclusions based on your personal observations and research. By the way, that previous statement is one of the major suggestions made by the late Dr. David Sackett, who was one of the first medical practitioners to coin the phrase “evidence-based medicine.” He said, “Good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough. Without clinical expertise, practice risks become tyrannized by evidence, for even external evidence may be inapplicable to or inappropriate for an individual patient.”1

Importance of Implants
The US Census tells us that there are currently approximately 247 million adults (over 18 years of age) in the United States. The American College of Prosthodontists states that about 178 million adults are missing at least one tooth and about 40 million adults are edentulous.

The importance of knowledge about implants to the American people is extremely high. Those patients with missing teeth should have education about implants. It can be provided by hygienists, assistants, front desk personnel, dentists, and professional organizations. Almost every treatment plan that I present to patients with missing teeth has some involvement with implants. Many will accept implant placement and fixed or removable restorations once they know about the availability and the relative success of dental implants.

Figure 2. This cone beam image shows inadequate facial-lingual bone for conventional-diameter implants in the mandibular anterior area. Placement of small-diameter implants (2 mm diameter) and a removable prosthesis have now served this patient for several years. See Figure 4.

Placement of Implants
Most general dentists in the United States are not placing implants, which, in my opinion, is unfortunate. Estimates show that about 80% to 90% of implants placed are single implants, which will be the focus of this article. If more dentists would place implants, the American public would be more likely to have this highly successful procedure for themselves. According to surveys of GPs placing implants, placement of a single implant in a healthy person with adequate bone is considered approximately equal to the difficulty of a placing a moderate-sized Class II composite resin restoration. When well-educated and trained GPs place implants, they soon draw limits on the difficulty with which they are comfortable, and, as a result, they refer more. Everyone wins: the dentist, the specialist, and the patient.

And, when the dentist places an implant, he or she knows the bone density and has a much better ability to judge whether the implant should be loaded immediately or later.

Diagnosis and Treatment Planning Using CBCT
After personally using cone beam images for more than 19 years, I can strongly say that they are mandatory for planning and placing implants, whether using either free-hand placement or guided placement. With the cost of cone beam equipment ranging approximately from $60,000 to $150,000, many dentists cannot afford to have a device in their own office (Figure 1). Most geographic locations have imaging clinics available if purchasing this technology is not financially possible. I consider cone beam to be the No. 1 dental technology that dentists should be making plans to integrate into their practices.

What Size Implant?
The diameter and length of the implant should be directly related to the amount of bone present, allowing at least 1.0 mm of bone facial and lingual to the implant and the recommended space from vital structures and teeth. Grafting can alter that suggestion if the patient can afford the additional cost and extra time necessary for graft healing.

When implants were first introduced, much longer implants were most commonly used. They were mostly pure titanium, which was not nearly as strong as the current titanium-alloy implants. Now, the most sold and placed implant size is about 4.0-plus mm in diameter and about 10.0 to 12.0 mm long. Later, short (6 mm) and fat (6 mm) implants, and narrow-diameter implants 1.8 to 2.9 mm in diameter and an average of 13.0 mm long, were introduced. Although both categories were criticized initially by some groups, both diameters have been shown to serve very well when placed adequately. Companies not selling both small-diameter (1.8 to 2.9 mm) and conventional-diameter (3.0 mm and larger) implants need to seriously consider doing so to help avoid the now in vogue removal of bone height to facilitate placement of wider root-form implants (Figure 2).

What Age To Place an Implant?
When a child reaches a height approximately between the height of the father and mother, plus about 1 inch for the known increase in the height of adolescents now observed, implant placement is probably acceptable. Of course, if uncertain, evaluation of the epiphyseal plate (growth plate) can be done.

Figure 6. The “secret” to implant placement without a guide is simple: Go between the 2 adjacent teeth and in the middle of the ridge facial-lingual.	Figure 7. Although some condemn attaching natural teeth and implants, the procedure is occasionally necessary. This example, placed by me, served the patient from age 79 until his death at 94.

Which Is Best for Replacement of an Anterior Tooth: Implant or FPD?
From a longevity standpoint, both an implant and a fixed partial denture (FPD) are acceptable. If the teeth mesial and distal to the missing tooth need crowns, and if the patient is financially challenged, a fixed prosthesis is probably best. Furthermore, it may be more aesthetically acceptable than many of the implant-crown combinations that are being done. If adjacent teeth are intact, an implant is usually the best option unless the patient has a high lip-line, potentially making the implant-crown alternative aesthetically difficult (Figure 3).

