Of the first 100 patients treated in the Dental Education Seminars* implant courses, 47 were single tooth replacements. This mirrors the US experience where the single tooth implant is now the most commonly performed implant intervention.1
The implant-supported single tooth replacement in non-esthetic areas in the presence of adequate bone is predictable and comparatively simple. It is a good way to begin learning implant treatment. It is important to note, however, that in the esthetic area of the anterior maxilla, especially with a high lip line, the implant-supported single tooth replacement is the most challenging case the implant dentist faces.2-7 That is, the least difficult and the most difficult can appear to be misleadingly similar. As in all aspects of clinical dentistry, an accurate diagnosis with good treatment planning is critical.
Our patients want to know how much pain they can expect as a result of the treatment, how long treatment results will last and how much the treatment will cost. They also want to know what alternatives we can offer them. This paper compares the implant-supported crown to the other available choices for replacing a single missing tooth.
Addressing the issues of pain first, simple implant surgery is frequently less painful than the tooth extraction that necessitated it. Simple implant surgery refers to treatment not needing bone grafting with donor sites being away from the area being treated.
Extracting a tooth involves tearing the periodontal ligament–one of the most richly enervated tissues of the body. The primary source of post-surgical pain for implant patients is the manipulation of the periosteum. After a surgical flap is raised, simple implant treatment primarily consists of alveolectomy and osteotomy preparation. Both of these procedures take place in bone–one of the least enervated tissues of the body. The use of proven techniques for raising a flap together with the usual pharmacologic regimen will allow reliable pain control.
The simplest and the most economical choice for replacing a single missing tooth is the removable partial denture. It is the most widely used transitional measure during implant healing but is not a good choice otherwise. It is commonly accepted in dentistry that a fixed prosthesis, if it can be placed, is better than a removable one.8 Patients primarily select the removable partial denture for economic reasons.
The resin-bonded prosthesis is the second option. It is intermediate in cost between the removable partial denture and the fixed partial denture. Debonding is the most common cause of failure of the resin-bonded prosthesis. In carefully selected cases with long clinical crowns and a favorable occlusal relationship, debonding can be minimized.9 However, debonding occurs unexpectedly during function and can result in embarrassment for our patients. The resin-bonded prosthesis has been used as a transitional measure during implant healing. If diastemata are present, the resin-bonded prosthesis is not an option.
The third option is the fixed partial denture or the fixed bridge supported by natural teeth. The long-term prognosis for this prosthesis is well-documented8 and it is the standard against which implant treatment is frequently compared. Common causes of failure of such a restoration are decay of abutment teeth and endodontic problems.10,11 These occur more frequently with teeth serving as bridge abutment than with unrestored teeth.
Hygiene is a challenge with fixed bridge work and periodontal health of the abutment teeth may be at greater risk.
As with the resin-bonded prosthesis, if diastemata are present, the fixed prosthesis is not an option.
The literature now contains long-term single implant studies with success rates ranging from 100% over 6.6 years12 to 98% over 4 to 7 years13 to an earlier one showing a 91% success rate over 3 years.14 Others report similar findings. Survival rates for the three-unit fixed bridge option over seven to nine years have been reported to be 75%.8
It is interesting to note that in the United States, The Food and Drug Administration which regulates medical device sales in that country recently moved dental implants from the Class III medical device category to the far less rigorous pre-market notification (PNS) submission level. The FDA website (www.fda.gov/cdrh) will allow those interested to study current requirements.
Regulatory agencies in all countries are only concerned with the safety and effectiveness of the products they regulate and have no interest in their commercial prospects. These agencies have become more cautious over the years having faced the tragedy of Thalidomide, the Corning breast implant, the Vitek interpostional TMJ implant and others. Lowering the barriers for dental implant market entry by eliminating pre-clinical and clinical studies is a significant indication that these devices are entering the mainstream.
Thus the single tooth implant is a justified treatment option notwithstanding the clinical challenges involved. It allows for easier daily hygiene measures than the other options mentioned and decreases the risk of decay, pulpitis and periodontitis of adjacent teeth. Patients should be given this option.
All cases illustrated were treated with the Tenax Dental Implant System.
r. Milan Somborac is the co-inventor of The Tenax Dental Implant System. He has an interest in Tenax Implant Inc.
Oral Health welcomes this original article. All cases illustrated were treated with the Tenax Dental Implant System.
REFERENCES
1.Watson MT: Implant dentistry, a 10 year retrospective report. Dent Prod Rep Dec 25-32, 1996
2.Laney WR, Jemt T, Harris D, Henry P J, Krogh PHJ, Polizzi G, Zarb GA Herrmann I. Osseointegrated Implants for Single-Tooth Replacement: Progress Report From a Multicenter Prospective Study After 3 Years. Int J Oral Maxillofac Implants 1994;9:49-54. (Report on a 3-year cumulative success rate of 97.2%)
3.Asavanant S, Jameson LM, Hesby RA. Single osseointegrated prostheses. Int J Prosthodont 1988;1:291-296.
4.Jemt T. A 3-year follow-up study of early single implant restorations ad modum Brnemark. Int J Periodont Rest Dent 1990;10:340-349.
5.Schmitt A, Zarb GA. The longitudinal clinical effectiveness of osseointegrated dental implants for single-tooth replacement. Int J Prosthodont 1993;6:197-202.
6.Jemt T, Petterson P. A 3-year follow-up study on single implant treatment. J Dent Res 1993;21:203-208.
7.Jemt T, Laney WR, Harris D, Henry PJ, Krogh PHJ Jr, Polizzi G, Zarb GA, Herrmann I. Osseointegrated implants for single-tooth replacement: A 1-year report from a multicenter prospective study. Int J Oral Maxillofac Implants 1991
8.Schillingburg HT, Hobo S, Whitsett LD et al: Fundamentals of fixed prosthodontics, ed 3, Chicago, 1997, Quintessence
9.Hansson O:Clinical results with resin bonded prostheses and an adhesive cement, Quintessence Int 25:125-132, 1994
10.Cheung GSP, Dimmer A, Mellor R et al: A clinical evaluation of conventional bridgework, J Oral Rehabil 17:131-136
11.Walton JN, Gardner FM, Agar JR: A survey of crown and fixed partial denture failures, length of service and reasons for replacement, J Prosthet Dent 56:416-421, 1986
12.Jemt T, Lekholm U, Grondhal K: Three year follow up study of early single implant restorations ad modum Branemark, Int J Perio Rest Dent 10:340-349, 1990
13.Schmitt A, Zarb GA: The longitudinal clinical effectiveness of osseointegrated dental implants for single tooth replacement Int J Prosthodont 6:187-202, 1993
14.Ekfeldt A, Carlsson L, Borgesson G: Clinical evaluation of single tooth restorations supported by osseointegrated implants. A retrospective study, Int J Oral Maxillofac Impl 9(2):179-183, 1994
* Dental Education Seminars. A Division of Seminar Marketing Services of Don Mills, ON