Where in the Mouth Should Dentists First Begin Placing Implants?
The mandibular arch, from canine to canine, is the least complicated location to start placing implants. With a few exceptions, there are few anatomic features about which to be worried, and there is usually adequate bone in that location. I estimate that most general practices have at least 100 to 200 of their (on average) approximately 2,000 patients who are edentulous. They are waiting to have you educate them about implants and are likely hoping that you are able to successfully place and restore them. The most logical minimal implant procedure for a patient with an edentulous mandible is one implant in each canine area and either LOCATORs (Zest Dental Solutions) or a spherical abutment on each canine (or 4 small-diameter implants). This procedure is a significant, life-changing technique. Practical Clinical Courses has 4 levels of hands-on courses showing any interested dentist how to be able to place and restore implants, including more complicated cases than this example (Figure 4).

Should All Implants Be Placed Using Guides?
I have more than 30 years’ experience placing and restoring implants, one-half of which was done without CBCT and, therefore, without surgical guides. To say that all implants need to be inserted using guides is not a logical statement. Some multiple implant placements, and some placements in situations with minimal bone, can be more adequately accomplished with guides. Also, dentists just starting with implant placement may find that the use of guides facilitates their learning curves (Figures 5 and 6).

Figure 9. The use of separate abutments is dying. When the implant is placed perpendicular to the occlusal plane, a screw can easily be placed through a hole in the crown. If the screw comes loose during service, it can easily be removed, and the hole can be refilled with composite.	Figure 10. Leaving cement debris is proven to cause implant failure. Use highly radiopaque implant cement allowing removal of the crown if necessary.

Figure 11. This new classification of ceramic crowns will soon be commonly known. Thanks to Geoffrey Morris, of the ADA/International Organization for Standardization committee, for putting it together.

Figure 12. The LOCATOR F-Tx (Zest Dental Solutions) provides greater simplicity for edentulous fixed prostheses over implants because there are no screw holes in the prosthesis and removal is relatively easy.

When To Load an Implant?
Many research projects have been published on when to load an implant. Most state that early loading is both feasible and acceptable. My candid, historical clinical appraisal makes me a late loader unless I’m attempting to facilitate the repair of a major papilla development problem. Most patients have been without the tooth/teeth for a long time. Is there any problem waiting for another few months? My preference is to allow 4 months for integration.

Connecting Natural Teeth to Implants
This is not the preferred first choice, but it is often necessary due to finances, lack of bone, etc. There is no question that this works well if the following characteristics are present (Figure 7):

• The natural tooth is periodontally sound and non-mobile
• The implant is stable and appears to be healthy
• Both are parallel and have at least 4 mm of length from gingival margin to occlusal table
• The implant abutment, tooth preparation, and internal of the FPD receive horizontal diamond retentive grooves at seating
• Resin cement is used because high strength is needed

Over years of doing this technique, I have observed a nearly 100% success rate (Figure 7).

Which Is Best: Custom or Manufacturer Abutments?
If the implant is perpendicular to the occlusal plane, then stock, manufacturer-made abutments can be considered. However, either the dental technician or the dentist must take time to contour them. In polls of implant dentists, the majority (including me) use custom abutments most of the time, saving time and also making the abutment exactly to the contour desired (Figure 8).

Figure 14. Removable implant-supported prostheses have several important advantages over typical fixed prostheses for edentulous patients.	Figure 15. The LOCATOR R-Tx (Zest Dental Solutions) provides optimal retention and stability for a removable implant-supported prosthesis. If the bone is less adequate in quality or quantity, the Sterngold spherical abutment provides somewhat more flexibility for the prosthesis.

Are Screw-on, Separate Abutments a Thing of the Past?
Most dentists are now screwing the crown to the implant rather than using a separate abutment. If the implants are placed in appropriate locations, this is by far the best procedure. When a screw comes loose, it is a short appointment to remove the plug in the crown and the old screw, clean out the hole in the crown, place a new screw, and refill the access hole. Abutments are only needed if access to the implant screw hole compromises aesthetics or strength (Figures 8 and 9).

When Using Screw-on Abutments, Which Type Is Best?
Glidewell Laboratories has data on tens of thousands of abutments comparing the relative acceptability of the several types of abutments. As you might expect, titanium alloy is almost foolproof. Although zirconia and hybrid (zirconia with a metal base) abutments have a few more failures than metal alone, both are acceptable abutments with proper planning.

Should Implant Cement Be Provisional or Final?
The topic of implant cement is somewhat controversial. I have polled large groups of dentists in CE courses, and almost everyone has had, and continues to have, abutment screws come loose. Provisional cements appear to be most logical to me. The implant cement Retrieve DC (Parkell), now with increased radiopacity, was recently designated as a Clinicians Report “CR Choice” in tests by Clinicians Report Foundation. It allows the relatively easy removal of a crown from a loose abutment and is radiopaque enough to provide the observation of remaining excess cement (Figure 10).

Should Impressions Be Conventional or Digital?
This decision depends on the availability of a scanner and your competency with each technology. Both are adequate, but digital impressions are only used about 20% of the time, according to labs. Nevertheless, digital will gradually dominate in the years to come.

What Type of Crown Material Is Best Over Single Implants?
Class 5 (tetragonal) zirconia is practically fail-proof but must be adjusted very carefully to avoid traumatizing the implant(s) and to prevent undue wear of the opposing tooth/teeth. PFM restorations with noble metal substructures are also well-proven. The Class 4 “aesthetic” zirconia materials still require a few more years of clinical observation for full acceptance. Class 3 lithium disilicate (such as IPS e.max [Ivoclar Vivadent]) has wonderful aesthetics but should be used with a bit more caution in bruxers. See Figure 11 for more.

Are Fixed or Removable Prostheses Better for Edentulous Patients?
The impressive current advertisements for fixed prostheses for edentulous patients may make patients feel that fixed is always better. The LOCATOR F-Tx abutment (Zest Dental Solutions) has made these fixed restorations much easier to use because there are no holes in the prosthesis. This concept has made these prostheses much less time consuming to place, remove, and repair. But how do they compare with removable prostheses over implants (Figure 12)?
What are the advantages of fixed prostheses (Figure 13)?

• They do not require removal daily
• They can feel similar to natural teeth
• They do not move during eating
• They provide a boost to patient self-esteem

What are the advantages of a removable prosthesis retained and stabilized by implants (Figure 14)?

• Aesthetics acceptability of removable prostheses can be and usually is superior to fixed because normal facial anatomy can be produced
• Oral hygiene is much easier than fixed
• Repair is not complicated
• Cost is significantly less than fixed prostheses
• Implants can be maintained more easily
• They do not usually require removal of bone

I have placed many “all-on-whatever-number of implants” for more than 30 years, and most have served quite well. Some patients have had oral hygiene problems, bad breath, breakage, facial and lip collapse, lisping, and implant failure. For some of my problem cases, I have changed from fixed prostheses to removable prostheses due to various fixed maladies. Afterward, patients often asked me, “Why didn’t you do that in the first place?”

Removable edentulous prostheses over implants, with LOCATOR R-Tx (Zest Dental Solutions) or spherical abutments (such as Sterngold), are excellent restorations for edentulous patients (Figure 15).

Should We Be Concerned About the Now-Proven Peri-mucocitis and Peri-implantitis Problems?
These problems are now extremely perplexing. I have attempted to determine why we are now seeing these challenges. I can name many potential factors/reasons, including metal allergies, oral hygiene, previous periodontal disease, occlusion, angulation of implants, improper placement, immune response, diet, poor bone, too early loading, and on and on. The seriousness of this problem brings us back to the historical success of conventional dentistry and my long-time mantra that there is nothing like a tooth. In my strong opinion, we should be teaching and promoting prevention and the proper restoration of teeth when indicated and using implants as the last resort!

CLOSING COMMENTS
Implants are the most significant innovation in my long career in dentistry. There is still much to learn and know about dental implants. The many topics included in this article are to assist you in making your own decisions and conclusions based upon available research and augmented with clinical observations. Implants are a fantastic service when needed and if placed and restored properly.

References

1. Sackett DL, Rosenberg WM, Gray JA, et al. Evidence based medicine: what it is and what it isn’t. BMJ. 1996;312:71-72.

Dr. Christensen is founder and CEO of Practical Clinical Courses (PCC); CEO of Clinicians Report Foundation (CR Foundation); and a practicing prosthodontist in Provo, Utah. He and Dr. Rella Christensen are cofounders of the non-profit CR Foundation (previously Clinical Research Associates [CRA]). Since 1976, they have conducted research in all areas of dentistry and published the findings to the profession in the well-known CRA Newsletter, now called Clinicians Report. Dr. Christensen received his DDS degree from the University of Southern California, his MSD from the University of Washington, and his PhD from the University of Denver and has received 2 honorary doctorates. Early in his career, he helped initiate the University of Kentucky and University of Colorado dental schools, taught at the University of Washington, and was the original dean of the Scottsdale Center. Currently, he is an adjunct professor at the University of Utah School of Dentistry. He is a member of numerous professional organizations. He can be reached at info@pccdental.com.

Disclosure: Dr. Christensen reports no disclosures.

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